Merge branch 'feat/tagfunc'

[vim_extended.git] / src / memline.c

/* vi:set ts=8 sts=4 sw=4:
 *
 * VIM - Vi IMproved    by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/* for debugging */
/* #define CHECK(c, s)  if (c) EMSG(s) */
#define CHECK(c, s)

/*
 * memline.c: Contains the functions for appending, deleting and changing the
 * text lines. The memfile functions are used to store the information in
 * blocks of memory, backed up by a file. The structure of the information is
 * a tree.  The root of the tree is a pointer block. The leaves of the tree
 * are data blocks. In between may be several layers of pointer blocks,
 * forming branches.
 *
 * Three types of blocks are used:
 * - Block nr 0 contains information for recovery
 * - Pointer blocks contain list of pointers to other blocks.
 * - Data blocks contain the actual text.
 *
 * Block nr 0 contains the block0 structure (see below).
 *
 * Block nr 1 is the first pointer block. It is the root of the tree.
 * Other pointer blocks are branches.
 *
 *  If a line is too big to fit in a single page, the block containing that
 *  line is made big enough to hold the line. It may span several pages.
 *  Otherwise all blocks are one page.
 *
 *  A data block that was filled when starting to edit a file and was not
 *  changed since then, can have a negative block number. This means that it
 *  has not yet been assigned a place in the file. When recovering, the lines
 *  in this data block can be read from the original file. When the block is
 *  changed (lines appended/deleted/changed) or when it is flushed it gets a
 *  positive number. Use mf_trans_del() to get the new number, before calling
 *  mf_get().
 */

#if defined(MSDOS) || defined(WIN16) || defined(WIN32) || defined(_WIN64)
# include "vimio.h"     /* for mch_open(), must be before vim.h */
#endif

#include "vim.h"

#ifndef UNIX            /* it's in os_unix.h for Unix */
# include <time.h>
#endif

#if defined(SASC) || defined(__amigaos4__)
# include <proto/dos.h>     /* for Open() and Close() */
#endif

#ifdef HAVE_ERRNO_H
# include <errno.h>
#endif

typedef struct block0           ZERO_BL;    /* contents of the first block */
typedef struct pointer_block    PTR_BL;     /* contents of a pointer block */
typedef struct data_block       DATA_BL;    /* contents of a data block */
typedef struct pointer_entry    PTR_EN;     /* block/line-count pair */

#define DATA_ID     (('d' << 8) + 'a')      /* data block id */
#define PTR_ID      (('p' << 8) + 't')      /* pointer block id */
#define BLOCK0_ID0  'b'                     /* block 0 id 0 */
#define BLOCK0_ID1  '0'                     /* block 0 id 1 */

/*
 * pointer to a block, used in a pointer block
 */
struct pointer_entry
{
    blocknr_T   pe_bnum;        /* block number */
    linenr_T    pe_line_count;  /* number of lines in this branch */
    linenr_T    pe_old_lnum;    /* lnum for this block (for recovery) */
    int         pe_page_count;  /* number of pages in block pe_bnum */
};

/*
 * A pointer block contains a list of branches in the tree.
 */
struct pointer_block
{
    short_u     pb_id;          /* ID for pointer block: PTR_ID */
    short_u     pb_count;       /* number of pointer in this block */
    short_u     pb_count_max;   /* maximum value for pb_count */
    PTR_EN      pb_pointer[1];  /* list of pointers to blocks (actually longer)
                                 * followed by empty space until end of page */
};

/*
 * A data block is a leaf in the tree.
 *
 * The text of the lines is at the end of the block. The text of the first line
 * in the block is put at the end, the text of the second line in front of it,
 * etc. Thus the order of the lines is the opposite of the line number.
 */
struct data_block
{
    short_u     db_id;          /* ID for data block: DATA_ID */
    unsigned    db_free;        /* free space available */
    unsigned    db_txt_start;   /* byte where text starts */
    unsigned    db_txt_end;     /* byte just after data block */
    linenr_T    db_line_count;  /* number of lines in this block */
    unsigned    db_index[1];    /* index for start of line (actually bigger)
                                 * followed by empty space upto db_txt_start
                                 * followed by the text in the lines until
                                 * end of page */
};

/*
 * The low bits of db_index hold the actual index. The topmost bit is
 * used for the global command to be able to mark a line.
 * This method is not clean, but otherwise there would be at least one extra
 * byte used for each line.
 * The mark has to be in this place to keep it with the correct line when other
 * lines are inserted or deleted.
 */
#define DB_MARKED       ((unsigned)1 << ((sizeof(unsigned) * 8) - 1))
#define DB_INDEX_MASK   (~DB_MARKED)

#define INDEX_SIZE  (sizeof(unsigned))      /* size of one db_index entry */
#define HEADER_SIZE (sizeof(DATA_BL) - INDEX_SIZE)  /* size of data block header */

#define B0_FNAME_SIZE_ORG       900     /* what it was in older versions */
#define B0_FNAME_SIZE           898
#define B0_UNAME_SIZE           40
#define B0_HNAME_SIZE           40
/*
 * Restrict the numbers to 32 bits, otherwise most compilers will complain.
 * This won't detect a 64 bit machine that only swaps a byte in the top 32
 * bits, but that is crazy anyway.
 */
#define B0_MAGIC_LONG   0x30313233L
#define B0_MAGIC_INT    0x20212223L
#define B0_MAGIC_SHORT  0x10111213L
#define B0_MAGIC_CHAR   0x55

/*
 * Block zero holds all info about the swap file.
 *
 * NOTE: DEFINITION OF BLOCK 0 SHOULD NOT CHANGE! It would make all existing
 * swap files unusable!
 *
 * If size of block0 changes anyway, adjust MIN_SWAP_PAGE_SIZE in vim.h!!
 *
 * This block is built up of single bytes, to make it portable across
 * different machines. b0_magic_* is used to check the byte order and size of
 * variables, because the rest of the swap file is not portable.
 */
struct block0
{
    char_u      b0_id[2];       /* id for block 0: BLOCK0_ID0 and BLOCK0_ID1 */
    char_u      b0_version[10]; /* Vim version string */
    char_u      b0_page_size[4];/* number of bytes per page */
    char_u      b0_mtime[4];    /* last modification time of file */
    char_u      b0_ino[4];      /* inode of b0_fname */
    char_u      b0_pid[4];      /* process id of creator (or 0) */
    char_u      b0_uname[B0_UNAME_SIZE]; /* name of user (uid if no name) */
    char_u      b0_hname[B0_HNAME_SIZE]; /* host name (if it has a name) */
    char_u      b0_fname[B0_FNAME_SIZE_ORG]; /* name of file being edited */
    long        b0_magic_long;  /* check for byte order of long */
    int         b0_magic_int;   /* check for byte order of int */
    short       b0_magic_short; /* check for byte order of short */
    char_u      b0_magic_char;  /* check for last char */
};

/*
 * Note: b0_dirty and b0_flags are put at the end of the file name.  For very
 * long file names in older versions of Vim they are invalid.
 * The 'fileencoding' comes before b0_flags, with a NUL in front.  But only
 * when there is room, for very long file names it's omitted.
 */
#define B0_DIRTY        0x55
#define b0_dirty        b0_fname[B0_FNAME_SIZE_ORG-1]

/*
 * The b0_flags field is new in Vim 7.0.
 */
#define b0_flags        b0_fname[B0_FNAME_SIZE_ORG-2]

/* The lowest two bits contain the fileformat.  Zero means it's not set
 * (compatible with Vim 6.x), otherwise it's EOL_UNIX + 1, EOL_DOS + 1 or
 * EOL_MAC + 1. */
#define B0_FF_MASK      3

/* Swap file is in directory of edited file.  Used to find the file from
 * different mount points. */
#define B0_SAME_DIR     4

/* The 'fileencoding' is at the end of b0_fname[], with a NUL in front of it.
 * When empty there is only the NUL. */
#define B0_HAS_FENC     8

#define STACK_INCR      5       /* nr of entries added to ml_stack at a time */

/*
 * The line number where the first mark may be is remembered.
 * If it is 0 there are no marks at all.
 * (always used for the current buffer only, no buffer change possible while
 * executing a global command).
 */
static linenr_T lowest_marked = 0;

/*
 * arguments for ml_find_line()
 */
#define ML_DELETE       0x11        /* delete line */
#define ML_INSERT       0x12        /* insert line */
#define ML_FIND         0x13        /* just find the line */
#define ML_FLUSH        0x02        /* flush locked block */
#define ML_SIMPLE(x)    (x & 0x10)  /* DEL, INS or FIND */

static void ml_upd_block0 __ARGS((buf_T *buf, int set_fname));
static void set_b0_fname __ARGS((ZERO_BL *, buf_T *buf));
static void set_b0_dir_flag __ARGS((ZERO_BL *b0p, buf_T *buf));
#ifdef FEAT_MBYTE
static void add_b0_fenc __ARGS((ZERO_BL *b0p, buf_T *buf));
#endif
static time_t swapfile_info __ARGS((char_u *));
static int recov_file_names __ARGS((char_u **, char_u *, int prepend_dot));
static int ml_append_int __ARGS((buf_T *, linenr_T, char_u *, colnr_T, int, int));
static int ml_delete_int __ARGS((buf_T *, linenr_T, int));
static char_u *findswapname __ARGS((buf_T *, char_u **, char_u *));
static void ml_flush_line __ARGS((buf_T *));
static bhdr_T *ml_new_data __ARGS((memfile_T *, int, int));
static bhdr_T *ml_new_ptr __ARGS((memfile_T *));
static bhdr_T *ml_find_line __ARGS((buf_T *, linenr_T, int));
static int ml_add_stack __ARGS((buf_T *));
static void ml_lineadd __ARGS((buf_T *, int));
static int b0_magic_wrong __ARGS((ZERO_BL *));
#ifdef CHECK_INODE
static int fnamecmp_ino __ARGS((char_u *, char_u *, long));
#endif
static void long_to_char __ARGS((long, char_u *));
static long char_to_long __ARGS((char_u *));
#if defined(UNIX) || defined(WIN3264)
static char_u *make_percent_swname __ARGS((char_u *dir, char_u *name));
#endif
#ifdef FEAT_BYTEOFF
static void ml_updatechunk __ARGS((buf_T *buf, long line, long len, int updtype));
#endif
#ifdef HAVE_READLINK
static int resolve_symlink __ARGS((char_u *fname, char_u *buf));
#endif

/*
 * Open a new memline for "buf".
 *
 * Return FAIL for failure, OK otherwise.
 */
    int
ml_open(buf)
    buf_T       *buf;
{
    memfile_T   *mfp;
    bhdr_T      *hp = NULL;
    ZERO_BL     *b0p;
    PTR_BL      *pp;
    DATA_BL     *dp;

    /*
     * init fields in memline struct
     */
    buf->b_ml.ml_stack_size = 0;        /* no stack yet */
    buf->b_ml.ml_stack = NULL;  /* no stack yet */
    buf->b_ml.ml_stack_top = 0; /* nothing in the stack */
    buf->b_ml.ml_locked = NULL; /* no cached block */
    buf->b_ml.ml_line_lnum = 0; /* no cached line */
#ifdef FEAT_BYTEOFF
    buf->b_ml.ml_chunksize = NULL;
#endif

    /*
     * When 'updatecount' is non-zero swap file may be opened later.
     */
    if (p_uc && buf->b_p_swf)
        buf->b_may_swap = TRUE;
    else
        buf->b_may_swap = FALSE;

    /*
     * Open the memfile.  No swap file is created yet.
     */
    mfp = mf_open(NULL, 0);
    if (mfp == NULL)
        goto error;

    buf->b_ml.ml_mfp = mfp;
    buf->b_ml.ml_flags = ML_EMPTY;
    buf->b_ml.ml_line_max = 0;
    buf->b_ml.ml_line_count = 1;
#ifdef FEAT_LINEBREAK
    curwin->w_nrwidth_line_count = 0;
#endif

#if defined(MSDOS) && !defined(DJGPP)
    /* for 16 bit MS-DOS create a swapfile now, because we run out of
     * memory very quickly */
    if (p_uc != 0)
        ml_open_file(buf);
#endif

/*
 * fill block0 struct and write page 0
 */
    if ((hp = mf_new(mfp, FALSE, 1)) == NULL)
        goto error;
    if (hp->bh_bnum != 0)
    {
        EMSG(_("E298: Didn't get block nr 0?"));
        goto error;
    }
    b0p = (ZERO_BL *)(hp->bh_data);

    b0p->b0_id[0] = BLOCK0_ID0;
    b0p->b0_id[1] = BLOCK0_ID1;
    b0p->b0_magic_long = (long)B0_MAGIC_LONG;
    b0p->b0_magic_int = (int)B0_MAGIC_INT;
    b0p->b0_magic_short = (short)B0_MAGIC_SHORT;
    b0p->b0_magic_char = B0_MAGIC_CHAR;
    STRNCPY(b0p->b0_version, "VIM ", 4);
    STRNCPY(b0p->b0_version + 4, Version, 6);
    long_to_char((long)mfp->mf_page_size, b0p->b0_page_size);

#ifdef FEAT_SPELL
    if (!buf->b_spell)
#endif
    {
        b0p->b0_dirty = buf->b_changed ? B0_DIRTY : 0;
        b0p->b0_flags = get_fileformat(buf) + 1;
        set_b0_fname(b0p, buf);
        (void)get_user_name(b0p->b0_uname, B0_UNAME_SIZE);
        b0p->b0_uname[B0_UNAME_SIZE - 1] = NUL;
        mch_get_host_name(b0p->b0_hname, B0_HNAME_SIZE);
        b0p->b0_hname[B0_HNAME_SIZE - 1] = NUL;
        long_to_char(mch_get_pid(), b0p->b0_pid);
    }

    /*
     * Always sync block number 0 to disk, so we can check the file name in
     * the swap file in findswapname(). Don't do this for help files though
     * and spell buffer though.
     * Only works when there's a swapfile, otherwise it's done when the file
     * is created.
     */
    mf_put(mfp, hp, TRUE, FALSE);
    if (!buf->b_help && !B_SPELL(buf))
        (void)mf_sync(mfp, 0);

    /*
     * Fill in root pointer block and write page 1.
     */
    if ((hp = ml_new_ptr(mfp)) == NULL)
        goto error;
    if (hp->bh_bnum != 1)
    {
        EMSG(_("E298: Didn't get block nr 1?"));
        goto error;
    }
    pp = (PTR_BL *)(hp->bh_data);
    pp->pb_count = 1;
    pp->pb_pointer[0].pe_bnum = 2;
    pp->pb_pointer[0].pe_page_count = 1;
    pp->pb_pointer[0].pe_old_lnum = 1;
    pp->pb_pointer[0].pe_line_count = 1;    /* line count after insertion */
    mf_put(mfp, hp, TRUE, FALSE);

    /*
     * Allocate first data block and create an empty line 1.
     */
    if ((hp = ml_new_data(mfp, FALSE, 1)) == NULL)
        goto error;
    if (hp->bh_bnum != 2)
    {
        EMSG(_("E298: Didn't get block nr 2?"));
        goto error;
    }

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_index[0] = --dp->db_txt_start;       /* at end of block */
    dp->db_free -= 1 + INDEX_SIZE;
    dp->db_line_count = 1;
    *((char_u *)dp + dp->db_txt_start) = NUL;   /* empty line */

    return OK;

error:
    if (mfp != NULL)
    {
        if (hp)
            mf_put(mfp, hp, FALSE, FALSE);
        mf_close(mfp, TRUE);        /* will also free(mfp->mf_fname) */
    }
    buf->b_ml.ml_mfp = NULL;
    return FAIL;
}

/*
 * ml_setname() is called when the file name of "buf" has been changed.
 * It may rename the swap file.
 */
    void
ml_setname(buf)
    buf_T       *buf;
{
    int         success = FALSE;
    memfile_T   *mfp;
    char_u      *fname;
    char_u      *dirp;
#if defined(MSDOS) || defined(MSWIN)
    char_u      *p;
#endif

    mfp = buf->b_ml.ml_mfp;
    if (mfp->mf_fd < 0)             /* there is no swap file yet */
    {
        /*
         * When 'updatecount' is 0 and 'noswapfile' there is no swap file.
         * For help files we will make a swap file now.
         */
        if (p_uc != 0)
            ml_open_file(buf);      /* create a swap file */
        return;
    }

    /*
     * Try all directories in the 'directory' option.
     */
    dirp = p_dir;
    for (;;)
    {
        if (*dirp == NUL)           /* tried all directories, fail */
            break;
        fname = findswapname(buf, &dirp, mfp->mf_fname);
                                                    /* alloc's fname */
        if (fname == NULL)          /* no file name found for this dir */
            continue;

#if defined(MSDOS) || defined(MSWIN)
        /*
         * Set full pathname for swap file now, because a ":!cd dir" may
         * change directory without us knowing it.
         */
        p = FullName_save(fname, FALSE);
        vim_free(fname);
        fname = p;
        if (fname == NULL)
            continue;
#endif
        /* if the file name is the same we don't have to do anything */
        if (fnamecmp(fname, mfp->mf_fname) == 0)
        {
            vim_free(fname);
            success = TRUE;
            break;
        }
        /* need to close the swap file before renaming */
        if (mfp->mf_fd >= 0)
        {
            close(mfp->mf_fd);
            mfp->mf_fd = -1;
        }

        /* try to rename the swap file */
        if (vim_rename(mfp->mf_fname, fname) == 0)
        {
            success = TRUE;
            vim_free(mfp->mf_fname);
            mfp->mf_fname = fname;
            vim_free(mfp->mf_ffname);
#if defined(MSDOS) || defined(MSWIN)
            mfp->mf_ffname = NULL;  /* mf_fname is full pathname already */
#else
            mf_set_ffname(mfp);
#endif
            ml_upd_block0(buf, FALSE);
            break;
        }
        vim_free(fname);            /* this fname didn't work, try another */
    }

    if (mfp->mf_fd == -1)           /* need to (re)open the swap file */
    {
        mfp->mf_fd = mch_open((char *)mfp->mf_fname, O_RDWR | O_EXTRA, 0);
        if (mfp->mf_fd < 0)
        {
            /* could not (re)open the swap file, what can we do???? */
            EMSG(_("E301: Oops, lost the swap file!!!"));
            return;
        }
#ifdef HAVE_FD_CLOEXEC
        {
            int fdflags = fcntl(mfp->mf_fd, F_GETFD);
            if (fdflags >= 0 && (fdflags & FD_CLOEXEC) == 0)
                fcntl(mfp->mf_fd, F_SETFD, fdflags | FD_CLOEXEC);
        }
#endif
    }
    if (!success)
        EMSG(_("E302: Could not rename swap file"));
}

/*
 * Open a file for the memfile for all buffers that are not readonly or have
 * been modified.
 * Used when 'updatecount' changes from zero to non-zero.
 */
    void
ml_open_files()
{
    buf_T       *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
        if (!buf->b_p_ro || buf->b_changed)
            ml_open_file(buf);
}

/*
 * Open a swap file for an existing memfile, if there is no swap file yet.
 * If we are unable to find a file name, mf_fname will be NULL
 * and the memfile will be in memory only (no recovery possible).
 */
    void
ml_open_file(buf)
    buf_T       *buf;
{
    memfile_T   *mfp;
    char_u      *fname;
    char_u      *dirp;

    mfp = buf->b_ml.ml_mfp;
    if (mfp == NULL || mfp->mf_fd >= 0 || !buf->b_p_swf)
        return;         /* nothing to do */

#ifdef FEAT_SPELL
    /* For a spell buffer use a temp file name. */
    if (buf->b_spell)
    {
        fname = vim_tempname('s');
        if (fname != NULL)
            (void)mf_open_file(mfp, fname);     /* consumes fname! */
        buf->b_may_swap = FALSE;
        return;
    }
#endif

    /*
     * Try all directories in 'directory' option.
     */
    dirp = p_dir;
    for (;;)
    {
        if (*dirp == NUL)
            break;
        /* There is a small chance that between chosing the swap file name and
         * creating it, another Vim creates the file.  In that case the
         * creation will fail and we will use another directory. */
        fname = findswapname(buf, &dirp, NULL); /* allocates fname */
        if (fname == NULL)
            continue;
        if (mf_open_file(mfp, fname) == OK)     /* consumes fname! */
        {
#if defined(MSDOS) || defined(MSWIN) || defined(RISCOS)
            /*
             * set full pathname for swap file now, because a ":!cd dir" may
             * change directory without us knowing it.
             */
            mf_fullname(mfp);
#endif
            ml_upd_block0(buf, FALSE);

            /* Flush block zero, so others can read it */
            if (mf_sync(mfp, MFS_ZERO) == OK)
            {
                /* Mark all blocks that should be in the swapfile as dirty.
                 * Needed for when the 'swapfile' option was reset, so that
                 * the swap file was deleted, and then on again. */
                mf_set_dirty(mfp);
                break;
            }
            /* Writing block 0 failed: close the file and try another dir */
            mf_close_file(buf, FALSE);
        }
    }

    if (mfp->mf_fname == NULL)          /* Failed! */
    {
        char_u *bname = (char_u *)buf_spname(buf);
        need_wait_return = TRUE;        /* call wait_return later */
        ++no_wait_return;
        (void)EMSG2(_("E303: Unable to open swap file for \"%s\", recovery impossible"),
                    bname
                        ? bname
                        : buf->b_fname);
        vim_free(bname);
        --no_wait_return;
    }

    /* don't try to open a swap file again */
    buf->b_may_swap = FALSE;
}

/*
 * If still need to create a swap file, and starting to edit a not-readonly
 * file, or reading into an existing buffer, create a swap file now.
 */
    void
check_need_swap(newfile)
    int     newfile;            /* reading file into new buffer */
{
    if (curbuf->b_may_swap && (!curbuf->b_p_ro || !newfile))
        ml_open_file(curbuf);
}

/*
 * Close memline for buffer 'buf'.
 * If 'del_file' is TRUE, delete the swap file
 */
    void
ml_close(buf, del_file)
    buf_T       *buf;
    int         del_file;
{
    if (buf->b_ml.ml_mfp == NULL)               /* not open */
        return;
    mf_close(buf->b_ml.ml_mfp, del_file);       /* close the .swp file */
    if (buf->b_ml.ml_line_lnum != 0 && (buf->b_ml.ml_flags & ML_LINE_DIRTY))
        vim_free(buf->b_ml.ml_line_ptr);
    vim_free(buf->b_ml.ml_stack);
#ifdef FEAT_BYTEOFF
    vim_free(buf->b_ml.ml_chunksize);
    buf->b_ml.ml_chunksize = NULL;
#endif
    buf->b_ml.ml_mfp = NULL;

    /* Reset the "recovered" flag, give the ATTENTION prompt the next time
     * this buffer is loaded. */
    buf->b_flags &= ~BF_RECOVERED;
}

/*
 * Close all existing memlines and memfiles.
 * Only used when exiting.
 * When 'del_file' is TRUE, delete the memfiles.
 * But don't delete files that were ":preserve"d when we are POSIX compatible.
 */
    void
ml_close_all(del_file)
    int         del_file;
{
    buf_T       *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
        ml_close(buf, del_file && ((buf->b_flags & BF_PRESERVED) == 0
                                 || vim_strchr(p_cpo, CPO_PRESERVE) == NULL));
#ifdef TEMPDIRNAMES
    vim_deltempdir();       /* delete created temp directory */
#endif
}

/*
 * Close all memfiles for not modified buffers.
 * Only use just before exiting!
 */
    void
ml_close_notmod()
{
    buf_T       *buf;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
        if (!bufIsChanged(buf))
            ml_close(buf, TRUE);    /* close all not-modified buffers */
}

/*
 * Update the timestamp in the .swp file.
 * Used when the file has been written.
 */
    void
ml_timestamp(buf)
    buf_T       *buf;
{
    ml_upd_block0(buf, TRUE);
}

/*
 * Update the timestamp or the B0_SAME_DIR flag of the .swp file.
 */
    static void
ml_upd_block0(buf, set_fname)
    buf_T       *buf;
    int         set_fname;
{
    memfile_T   *mfp;
    bhdr_T      *hp;
    ZERO_BL     *b0p;

    mfp = buf->b_ml.ml_mfp;
    if (mfp == NULL || (hp = mf_get(mfp, (blocknr_T)0, 1)) == NULL)
        return;
    b0p = (ZERO_BL *)(hp->bh_data);
    if (b0p->b0_id[0] != BLOCK0_ID0 || b0p->b0_id[1] != BLOCK0_ID1)
        EMSG(_("E304: ml_upd_block0(): Didn't get block 0??"));
    else
    {
        if (set_fname)
            set_b0_fname(b0p, buf);
        else
            set_b0_dir_flag(b0p, buf);
    }
    mf_put(mfp, hp, TRUE, FALSE);
}

/*
 * Write file name and timestamp into block 0 of a swap file.
 * Also set buf->b_mtime.
 * Don't use NameBuff[]!!!
 */
    static void
set_b0_fname(b0p, buf)
    ZERO_BL     *b0p;
    buf_T       *buf;
{
    struct stat st;

    if (buf->b_ffname == NULL)
        b0p->b0_fname[0] = NUL;
    else
    {
#if defined(MSDOS) || defined(MSWIN) || defined(AMIGA) || defined(RISCOS)
        /* Systems that cannot translate "~user" back into a path: copy the
         * file name unmodified.  Do use slashes instead of backslashes for
         * portability. */
        vim_strncpy(b0p->b0_fname, buf->b_ffname, B0_FNAME_SIZE - 1);
# ifdef BACKSLASH_IN_FILENAME
        forward_slash(b0p->b0_fname);
# endif
#else
        size_t  flen, ulen;
        char_u  uname[B0_UNAME_SIZE];

        /*
         * For a file under the home directory of the current user, we try to
         * replace the home directory path with "~user". This helps when
         * editing the same file on different machines over a network.
         * First replace home dir path with "~/" with home_replace().
         * Then insert the user name to get "~user/".
         */
        home_replace(NULL, buf->b_ffname, b0p->b0_fname, B0_FNAME_SIZE, TRUE);
        if (b0p->b0_fname[0] == '~')
        {
            flen = STRLEN(b0p->b0_fname);
            /* If there is no user name or it is too long, don't use "~/" */
            if (get_user_name(uname, B0_UNAME_SIZE) == FAIL
                         || (ulen = STRLEN(uname)) + flen > B0_FNAME_SIZE - 1)
                vim_strncpy(b0p->b0_fname, buf->b_ffname, B0_FNAME_SIZE - 1);
            else
            {
                mch_memmove(b0p->b0_fname + ulen + 1, b0p->b0_fname + 1, flen);
                mch_memmove(b0p->b0_fname + 1, uname, ulen);
            }
        }
#endif
        if (mch_stat((char *)buf->b_ffname, &st) >= 0)
        {
            long_to_char((long)st.st_mtime, b0p->b0_mtime);
#ifdef CHECK_INODE
            long_to_char((long)st.st_ino, b0p->b0_ino);
#endif
            buf_store_time(buf, &st, buf->b_ffname);
            buf->b_mtime_read = buf->b_mtime;
        }
        else
        {
            long_to_char(0L, b0p->b0_mtime);
#ifdef CHECK_INODE
            long_to_char(0L, b0p->b0_ino);
#endif
            buf->b_mtime = 0;
            buf->b_mtime_read = 0;
            buf->b_orig_size = 0;
            buf->b_orig_mode = 0;
        }
    }

#ifdef FEAT_MBYTE
    /* Also add the 'fileencoding' if there is room. */
    add_b0_fenc(b0p, curbuf);
#endif
}

/*
 * Update the B0_SAME_DIR flag of the swap file.  It's set if the file and the
 * swapfile for "buf" are in the same directory.
 * This is fail safe: if we are not sure the directories are equal the flag is
 * not set.
 */
    static void
set_b0_dir_flag(b0p, buf)
    ZERO_BL     *b0p;
    buf_T       *buf;
{
    if (same_directory(buf->b_ml.ml_mfp->mf_fname, buf->b_ffname))
        b0p->b0_flags |= B0_SAME_DIR;
    else
        b0p->b0_flags &= ~B0_SAME_DIR;
}

#ifdef FEAT_MBYTE
/*
 * When there is room, add the 'fileencoding' to block zero.
 */
    static void
add_b0_fenc(b0p, buf)
    ZERO_BL     *b0p;
    buf_T       *buf;
{
    int         n;

    n = (int)STRLEN(buf->b_p_fenc);
    if (STRLEN(b0p->b0_fname) + n + 1 > B0_FNAME_SIZE)
        b0p->b0_flags &= ~B0_HAS_FENC;
    else
    {
        mch_memmove((char *)b0p->b0_fname + B0_FNAME_SIZE - n,
                                            (char *)buf->b_p_fenc, (size_t)n);
        *(b0p->b0_fname + B0_FNAME_SIZE - n - 1) = NUL;
        b0p->b0_flags |= B0_HAS_FENC;
    }
}
#endif


/*
 * try to recover curbuf from the .swp file
 */
    void
ml_recover()
{
    buf_T       *buf = NULL;
    memfile_T   *mfp = NULL;
    char_u      *fname;
    bhdr_T      *hp = NULL;
    ZERO_BL     *b0p;
    int         b0_ff;
    char_u      *b0_fenc = NULL;
    PTR_BL      *pp;
    DATA_BL     *dp;
    infoptr_T   *ip;
    blocknr_T   bnum;
    int         page_count;
    struct stat org_stat, swp_stat;
    int         len;
    int         directly;
    linenr_T    lnum;
    char_u      *p;
    int         i;
    long        error;
    int         cannot_open;
    linenr_T    line_count;
    int         has_error;
    int         idx;
    int         top;
    int         txt_start;
    off_t       size;
    int         called_from_main;
    int         serious_error = TRUE;
    long        mtime;
    int         attr;
    char_u      *bname;

    recoverymode = TRUE;
    called_from_main = (curbuf->b_ml.ml_mfp == NULL);
    attr = hl_attr(HLF_E);

    /*
     * If the file name ends in ".s[uvw][a-z]" we assume this is the swap file.
     * Otherwise a search is done to find the swap file(s).
     */
    fname = curbuf->b_fname;
    if (fname == NULL)              /* When there is no file name */
        fname = (char_u *)"";
    len = (int)STRLEN(fname);
    if (len >= 4 &&
#if defined(VMS) || defined(RISCOS)
            STRNICMP(fname + len - 4, "_s" , 2)
#else
            STRNICMP(fname + len - 4, ".s" , 2)
#endif
                == 0
                && vim_strchr((char_u *)"UVWuvw", fname[len - 2]) != NULL
                && ASCII_ISALPHA(fname[len - 1]))
    {
        directly = TRUE;
        fname = vim_strsave(fname); /* make a copy for mf_open() */
    }
    else
    {
        directly = FALSE;

        /* count the number of matching swap files */
        len = recover_names(&fname, FALSE, 0);
        if (len == 0)               /* no swap files found */
        {
            EMSG2(_("E305: No swap file found for %s"), fname);
            goto theend;
        }
        if (len == 1)               /* one swap file found, use it */
            i = 1;
        else                        /* several swap files found, choose */
        {
            /* list the names of the swap files */
            (void)recover_names(&fname, TRUE, 0);
            msg_putchar('\n');
            MSG_PUTS(_("Enter number of swap file to use (0 to quit): "));
            i = get_number(FALSE, NULL);
            if (i < 1 || i > len)
                goto theend;
        }
        /* get the swap file name that will be used */
        (void)recover_names(&fname, FALSE, i);
    }
    if (fname == NULL)
        goto theend;                    /* out of memory */

    /* When called from main() still need to initialize storage structure */
    if (called_from_main && ml_open(curbuf) == FAIL)
        getout(1);

/*
 * allocate a buffer structure (only the memline in it is really used)
 */
    buf = (buf_T *)alloc((unsigned)sizeof(buf_T));
    if (buf == NULL)
    {
        vim_free(fname);
        goto theend;
    }

/*
 * init fields in memline struct
 */
    buf->b_ml.ml_stack_size = 0;        /* no stack yet */
    buf->b_ml.ml_stack = NULL;          /* no stack yet */
    buf->b_ml.ml_stack_top = 0;         /* nothing in the stack */
    buf->b_ml.ml_line_lnum = 0;         /* no cached line */
    buf->b_ml.ml_locked = NULL;         /* no locked block */
    buf->b_ml.ml_flags = 0;

/*
 * open the memfile from the old swap file
 */
    p = vim_strsave(fname);             /* save fname for the message
                                           (mf_open() may free fname) */
    mfp = mf_open(fname, O_RDONLY);     /* consumes fname! */
    if (mfp == NULL || mfp->mf_fd < 0)
    {
        if (p != NULL)
        {
            EMSG2(_("E306: Cannot open %s"), p);
            vim_free(p);
        }
        goto theend;
    }
    vim_free(p);
    buf->b_ml.ml_mfp = mfp;

    /*
     * The page size set in mf_open() might be different from the page size
     * used in the swap file, we must get it from block 0.  But to read block
     * 0 we need a page size.  Use the minimal size for block 0 here, it will
     * be set to the real value below.
     */
    mfp->mf_page_size = MIN_SWAP_PAGE_SIZE;

/*
 * try to read block 0
 */
    if ((hp = mf_get(mfp, (blocknr_T)0, 1)) == NULL)
    {
        msg_start();
        MSG_PUTS_ATTR(_("Unable to read block 0 from "), attr | MSG_HIST);
        msg_outtrans_attr(mfp->mf_fname, attr | MSG_HIST);
        MSG_PUTS_ATTR(
           _("\nMaybe no changes were made or Vim did not update the swap file."),
                attr | MSG_HIST);
        msg_end();
        goto theend;
    }
    b0p = (ZERO_BL *)(hp->bh_data);
    if (STRNCMP(b0p->b0_version, "VIM 3.0", 7) == 0)
    {
        msg_start();
        msg_outtrans_attr(mfp->mf_fname, MSG_HIST);
        MSG_PUTS_ATTR(_(" cannot be used with this version of Vim.\n"),
                                                                    MSG_HIST);
        MSG_PUTS_ATTR(_("Use Vim version 3.0.\n"), MSG_HIST);
        msg_end();
        goto theend;
    }
    if (b0p->b0_id[0] != BLOCK0_ID0 || b0p->b0_id[1] != BLOCK0_ID1)
    {
        EMSG2(_("E307: %s does not look like a Vim swap file"), mfp->mf_fname);
        goto theend;
    }
    if (b0_magic_wrong(b0p))
    {
        msg_start();
        msg_outtrans_attr(mfp->mf_fname, attr | MSG_HIST);
#if defined(MSDOS) || defined(MSWIN)
        if (STRNCMP(b0p->b0_hname, "PC ", 3) == 0)
            MSG_PUTS_ATTR(_(" cannot be used with this version of Vim.\n"),
                                                             attr | MSG_HIST);
        else
#endif
            MSG_PUTS_ATTR(_(" cannot be used on this computer.\n"),
                                                             attr | MSG_HIST);
        MSG_PUTS_ATTR(_("The file was created on "), attr | MSG_HIST);
        /* avoid going past the end of a currupted hostname */
        b0p->b0_fname[0] = NUL;
        MSG_PUTS_ATTR(b0p->b0_hname, attr | MSG_HIST);
        MSG_PUTS_ATTR(_(",\nor the file has been damaged."), attr | MSG_HIST);
        msg_end();
        goto theend;
    }

    /*
     * If we guessed the wrong page size, we have to recalculate the
     * highest block number in the file.
     */
    if (mfp->mf_page_size != (unsigned)char_to_long(b0p->b0_page_size))
    {
        unsigned previous_page_size = mfp->mf_page_size;

        mf_new_page_size(mfp, (unsigned)char_to_long(b0p->b0_page_size));
        if (mfp->mf_page_size < previous_page_size)
        {
            msg_start();
            msg_outtrans_attr(mfp->mf_fname, attr | MSG_HIST);
            MSG_PUTS_ATTR(_(" has been damaged (page size is smaller than minimum value).\n"),
                        attr | MSG_HIST);
            msg_end();
            goto theend;
        }
        if ((size = lseek(mfp->mf_fd, (off_t)0L, SEEK_END)) <= 0)
            mfp->mf_blocknr_max = 0;        /* no file or empty file */
        else
            mfp->mf_blocknr_max = (blocknr_T)(size / mfp->mf_page_size);
        mfp->mf_infile_count = mfp->mf_blocknr_max;

        /* need to reallocate the memory used to store the data */
        p = alloc(mfp->mf_page_size);
        if (p == NULL)
            goto theend;
        mch_memmove(p, hp->bh_data, previous_page_size);
        vim_free(hp->bh_data);
        hp->bh_data = p;
        b0p = (ZERO_BL *)(hp->bh_data);
    }

/*
 * If .swp file name given directly, use name from swap file for buffer.
 */
    if (directly)
    {
        expand_env(b0p->b0_fname, NameBuff, MAXPATHL);
        if (setfname(curbuf, NameBuff, NULL, TRUE) == FAIL)
            goto theend;
    }

    home_replace(NULL, mfp->mf_fname, NameBuff, MAXPATHL, TRUE);
    smsg((char_u *)_("Using swap file \"%s\""), NameBuff);

    if ((bname = (char_u *)buf_spname(curbuf)) != NULL)
    {
        vim_strncpy(NameBuff, bname, MAXPATHL - 1);
        vim_free(bname);
    }
    else
        home_replace(NULL, curbuf->b_ffname, NameBuff, MAXPATHL, TRUE);
    smsg((char_u *)_("Original file \"%s\""), NameBuff);
    msg_putchar('\n');

/*
 * check date of swap file and original file
 */
    mtime = char_to_long(b0p->b0_mtime);
    if (curbuf->b_ffname != NULL
            && mch_stat((char *)curbuf->b_ffname, &org_stat) != -1
            && ((mch_stat((char *)mfp->mf_fname, &swp_stat) != -1
                    && org_stat.st_mtime > swp_stat.st_mtime)
                || org_stat.st_mtime != mtime))
    {
        EMSG(_("E308: Warning: Original file may have been changed"));
    }
    out_flush();

    /* Get the 'fileformat' and 'fileencoding' from block zero. */
    b0_ff = (b0p->b0_flags & B0_FF_MASK);
    if (b0p->b0_flags & B0_HAS_FENC)
    {
        for (p = b0p->b0_fname + B0_FNAME_SIZE;
                                       p > b0p->b0_fname && p[-1] != NUL; --p)
            ;
        b0_fenc = vim_strnsave(p, (int)(b0p->b0_fname + B0_FNAME_SIZE - p));
    }

    mf_put(mfp, hp, FALSE, FALSE);      /* release block 0 */
    hp = NULL;

    /*
     * Now that we are sure that the file is going to be recovered, clear the
     * contents of the current buffer.
     */
    while (!(curbuf->b_ml.ml_flags & ML_EMPTY))
        ml_delete((linenr_T)1, FALSE);

    /*
     * Try reading the original file to obtain the values of 'fileformat',
     * 'fileencoding', etc.  Ignore errors.  The text itself is not used.
     */
    if (curbuf->b_ffname != NULL)
    {
        (void)readfile(curbuf->b_ffname, NULL, (linenr_T)0,
                              (linenr_T)0, (linenr_T)MAXLNUM, NULL, READ_NEW);
        while (!(curbuf->b_ml.ml_flags & ML_EMPTY))
            ml_delete((linenr_T)1, FALSE);
    }

    /* Use the 'fileformat' and 'fileencoding' as stored in the swap file. */
    if (b0_ff != 0)
        set_fileformat(b0_ff - 1, OPT_LOCAL);
    if (b0_fenc != NULL)
    {
        set_option_value((char_u *)"fenc", 0L, b0_fenc, OPT_LOCAL);
        vim_free(b0_fenc);
    }
    unchanged(curbuf, TRUE);

    bnum = 1;           /* start with block 1 */
    page_count = 1;     /* which is 1 page */
    lnum = 0;           /* append after line 0 in curbuf */
    line_count = 0;
    idx = 0;            /* start with first index in block 1 */
    error = 0;
    buf->b_ml.ml_stack_top = 0;
    buf->b_ml.ml_stack = NULL;
    buf->b_ml.ml_stack_size = 0;        /* no stack yet */

    if (curbuf->b_ffname == NULL)
        cannot_open = TRUE;
    else
        cannot_open = FALSE;

    serious_error = FALSE;
    for ( ; !got_int; line_breakcheck())
    {
        if (hp != NULL)
            mf_put(mfp, hp, FALSE, FALSE);      /* release previous block */

        /*
         * get block
         */
        if ((hp = mf_get(mfp, (blocknr_T)bnum, page_count)) == NULL)
        {
            if (bnum == 1)
            {
                EMSG2(_("E309: Unable to read block 1 from %s"), mfp->mf_fname);
                goto theend;
            }
            ++error;
            ml_append(lnum++, (char_u *)_("???MANY LINES MISSING"),
                                                            (colnr_T)0, TRUE);
        }
        else            /* there is a block */
        {
            pp = (PTR_BL *)(hp->bh_data);
            if (pp->pb_id == PTR_ID)            /* it is a pointer block */
            {
                /* check line count when using pointer block first time */
                if (idx == 0 && line_count != 0)
                {
                    for (i = 0; i < (int)pp->pb_count; ++i)
                        line_count -= pp->pb_pointer[i].pe_line_count;
                    if (line_count != 0)
                    {
                        ++error;
                        ml_append(lnum++, (char_u *)_("???LINE COUNT WRONG"),
                                                            (colnr_T)0, TRUE);
                    }
                }

                if (pp->pb_count == 0)
                {
                    ml_append(lnum++, (char_u *)_("???EMPTY BLOCK"),
                                                            (colnr_T)0, TRUE);
                    ++error;
                }
                else if (idx < (int)pp->pb_count)       /* go a block deeper */
                {
                    if (pp->pb_pointer[idx].pe_bnum < 0)
                    {
                        /*
                         * Data block with negative block number.
                         * Try to read lines from the original file.
                         * This is slow, but it works.
                         */
                        if (!cannot_open)
                        {
                            line_count = pp->pb_pointer[idx].pe_line_count;
                            if (readfile(curbuf->b_ffname, NULL, lnum,
                                        pp->pb_pointer[idx].pe_old_lnum - 1,
                                        line_count, NULL, 0) == FAIL)
                                cannot_open = TRUE;
                            else
                                lnum += line_count;
                        }
                        if (cannot_open)
                        {
                            ++error;
                            ml_append(lnum++, (char_u *)_("???LINES MISSING"),
                                                            (colnr_T)0, TRUE);
                        }
                        ++idx;      /* get same block again for next index */
                        continue;
                    }

                    /*
                     * going one block deeper in the tree
                     */
                    if ((top = ml_add_stack(buf)) < 0)  /* new entry in stack */
                    {
                        ++error;
                        break;              /* out of memory */
                    }
                    ip = &(buf->b_ml.ml_stack[top]);
                    ip->ip_bnum = bnum;
                    ip->ip_index = idx;

                    bnum = pp->pb_pointer[idx].pe_bnum;
                    line_count = pp->pb_pointer[idx].pe_line_count;
                    page_count = pp->pb_pointer[idx].pe_page_count;
                    continue;
                }
            }
            else            /* not a pointer block */
            {
                dp = (DATA_BL *)(hp->bh_data);
                if (dp->db_id != DATA_ID)       /* block id wrong */
                {
                    if (bnum == 1)
                    {
                        EMSG2(_("E310: Block 1 ID wrong (%s not a .swp file?)"),
                                                               mfp->mf_fname);
                        goto theend;
                    }
                    ++error;
                    ml_append(lnum++, (char_u *)_("???BLOCK MISSING"),
                                                            (colnr_T)0, TRUE);
                }
                else
                {
                    /*
                     * it is a data block
                     * Append all the lines in this block
                     */
                    has_error = FALSE;
                        /*
                         * check length of block
                         * if wrong, use length in pointer block
                         */
                    if (page_count * mfp->mf_page_size != dp->db_txt_end)
                    {
                        ml_append(lnum++, (char_u *)_("??? from here until ???END lines may be messed up"),
                                                            (colnr_T)0, TRUE);
                        ++error;
                        has_error = TRUE;
                        dp->db_txt_end = page_count * mfp->mf_page_size;
                    }

                        /* make sure there is a NUL at the end of the block */
                    *((char_u *)dp + dp->db_txt_end - 1) = NUL;

                        /*
                         * check number of lines in block
                         * if wrong, use count in data block
                         */
                    if (line_count != dp->db_line_count)
                    {
                        ml_append(lnum++, (char_u *)_("??? from here until ???END lines may have been inserted/deleted"),
                                                            (colnr_T)0, TRUE);
                        ++error;
                        has_error = TRUE;
                    }

                    for (i = 0; i < dp->db_line_count; ++i)
                    {
                        txt_start = (dp->db_index[i] & DB_INDEX_MASK);
                        if (txt_start <= (int)HEADER_SIZE
                                          || txt_start >= (int)dp->db_txt_end)
                        {
                            p = (char_u *)"???";
                            ++error;
                        }
                        else
                            p = (char_u *)dp + txt_start;
                        ml_append(lnum++, p, (colnr_T)0, TRUE);
                    }
                    if (has_error)
                        ml_append(lnum++, (char_u *)_("???END"),
                                                            (colnr_T)0, TRUE);
                }
            }
        }

        if (buf->b_ml.ml_stack_top == 0)        /* finished */
            break;

        /*
         * go one block up in the tree
         */
        ip = &(buf->b_ml.ml_stack[--(buf->b_ml.ml_stack_top)]);
        bnum = ip->ip_bnum;
        idx = ip->ip_index + 1;     /* go to next index */
        page_count = 1;
    }

    /*
     * The dummy line from the empty buffer will now be after the last line in
     * the buffer. Delete it.
     */
    ml_delete(curbuf->b_ml.ml_line_count, FALSE);
    curbuf->b_flags |= BF_RECOVERED;

    recoverymode = FALSE;
    if (got_int)
        EMSG(_("E311: Recovery Interrupted"));
    else if (error)
    {
        ++no_wait_return;
        MSG(">>>>>>>>>>>>>");
        EMSG(_("E312: Errors detected while recovering; look for lines starting with ???"));
        --no_wait_return;
        MSG(_("See \":help E312\" for more information."));
        MSG(">>>>>>>>>>>>>");
    }
    else
    {
        MSG(_("Recovery completed. You should check if everything is OK."));
        MSG_PUTS(_("\n(You might want to write out this file under another name\n"));
        MSG_PUTS(_("and run diff with the original file to check for changes)\n"));
        MSG_PUTS(_("Delete the .swp file afterwards.\n\n"));
        cmdline_row = msg_row;
    }
    redraw_curbuf_later(NOT_VALID);

theend:
    recoverymode = FALSE;
    if (mfp != NULL)
    {
        if (hp != NULL)
            mf_put(mfp, hp, FALSE, FALSE);
        mf_close(mfp, FALSE);       /* will also vim_free(mfp->mf_fname) */
    }
    if (buf != NULL)
    {
        vim_free(buf->b_ml.ml_stack);
        vim_free(buf);
    }
    if (serious_error && called_from_main)
        ml_close(curbuf, TRUE);
#ifdef FEAT_AUTOCMD
    else
    {
        apply_autocmds(EVENT_BUFREADPOST, NULL, curbuf->b_fname, FALSE, curbuf);
        apply_autocmds(EVENT_BUFWINENTER, NULL, curbuf->b_fname, FALSE, curbuf);
    }
#endif
    return;
}

/*
 * Find the names of swap files in current directory and the directory given
 * with the 'directory' option.
 *
 * Used to:
 * - list the swap files for "vim -r"
 * - count the number of swap files when recovering
 * - list the swap files when recovering
 * - find the name of the n'th swap file when recovering
 */
    int
recover_names(fname, list, nr)
    char_u      **fname;    /* base for swap file name */
    int         list;       /* when TRUE, list the swap file names */
    int         nr;         /* when non-zero, return nr'th swap file name */
{
    int         num_names;
    char_u      *(names[6]);
    char_u      *tail;
    char_u      *p;
    int         num_files;
    int         file_count = 0;
    char_u      **files;
    int         i;
    char_u      *dirp;
    char_u      *dir_name;
    char_u      *fname_res = NULL;
#ifdef HAVE_READLINK
    char_u      fname_buf[MAXPATHL];
#endif

    if (fname != NULL)
    {
#ifdef HAVE_READLINK
    /* Expand symlink in the file name, because the swap file is created with
     * the actual file instead of with the symlink. */
    if (resolve_symlink(*fname, fname_buf) == OK)
        fname_res = fname_buf;
    else
#endif
        fname_res = *fname;
    }

    if (list)
    {
        /* use msg() to start the scrolling properly */
        msg((char_u *)_("Swap files found:"));
        msg_putchar('\n');
    }

    /*
     * Do the loop for every directory in 'directory'.
     * First allocate some memory to put the directory name in.
     */
    dir_name = alloc((unsigned)STRLEN(p_dir) + 1);
    dirp = p_dir;
    while (dir_name != NULL && *dirp)
    {
        /*
         * Isolate a directory name from *dirp and put it in dir_name (we know
         * it is large enough, so use 31000 for length).
         * Advance dirp to next directory name.
         */
        (void)copy_option_part(&dirp, dir_name, 31000, ",");

        if (dir_name[0] == '.' && dir_name[1] == NUL)   /* check current dir */
        {
            if (fname == NULL || *fname == NULL)
            {
#ifdef VMS
                names[0] = vim_strsave((char_u *)"*_sw%");
#else
# ifdef RISCOS
                names[0] = vim_strsave((char_u *)"*_sw#");
# else
                names[0] = vim_strsave((char_u *)"*.sw?");
# endif
#endif
#if defined(UNIX) || defined(WIN3264)
                /* For Unix names starting with a dot are special.  MS-Windows
                 * supports this too, on some file systems. */
                names[1] = vim_strsave((char_u *)".*.sw?");
                names[2] = vim_strsave((char_u *)".sw?");
                num_names = 3;
#else
# ifdef VMS
                names[1] = vim_strsave((char_u *)".*_sw%");
                num_names = 2;
# else
                num_names = 1;
# endif
#endif
            }
            else
                num_names = recov_file_names(names, fname_res, TRUE);
        }
        else                        /* check directory dir_name */
        {
            if (fname == NULL || *fname == NULL)
            {
#ifdef VMS
                names[0] = concat_fnames(dir_name, (char_u *)"*_sw%", TRUE);
#else
# ifdef RISCOS
                names[0] = concat_fnames(dir_name, (char_u *)"*_sw#", TRUE);
# else
                names[0] = concat_fnames(dir_name, (char_u *)"*.sw?", TRUE);
# endif
#endif
#if defined(UNIX) || defined(WIN3264)
                /* For Unix names starting with a dot are special.  MS-Windows
                 * supports this too, on some file systems. */
                names[1] = concat_fnames(dir_name, (char_u *)".*.sw?", TRUE);
                names[2] = concat_fnames(dir_name, (char_u *)".sw?", TRUE);
                num_names = 3;
#else
# ifdef VMS
                names[1] = concat_fnames(dir_name, (char_u *)".*_sw%", TRUE);
                num_names = 2;
# else
                num_names = 1;
# endif
#endif
            }
            else
            {
#if defined(UNIX) || defined(WIN3264)
                p = dir_name + STRLEN(dir_name);
                if (after_pathsep(dir_name, p) && p[-1] == p[-2])
                {
                    /* Ends with '//', Use Full path for swap name */
                    tail = make_percent_swname(dir_name, fname_res);
                }
                else
#endif
                {
                    tail = gettail(fname_res);
                    tail = concat_fnames(dir_name, tail, TRUE);
                }
                if (tail == NULL)
                    num_names = 0;
                else
                {
                    num_names = recov_file_names(names, tail, FALSE);
                    vim_free(tail);
                }
            }
        }

            /* check for out-of-memory */
        for (i = 0; i < num_names; ++i)
        {
            if (names[i] == NULL)
            {
                for (i = 0; i < num_names; ++i)
                    vim_free(names[i]);
                num_names = 0;
            }
        }
        if (num_names == 0)
            num_files = 0;
        else if (expand_wildcards(num_names, names, &num_files, &files,
                                        EW_KEEPALL|EW_FILE|EW_SILENT) == FAIL)
            num_files = 0;

        /*
         * When no swap file found, wildcard expansion might have failed (e.g.
         * not able to execute the shell).
         * Try finding a swap file by simply adding ".swp" to the file name.
         */
        if (*dirp == NUL && file_count + num_files == 0
                                           && fname != NULL && *fname != NULL)
        {
            struct stat     st;
            char_u          *swapname;

            swapname = modname(fname_res,
#if defined(VMS) || defined(RISCOS)
                               (char_u *)"_swp", FALSE
#else
                               (char_u *)".swp", TRUE
#endif
                              );
            if (swapname != NULL)
            {
                if (mch_stat((char *)swapname, &st) != -1)          /* It exists! */
                {
                    files = (char_u **)alloc((unsigned)sizeof(char_u *));
                    if (files != NULL)
                    {
                        files[0] = swapname;
                        swapname = NULL;
                        num_files = 1;
                    }
                }
                vim_free(swapname);
            }
        }

        /*
         * remove swapfile name of the current buffer, it must be ignored
         */
        if (curbuf->b_ml.ml_mfp != NULL
                               && (p = curbuf->b_ml.ml_mfp->mf_fname) != NULL)
        {
            for (i = 0; i < num_files; ++i)
                if (fullpathcmp(p, files[i], TRUE) & FPC_SAME)
                {
                    /* Remove the name from files[i].  Move further entries
                     * down.  When the array becomes empty free it here, since
                     * FreeWild() won't be called below. */
                    vim_free(files[i]);
                    if (--num_files == 0)
                        vim_free(files);
                    else
                        for ( ; i < num_files; ++i)
                            files[i] = files[i + 1];
                }
        }
        if (nr > 0)
        {
            file_count += num_files;
            if (nr <= file_count)
            {
                *fname = vim_strsave(files[nr - 1 + num_files - file_count]);
                dirp = (char_u *)"";                /* stop searching */
            }
        }
        else if (list)
        {
            if (dir_name[0] == '.' && dir_name[1] == NUL)
            {
                if (fname == NULL || *fname == NULL)
                    MSG_PUTS(_("   In current directory:\n"));
                else
                    MSG_PUTS(_("   Using specified name:\n"));
            }
            else
            {
                MSG_PUTS(_("   In directory "));
                msg_home_replace(dir_name);
                MSG_PUTS(":\n");
            }

            if (num_files)
            {
                for (i = 0; i < num_files; ++i)
                {
                    /* print the swap file name */
                    msg_outnum((long)++file_count);
                    MSG_PUTS(".    ");
                    msg_puts(gettail(files[i]));
                    msg_putchar('\n');
                    (void)swapfile_info(files[i]);
                }
            }
            else
                MSG_PUTS(_("      -- none --\n"));
            out_flush();
        }
        else
            file_count += num_files;

        for (i = 0; i < num_names; ++i)
            vim_free(names[i]);
        if (num_files > 0)
            FreeWild(num_files, files);
    }
    vim_free(dir_name);
    return file_count;
}

#if defined(UNIX) || defined(WIN3264)  /* Need _very_ long file names */
/*
 * Append the full path to name with path separators made into percent
 * signs, to dir. An unnamed buffer is handled as "" (<currentdir>/"")
 */
    static char_u *
make_percent_swname(dir, name)
    char_u      *dir;
    char_u      *name;
{
    char_u *d, *s, *f;

    f = fix_fname(name != NULL ? name : (char_u *) "");
    d = NULL;
    if (f != NULL)
    {
        s = alloc((unsigned)(STRLEN(f) + 1));
        if (s != NULL)
        {
            STRCPY(s, f);
            for (d = s; *d != NUL; mb_ptr_adv(d))
                if (vim_ispathsep(*d))
                    *d = '%';
            d = concat_fnames(dir, s, TRUE);
            vim_free(s);
        }
        vim_free(f);
    }
    return d;
}
#endif

#if (defined(UNIX) || defined(__EMX__) || defined(VMS)) && (defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG))
static int process_still_running;
#endif

/*
 * Give information about an existing swap file.
 * Returns timestamp (0 when unknown).
 */
    static time_t
swapfile_info(fname)
    char_u      *fname;
{
    struct stat     st;
    int             fd;
    struct block0   b0;
    time_t          x = (time_t)0;
    char            *p;
#ifdef UNIX
    char_u          uname[B0_UNAME_SIZE];
#endif

    /* print the swap file date */
    if (mch_stat((char *)fname, &st) != -1)
    {
#ifdef UNIX
        /* print name of owner of the file */
        if (mch_get_uname(st.st_uid, uname, B0_UNAME_SIZE) == OK)
        {
            MSG_PUTS(_("          owned by: "));
            msg_outtrans(uname);
            MSG_PUTS(_("   dated: "));
        }
        else
#endif
            MSG_PUTS(_("             dated: "));
        x = st.st_mtime;                    /* Manx C can't do &st.st_mtime */
        p = ctime(&x);                      /* includes '\n' */
        if (p == NULL)
            MSG_PUTS("(invalid)\n");
        else
            MSG_PUTS(p);
    }

    /*
     * print the original file name
     */
    fd = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
    if (fd >= 0)
    {
        if (read(fd, (char *)&b0, sizeof(b0)) == sizeof(b0))
        {
            if (STRNCMP(b0.b0_version, "VIM 3.0", 7) == 0)
            {
                MSG_PUTS(_("         [from Vim version 3.0]"));
            }
            else if (b0.b0_id[0] != BLOCK0_ID0 || b0.b0_id[1] != BLOCK0_ID1)
            {
                MSG_PUTS(_("         [does not look like a Vim swap file]"));
            }
            else
            {
                MSG_PUTS(_("         file name: "));
                if (b0.b0_fname[0] == NUL)
                    MSG_PUTS(_("[No Name]"));
                else
                    msg_outtrans(b0.b0_fname);

                MSG_PUTS(_("\n          modified: "));
                MSG_PUTS(b0.b0_dirty ? _("YES") : _("no"));

                if (*(b0.b0_uname) != NUL)
                {
                    MSG_PUTS(_("\n         user name: "));
                    msg_outtrans(b0.b0_uname);
                }

                if (*(b0.b0_hname) != NUL)
                {
                    if (*(b0.b0_uname) != NUL)
                        MSG_PUTS(_("   host name: "));
                    else
                        MSG_PUTS(_("\n         host name: "));
                    msg_outtrans(b0.b0_hname);
                }

                if (char_to_long(b0.b0_pid) != 0L)
                {
                    MSG_PUTS(_("\n        process ID: "));
                    msg_outnum(char_to_long(b0.b0_pid));
#if defined(UNIX) || defined(__EMX__)
                    /* EMX kill() not working correctly, it seems */
                    if (kill((pid_t)char_to_long(b0.b0_pid), 0) == 0)
                    {
                        MSG_PUTS(_(" (still running)"));
# if defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG)
                        process_still_running = TRUE;
# endif
                    }
#endif
                }

                if (b0_magic_wrong(&b0))
                {
#if defined(MSDOS) || defined(MSWIN)
                    if (STRNCMP(b0.b0_hname, "PC ", 3) == 0)
                        MSG_PUTS(_("\n         [not usable with this version of Vim]"));
                    else
#endif
                        MSG_PUTS(_("\n         [not usable on this computer]"));
                }
            }
        }
        else
            MSG_PUTS(_("         [cannot be read]"));
        close(fd);
    }
    else
        MSG_PUTS(_("         [cannot be opened]"));
    msg_putchar('\n');

    return x;
}

    static int
recov_file_names(names, path, prepend_dot)
    char_u      **names;
    char_u      *path;
    int         prepend_dot;
{
    int         num_names;

#ifdef SHORT_FNAME
    /*
     * (MS-DOS) always short names
     */
    names[0] = modname(path, (char_u *)".sw?", FALSE);
    num_names = 1;
#else /* !SHORT_FNAME */
    /*
     * (Win32 and Win64) never short names, but do prepend a dot.
     * (Not MS-DOS or Win32 or Win64) maybe short name, maybe not: Try both.
     * Only use the short name if it is different.
     */
    char_u      *p;
    int         i;
# ifndef WIN3264
    int     shortname = curbuf->b_shortname;

    curbuf->b_shortname = FALSE;
# endif

    num_names = 0;

    /*
     * May also add the file name with a dot prepended, for swap file in same
     * dir as original file.
     */
    if (prepend_dot)
    {
        names[num_names] = modname(path, (char_u *)".sw?", TRUE);
        if (names[num_names] == NULL)
            goto end;
        ++num_names;
    }

    /*
     * Form the normal swap file name pattern by appending ".sw?".
     */
#ifdef VMS
    names[num_names] = concat_fnames(path, (char_u *)"_sw%", FALSE);
#else
# ifdef RISCOS
    names[num_names] = concat_fnames(path, (char_u *)"_sw#", FALSE);
# else
    names[num_names] = concat_fnames(path, (char_u *)".sw?", FALSE);
# endif
#endif
    if (names[num_names] == NULL)
        goto end;
    if (num_names >= 1)     /* check if we have the same name twice */
    {
        p = names[num_names - 1];
        i = (int)STRLEN(names[num_names - 1]) - (int)STRLEN(names[num_names]);
        if (i > 0)
            p += i;         /* file name has been expanded to full path */

        if (STRCMP(p, names[num_names]) != 0)
            ++num_names;
        else
            vim_free(names[num_names]);
    }
    else
        ++num_names;

# ifndef WIN3264
    /*
     * Also try with 'shortname' set, in case the file is on a DOS filesystem.
     */
    curbuf->b_shortname = TRUE;
#ifdef VMS
    names[num_names] = modname(path, (char_u *)"_sw%", FALSE);
#else
# ifdef RISCOS
    names[num_names] = modname(path, (char_u *)"_sw#", FALSE);
# else
    names[num_names] = modname(path, (char_u *)".sw?", FALSE);
# endif
#endif
    if (names[num_names] == NULL)
        goto end;

    /*
     * Remove the one from 'shortname', if it's the same as with 'noshortname'.
     */
    p = names[num_names];
    i = STRLEN(names[num_names]) - STRLEN(names[num_names - 1]);
    if (i > 0)
        p += i;         /* file name has been expanded to full path */
    if (STRCMP(names[num_names - 1], p) == 0)
        vim_free(names[num_names]);
    else
        ++num_names;
# endif

end:
# ifndef WIN3264
    curbuf->b_shortname = shortname;
# endif

#endif /* !SHORT_FNAME */

    return num_names;
}

/*
 * sync all memlines
 *
 * If 'check_file' is TRUE, check if original file exists and was not changed.
 * If 'check_char' is TRUE, stop syncing when character becomes available, but
 * always sync at least one block.
 */
    void
ml_sync_all(check_file, check_char)
    int     check_file;
    int     check_char;
{
    buf_T               *buf;
    struct stat         st;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    {
        if (buf->b_ml.ml_mfp == NULL || buf->b_ml.ml_mfp->mf_fname == NULL)
            continue;                       /* no file */

        ml_flush_line(buf);                 /* flush buffered line */
                                            /* flush locked block */
        (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH);
        if (bufIsChanged(buf) && check_file && mf_need_trans(buf->b_ml.ml_mfp)
                                                     && buf->b_ffname != NULL)
        {
            /*
             * If the original file does not exist anymore or has been changed
             * call ml_preserve() to get rid of all negative numbered blocks.
             */
            if (mch_stat((char *)buf->b_ffname, &st) == -1
                    || st.st_mtime != buf->b_mtime_read
                    || (size_t)st.st_size != buf->b_orig_size)
            {
                ml_preserve(buf, FALSE);
                did_check_timestamps = FALSE;
                need_check_timestamps = TRUE;   /* give message later */
            }
        }
        if (buf->b_ml.ml_mfp->mf_dirty)
        {
            (void)mf_sync(buf->b_ml.ml_mfp, (check_char ? MFS_STOP : 0)
                                        | (bufIsChanged(buf) ? MFS_FLUSH : 0));
            if (check_char && ui_char_avail())  /* character available now */
                break;
        }
    }
}

/*
 * sync one buffer, including negative blocks
 *
 * after this all the blocks are in the swap file
 *
 * Used for the :preserve command and when the original file has been
 * changed or deleted.
 *
 * when message is TRUE the success of preserving is reported
 */
    void
ml_preserve(buf, message)
    buf_T       *buf;
    int         message;
{
    bhdr_T      *hp;
    linenr_T    lnum;
    memfile_T   *mfp = buf->b_ml.ml_mfp;
    int         status;
    int         got_int_save = got_int;

    if (mfp == NULL || mfp->mf_fname == NULL)
    {
        if (message)
            EMSG(_("E313: Cannot preserve, there is no swap file"));
        return;
    }

    /* We only want to stop when interrupted here, not when interrupted
     * before. */
    got_int = FALSE;

    ml_flush_line(buf);                             /* flush buffered line */
    (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH); /* flush locked block */
    status = mf_sync(mfp, MFS_ALL | MFS_FLUSH);

    /* stack is invalid after mf_sync(.., MFS_ALL) */
    buf->b_ml.ml_stack_top = 0;

    /*
     * Some of the data blocks may have been changed from negative to
     * positive block number. In that case the pointer blocks need to be
     * updated.
     *
     * We don't know in which pointer block the references are, so we visit
     * all data blocks until there are no more translations to be done (or
     * we hit the end of the file, which can only happen in case a write fails,
     * e.g. when file system if full).
     * ml_find_line() does the work by translating the negative block numbers
     * when getting the first line of each data block.
     */
    if (mf_need_trans(mfp) && !got_int)
    {
        lnum = 1;
        while (mf_need_trans(mfp) && lnum <= buf->b_ml.ml_line_count)
        {
            hp = ml_find_line(buf, lnum, ML_FIND);
            if (hp == NULL)
            {
                status = FAIL;
                goto theend;
            }
            CHECK(buf->b_ml.ml_locked_low != lnum, "low != lnum");
            lnum = buf->b_ml.ml_locked_high + 1;
        }
        (void)ml_find_line(buf, (linenr_T)0, ML_FLUSH); /* flush locked block */
        /* sync the updated pointer blocks */
        if (mf_sync(mfp, MFS_ALL | MFS_FLUSH) == FAIL)
            status = FAIL;
        buf->b_ml.ml_stack_top = 0;         /* stack is invalid now */
    }
theend:
    got_int |= got_int_save;

    if (message)
    {
        if (status == OK)
            MSG(_("File preserved"));
        else
            EMSG(_("E314: Preserve failed"));
    }
}

/*
 * NOTE: The pointer returned by the ml_get_*() functions only remains valid
 * until the next call!
 *  line1 = ml_get(1);
 *  line2 = ml_get(2);  // line1 is now invalid!
 * Make a copy of the line if necessary.
 */
/*
 * get a pointer to a (read-only copy of a) line
 *
 * On failure an error message is given and IObuff is returned (to avoid
 * having to check for error everywhere).
 */
    char_u  *
ml_get(lnum)
    linenr_T    lnum;
{
    return ml_get_buf(curbuf, lnum, FALSE);
}

/*
 * ml_get_pos: get pointer to position 'pos'
 */
    char_u *
ml_get_pos(pos)
    pos_T       *pos;
{
    return (ml_get_buf(curbuf, pos->lnum, FALSE) + pos->col);
}

/*
 * ml_get_curline: get pointer to cursor line.
 */
    char_u *
ml_get_curline()
{
    return ml_get_buf(curbuf, curwin->w_cursor.lnum, FALSE);
}

/*
 * ml_get_cursor: get pointer to cursor position
 */
    char_u *
ml_get_cursor()
{
    return (ml_get_buf(curbuf, curwin->w_cursor.lnum, FALSE) +
                                                        curwin->w_cursor.col);
}

/*
 * get a pointer to a line in a specific buffer
 *
 * "will_change": if TRUE mark the buffer dirty (chars in the line will be
 * changed)
 */
    char_u  *
ml_get_buf(buf, lnum, will_change)
    buf_T       *buf;
    linenr_T    lnum;
    int         will_change;            /* line will be changed */
{
    bhdr_T      *hp;
    DATA_BL     *dp;
    char_u      *ptr;
    static int  recursive = 0;

    if (lnum > buf->b_ml.ml_line_count) /* invalid line number */
    {
        if (recursive == 0)
        {
            /* Avoid giving this message for a recursive call, may happen when
             * the GUI redraws part of the text. */
            ++recursive;
            EMSGN(_("E315: ml_get: invalid lnum: %ld"), lnum);
            --recursive;
        }
errorret:
        STRCPY(IObuff, "???");
        return IObuff;
    }
    if (lnum <= 0)                      /* pretend line 0 is line 1 */
        lnum = 1;

    if (buf->b_ml.ml_mfp == NULL)       /* there are no lines */
        return (char_u *)"";

    /*
     * See if it is the same line as requested last time.
     * Otherwise may need to flush last used line.
     * Don't use the last used line when 'swapfile' is reset, need to load all
     * blocks.
     */
    if (buf->b_ml.ml_line_lnum != lnum || mf_dont_release)
    {
        ml_flush_line(buf);

        /*
         * Find the data block containing the line.
         * This also fills the stack with the blocks from the root to the data
         * block and releases any locked block.
         */
        if ((hp = ml_find_line(buf, lnum, ML_FIND)) == NULL)
        {
            if (recursive == 0)
            {
                /* Avoid giving this message for a recursive call, may happen
                 * when the GUI redraws part of the text. */
                ++recursive;
                EMSGN(_("E316: ml_get: cannot find line %ld"), lnum);
                --recursive;
            }
            goto errorret;
        }

        dp = (DATA_BL *)(hp->bh_data);

        ptr = (char_u *)dp + ((dp->db_index[lnum - buf->b_ml.ml_locked_low]) & DB_INDEX_MASK);
        buf->b_ml.ml_line_ptr = ptr;
        buf->b_ml.ml_line_lnum = lnum;
        buf->b_ml.ml_flags &= ~ML_LINE_DIRTY;
    }
    if (will_change)
        buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);

    return buf->b_ml.ml_line_ptr;
}

/*
 * Check if a line that was just obtained by a call to ml_get
 * is in allocated memory.
 */
    int
ml_line_alloced()
{
    return (curbuf->b_ml.ml_flags & ML_LINE_DIRTY);
}

/*
 * Append a line after lnum (may be 0 to insert a line in front of the file).
 * "line" does not need to be allocated, but can't be another line in a
 * buffer, unlocking may make it invalid.
 *
 *   newfile: TRUE when starting to edit a new file, meaning that pe_old_lnum
 *              will be set for recovery
 * Check: The caller of this function should probably also call
 * appended_lines().
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_append(lnum, line, len, newfile)
    linenr_T    lnum;           /* append after this line (can be 0) */
    char_u      *line;          /* text of the new line */
    colnr_T     len;            /* length of new line, including NUL, or 0 */
    int         newfile;        /* flag, see above */
{
    /* When starting up, we might still need to create the memfile */
    if (curbuf->b_ml.ml_mfp == NULL && open_buffer(FALSE, NULL) == FAIL)
        return FAIL;

    if (curbuf->b_ml.ml_line_lnum != 0)
        ml_flush_line(curbuf);
    return ml_append_int(curbuf, lnum, line, len, newfile, FALSE);
}

/*
 * Append string to line lnum, with buffering, in current buffer.
 *
 * Always makes a copy of the incoming string
 *
 * Check: The caller of this function should probably also call
 * changed_lines(), unless update_screen(NOT_VALID) is used.
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_append_string(lnum, string, slen)
    linenr_T    lnum;
    char_u  *string;
    int     slen;
{
    int append_len = 0;
    int line_len = 0;
    if (slen == -1)
        append_len = STRLEN(string);
    else
        append_len = slen;
    if (string == NULL)     /* just checking... */
        return FAIL;

    if (lnum == 0)
        ml_append (lnum, string, slen, 0);

    /* When starting up, we might still need to create the memfile */
    if (curbuf->b_ml.ml_mfp == NULL && open_buffer(FALSE, NULL) == FAIL)
        return FAIL;

#ifdef FEAT_NETBEANS_INTG
    /*
#error I am 99% sure this is broken
    if (usingNetbeans)
    {
        netbeans_removed(curbuf, lnum, 0, (long)STRLEN(ml_get(lnum)));
        netbeans_inserted(curbuf, lnum, 0, string, (int)STRLEN(string));
    }
    */
#endif
    if ((curbuf->b_ml.ml_line_lnum != lnum) ||   /* other line buffered */ 
        (curbuf->b_ml.ml_flags & ML_LINE_DIRTY) == 0)
    {
        ml_flush_line(curbuf);              /* flush it, this frees ml_line_ptr */

        /* Take a pointer to the existing line, will get re-alloced right
         * away below because it is not big enough */
        curbuf->b_ml.ml_line_ptr = ml_get(lnum);
        curbuf->b_ml.ml_flags &= ~ML_LINE_DIRTY;
        curbuf->b_ml.ml_line_max = STRLEN(curbuf->b_ml.ml_line_ptr);
        curbuf->b_ml.ml_line_lnum = lnum;
    }
    /* By here, 
     * curbuf->b_ml.ml_line_ptr - is filled with the correct existing line
     * curbuf->b_ml.ml_line_max - is the alloced size of the line
     */
    line_len = STRLEN(curbuf->b_ml.ml_line_ptr);
    if (curbuf->b_ml.ml_line_max < line_len + append_len + 1)
    {
        int new_len = (curbuf->b_ml.ml_line_max + append_len + 2) * 2;
        char_u *new_line;
        if (new_len < 80) new_len = 80;
        new_line = vim_strnsave(curbuf->b_ml.ml_line_ptr, new_len);
        if (curbuf->b_ml.ml_flags & ML_LINE_DIRTY)
                vim_free(curbuf->b_ml.ml_line_ptr);
        curbuf->b_ml.ml_line_ptr = new_line;
        curbuf->b_ml.ml_line_max = new_len;
        curbuf->b_ml.ml_flags = (curbuf->b_ml.ml_flags | ML_LINE_DIRTY) & ~ML_EMPTY;
    }
    /* by here:
     * ml_line_ptr is allocated to fit the current line + the append
     * ml_line_max is the total alloced size of the line
     */
    STRCPY (&curbuf->b_ml.ml_line_ptr[line_len], string);  /* Append our string */
    curbuf->b_ml.ml_line_ptr[line_len + append_len] = NUL; /* End the line */
    return OK;
}



#if defined(FEAT_SPELL) || defined(PROTO)
/*
 * Like ml_append() but for an arbitrary buffer.  The buffer must already have
 * a memline.
 */
    int
ml_append_buf(buf, lnum, line, len, newfile)
    buf_T       *buf;
    linenr_T    lnum;           /* append after this line (can be 0) */
    char_u      *line;          /* text of the new line */
    colnr_T     len;            /* length of new line, including NUL, or 0 */
    int         newfile;        /* flag, see above */
{
    if (buf->b_ml.ml_mfp == NULL)
        return FAIL;

    if (buf->b_ml.ml_line_lnum != 0)
        ml_flush_line(buf);
    return ml_append_int(buf, lnum, line, len, newfile, FALSE);
}
#endif

    static int
ml_append_int(buf, lnum, line, len, newfile, mark)
    buf_T       *buf;
    linenr_T    lnum;           /* append after this line (can be 0) */
    char_u      *line;          /* text of the new line */
    colnr_T     len;            /* length of line, including NUL, or 0 */
    int         newfile;        /* flag, see above */
    int         mark;           /* mark the new line */
{
    int         i;
    int         line_count;     /* number of indexes in current block */
    int         offset;
    int         from, to;
    int         space_needed;   /* space needed for new line */
    int         page_size;
    int         page_count;
    int         db_idx;         /* index for lnum in data block */
    bhdr_T      *hp;
    memfile_T   *mfp;
    DATA_BL     *dp;
    PTR_BL      *pp;
    infoptr_T   *ip;

                                        /* lnum out of range */
    if (lnum > buf->b_ml.ml_line_count || buf->b_ml.ml_mfp == NULL)
        return FAIL;

    if (lowest_marked && lowest_marked > lnum)
        lowest_marked = lnum + 1;

    if (len == 0)
        len = (colnr_T)STRLEN(line) + 1;        /* space needed for the text */
    space_needed = len + INDEX_SIZE;    /* space needed for text + index */

    mfp = buf->b_ml.ml_mfp;
    page_size = mfp->mf_page_size;

/*
 * find the data block containing the previous line
 * This also fills the stack with the blocks from the root to the data block
 * This also releases any locked block.
 */
    if ((hp = ml_find_line(buf, lnum == 0 ? (linenr_T)1 : lnum,
                                                          ML_INSERT)) == NULL)
        return FAIL;

    buf->b_ml.ml_flags &= ~ML_EMPTY;

    if (lnum == 0)              /* got line one instead, correct db_idx */
        db_idx = -1;            /* careful, it is negative! */
    else
        db_idx = lnum - buf->b_ml.ml_locked_low;
                /* get line count before the insertion */
    line_count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low;

    dp = (DATA_BL *)(hp->bh_data);

/*
 * If
 * - there is not enough room in the current block
 * - appending to the last line in the block
 * - not appending to the last line in the file
 * insert in front of the next block.
 */
    if ((int)dp->db_free < space_needed && db_idx == line_count - 1
                                            && lnum < buf->b_ml.ml_line_count)
    {
        /*
         * Now that the line is not going to be inserted in the block that we
         * expected, the line count has to be adjusted in the pointer blocks
         * by using ml_locked_lineadd.
         */
        --(buf->b_ml.ml_locked_lineadd);
        --(buf->b_ml.ml_locked_high);
        if ((hp = ml_find_line(buf, lnum + 1, ML_INSERT)) == NULL)
            return FAIL;

        db_idx = -1;                /* careful, it is negative! */
                    /* get line count before the insertion */
        line_count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low;
        CHECK(buf->b_ml.ml_locked_low != lnum + 1, "locked_low != lnum + 1");

        dp = (DATA_BL *)(hp->bh_data);
    }

    ++buf->b_ml.ml_line_count;

    if ((int)dp->db_free >= space_needed)       /* enough room in data block */
    {
/*
 * Insert new line in existing data block, or in data block allocated above.
 */
        dp->db_txt_start -= len;
        dp->db_free -= space_needed;
        ++(dp->db_line_count);

        /*
         * move the text of the lines that follow to the front
         * adjust the indexes of the lines that follow
         */
        if (line_count > db_idx + 1)        /* if there are following lines */
        {
            /*
             * Offset is the start of the previous line.
             * This will become the character just after the new line.
             */
            if (db_idx < 0)
                offset = dp->db_txt_end;
            else
                offset = ((dp->db_index[db_idx]) & DB_INDEX_MASK);
            mch_memmove((char *)dp + dp->db_txt_start,
                                          (char *)dp + dp->db_txt_start + len,
                                 (size_t)(offset - (dp->db_txt_start + len)));
            for (i = line_count - 1; i > db_idx; --i)
                dp->db_index[i + 1] = dp->db_index[i] - len;
            dp->db_index[db_idx + 1] = offset - len;
        }
        else                                /* add line at the end */
            dp->db_index[db_idx + 1] = dp->db_txt_start;

        /*
         * copy the text into the block
         */
        mch_memmove((char *)dp + dp->db_index[db_idx + 1], line, (size_t)len);
        if (mark)
            dp->db_index[db_idx + 1] |= DB_MARKED;

        /*
         * Mark the block dirty.
         */
        buf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
        if (!newfile)
            buf->b_ml.ml_flags |= ML_LOCKED_POS;
    }
    else            /* not enough space in data block */
    {
/*
 * If there is not enough room we have to create a new data block and copy some
 * lines into it.
 * Then we have to insert an entry in the pointer block.
 * If this pointer block also is full, we go up another block, and so on, up
 * to the root if necessary.
 * The line counts in the pointer blocks have already been adjusted by
 * ml_find_line().
 */
        long        line_count_left, line_count_right;
        int         page_count_left, page_count_right;
        bhdr_T      *hp_left;
        bhdr_T      *hp_right;
        bhdr_T      *hp_new;
        int         lines_moved;
        int         data_moved = 0;         /* init to shut up gcc */
        int         total_moved = 0;        /* init to shut up gcc */
        DATA_BL     *dp_right, *dp_left;
        int         stack_idx;
        int         in_left;
        int         lineadd;
        blocknr_T   bnum_left, bnum_right;
        linenr_T    lnum_left, lnum_right;
        int         pb_idx;
        PTR_BL      *pp_new;

        /*
         * We are going to allocate a new data block. Depending on the
         * situation it will be put to the left or right of the existing
         * block.  If possible we put the new line in the left block and move
         * the lines after it to the right block. Otherwise the new line is
         * also put in the right block. This method is more efficient when
         * inserting a lot of lines at one place.
         */
        if (db_idx < 0)         /* left block is new, right block is existing */
        {
            lines_moved = 0;
            in_left = TRUE;
            /* space_needed does not change */
        }
        else                    /* left block is existing, right block is new */
        {
            lines_moved = line_count - db_idx - 1;
            if (lines_moved == 0)
                in_left = FALSE;        /* put new line in right block */
                                        /* space_needed does not change */
            else
            {
                data_moved = ((dp->db_index[db_idx]) & DB_INDEX_MASK) -
                                                            dp->db_txt_start;
                total_moved = data_moved + lines_moved * INDEX_SIZE;
                if ((int)dp->db_free + total_moved >= space_needed)
                {
                    in_left = TRUE;     /* put new line in left block */
                    space_needed = total_moved;
                }
                else
                {
                    in_left = FALSE;        /* put new line in right block */
                    space_needed += total_moved;
                }
            }
        }

        page_count = ((space_needed + HEADER_SIZE) + page_size - 1) / page_size;
        if ((hp_new = ml_new_data(mfp, newfile, page_count)) == NULL)
        {
                        /* correct line counts in pointer blocks */
            --(buf->b_ml.ml_locked_lineadd);
            --(buf->b_ml.ml_locked_high);
            return FAIL;
        }
        if (db_idx < 0)         /* left block is new */
        {
            hp_left = hp_new;
            hp_right = hp;
            line_count_left = 0;
            line_count_right = line_count;
        }
        else                    /* right block is new */
        {
            hp_left = hp;
            hp_right = hp_new;
            line_count_left = line_count;
            line_count_right = 0;
        }
        dp_right = (DATA_BL *)(hp_right->bh_data);
        dp_left = (DATA_BL *)(hp_left->bh_data);
        bnum_left = hp_left->bh_bnum;
        bnum_right = hp_right->bh_bnum;
        page_count_left = hp_left->bh_page_count;
        page_count_right = hp_right->bh_page_count;

        /*
         * May move the new line into the right/new block.
         */
        if (!in_left)
        {
            dp_right->db_txt_start -= len;
            dp_right->db_free -= len + INDEX_SIZE;
            dp_right->db_index[0] = dp_right->db_txt_start;
            if (mark)
                dp_right->db_index[0] |= DB_MARKED;

            mch_memmove((char *)dp_right + dp_right->db_txt_start,
                                                           line, (size_t)len);
            ++line_count_right;
        }
        /*
         * may move lines from the left/old block to the right/new one.
         */
        if (lines_moved)
        {
            /*
             */
            dp_right->db_txt_start -= data_moved;
            dp_right->db_free -= total_moved;
            mch_memmove((char *)dp_right + dp_right->db_txt_start,
                        (char *)dp_left + dp_left->db_txt_start,
                        (size_t)data_moved);
            offset = dp_right->db_txt_start - dp_left->db_txt_start;
            dp_left->db_txt_start += data_moved;
            dp_left->db_free += total_moved;

            /*
             * update indexes in the new block
             */
            for (to = line_count_right, from = db_idx + 1;
                                         from < line_count_left; ++from, ++to)
                dp_right->db_index[to] = dp->db_index[from] + offset;
            line_count_right += lines_moved;
            line_count_left -= lines_moved;
        }

        /*
         * May move the new line into the left (old or new) block.
         */
        if (in_left)
        {
            dp_left->db_txt_start -= len;
            dp_left->db_free -= len + INDEX_SIZE;
            dp_left->db_index[line_count_left] = dp_left->db_txt_start;
            if (mark)
                dp_left->db_index[line_count_left] |= DB_MARKED;
            mch_memmove((char *)dp_left + dp_left->db_txt_start,
                                                           line, (size_t)len);
            ++line_count_left;
        }

        if (db_idx < 0)         /* left block is new */
        {
            lnum_left = lnum + 1;
            lnum_right = 0;
        }
        else                    /* right block is new */
        {
            lnum_left = 0;
            if (in_left)
                lnum_right = lnum + 2;
            else
                lnum_right = lnum + 1;
        }
        dp_left->db_line_count = line_count_left;
        dp_right->db_line_count = line_count_right;

        /*
         * release the two data blocks
         * The new one (hp_new) already has a correct blocknumber.
         * The old one (hp, in ml_locked) gets a positive blocknumber if
         * we changed it and we are not editing a new file.
         */
        if (lines_moved || in_left)
            buf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
        if (!newfile && db_idx >= 0 && in_left)
            buf->b_ml.ml_flags |= ML_LOCKED_POS;
        mf_put(mfp, hp_new, TRUE, FALSE);

        /*
         * flush the old data block
         * set ml_locked_lineadd to 0, because the updating of the
         * pointer blocks is done below
         */
        lineadd = buf->b_ml.ml_locked_lineadd;
        buf->b_ml.ml_locked_lineadd = 0;
        ml_find_line(buf, (linenr_T)0, ML_FLUSH);   /* flush data block */

        /*
         * update pointer blocks for the new data block
         */
        for (stack_idx = buf->b_ml.ml_stack_top - 1; stack_idx >= 0;
                                                                  --stack_idx)
        {
            ip = &(buf->b_ml.ml_stack[stack_idx]);
            pb_idx = ip->ip_index;
            if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
                return FAIL;
            pp = (PTR_BL *)(hp->bh_data);   /* must be pointer block */
            if (pp->pb_id != PTR_ID)
            {
                EMSG(_("E317: pointer block id wrong 3"));
                mf_put(mfp, hp, FALSE, FALSE);
                return FAIL;
            }
            /*
             * TODO: If the pointer block is full and we are adding at the end
             * try to insert in front of the next block
             */
            /* block not full, add one entry */
            if (pp->pb_count < pp->pb_count_max)
            {
                if (pb_idx + 1 < (int)pp->pb_count)
                    mch_memmove(&pp->pb_pointer[pb_idx + 2],
                                &pp->pb_pointer[pb_idx + 1],
                        (size_t)(pp->pb_count - pb_idx - 1) * sizeof(PTR_EN));
                ++pp->pb_count;
                pp->pb_pointer[pb_idx].pe_line_count = line_count_left;
                pp->pb_pointer[pb_idx].pe_bnum = bnum_left;
                pp->pb_pointer[pb_idx].pe_page_count = page_count_left;
                pp->pb_pointer[pb_idx + 1].pe_line_count = line_count_right;
                pp->pb_pointer[pb_idx + 1].pe_bnum = bnum_right;
                pp->pb_pointer[pb_idx + 1].pe_page_count = page_count_right;

                if (lnum_left != 0)
                    pp->pb_pointer[pb_idx].pe_old_lnum = lnum_left;
                if (lnum_right != 0)
                    pp->pb_pointer[pb_idx + 1].pe_old_lnum = lnum_right;

                mf_put(mfp, hp, TRUE, FALSE);
                buf->b_ml.ml_stack_top = stack_idx + 1;     /* truncate stack */

                if (lineadd)
                {
                    --(buf->b_ml.ml_stack_top);
                    /* fix line count for rest of blocks in the stack */
                    ml_lineadd(buf, lineadd);
                                                        /* fix stack itself */
                    buf->b_ml.ml_stack[buf->b_ml.ml_stack_top].ip_high +=
                                                                      lineadd;
                    ++(buf->b_ml.ml_stack_top);
                }

                /*
                 * We are finished, break the loop here.
                 */
                break;
            }
            else                        /* pointer block full */
            {
                /*
                 * split the pointer block
                 * allocate a new pointer block
                 * move some of the pointer into the new block
                 * prepare for updating the parent block
                 */
                for (;;)        /* do this twice when splitting block 1 */
                {
                    hp_new = ml_new_ptr(mfp);
                    if (hp_new == NULL)     /* TODO: try to fix tree */
                        return FAIL;
                    pp_new = (PTR_BL *)(hp_new->bh_data);

                    if (hp->bh_bnum != 1)
                        break;

                    /*
                     * if block 1 becomes full the tree is given an extra level
                     * The pointers from block 1 are moved into the new block.
                     * block 1 is updated to point to the new block
                     * then continue to split the new block
                     */
                    mch_memmove(pp_new, pp, (size_t)page_size);
                    pp->pb_count = 1;
                    pp->pb_pointer[0].pe_bnum = hp_new->bh_bnum;
                    pp->pb_pointer[0].pe_line_count = buf->b_ml.ml_line_count;
                    pp->pb_pointer[0].pe_old_lnum = 1;
                    pp->pb_pointer[0].pe_page_count = 1;
                    mf_put(mfp, hp, TRUE, FALSE);   /* release block 1 */
                    hp = hp_new;                /* new block is to be split */
                    pp = pp_new;
                    CHECK(stack_idx != 0, _("stack_idx should be 0"));
                    ip->ip_index = 0;
                    ++stack_idx;        /* do block 1 again later */
                }
                /*
                 * move the pointers after the current one to the new block
                 * If there are none, the new entry will be in the new block.
                 */
                total_moved = pp->pb_count - pb_idx - 1;
                if (total_moved)
                {
                    mch_memmove(&pp_new->pb_pointer[0],
                                &pp->pb_pointer[pb_idx + 1],
                                (size_t)(total_moved) * sizeof(PTR_EN));
                    pp_new->pb_count = total_moved;
                    pp->pb_count -= total_moved - 1;
                    pp->pb_pointer[pb_idx + 1].pe_bnum = bnum_right;
                    pp->pb_pointer[pb_idx + 1].pe_line_count = line_count_right;
                    pp->pb_pointer[pb_idx + 1].pe_page_count = page_count_right;
                    if (lnum_right)
                        pp->pb_pointer[pb_idx + 1].pe_old_lnum = lnum_right;
                }
                else
                {
                    pp_new->pb_count = 1;
                    pp_new->pb_pointer[0].pe_bnum = bnum_right;
                    pp_new->pb_pointer[0].pe_line_count = line_count_right;
                    pp_new->pb_pointer[0].pe_page_count = page_count_right;
                    pp_new->pb_pointer[0].pe_old_lnum = lnum_right;
                }
                pp->pb_pointer[pb_idx].pe_bnum = bnum_left;
                pp->pb_pointer[pb_idx].pe_line_count = line_count_left;
                pp->pb_pointer[pb_idx].pe_page_count = page_count_left;
                if (lnum_left)
                    pp->pb_pointer[pb_idx].pe_old_lnum = lnum_left;
                lnum_left = 0;
                lnum_right = 0;

                /*
                 * recompute line counts
                 */
                line_count_right = 0;
                for (i = 0; i < (int)pp_new->pb_count; ++i)
                    line_count_right += pp_new->pb_pointer[i].pe_line_count;
                line_count_left = 0;
                for (i = 0; i < (int)pp->pb_count; ++i)
                    line_count_left += pp->pb_pointer[i].pe_line_count;

                bnum_left = hp->bh_bnum;
                bnum_right = hp_new->bh_bnum;
                page_count_left = 1;
                page_count_right = 1;
                mf_put(mfp, hp, TRUE, FALSE);
                mf_put(mfp, hp_new, TRUE, FALSE);
            }
        }

        /*
         * Safety check: fallen out of for loop?
         */
        if (stack_idx < 0)
        {
            EMSG(_("E318: Updated too many blocks?"));
            buf->b_ml.ml_stack_top = 0; /* invalidate stack */
        }
    }

#ifdef FEAT_BYTEOFF
    /* The line was inserted below 'lnum' */
    ml_updatechunk(buf, lnum + 1, (long)len, ML_CHNK_ADDLINE);
#endif
#ifdef FEAT_NETBEANS_INTG
    if (usingNetbeans)
    {
        if (STRLEN(line) > 0)
            netbeans_inserted(buf, lnum+1, (colnr_T)0, line, (int)STRLEN(line));
        netbeans_inserted(buf, lnum+1, (colnr_T)STRLEN(line),
                                                           (char_u *)"\n", 1);
    }
#endif
    return OK;
}

/*
 * Replace line lnum, with buffering, in current buffer.
 *
 * If "copy" is TRUE, make a copy of the line, otherwise the line has been
 * copied to allocated memory already.
 *
 * Check: The caller of this function should probably also call
 * changed_lines(), unless update_screen(NOT_VALID) is used.
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_replace(lnum, line, copy)
    linenr_T    lnum;
    char_u      *line;
    int         copy;
{
    if (line == NULL)           /* just checking... */
        return FAIL;

    /* When starting up, we might still need to create the memfile */
    if (curbuf->b_ml.ml_mfp == NULL && open_buffer(FALSE, NULL) == FAIL)
        return FAIL;

    if (copy && (line = vim_strsave(line)) == NULL) /* allocate memory */
        return FAIL;
#ifdef FEAT_NETBEANS_INTG
    if (usingNetbeans)
    {
        netbeans_removed(curbuf, lnum, 0, (long)STRLEN(ml_get(lnum)));
        netbeans_inserted(curbuf, lnum, 0, line, (int)STRLEN(line));
    }
#endif
    if (curbuf->b_ml.ml_line_lnum != lnum)          /* other line buffered */
        ml_flush_line(curbuf);                      /* flush it */
    else if (curbuf->b_ml.ml_flags & ML_LINE_DIRTY) /* same line allocated */
        vim_free(curbuf->b_ml.ml_line_ptr);         /* free it */
    curbuf->b_ml.ml_line_ptr = line;
    curbuf->b_ml.ml_line_lnum = lnum;
    curbuf->b_ml.ml_line_max = 0;
    curbuf->b_ml.ml_flags = (curbuf->b_ml.ml_flags | ML_LINE_DIRTY) & ~ML_EMPTY;

    return OK;
}

/*
 * Delete line 'lnum' in the current buffer.
 *
 * Check: The caller of this function should probably also call
 * deleted_lines() after this.
 *
 * return FAIL for failure, OK otherwise
 */
    int
ml_delete(lnum, message)
    linenr_T    lnum;
    int         message;
{
    ml_flush_line(curbuf);
    return ml_delete_int(curbuf, lnum, message);
}

    static int
ml_delete_int(buf, lnum, message)
    buf_T       *buf;
    linenr_T    lnum;
    int         message;
{
    bhdr_T      *hp;
    memfile_T   *mfp;
    DATA_BL     *dp;
    PTR_BL      *pp;
    infoptr_T   *ip;
    int         count;      /* number of entries in block */
    int         idx;
    int         stack_idx;
    int         text_start;
    int         line_start;
    long        line_size;
    int         i;

    if (lnum < 1 || lnum > buf->b_ml.ml_line_count)
        return FAIL;

    if (lowest_marked && lowest_marked > lnum)
        lowest_marked--;

/*
 * If the file becomes empty the last line is replaced by an empty line.
 */
    if (buf->b_ml.ml_line_count == 1)       /* file becomes empty */
    {
        if (message
#ifdef FEAT_NETBEANS_INTG
                && !netbeansSuppressNoLines
#endif
           )
            set_keep_msg((char_u *)_(no_lines_msg), 0);

        /* FEAT_BYTEOFF already handled in there, dont worry 'bout it below */
        i = ml_replace((linenr_T)1, (char_u *)"", TRUE);
        buf->b_ml.ml_flags |= ML_EMPTY;

        return i;
    }

/*
 * find the data block containing the line
 * This also fills the stack with the blocks from the root to the data block
 * This also releases any locked block.
 */
    mfp = buf->b_ml.ml_mfp;
    if (mfp == NULL)
        return FAIL;

    if ((hp = ml_find_line(buf, lnum, ML_DELETE)) == NULL)
        return FAIL;

    dp = (DATA_BL *)(hp->bh_data);
    /* compute line count before the delete */
    count = (long)(buf->b_ml.ml_locked_high)
                                        - (long)(buf->b_ml.ml_locked_low) + 2;
    idx = lnum - buf->b_ml.ml_locked_low;

    --buf->b_ml.ml_line_count;

    line_start = ((dp->db_index[idx]) & DB_INDEX_MASK);
    if (idx == 0)               /* first line in block, text at the end */
        line_size = dp->db_txt_end - line_start;
    else
        line_size = ((dp->db_index[idx - 1]) & DB_INDEX_MASK) - line_start;

#ifdef FEAT_NETBEANS_INTG
    if (usingNetbeans)
        netbeans_removed(buf, lnum, 0, (long)line_size);
#endif

/*
 * special case: If there is only one line in the data block it becomes empty.
 * Then we have to remove the entry, pointing to this data block, from the
 * pointer block. If this pointer block also becomes empty, we go up another
 * block, and so on, up to the root if necessary.
 * The line counts in the pointer blocks have already been adjusted by
 * ml_find_line().
 */
    if (count == 1)
    {
        mf_free(mfp, hp);       /* free the data block */
        buf->b_ml.ml_locked = NULL;

        for (stack_idx = buf->b_ml.ml_stack_top - 1; stack_idx >= 0; --stack_idx)
        {
            buf->b_ml.ml_stack_top = 0;     /* stack is invalid when failing */
            ip = &(buf->b_ml.ml_stack[stack_idx]);
            idx = ip->ip_index;
            if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
                return FAIL;
            pp = (PTR_BL *)(hp->bh_data);   /* must be pointer block */
            if (pp->pb_id != PTR_ID)
            {
                EMSG(_("E317: pointer block id wrong 4"));
                mf_put(mfp, hp, FALSE, FALSE);
                return FAIL;
            }
            count = --(pp->pb_count);
            if (count == 0)         /* the pointer block becomes empty! */
                mf_free(mfp, hp);
            else
            {
                if (count != idx)       /* move entries after the deleted one */
                    mch_memmove(&pp->pb_pointer[idx], &pp->pb_pointer[idx + 1],
                                      (size_t)(count - idx) * sizeof(PTR_EN));
                mf_put(mfp, hp, TRUE, FALSE);

                buf->b_ml.ml_stack_top = stack_idx;     /* truncate stack */
                /* fix line count for rest of blocks in the stack */
                if (buf->b_ml.ml_locked_lineadd != 0)
                {
                    ml_lineadd(buf, buf->b_ml.ml_locked_lineadd);
                    buf->b_ml.ml_stack[buf->b_ml.ml_stack_top].ip_high +=
                                                  buf->b_ml.ml_locked_lineadd;
                }
                ++(buf->b_ml.ml_stack_top);

                break;
            }
        }
        CHECK(stack_idx < 0, _("deleted block 1?"));
    }
    else
    {
        /*
         * delete the text by moving the next lines forwards
         */
        text_start = dp->db_txt_start;
        mch_memmove((char *)dp + text_start + line_size,
                  (char *)dp + text_start, (size_t)(line_start - text_start));

        /*
         * delete the index by moving the next indexes backwards
         * Adjust the indexes for the text movement.
         */
        for (i = idx; i < count - 1; ++i)
            dp->db_index[i] = dp->db_index[i + 1] + line_size;

        dp->db_free += line_size + INDEX_SIZE;
        dp->db_txt_start += line_size;
        --(dp->db_line_count);

        /*
         * mark the block dirty and make sure it is in the file (for recovery)
         */
        buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);
    }

#ifdef FEAT_BYTEOFF
    ml_updatechunk(buf, lnum, line_size, ML_CHNK_DELLINE);
#endif
    return OK;
}

/*
 * set the B_MARKED flag for line 'lnum'
 */
    void
ml_setmarked(lnum)
    linenr_T lnum;
{
    bhdr_T    *hp;
    DATA_BL *dp;
                                    /* invalid line number */
    if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count
                                               || curbuf->b_ml.ml_mfp == NULL)
        return;                     /* give error message? */

    if (lowest_marked == 0 || lowest_marked > lnum)
        lowest_marked = lnum;

    /*
     * find the data block containing the line
     * This also fills the stack with the blocks from the root to the data block
     * This also releases any locked block.
     */
    if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
        return;             /* give error message? */

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_index[lnum - curbuf->b_ml.ml_locked_low] |= DB_MARKED;
    curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
}

/*
 * find the first line with its B_MARKED flag set
 */
    linenr_T
ml_firstmarked()
{
    bhdr_T      *hp;
    DATA_BL     *dp;
    linenr_T    lnum;
    int         i;

    if (curbuf->b_ml.ml_mfp == NULL)
        return (linenr_T) 0;

    /*
     * The search starts with lowest_marked line. This is the last line where
     * a mark was found, adjusted by inserting/deleting lines.
     */
    for (lnum = lowest_marked; lnum <= curbuf->b_ml.ml_line_count; )
    {
        /*
         * Find the data block containing the line.
         * This also fills the stack with the blocks from the root to the data
         * block This also releases any locked block.
         */
        if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
            return (linenr_T)0;             /* give error message? */

        dp = (DATA_BL *)(hp->bh_data);

        for (i = lnum - curbuf->b_ml.ml_locked_low;
                            lnum <= curbuf->b_ml.ml_locked_high; ++i, ++lnum)
            if ((dp->db_index[i]) & DB_MARKED)
            {
                (dp->db_index[i]) &= DB_INDEX_MASK;
                curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
                lowest_marked = lnum + 1;
                return lnum;
            }
    }

    return (linenr_T) 0;
}

#if 0  /* not used */
/*
 * return TRUE if line 'lnum' has a mark
 */
    int
ml_has_mark(lnum)
    linenr_T    lnum;
{
    bhdr_T      *hp;
    DATA_BL     *dp;

    if (curbuf->b_ml.ml_mfp == NULL
                        || (hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
        return FALSE;

    dp = (DATA_BL *)(hp->bh_data);
    return (int)((dp->db_index[lnum - curbuf->b_ml.ml_locked_low]) & DB_MARKED);
}
#endif

/*
 * clear all DB_MARKED flags
 */
    void
ml_clearmarked()
{
    bhdr_T      *hp;
    DATA_BL     *dp;
    linenr_T    lnum;
    int         i;

    if (curbuf->b_ml.ml_mfp == NULL)        /* nothing to do */
        return;

    /*
     * The search starts with line lowest_marked.
     */
    for (lnum = lowest_marked; lnum <= curbuf->b_ml.ml_line_count; )
    {
        /*
         * Find the data block containing the line.
         * This also fills the stack with the blocks from the root to the data
         * block and releases any locked block.
         */
        if ((hp = ml_find_line(curbuf, lnum, ML_FIND)) == NULL)
            return;             /* give error message? */

        dp = (DATA_BL *)(hp->bh_data);

        for (i = lnum - curbuf->b_ml.ml_locked_low;
                            lnum <= curbuf->b_ml.ml_locked_high; ++i, ++lnum)
            if ((dp->db_index[i]) & DB_MARKED)
            {
                (dp->db_index[i]) &= DB_INDEX_MASK;
                curbuf->b_ml.ml_flags |= ML_LOCKED_DIRTY;
            }
    }

    lowest_marked = 0;
    return;
}

/*
 * flush ml_line if necessary
 */
    static void
ml_flush_line(buf)
    buf_T       *buf;
{
    bhdr_T      *hp;
    DATA_BL     *dp;
    linenr_T    lnum;
    char_u      *new_line;
    char_u      *old_line;
    colnr_T     new_len;
    int         old_len;
    int         extra;
    int         idx;
    int         start;
    int         count;
    int         i;
    static int  entered = FALSE;

    if (buf->b_ml.ml_line_lnum == 0 || buf->b_ml.ml_mfp == NULL)
        return;         /* nothing to do */

    if (buf->b_ml.ml_flags & ML_LINE_DIRTY)
    {
        /* This code doesn't work recursively, but Netbeans may call back here
         * when obtaining the cursor position. */
        if (entered)
            return;
        entered = TRUE;

        lnum = buf->b_ml.ml_line_lnum;
        new_line = buf->b_ml.ml_line_ptr;

        hp = ml_find_line(buf, lnum, ML_FIND);
        if (hp == NULL)
            EMSGN(_("E320: Cannot find line %ld"), lnum);
        else
        {
            dp = (DATA_BL *)(hp->bh_data);
            idx = lnum - buf->b_ml.ml_locked_low;
            start = ((dp->db_index[idx]) & DB_INDEX_MASK);
            old_line = (char_u *)dp + start;
            if (idx == 0)       /* line is last in block */
                old_len = dp->db_txt_end - start;
            else                /* text of previous line follows */
                old_len = (dp->db_index[idx - 1] & DB_INDEX_MASK) - start;
            new_len = (colnr_T)STRLEN(new_line) + 1;
            extra = new_len - old_len;      /* negative if lines gets smaller */

            /*
             * if new line fits in data block, replace directly
             */
            if ((int)dp->db_free >= extra)
            {
                /* if the length changes and there are following lines */
                count = buf->b_ml.ml_locked_high - buf->b_ml.ml_locked_low + 1;
                if (extra != 0 && idx < count - 1)
                {
                    /* move text of following lines */
                    mch_memmove((char *)dp + dp->db_txt_start - extra,
                                (char *)dp + dp->db_txt_start,
                                (size_t)(start - dp->db_txt_start));

                    /* adjust pointers of this and following lines */
                    for (i = idx + 1; i < count; ++i)
                        dp->db_index[i] -= extra;
                }
                dp->db_index[idx] -= extra;

                /* adjust free space */
                dp->db_free -= extra;
                dp->db_txt_start -= extra;

                /* copy new line into the data block */
                mch_memmove(old_line - extra, new_line, (size_t)new_len);
                buf->b_ml.ml_flags |= (ML_LOCKED_DIRTY | ML_LOCKED_POS);
#ifdef FEAT_BYTEOFF
                /* The else case is already covered by the insert and delete */
                ml_updatechunk(buf, lnum, (long)extra, ML_CHNK_UPDLINE);
#endif
            }
            else
            {
                /*
                 * Cannot do it in one data block: Delete and append.
                 * Append first, because ml_delete_int() cannot delete the
                 * last line in a buffer, which causes trouble for a buffer
                 * that has only one line.
                 * Don't forget to copy the mark!
                 */
                /* How about handling errors??? */
                (void)ml_append_int(buf, lnum, new_line, new_len, FALSE,
                                             (dp->db_index[idx] & DB_MARKED));
                (void)ml_delete_int(buf, lnum, FALSE);
            }
        }
        vim_free(new_line);

        entered = FALSE;
    }

    buf->b_ml.ml_line_lnum = 0;
}

/*
 * create a new, empty, data block
 */
    static bhdr_T *
ml_new_data(mfp, negative, page_count)
    memfile_T   *mfp;
    int         negative;
    int         page_count;
{
    bhdr_T      *hp;
    DATA_BL     *dp;

    if ((hp = mf_new(mfp, negative, page_count)) == NULL)
        return NULL;

    dp = (DATA_BL *)(hp->bh_data);
    dp->db_id = DATA_ID;
    dp->db_txt_start = dp->db_txt_end = page_count * mfp->mf_page_size;
    dp->db_free = dp->db_txt_start - HEADER_SIZE;
    dp->db_line_count = 0;

    return hp;
}

/*
 * create a new, empty, pointer block
 */
    static bhdr_T *
ml_new_ptr(mfp)
    memfile_T   *mfp;
{
    bhdr_T      *hp;
    PTR_BL      *pp;

    if ((hp = mf_new(mfp, FALSE, 1)) == NULL)
        return NULL;

    pp = (PTR_BL *)(hp->bh_data);
    pp->pb_id = PTR_ID;
    pp->pb_count = 0;
    pp->pb_count_max = (short_u)((mfp->mf_page_size - sizeof(PTR_BL)) / sizeof(PTR_EN) + 1);

    return hp;
}

/*
 * lookup line 'lnum' in a memline
 *
 *   action: if ML_DELETE or ML_INSERT the line count is updated while searching
 *           if ML_FLUSH only flush a locked block
 *           if ML_FIND just find the line
 *
 * If the block was found it is locked and put in ml_locked.
 * The stack is updated to lead to the locked block. The ip_high field in
 * the stack is updated to reflect the last line in the block AFTER the
 * insert or delete, also if the pointer block has not been updated yet. But
 * if ml_locked != NULL ml_locked_lineadd must be added to ip_high.
 *
 * return: NULL for failure, pointer to block header otherwise
 */
    static bhdr_T *
ml_find_line(buf, lnum, action)
    buf_T       *buf;
    linenr_T    lnum;
    int         action;
{
    DATA_BL     *dp;
    PTR_BL      *pp;
    infoptr_T   *ip;
    bhdr_T      *hp;
    memfile_T   *mfp;
    linenr_T    t;
    blocknr_T   bnum, bnum2;
    int         dirty;
    linenr_T    low, high;
    int         top;
    int         page_count;
    int         idx;

    mfp = buf->b_ml.ml_mfp;

    /*
     * If there is a locked block check if the wanted line is in it.
     * If not, flush and release the locked block.
     * Don't do this for ML_INSERT_SAME, because the stack need to be updated.
     * Don't do this for ML_FLUSH, because we want to flush the locked block.
     * Don't do this when 'swapfile' is reset, we want to load all the blocks.
     */
    if (buf->b_ml.ml_locked)
    {
        if (ML_SIMPLE(action)
                && buf->b_ml.ml_locked_low <= lnum
                && buf->b_ml.ml_locked_high >= lnum
                && !mf_dont_release)
        {
            /* remember to update pointer blocks and stack later */
            if (action == ML_INSERT)
            {
                ++(buf->b_ml.ml_locked_lineadd);
                ++(buf->b_ml.ml_locked_high);
            }
            else if (action == ML_DELETE)
            {
                --(buf->b_ml.ml_locked_lineadd);
                --(buf->b_ml.ml_locked_high);
            }
            return (buf->b_ml.ml_locked);
        }

        mf_put(mfp, buf->b_ml.ml_locked, buf->b_ml.ml_flags & ML_LOCKED_DIRTY,
                                            buf->b_ml.ml_flags & ML_LOCKED_POS);
        buf->b_ml.ml_locked = NULL;

        /*
         * If lines have been added or deleted in the locked block, need to
         * update the line count in pointer blocks.
         */
        if (buf->b_ml.ml_locked_lineadd != 0)
            ml_lineadd(buf, buf->b_ml.ml_locked_lineadd);
    }

    if (action == ML_FLUSH)         /* nothing else to do */
        return NULL;

    bnum = 1;                       /* start at the root of the tree */
    page_count = 1;
    low = 1;
    high = buf->b_ml.ml_line_count;

    if (action == ML_FIND)      /* first try stack entries */
    {
        for (top = buf->b_ml.ml_stack_top - 1; top >= 0; --top)
        {
            ip = &(buf->b_ml.ml_stack[top]);
            if (ip->ip_low <= lnum && ip->ip_high >= lnum)
            {
                bnum = ip->ip_bnum;
                low = ip->ip_low;
                high = ip->ip_high;
                buf->b_ml.ml_stack_top = top;   /* truncate stack at prev entry */
                break;
            }
        }
        if (top < 0)
            buf->b_ml.ml_stack_top = 0;         /* not found, start at the root */
    }
    else        /* ML_DELETE or ML_INSERT */
        buf->b_ml.ml_stack_top = 0;     /* start at the root */

/*
 * search downwards in the tree until a data block is found
 */
    for (;;)
    {
        if ((hp = mf_get(mfp, bnum, page_count)) == NULL)
            goto error_noblock;

        /*
         * update high for insert/delete
         */
        if (action == ML_INSERT)
            ++high;
        else if (action == ML_DELETE)
            --high;

        dp = (DATA_BL *)(hp->bh_data);
        if (dp->db_id == DATA_ID)       /* data block */
        {
            buf->b_ml.ml_locked = hp;
            buf->b_ml.ml_locked_low = low;
            buf->b_ml.ml_locked_high = high;
            buf->b_ml.ml_locked_lineadd = 0;
            buf->b_ml.ml_flags &= ~(ML_LOCKED_DIRTY | ML_LOCKED_POS);
            return hp;
        }

        pp = (PTR_BL *)(dp);            /* must be pointer block */
        if (pp->pb_id != PTR_ID)
        {
            EMSG(_("E317: pointer block id wrong"));
            goto error_block;
        }

        if ((top = ml_add_stack(buf)) < 0)      /* add new entry to stack */
            goto error_block;
        ip = &(buf->b_ml.ml_stack[top]);
        ip->ip_bnum = bnum;
        ip->ip_low = low;
        ip->ip_high = high;
        ip->ip_index = -1;              /* index not known yet */

        dirty = FALSE;
        for (idx = 0; idx < (int)pp->pb_count; ++idx)
        {
            t = pp->pb_pointer[idx].pe_line_count;
            CHECK(t == 0, _("pe_line_count is zero"));
            if ((low += t) > lnum)
            {
                ip->ip_index = idx;
                bnum = pp->pb_pointer[idx].pe_bnum;
                page_count = pp->pb_pointer[idx].pe_page_count;
                high = low - 1;
                low -= t;

                /*
                 * a negative block number may have been changed
                 */
                if (bnum < 0)
                {
                    bnum2 = mf_trans_del(mfp, bnum);
                    if (bnum != bnum2)
                    {
                        bnum = bnum2;
                        pp->pb_pointer[idx].pe_bnum = bnum;
                        dirty = TRUE;
                    }
                }

                break;
            }
        }
        if (idx >= (int)pp->pb_count)       /* past the end: something wrong! */
        {
            if (lnum > buf->b_ml.ml_line_count)
                EMSGN(_("E322: line number out of range: %ld past the end"),
                                              lnum - buf->b_ml.ml_line_count);

            else
                EMSGN(_("E323: line count wrong in block %ld"), bnum);
            goto error_block;
        }
        if (action == ML_DELETE)
        {
            pp->pb_pointer[idx].pe_line_count--;
            dirty = TRUE;
        }
        else if (action == ML_INSERT)
        {
            pp->pb_pointer[idx].pe_line_count++;
            dirty = TRUE;
        }
        mf_put(mfp, hp, dirty, FALSE);
    }

error_block:
    mf_put(mfp, hp, FALSE, FALSE);
error_noblock:
/*
 * If action is ML_DELETE or ML_INSERT we have to correct the tree for
 * the incremented/decremented line counts, because there won't be a line
 * inserted/deleted after all.
 */
    if (action == ML_DELETE)
        ml_lineadd(buf, 1);
    else if (action == ML_INSERT)
        ml_lineadd(buf, -1);
    buf->b_ml.ml_stack_top = 0;
    return NULL;
}

/*
 * add an entry to the info pointer stack
 *
 * return -1 for failure, number of the new entry otherwise
 */
    static int
ml_add_stack(buf)
    buf_T       *buf;
{
    int         top;
    infoptr_T   *newstack;

    top = buf->b_ml.ml_stack_top;

        /* may have to increase the stack size */
    if (top == buf->b_ml.ml_stack_size)
    {
        CHECK(top > 0, _("Stack size increases"));      /* more than 5 levels??? */

        newstack = (infoptr_T *)alloc((unsigned)sizeof(infoptr_T) *
                                        (buf->b_ml.ml_stack_size + STACK_INCR));
        if (newstack == NULL)
            return -1;
        mch_memmove(newstack, buf->b_ml.ml_stack,
                                             (size_t)top * sizeof(infoptr_T));
        vim_free(buf->b_ml.ml_stack);
        buf->b_ml.ml_stack = newstack;
        buf->b_ml.ml_stack_size += STACK_INCR;
    }

    buf->b_ml.ml_stack_top++;
    return top;
}

/*
 * Update the pointer blocks on the stack for inserted/deleted lines.
 * The stack itself is also updated.
 *
 * When a insert/delete line action fails, the line is not inserted/deleted,
 * but the pointer blocks have already been updated. That is fixed here by
 * walking through the stack.
 *
 * Count is the number of lines added, negative if lines have been deleted.
 */
    static void
ml_lineadd(buf, count)
    buf_T       *buf;
    int         count;
{
    int         idx;
    infoptr_T   *ip;
    PTR_BL      *pp;
    memfile_T   *mfp = buf->b_ml.ml_mfp;
    bhdr_T      *hp;

    for (idx = buf->b_ml.ml_stack_top - 1; idx >= 0; --idx)
    {
        ip = &(buf->b_ml.ml_stack[idx]);
        if ((hp = mf_get(mfp, ip->ip_bnum, 1)) == NULL)
            break;
        pp = (PTR_BL *)(hp->bh_data);   /* must be pointer block */
        if (pp->pb_id != PTR_ID)
        {
            mf_put(mfp, hp, FALSE, FALSE);
            EMSG(_("E317: pointer block id wrong 2"));
            break;
        }
        pp->pb_pointer[ip->ip_index].pe_line_count += count;
        ip->ip_high += count;
        mf_put(mfp, hp, TRUE, FALSE);
    }
}

#ifdef HAVE_READLINK
/*
 * Resolve a symlink in the last component of a file name.
 * Note that f_resolve() does it for every part of the path, we don't do that
 * here.
 * If it worked returns OK and the resolved link in "buf[MAXPATHL]".
 * Otherwise returns FAIL.
 */
    static int
resolve_symlink(fname, buf)
    char_u      *fname;
    char_u      *buf;
{
    char_u      tmp[MAXPATHL];
    int         ret;
    int         depth = 0;

    if (fname == NULL)
        return FAIL;

    /* Put the result so far in tmp[], starting with the original name. */
    vim_strncpy(tmp, fname, MAXPATHL - 1);

    for (;;)
    {
        /* Limit symlink depth to 100, catch recursive loops. */
        if (++depth == 100)
        {
            EMSG2(_("E773: Symlink loop for \"%s\""), fname);
            return FAIL;
        }

        ret = readlink((char *)tmp, (char *)buf, MAXPATHL - 1);
        if (ret <= 0)
        {
            if (errno == EINVAL || errno == ENOENT)
            {
                /* Found non-symlink or not existing file, stop here.
                 * When at the first level use the unmodified name, skip the
                 * call to vim_FullName(). */
                if (depth == 1)
                    return FAIL;

                /* Use the resolved name in tmp[]. */
                break;
            }

            /* There must be some error reading links, use original name. */
            return FAIL;
        }
        buf[ret] = NUL;

        /*
         * Check whether the symlink is relative or absolute.
         * If it's relative, build a new path based on the directory
         * portion of the filename (if any) and the path the symlink
         * points to.
         */
        if (mch_isFullName(buf))
            STRCPY(tmp, buf);
        else
        {
            char_u *tail;

            tail = gettail(tmp);
            if (STRLEN(tail) + STRLEN(buf) >= MAXPATHL)
                return FAIL;
            STRCPY(tail, buf);
        }
    }

    /*
     * Try to resolve the full name of the file so that the swapfile name will
     * be consistent even when opening a relative symlink from different
     * working directories.
     */
    return vim_FullName(tmp, buf, MAXPATHL, TRUE);
}
#endif

/*
 * Make swap file name out of the file name and a directory name.
 * Returns pointer to allocated memory or NULL.
 */
    char_u *
makeswapname(fname, ffname, buf, dir_name)
    char_u      *fname;
    char_u      *ffname UNUSED;
    buf_T       *buf;
    char_u      *dir_name;
{
    char_u      *r, *s;
    char_u      *fname_res = fname;
#ifdef HAVE_READLINK
    char_u      fname_buf[MAXPATHL];
#endif

#if defined(UNIX) || defined(WIN3264)  /* Need _very_ long file names */
    s = dir_name + STRLEN(dir_name);
    if (after_pathsep(dir_name, s) && s[-1] == s[-2])
    {                          /* Ends with '//', Use Full path */
        r = NULL;
        if ((s = make_percent_swname(dir_name, fname)) != NULL)
        {
            r = modname(s, (char_u *)".swp", FALSE);
            vim_free(s);
        }
        return r;
    }
#endif

#ifdef HAVE_READLINK
    /* Expand symlink in the file name, so that we put the swap file with the
     * actual file instead of with the symlink. */
    if (resolve_symlink(fname, fname_buf) == OK)
        fname_res = fname_buf;
#endif

    r = buf_modname(
#ifdef SHORT_FNAME
            TRUE,
#else
            (buf->b_p_sn || buf->b_shortname),
#endif
#ifdef RISCOS
            /* Avoid problems if fname has special chars, eg <Wimp$Scrap> */
            ffname,
#else
            fname_res,
#endif
            (char_u *)
#if defined(VMS) || defined(RISCOS)
            "_swp",
#else
            ".swp",
#endif
#ifdef SHORT_FNAME              /* always 8.3 file name */
            FALSE
#else
            /* Prepend a '.' to the swap file name for the current directory. */
            dir_name[0] == '.' && dir_name[1] == NUL
#endif
               );
    if (r == NULL)          /* out of memory */
        return NULL;

    s = get_file_in_dir(r, dir_name);
    vim_free(r);
    return s;
}

/*
 * Get file name to use for swap file or backup file.
 * Use the name of the edited file "fname" and an entry in the 'dir' or 'bdir'
 * option "dname".
 * - If "dname" is ".", return "fname" (swap file in dir of file).
 * - If "dname" starts with "./", insert "dname" in "fname" (swap file
 *   relative to dir of file).
 * - Otherwise, prepend "dname" to the tail of "fname" (swap file in specific
 *   dir).
 *
 * The return value is an allocated string and can be NULL.
 */
    char_u *
get_file_in_dir(fname, dname)
    char_u  *fname;
    char_u  *dname;     /* don't use "dirname", it is a global for Alpha */
{
    char_u      *t;
    char_u      *tail;
    char_u      *retval;
    int         save_char;

    tail = gettail(fname);

    if (dname[0] == '.' && dname[1] == NUL)
        retval = vim_strsave(fname);
    else if (dname[0] == '.' && vim_ispathsep(dname[1]))
    {
        if (tail == fname)          /* no path before file name */
            retval = concat_fnames(dname + 2, tail, TRUE);
        else
        {
            save_char = *tail;
            *tail = NUL;
            t = concat_fnames(fname, dname + 2, TRUE);
            *tail = save_char;
            if (t == NULL)          /* out of memory */
                retval = NULL;
            else
            {
                retval = concat_fnames(t, tail, TRUE);
                vim_free(t);
            }
        }
    }
    else
        retval = concat_fnames(dname, tail, TRUE);

    return retval;
}

static void attention_message __ARGS((buf_T *buf, char_u *fname));

/*
 * Print the ATTENTION message: info about an existing swap file.
 */
    static void
attention_message(buf, fname)
    buf_T   *buf;       /* buffer being edited */
    char_u  *fname;     /* swap file name */
{
    struct stat st;
    time_t      x, sx;
    char        *p;

    ++no_wait_return;
    (void)EMSG(_("E325: ATTENTION"));
    MSG_PUTS(_("\nFound a swap file by the name \""));
    msg_home_replace(fname);
    MSG_PUTS("\"\n");
    sx = swapfile_info(fname);
    MSG_PUTS(_("While opening file \""));
    msg_outtrans(buf->b_fname);
    MSG_PUTS("\"\n");
    if (mch_stat((char *)buf->b_fname, &st) != -1)
    {
        MSG_PUTS(_("             dated: "));
        x = st.st_mtime;    /* Manx C can't do &st.st_mtime */
        p = ctime(&x);                      /* includes '\n' */
        if (p == NULL)
            MSG_PUTS("(invalid)\n");
        else
            MSG_PUTS(p);
        if (sx != 0 && x > sx)
            MSG_PUTS(_("      NEWER than swap file!\n"));
    }
    /* Some of these messages are long to allow translation to
     * other languages. */
    MSG_PUTS(_("\n(1) Another program may be editing the same file.\n    If this is the case, be careful not to end up with two\n    different instances of the same file when making changes.\n"));
    MSG_PUTS(_("    Quit, or continue with caution.\n"));
    MSG_PUTS(_("\n(2) An edit session for this file crashed.\n"));
    MSG_PUTS(_("    If this is the case, use \":recover\" or \"vim -r "));
    msg_outtrans(buf->b_fname);
    MSG_PUTS(_("\"\n    to recover the changes (see \":help recovery\").\n"));
    MSG_PUTS(_("    If you did this already, delete the swap file \""));
    msg_outtrans(fname);
    MSG_PUTS(_("\"\n    to avoid this message.\n"));
    cmdline_row = msg_row;
    --no_wait_return;
}

#ifdef FEAT_AUTOCMD
static int do_swapexists __ARGS((buf_T *buf, char_u *fname));

/*
 * Trigger the SwapExists autocommands.
 * Returns a value for equivalent to do_dialog() (see below):
 * 0: still need to ask for a choice
 * 1: open read-only
 * 2: edit anyway
 * 3: recover
 * 4: delete it
 * 5: quit
 * 6: abort
 */
    static int
do_swapexists(buf, fname)
    buf_T       *buf;
    char_u      *fname;
{
    set_vim_var_string(VV_SWAPNAME, fname, -1);
    set_vim_var_string(VV_SWAPCHOICE, NULL, -1);

    /* Trigger SwapExists autocommands with <afile> set to the file being
     * edited.  Disallow changing directory here. */
    ++allbuf_lock;
    apply_autocmds(EVENT_SWAPEXISTS, buf->b_fname, NULL, FALSE, NULL);
    --allbuf_lock;

    set_vim_var_string(VV_SWAPNAME, NULL, -1);

    switch (*get_vim_var_str(VV_SWAPCHOICE))
    {
        case 'o': return 1;
        case 'e': return 2;
        case 'r': return 3;
        case 'd': return 4;
        case 'q': return 5;
        case 'a': return 6;
    }

    return 0;
}
#endif

/*
 * Find out what name to use for the swap file for buffer 'buf'.
 *
 * Several names are tried to find one that does not exist
 * Returns the name in allocated memory or NULL.
 *
 * Note: If BASENAMELEN is not correct, you will get error messages for
 *       not being able to open the swap or undo file
 * Note: May trigger SwapExists autocmd, pointers may change!
 */
    static char_u *
findswapname(buf, dirp, old_fname)
    buf_T       *buf;
    char_u      **dirp;         /* pointer to list of directories */
    char_u      *old_fname;     /* don't give warning for this file name */
{
    char_u      *fname;
    int         n;
    char_u      *dir_name;
#ifdef AMIGA
    BPTR        fh;
#endif
#ifndef SHORT_FNAME
    int         r;
#endif

#if !defined(SHORT_FNAME) \
                     && ((!defined(UNIX) && !defined(OS2)) || defined(ARCHIE))
# define CREATE_DUMMY_FILE
    FILE        *dummyfd = NULL;

/*
 * If we start editing a new file, e.g. "test.doc", which resides on an MSDOS
 * compatible filesystem, it is possible that the file "test.doc.swp" which we
 * create will be exactly the same file. To avoid this problem we temporarily
 * create "test.doc".
 * Don't do this when the check below for a 8.3 file name is used.
 */
    if (!(buf->b_p_sn || buf->b_shortname) && buf->b_fname != NULL
                                             && mch_getperm(buf->b_fname) < 0)
        dummyfd = mch_fopen((char *)buf->b_fname, "w");
#endif

/*
 * Isolate a directory name from *dirp and put it in dir_name.
 * First allocate some memory to put the directory name in.
 */
    dir_name = alloc((unsigned)STRLEN(*dirp) + 1);
    if (dir_name != NULL)
        (void)copy_option_part(dirp, dir_name, 31000, ",");

/*
 * we try different names until we find one that does not exist yet
 */
    if (dir_name == NULL)           /* out of memory */
        fname = NULL;
    else
        fname = makeswapname(buf->b_fname, buf->b_ffname, buf, dir_name);

    for (;;)
    {
        if (fname == NULL)      /* must be out of memory */
            break;
        if ((n = (int)STRLEN(fname)) == 0)      /* safety check */
        {
            vim_free(fname);
            fname = NULL;
            break;
        }
#if (defined(UNIX) || defined(OS2)) && !defined(ARCHIE) && !defined(SHORT_FNAME)
/*
 * Some systems have a MS-DOS compatible filesystem that use 8.3 character
 * file names. If this is the first try and the swap file name does not fit in
 * 8.3, detect if this is the case, set shortname and try again.
 */
        if (fname[n - 2] == 'w' && fname[n - 1] == 'p'
                                        && !(buf->b_p_sn || buf->b_shortname))
        {
            char_u          *tail;
            char_u          *fname2;
            struct stat     s1, s2;
            int             f1, f2;
            int             created1 = FALSE, created2 = FALSE;
            int             same = FALSE;

            /*
             * Check if swapfile name does not fit in 8.3:
             * It either contains two dots, is longer than 8 chars, or starts
             * with a dot.
             */
            tail = gettail(buf->b_fname);
            if (       vim_strchr(tail, '.') != NULL
                    || STRLEN(tail) > (size_t)8
                    || *gettail(fname) == '.')
            {
                fname2 = alloc(n + 2);
                if (fname2 != NULL)
                {
                    STRCPY(fname2, fname);
                    /* if fname == "xx.xx.swp",     fname2 = "xx.xx.swx"
                     * if fname == ".xx.swp",       fname2 = ".xx.swpx"
                     * if fname == "123456789.swp", fname2 = "12345678x.swp"
                     */
                    if (vim_strchr(tail, '.') != NULL)
                        fname2[n - 1] = 'x';
                    else if (*gettail(fname) == '.')
                    {
                        fname2[n] = 'x';
                        fname2[n + 1] = NUL;
                    }
                    else
                        fname2[n - 5] += 1;
                    /*
                     * may need to create the files to be able to use mch_stat()
                     */
                    f1 = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
                    if (f1 < 0)
                    {
                        f1 = mch_open_rw((char *)fname,
                                               O_RDWR|O_CREAT|O_EXCL|O_EXTRA);
#if defined(OS2)
                        if (f1 < 0 && errno == ENOENT)
                            same = TRUE;
#endif
                        created1 = TRUE;
                    }
                    if (f1 >= 0)
                    {
                        f2 = mch_open((char *)fname2, O_RDONLY | O_EXTRA, 0);
                        if (f2 < 0)
                        {
                            f2 = mch_open_rw((char *)fname2,
                                               O_RDWR|O_CREAT|O_EXCL|O_EXTRA);
                            created2 = TRUE;
                        }
                        if (f2 >= 0)
                        {
                            /*
                             * Both files exist now. If mch_stat() returns the
                             * same device and inode they are the same file.
                             */
                            if (mch_fstat(f1, &s1) != -1
                                    && mch_fstat(f2, &s2) != -1
                                    && s1.st_dev == s2.st_dev
                                    && s1.st_ino == s2.st_ino)
                                same = TRUE;
                            close(f2);
                            if (created2)
                                mch_remove(fname2);
                        }
                        close(f1);
                        if (created1)
                            mch_remove(fname);
                    }
                    vim_free(fname2);
                    if (same)
                    {
                        buf->b_shortname = TRUE;
                        vim_free(fname);
                        fname = makeswapname(buf->b_fname, buf->b_ffname,
                                                               buf, dir_name);
                        continue;       /* try again with b_shortname set */
                    }
                }
            }
        }
#endif
        /*
         * check if the swapfile already exists
         */
        if (mch_getperm(fname) < 0)     /* it does not exist */
        {
#ifdef HAVE_LSTAT
            struct stat sb;

            /*
             * Extra security check: When a swap file is a symbolic link, this
             * is most likely a symlink attack.
             */
            if (mch_lstat((char *)fname, &sb) < 0)
#else
# ifdef AMIGA
            fh = Open((UBYTE *)fname, (long)MODE_NEWFILE);
            /*
             * on the Amiga mch_getperm() will return -1 when the file exists
             * but is being used by another program. This happens if you edit
             * a file twice.
             */
            if (fh != (BPTR)NULL)       /* can open file, OK */
            {
                Close(fh);
                mch_remove(fname);
                break;
            }
            if (IoErr() != ERROR_OBJECT_IN_USE
                                            && IoErr() != ERROR_OBJECT_EXISTS)
# endif
#endif
                break;
        }

        /*
         * A file name equal to old_fname is OK to use.
         */
        if (old_fname != NULL && fnamecmp(fname, old_fname) == 0)
            break;

        /*
         * get here when file already exists
         */
        if (fname[n - 2] == 'w' && fname[n - 1] == 'p') /* first try */
        {
#ifndef SHORT_FNAME
            /*
             * on MS-DOS compatible filesystems (e.g. messydos) file.doc.swp
             * and file.doc are the same file. To guess if this problem is
             * present try if file.doc.swx exists. If it does, we set
             * buf->b_shortname and try file_doc.swp (dots replaced by
             * underscores for this file), and try again. If it doesn't we
             * assume that "file.doc.swp" already exists.
             */
            if (!(buf->b_p_sn || buf->b_shortname))     /* not tried yet */
            {
                fname[n - 1] = 'x';
                r = mch_getperm(fname);         /* try "file.swx" */
                fname[n - 1] = 'p';
                if (r >= 0)                 /* "file.swx" seems to exist */
                {
                    buf->b_shortname = TRUE;
                    vim_free(fname);
                    fname = makeswapname(buf->b_fname, buf->b_ffname,
                                                               buf, dir_name);
                    continue;       /* try again with '.' replaced with '_' */
                }
            }
#endif
            /*
             * If we get here the ".swp" file really exists.
             * Give an error message, unless recovering, no file name, we are
             * viewing a help file or when the path of the file is different
             * (happens when all .swp files are in one directory).
             */
            if (!recoverymode && buf->b_fname != NULL
                                && !buf->b_help && !(buf->b_flags & BF_DUMMY))
            {
                int             fd;
                struct block0   b0;
                int             differ = FALSE;

                /*
                 * Try to read block 0 from the swap file to get the original
                 * file name (and inode number).
                 */
                fd = mch_open((char *)fname, O_RDONLY | O_EXTRA, 0);
                if (fd >= 0)
                {
                    if (read(fd, (char *)&b0, sizeof(b0)) == sizeof(b0))
                    {
                        /*
                         * If the swapfile has the same directory as the
                         * buffer don't compare the directory names, they can
                         * have a different mountpoint.
                         */
                        if (b0.b0_flags & B0_SAME_DIR)
                        {
                            if (fnamecmp(gettail(buf->b_ffname),
                                                   gettail(b0.b0_fname)) != 0
                                    || !same_directory(fname, buf->b_ffname))
                            {
#ifdef CHECK_INODE
                                /* Symlinks may point to the same file even
                                 * when the name differs, need to check the
                                 * inode too. */
                                expand_env(b0.b0_fname, NameBuff, MAXPATHL);
                                if (fnamecmp_ino(buf->b_ffname, NameBuff,
                                                     char_to_long(b0.b0_ino)))
#endif
                                    differ = TRUE;
                            }
                        }
                        else
                        {
                            /*
                             * The name in the swap file may be
                             * "~user/path/file".  Expand it first.
                             */
                            expand_env(b0.b0_fname, NameBuff, MAXPATHL);
#ifdef CHECK_INODE
                            if (fnamecmp_ino(buf->b_ffname, NameBuff,
                                                     char_to_long(b0.b0_ino)))
                                differ = TRUE;
#else
                            if (fnamecmp(NameBuff, buf->b_ffname) != 0)
                                differ = TRUE;
#endif
                        }
                    }
                    close(fd);
                }
#ifdef RISCOS
                else
                    /* Can't open swap file, though it does exist.
                     * Assume that the user is editing two files with
                     * the same name in different directories. No error.
                     */
                    differ = TRUE;
#endif

                /* give the ATTENTION message when there is an old swap file
                 * for the current file, and the buffer was not recovered. */
                if (differ == FALSE && !(curbuf->b_flags & BF_RECOVERED)
                        && vim_strchr(p_shm, SHM_ATTENTION) == NULL)
                {
#if defined(HAS_SWAP_EXISTS_ACTION)
                    int         choice = 0;
#endif
#ifdef CREATE_DUMMY_FILE
                    int         did_use_dummy = FALSE;

                    /* Avoid getting a warning for the file being created
                     * outside of Vim, it was created at the start of this
                     * function.  Delete the file now, because Vim might exit
                     * here if the window is closed. */
                    if (dummyfd != NULL)
                    {
                        fclose(dummyfd);
                        dummyfd = NULL;
                        mch_remove(buf->b_fname);
                        did_use_dummy = TRUE;
                    }
#endif

#if (defined(UNIX) || defined(__EMX__) || defined(VMS)) && (defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG))
                    process_still_running = FALSE;
#endif
#ifdef FEAT_AUTOCMD
                    /*
                     * If there is an SwapExists autocommand and we can handle
                     * the response, trigger it.  It may return 0 to ask the
                     * user anyway.
                     */
                    if (swap_exists_action != SEA_NONE
                            && has_autocmd(EVENT_SWAPEXISTS, buf->b_fname, buf))
                        choice = do_swapexists(buf, fname);

                    if (choice == 0)
#endif
                    {
#ifdef FEAT_GUI
                        /* If we are supposed to start the GUI but it wasn't
                         * completely started yet, start it now.  This makes
                         * the messages displayed in the Vim window when
                         * loading a session from the .gvimrc file. */
                        if (gui.starting && !gui.in_use)
                            gui_start();
#endif
                        /* Show info about the existing swap file. */
                        attention_message(buf, fname);

                        /* We don't want a 'q' typed at the more-prompt
                         * interrupt loading a file. */
                        got_int = FALSE;
                    }

#if defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG)
                    if (swap_exists_action != SEA_NONE && choice == 0)
                    {
                        char_u  *name;

                        name = alloc((unsigned)(STRLEN(fname)
                                + STRLEN(_("Swap file \""))
                                + STRLEN(_("\" already exists!")) + 5));
                        if (name != NULL)
                        {
                            STRCPY(name, _("Swap file \""));
                            home_replace(NULL, fname, name + STRLEN(name),
                                                                  1000, TRUE);
                            STRCAT(name, _("\" already exists!"));
                        }
                        choice = do_dialog(VIM_WARNING,
                                    (char_u *)_("VIM - ATTENTION"),
                                    name == NULL
                                        ?  (char_u *)_("Swap file already exists!")
                                        : name,
# if defined(UNIX) || defined(__EMX__) || defined(VMS)
                                    process_still_running
                                        ? (char_u *)_("&Open Read-Only\n&Edit anyway\n&Recover\n&Quit\n&Abort") :
# endif
                                        (char_u *)_("&Open Read-Only\n&Edit anyway\n&Recover\n&Delete it\n&Quit\n&Abort"), 1, NULL);

# if defined(UNIX) || defined(__EMX__) || defined(VMS)
                        if (process_still_running && choice >= 4)
                            choice++;   /* Skip missing "Delete it" button */
# endif
                        vim_free(name);

                        /* pretend screen didn't scroll, need redraw anyway */
                        msg_scrolled = 0;
                        redraw_all_later(NOT_VALID);
                    }
#endif

#if defined(HAS_SWAP_EXISTS_ACTION)
                    if (choice > 0)
                    {
                        switch (choice)
                        {
                            case 1:
                                buf->b_p_ro = TRUE;
                                break;
                            case 2:
                                break;
                            case 3:
                                swap_exists_action = SEA_RECOVER;
                                break;
                            case 4:
                                mch_remove(fname);
                                break;
                            case 5:
                                swap_exists_action = SEA_QUIT;
                                break;
                            case 6:
                                swap_exists_action = SEA_QUIT;
                                got_int = TRUE;
                                break;
                        }

                        /* If the file was deleted this fname can be used. */
                        if (mch_getperm(fname) < 0)
                            break;
                    }
                    else
#endif
                    {
                        MSG_PUTS("\n");
                        if (msg_silent == 0)
                            /* call wait_return() later */
                            need_wait_return = TRUE;
                    }

#ifdef CREATE_DUMMY_FILE
                    /* Going to try another name, need the dummy file again. */
                    if (did_use_dummy)
                        dummyfd = mch_fopen((char *)buf->b_fname, "w");
#endif
                }
            }
        }

        /*
         * Change the ".swp" extension to find another file that can be used.
         * First decrement the last char: ".swo", ".swn", etc.
         * If that still isn't enough decrement the last but one char: ".svz"
         * Can happen when editing many "No Name" buffers.
         */
        if (fname[n - 1] == 'a')        /* ".s?a" */
        {
            if (fname[n - 2] == 'a')    /* ".saa": tried enough, give up */
            {
                EMSG(_("E326: Too many swap files found"));
                vim_free(fname);
                fname = NULL;
                break;
            }
            --fname[n - 2];             /* ".svz", ".suz", etc. */
            fname[n - 1] = 'z' + 1;
        }
        --fname[n - 1];                 /* ".swo", ".swn", etc. */
    }

    vim_free(dir_name);
#ifdef CREATE_DUMMY_FILE
    if (dummyfd != NULL)        /* file has been created temporarily */
    {
        fclose(dummyfd);
        mch_remove(buf->b_fname);
    }
#endif
    return fname;
}

    static int
b0_magic_wrong(b0p)
    ZERO_BL *b0p;
{
    return (b0p->b0_magic_long != (long)B0_MAGIC_LONG
            || b0p->b0_magic_int != (int)B0_MAGIC_INT
            || b0p->b0_magic_short != (short)B0_MAGIC_SHORT
            || b0p->b0_magic_char != B0_MAGIC_CHAR);
}

#ifdef CHECK_INODE
/*
 * Compare current file name with file name from swap file.
 * Try to use inode numbers when possible.
 * Return non-zero when files are different.
 *
 * When comparing file names a few things have to be taken into consideration:
 * - When working over a network the full path of a file depends on the host.
 *   We check the inode number if possible.  It is not 100% reliable though,
 *   because the device number cannot be used over a network.
 * - When a file does not exist yet (editing a new file) there is no inode
 *   number.
 * - The file name in a swap file may not be valid on the current host.  The
 *   "~user" form is used whenever possible to avoid this.
 *
 * This is getting complicated, let's make a table:
 *
 *              ino_c  ino_s  fname_c  fname_s  differ =
 *
 * both files exist -> compare inode numbers:
 *              != 0   != 0     X        X      ino_c != ino_s
 *
 * inode number(s) unknown, file names available -> compare file names
 *              == 0    X       OK       OK     fname_c != fname_s
 *               X     == 0     OK       OK     fname_c != fname_s
 *
 * current file doesn't exist, file for swap file exist, file name(s) not
 * available -> probably different
 *              == 0   != 0    FAIL      X      TRUE
 *              == 0   != 0     X       FAIL    TRUE
 *
 * current file exists, inode for swap unknown, file name(s) not
 * available -> probably different
 *              != 0   == 0    FAIL      X      TRUE
 *              != 0   == 0     X       FAIL    TRUE
 *
 * current file doesn't exist, inode for swap unknown, one file name not
 * available -> probably different
 *              == 0   == 0    FAIL      OK     TRUE
 *              == 0   == 0     OK      FAIL    TRUE
 *
 * current file doesn't exist, inode for swap unknown, both file names not
 * available -> probably same file
 *              == 0   == 0    FAIL     FAIL    FALSE
 *
 * Note that when the ino_t is 64 bits, only the last 32 will be used.  This
 * can't be changed without making the block 0 incompatible with 32 bit
 * versions.
 */

    static int
fnamecmp_ino(fname_c, fname_s, ino_block0)
    char_u      *fname_c;           /* current file name */
    char_u      *fname_s;           /* file name from swap file */
    long        ino_block0;
{
    struct stat st;
    ino_t       ino_c = 0;          /* ino of current file */
    ino_t       ino_s;              /* ino of file from swap file */
    char_u      buf_c[MAXPATHL];    /* full path of fname_c */
    char_u      buf_s[MAXPATHL];    /* full path of fname_s */
    int         retval_c;           /* flag: buf_c valid */
    int         retval_s;           /* flag: buf_s valid */

    if (mch_stat((char *)fname_c, &st) == 0)
        ino_c = (ino_t)st.st_ino;

    /*
     * First we try to get the inode from the file name, because the inode in
     * the swap file may be outdated.  If that fails (e.g. this path is not
     * valid on this machine), use the inode from block 0.
     */
    if (mch_stat((char *)fname_s, &st) == 0)
        ino_s = (ino_t)st.st_ino;
    else
        ino_s = (ino_t)ino_block0;

    if (ino_c && ino_s)
        return (ino_c != ino_s);

    /*
     * One of the inode numbers is unknown, try a forced vim_FullName() and
     * compare the file names.
     */
    retval_c = vim_FullName(fname_c, buf_c, MAXPATHL, TRUE);
    retval_s = vim_FullName(fname_s, buf_s, MAXPATHL, TRUE);
    if (retval_c == OK && retval_s == OK)
        return (STRCMP(buf_c, buf_s) != 0);

    /*
     * Can't compare inodes or file names, guess that the files are different,
     * unless both appear not to exist at all.
     */
    if (ino_s == 0 && ino_c == 0 && retval_c == FAIL && retval_s == FAIL)
        return FALSE;
    return TRUE;
}
#endif /* CHECK_INODE */

/*
 * Move a long integer into a four byte character array.
 * Used for machine independency in block zero.
 */
    static void
long_to_char(n, s)
    long    n;
    char_u  *s;
{
    s[0] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[1] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[2] = (char_u)(n & 0xff);
    n = (unsigned)n >> 8;
    s[3] = (char_u)(n & 0xff);
}

    static long
char_to_long(s)
    char_u  *s;
{
    long    retval;

    retval = s[3];
    retval <<= 8;
    retval |= s[2];
    retval <<= 8;
    retval |= s[1];
    retval <<= 8;
    retval |= s[0];

    return retval;
}

/*
 * Set the flags in the first block of the swap file:
 * - file is modified or not: buf->b_changed
 * - 'fileformat'
 * - 'fileencoding'
 */
    void
ml_setflags(buf)
    buf_T       *buf;
{
    bhdr_T      *hp;
    ZERO_BL     *b0p;

    if (!buf->b_ml.ml_mfp)
        return;
    for (hp = buf->b_ml.ml_mfp->mf_used_last; hp != NULL; hp = hp->bh_prev)
    {
        if (hp->bh_bnum == 0)
        {
            b0p = (ZERO_BL *)(hp->bh_data);
            b0p->b0_dirty = buf->b_changed ? B0_DIRTY : 0;
            b0p->b0_flags = (b0p->b0_flags & ~B0_FF_MASK)
                                                  | (get_fileformat(buf) + 1);
#ifdef FEAT_MBYTE
            add_b0_fenc(b0p, buf);
#endif
            hp->bh_flags |= BH_DIRTY;
            mf_sync(buf->b_ml.ml_mfp, MFS_ZERO);
            break;
        }
    }
}

#if defined(FEAT_BYTEOFF) || defined(PROTO)

#define MLCS_MAXL 800   /* max no of lines in chunk */
#define MLCS_MINL 400   /* should be half of MLCS_MAXL */

/*
 * Keep information for finding byte offset of a line, updtytpe may be one of:
 * ML_CHNK_ADDLINE: Add len to parent chunk, possibly splitting it
 *         Careful: ML_CHNK_ADDLINE may cause ml_find_line() to be called.
 * ML_CHNK_DELLINE: Subtract len from parent chunk, possibly deleting it
 * ML_CHNK_UPDLINE: Add len to parent chunk, as a signed entity.
 */
    static void
ml_updatechunk(buf, line, len, updtype)
    buf_T       *buf;
    linenr_T    line;
    long        len;
    int         updtype;
{
    static buf_T        *ml_upd_lastbuf = NULL;
    static linenr_T     ml_upd_lastline;
    static linenr_T     ml_upd_lastcurline;
    static int          ml_upd_lastcurix;

    linenr_T            curline = ml_upd_lastcurline;
    int                 curix = ml_upd_lastcurix;
    long                size;
    chunksize_T         *curchnk;
    int                 rest;
    bhdr_T              *hp;
    DATA_BL             *dp;

    if (buf->b_ml.ml_usedchunks == -1 || len == 0)
        return;
    if (buf->b_ml.ml_chunksize == NULL)
    {
        buf->b_ml.ml_chunksize = (chunksize_T *)
                                  alloc((unsigned)sizeof(chunksize_T) * 100);
        if (buf->b_ml.ml_chunksize == NULL)
        {
            buf->b_ml.ml_usedchunks = -1;
            return;
        }
        buf->b_ml.ml_numchunks = 100;
        buf->b_ml.ml_usedchunks = 1;
        buf->b_ml.ml_chunksize[0].mlcs_numlines = 1;
        buf->b_ml.ml_chunksize[0].mlcs_totalsize = 1;
    }

    if (updtype == ML_CHNK_UPDLINE && buf->b_ml.ml_line_count == 1)
    {
        /*
         * First line in empty buffer from ml_flush_line() -- reset
         */
        buf->b_ml.ml_usedchunks = 1;
        buf->b_ml.ml_chunksize[0].mlcs_numlines = 1;
        buf->b_ml.ml_chunksize[0].mlcs_totalsize =
                                  (long)STRLEN(buf->b_ml.ml_line_ptr) + 1;
        return;
    }

    /*
     * Find chunk that our line belongs to, curline will be at start of the
     * chunk.
     */
    if (buf != ml_upd_lastbuf || line != ml_upd_lastline + 1
            || updtype != ML_CHNK_ADDLINE)
    {
        for (curline = 1, curix = 0;
             curix < buf->b_ml.ml_usedchunks - 1
             && line >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines;
             curix++)
        {
            curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
        }
    }
    else if (line >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines
                 && curix < buf->b_ml.ml_usedchunks - 1)
    {
        /* Adjust cached curix & curline */
        curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
        curix++;
    }
    curchnk = buf->b_ml.ml_chunksize + curix;

    if (updtype == ML_CHNK_DELLINE)
        len = -len;
    curchnk->mlcs_totalsize += len;
    if (updtype == ML_CHNK_ADDLINE)
    {
        curchnk->mlcs_numlines++;

        /* May resize here so we don't have to do it in both cases below */
        if (buf->b_ml.ml_usedchunks + 1 >= buf->b_ml.ml_numchunks)
        {
            buf->b_ml.ml_numchunks = buf->b_ml.ml_numchunks * 3 / 2;
            buf->b_ml.ml_chunksize = (chunksize_T *)
                vim_realloc(buf->b_ml.ml_chunksize,
                            sizeof(chunksize_T) * buf->b_ml.ml_numchunks);
            if (buf->b_ml.ml_chunksize == NULL)
            {
                /* Hmmmm, Give up on offset for this buffer */
                buf->b_ml.ml_usedchunks = -1;
                return;
            }
        }

        if (buf->b_ml.ml_chunksize[curix].mlcs_numlines >= MLCS_MAXL)
        {
            int     count;          /* number of entries in block */
            int     idx;
            int     text_end;
            int     linecnt;

            mch_memmove(buf->b_ml.ml_chunksize + curix + 1,
                        buf->b_ml.ml_chunksize + curix,
                        (buf->b_ml.ml_usedchunks - curix) *
                        sizeof(chunksize_T));
            /* Compute length of first half of lines in the split chunk */
            size = 0;
            linecnt = 0;
            while (curline < buf->b_ml.ml_line_count
                        && linecnt < MLCS_MINL)
            {
                if ((hp = ml_find_line(buf, curline, ML_FIND)) == NULL)
                {
                    buf->b_ml.ml_usedchunks = -1;
                    return;
                }
                dp = (DATA_BL *)(hp->bh_data);
                count = (long)(buf->b_ml.ml_locked_high) -
                        (long)(buf->b_ml.ml_locked_low) + 1;
                idx = curline - buf->b_ml.ml_locked_low;
                curline = buf->b_ml.ml_locked_high + 1;
                if (idx == 0)/* first line in block, text at the end */
                    text_end = dp->db_txt_end;
                else
                    text_end = ((dp->db_index[idx - 1]) & DB_INDEX_MASK);
                /* Compute index of last line to use in this MEMLINE */
                rest = count - idx;
                if (linecnt + rest > MLCS_MINL)
                {
                    idx += MLCS_MINL - linecnt - 1;
                    linecnt = MLCS_MINL;
                }
                else
                {
                    idx = count - 1;
                    linecnt += rest;
                }
                size += text_end - ((dp->db_index[idx]) & DB_INDEX_MASK);
            }
            buf->b_ml.ml_chunksize[curix].mlcs_numlines = linecnt;
            buf->b_ml.ml_chunksize[curix + 1].mlcs_numlines -= linecnt;
            buf->b_ml.ml_chunksize[curix].mlcs_totalsize = size;
            buf->b_ml.ml_chunksize[curix + 1].mlcs_totalsize -= size;
            buf->b_ml.ml_usedchunks++;
            ml_upd_lastbuf = NULL;   /* Force recalc of curix & curline */
            return;
        }
        else if (buf->b_ml.ml_chunksize[curix].mlcs_numlines >= MLCS_MINL
                     && curix == buf->b_ml.ml_usedchunks - 1
                     && buf->b_ml.ml_line_count - line <= 1)
        {
            /*
             * We are in the last chunk and it is cheap to crate a new one
             * after this. Do it now to avoid the loop above later on
             */
            curchnk = buf->b_ml.ml_chunksize + curix + 1;
            buf->b_ml.ml_usedchunks++;
            if (line == buf->b_ml.ml_line_count)
            {
                curchnk->mlcs_numlines = 0;
                curchnk->mlcs_totalsize = 0;
            }
            else
            {
                /*
                 * Line is just prior to last, move count for last
                 * This is the common case  when loading a new file
                 */
                hp = ml_find_line(buf, buf->b_ml.ml_line_count, ML_FIND);
                if (hp == NULL)
                {
                    buf->b_ml.ml_usedchunks = -1;
                    return;
                }
                dp = (DATA_BL *)(hp->bh_data);
                if (dp->db_line_count == 1)
                    rest = dp->db_txt_end - dp->db_txt_start;
                else
                    rest =
                        ((dp->db_index[dp->db_line_count - 2]) & DB_INDEX_MASK)
                        - dp->db_txt_start;
                curchnk->mlcs_totalsize = rest;
                curchnk->mlcs_numlines = 1;
                curchnk[-1].mlcs_totalsize -= rest;
                curchnk[-1].mlcs_numlines -= 1;
            }
        }
    }
    else if (updtype == ML_CHNK_DELLINE)
    {
        curchnk->mlcs_numlines--;
        ml_upd_lastbuf = NULL;   /* Force recalc of curix & curline */
        if (curix < (buf->b_ml.ml_usedchunks - 1)
                && (curchnk->mlcs_numlines + curchnk[1].mlcs_numlines)
                   <= MLCS_MINL)
        {
            curix++;
            curchnk = buf->b_ml.ml_chunksize + curix;
        }
        else if (curix == 0 && curchnk->mlcs_numlines <= 0)
        {
            buf->b_ml.ml_usedchunks--;
            mch_memmove(buf->b_ml.ml_chunksize, buf->b_ml.ml_chunksize + 1,
                        buf->b_ml.ml_usedchunks * sizeof(chunksize_T));
            return;
        }
        else if (curix == 0 || (curchnk->mlcs_numlines > 10
                    && (curchnk->mlcs_numlines + curchnk[-1].mlcs_numlines)
                       > MLCS_MINL))
        {
            return;
        }

        /* Collapse chunks */
        curchnk[-1].mlcs_numlines += curchnk->mlcs_numlines;
        curchnk[-1].mlcs_totalsize += curchnk->mlcs_totalsize;
        buf->b_ml.ml_usedchunks--;
        if (curix < buf->b_ml.ml_usedchunks)
        {
            mch_memmove(buf->b_ml.ml_chunksize + curix,
                        buf->b_ml.ml_chunksize + curix + 1,
                        (buf->b_ml.ml_usedchunks - curix) *
                        sizeof(chunksize_T));
        }
        return;
    }
    ml_upd_lastbuf = buf;
    ml_upd_lastline = line;
    ml_upd_lastcurline = curline;
    ml_upd_lastcurix = curix;
}

/*
 * Find offset for line or line with offset.
 * Find line with offset if "lnum" is 0; return remaining offset in offp
 * Find offset of line if "lnum" > 0
 * return -1 if information is not available
 */
    long
ml_find_line_or_offset(buf, lnum, offp)
    buf_T       *buf;
    linenr_T    lnum;
    long        *offp;
{
    linenr_T    curline;
    int         curix;
    long        size;
    bhdr_T      *hp;
    DATA_BL     *dp;
    int         count;          /* number of entries in block */
    int         idx;
    int         start_idx;
    int         text_end;
    long        offset;
    int         len;
    int         ffdos = (get_fileformat(buf) == EOL_DOS);
    int         extra = 0;

    /* take care of cached line first */
    ml_flush_line(curbuf);

    if (buf->b_ml.ml_usedchunks == -1
            || buf->b_ml.ml_chunksize == NULL
            || lnum < 0)
        return -1;

    if (offp == NULL)
        offset = 0;
    else
        offset = *offp;
    if (lnum == 0 && offset <= 0)
        return 1;   /* Not a "find offset" and offset 0 _must_ be in line 1 */
    /*
     * Find the last chunk before the one containing our line. Last chunk is
     * special because it will never qualify
     */
    curline = 1;
    curix = size = 0;
    while (curix < buf->b_ml.ml_usedchunks - 1
            && ((lnum != 0
             && lnum >= curline + buf->b_ml.ml_chunksize[curix].mlcs_numlines)
                || (offset != 0
               && offset > size + buf->b_ml.ml_chunksize[curix].mlcs_totalsize
                      + ffdos * buf->b_ml.ml_chunksize[curix].mlcs_numlines)))
    {
        curline += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
        size += buf->b_ml.ml_chunksize[curix].mlcs_totalsize;
        if (offset && ffdos)
            size += buf->b_ml.ml_chunksize[curix].mlcs_numlines;
        curix++;
    }

    while ((lnum != 0 && curline < lnum) || (offset != 0 && size < offset))
    {
        if (curline > buf->b_ml.ml_line_count
                || (hp = ml_find_line(buf, curline, ML_FIND)) == NULL)
            return -1;
        dp = (DATA_BL *)(hp->bh_data);
        count = (long)(buf->b_ml.ml_locked_high) -
                (long)(buf->b_ml.ml_locked_low) + 1;
        start_idx = idx = curline - buf->b_ml.ml_locked_low;
        if (idx == 0)/* first line in block, text at the end */
            text_end = dp->db_txt_end;
        else
            text_end = ((dp->db_index[idx - 1]) & DB_INDEX_MASK);
        /* Compute index of last line to use in this MEMLINE */
        if (lnum != 0)
        {
            if (curline + (count - idx) >= lnum)
                idx += lnum - curline - 1;
            else
                idx = count - 1;
        }
        else
        {
            extra = 0;
            while (offset >= size
                       + text_end - (int)((dp->db_index[idx]) & DB_INDEX_MASK)
                                                                      + ffdos)
            {
                if (ffdos)
                    size++;
                if (idx == count - 1)
                {
                    extra = 1;
                    break;
                }
                idx++;
            }
        }
        len = text_end - ((dp->db_index[idx]) & DB_INDEX_MASK);
        size += len;
        if (offset != 0 && size >= offset)
        {
            if (size + ffdos == offset)
                *offp = 0;
            else if (idx == start_idx)
                *offp = offset - size + len;
            else
                *offp = offset - size + len
                     - (text_end - ((dp->db_index[idx - 1]) & DB_INDEX_MASK));
            curline += idx - start_idx + extra;
            if (curline > buf->b_ml.ml_line_count)
                return -1;      /* exactly one byte beyond the end */
            return curline;
        }
        curline = buf->b_ml.ml_locked_high + 1;
    }

    if (lnum != 0)
    {
        /* Count extra CR characters. */
        if (ffdos)
            size += lnum - 1;

        /* Don't count the last line break if 'bin' and 'noeol'. */
        if (buf->b_p_bin && !buf->b_p_eol)
            size -= ffdos + 1;
    }

    return size;
}

/*
 * Goto byte in buffer with offset 'cnt'.
 */
    void
goto_byte(cnt)
    long        cnt;
{
    long        boff = cnt;
    linenr_T    lnum;

    ml_flush_line(curbuf);      /* cached line may be dirty */
    setpcmark();
    if (boff)
        --boff;
    lnum = ml_find_line_or_offset(curbuf, (linenr_T)0, &boff);
    if (lnum < 1)       /* past the end */
    {
        curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
        curwin->w_curswant = MAXCOL;
        coladvance((colnr_T)MAXCOL);
    }
    else
    {
        curwin->w_cursor.lnum = lnum;
        curwin->w_cursor.col = (colnr_T)boff;
# ifdef FEAT_VIRTUALEDIT
        curwin->w_cursor.coladd = 0;
# endif
        curwin->w_set_curswant = TRUE;
    }
    check_cursor();

# ifdef FEAT_MBYTE
    /* Make sure the cursor is on the first byte of a multi-byte char. */
    if (has_mbyte)
        mb_adjust_cursor();
# endif
}
#endif