* Do not define _BSD_SOURCE but define _DEFAULT_SOURCE instead.

[alpine.git] / imap / src / osdep / unix / mmdf.c

/* ========================================================================
 * Copyright 1988-2008 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 
 * ========================================================================
 */

/*
 * Program:     MMDF mail routines
 *
 * Author:      Mark Crispin
 *              UW Technology
 *              University of Washington
 *              Seattle, WA  98195
 *              Internet: MRC@Washington.EDU
 *
 * Date:        20 December 1989
 * Last Edited: 27 March 2008
 */


#include <stdio.h>
#include <ctype.h>
#include <errno.h>
extern int errno;               /* just in case */
#include <signal.h>
#include "mail.h"
#include "osdep.h"
#include <time.h>
#include <sys/stat.h>
#include "pseudo.h"
#include "fdstring.h"
#include "misc.h"
#include "dummy.h"
\f
/* Supposedly, this page has everything the MMDF driver needs to know about
 * the MMDF delimiter.  By changing these macros, the MMDF driver should
 * change with it.  Note that if you change the length of MMDFHDRTXT you
 * also need to change the ISMMDF and RETIFMMDFWRD macros to reflect the new
 * size.
 */


/* Useful MMDF constants */

#define MMDFCHR '\01'           /* MMDF character */
#define MMDFCHRS 0x01010101     /* MMDF header character spread in a word */
                                /* MMDF header text */
#define MMDFHDRTXT "\01\01\01\01\n"
                                /* length of MMDF header text */
#define MMDFHDRLEN (sizeof (MMDFHDRTXT) - 1)


/* Validate MMDF header
 * Accepts: pointer to candidate string to validate as an MMDF header
 * Returns: T if valid; else NIL
 */

#define ISMMDF(s)                                                       \
  ((*(s) == MMDFCHR) && ((s)[1] == MMDFCHR) && ((s)[2] == MMDFCHR) &&   \
   ((s)[3] == MMDFCHR) && ((s)[4] == '\n'))


/* Return if a 32-bit word has the start of an MMDF header
 * Accepts: pointer to word of four bytes to validate as an MMDF header
 * Returns: pointer to MMDF header, else proceeds
 */

#define RETIFMMDFWRD(s) {                                               \
  if (s[3] == MMDFCHR) {                                                \
    if ((s[4] == MMDFCHR) && (s[5] == MMDFCHR) && (s[6] == MMDFCHR) &&  \
        (s[7] == '\n')) return s + 3;                                   \
    else if (s[2] == MMDFCHR) {                                         \
      if ((s[4] == MMDFCHR) && (s[5] == MMDFCHR) && (s[6] == '\n'))     \
        return s + 2;                                                   \
      else if (s[1] == MMDFCHR) {                                       \
        if ((s[4] == MMDFCHR) && (s[5] == '\n')) return s + 1;          \
        else if ((*s == MMDFCHR) && (s[4] == '\n')) return s;           \
      }                                                                 \
    }                                                                   \
  }                                                                     \
}
\f
/* Validate line
 * Accepts: pointer to candidate string to validate as a From header
 *          return pointer to end of date/time field
 *          return pointer to offset from t of time (hours of ``mmm dd hh:mm'')
 *          return pointer to offset from t of time zone (if non-zero)
 * Returns: t,ti,zn set if valid From string, else ti is NIL
 */

#define VALID(s,x,ti,zn) {                                              \
  ti = 0;                                                               \
  if ((*s == 'F') && (s[1] == 'r') && (s[2] == 'o') && (s[3] == 'm') && \
      (s[4] == ' ')) {                                                  \
    for (x = s + 5; *x && *x != '\n'; x++);                             \
    if (*x) {                                                           \
      if (x - s >= 41) {                                                \
        for (zn = -1; x[zn] != ' '; zn--);                              \
        if ((x[zn-1] == 'm') && (x[zn-2] == 'o') && (x[zn-3] == 'r') && \
            (x[zn-4] == 'f') && (x[zn-5] == ' ') && (x[zn-6] == 'e') && \
            (x[zn-7] == 't') && (x[zn-8] == 'o') && (x[zn-9] == 'm') && \
            (x[zn-10] == 'e') && (x[zn-11] == 'r') && (x[zn-12] == ' '))\
          x += zn - 12;                                                 \
      }                                                                 \
      if (x - s >= 27) {                                                \
        if (x[-5] == ' ') {                                             \
          if (x[-8] == ':') zn = 0,ti = -5;                             \
          else if (x[-9] == ' ') ti = zn = -9;                          \
          else if ((x[-11] == ' ') && ((x[-10]=='+') || (x[-10]=='-'))) \
            ti = zn = -11;                                              \
        }                                                               \
        else if (x[-4] == ' ') {                                        \
          if (x[-9] == ' ') zn = -4,ti = -9;                            \
        }                                                               \
        else if (x[-6] == ' ') {                                        \
          if ((x[-11] == ' ') && ((x[-5] == '+') || (x[-5] == '-')))    \
            zn = -6,ti = -11;                                           \
        }                                                               \
        if (ti && !((x[ti - 3] == ':') &&                               \
                    (x[ti -= ((x[ti - 6] == ':') ? 9 : 6)] == ' ') &&   \
                    (x[ti - 3] == ' ') && (x[ti - 7] == ' ') &&         \
                    (x[ti - 11] == ' '))) ti = 0;                       \
      }                                                                 \
    }                                                                   \
  }                                                                     \
}

/* You are not expected to understand this macro, but read the next page if
 * you are not faint of heart.
 *
 * Known formats to the VALID macro are:
 *              From user Wed Dec  2 05:53 1992
 * BSD          From user Wed Dec  2 05:53:22 1992
 * SysV         From user Wed Dec  2 05:53 PST 1992
 * rn           From user Wed Dec  2 05:53:22 PST 1992
 *              From user Wed Dec  2 05:53 -0700 1992
 * emacs        From user Wed Dec  2 05:53:22 -0700 1992
 *              From user Wed Dec  2 05:53 1992 PST
 *              From user Wed Dec  2 05:53:22 1992 PST
 *              From user Wed Dec  2 05:53 1992 -0700
 * Solaris      From user Wed Dec  2 05:53:22 1992 -0700
 *
 * Plus all of the above with `` remote from xxx'' after it. Thank you very
 * much, smail and Solaris, for making my life considerably more complicated.
 */
\f
/*
 * What?  You want to understand the VALID macro anyway?  Alright, since you
 * insist.  Actually, it isn't really all that difficult, provided that you
 * take it step by step.
 *
 * Line 1       Initializes the return ti value to failure (0);
 * Lines 2-3    Validates that the 1st-5th characters are ``From ''.
 * Lines 4-5    Validates that there is an end of line and points x at it.
 * Lines 6-13   First checks to see if the line is at least 41 characters long.
 *              If so, it scans backwards to find the rightmost space.  From
 *              that point, it scans backwards to see if the string matches
 *              `` remote from''.  If so, it sets x to point to the space at
 *              the start of the string.
 * Line 14      Makes sure that there are at least 27 characters in the line.
 * Lines 15-20  Checks if the date/time ends with the year (there is a space
 *              five characters back).  If there is a colon three characters
 *              further back, there is no timezone field, so zn is set to 0
 *              and ti is set in front of the year.  Otherwise, there must
 *              either to be a space four characters back for a three-letter
 *              timezone, or a space six characters back followed by a + or -
 *              for a numeric timezone; in either case, zn and ti become the
 *              offset of the space immediately before it.
 * Lines 21-23  Are the failure case for line 14.  If there is a space four
 *              characters back, it is a three-letter timezone; there must be a
 *              space for the year nine characters back.  zn is the zone
 *              offset; ti is the offset of the space.
 * Lines 24-27  Are the failure case for line 20.  If there is a space six
 *              characters back, it is a numeric timezone; there must be a
 *              space eleven characters back and a + or - five characters back.
 *              zn is the zone offset; ti is the offset of the space.
 * Line 28-31   If ti is valid, make sure that the string before ti is of the
 *              form www mmm dd hh:mm or www mmm dd hh:mm:ss, otherwise
 *              invalidate ti.  There must be a colon three characters back
 *              and a space six or nine characters back (depending upon
 *              whether or not the character six characters back is a colon).
 *              There must be a space three characters further back (in front
 *              of the day), one seven characters back (in front of the month),
 *              and one eleven characters back (in front of the day of week).
 *              ti is set to be the offset of the space before the time.
 *
 * Why a macro?  It gets invoked a *lot* in a tight loop.  On some of the
 * newer pipelined machines it is faster being open-coded than it would be if
 * subroutines are called.
 *
 * Why does it scan backwards from the end of the line, instead of doing the
 * much easier forward scan?  There is no deterministic way to parse the
 * ``user'' field, because it may contain unquoted spaces!  Yes, I tested it to
 * see if unquoted spaces were possible.  They are, and I've encountered enough
 * evil mail to be totally unwilling to trust that ``it will never happen''.
 */
\f
/* Build parameters */

#define KODRETRY 15             /* kiss-of-death retry in seconds */
#define LOCKTIMEOUT 5           /* lock timeout in minutes */


/* MMDF I/O stream local data */

typedef struct mmdf_local {
  unsigned int dirty : 1;       /* disk copy needs updating */
  unsigned int ddirty : 1;      /* double-dirty, ping becomes checkpoint */
  unsigned int pseudo : 1;      /* uses a pseudo message */
  unsigned int appending : 1;   /* don't mark new messages as old */
  int fd;                       /* mailbox file descriptor */
  int ld;                       /* lock file descriptor */
  char *lname;                  /* lock file name */
  off_t filesize;               /* file size parsed */
  time_t filetime;              /* last file time */
  unsigned char *buf;           /* temporary buffer */
  unsigned long buflen;         /* current size of temporary buffer */
  unsigned long uid;            /* current text uid */
  SIZEDTEXT text;               /* current text */
  unsigned long textlen;        /* current text length */
  char *line;                   /* returned line */
  char *linebuf;                /* line readin buffer */
  unsigned long linebuflen;     /* current line readin buffer length */
} MMDFLOCAL;


/* Convenient access to local data */

#define LOCAL ((MMDFLOCAL *) stream->local)


/* MMDF protected file structure */

typedef struct mmdf_file {
  MAILSTREAM *stream;           /* current stream */
  off_t curpos;                 /* current file position */
  off_t protect;                /* protected position */
  off_t filepos;                /* current last written file position */
  char *buf;                    /* overflow buffer */
  size_t buflen;                /* current overflow buffer length */
  char *bufpos;                 /* current buffer position */
} MMDFFILE;
\f
/* Function prototypes */

DRIVER *mmdf_valid (char *name);
long mmdf_isvalid (char *name,char *tmp);
long mmdf_isvalid_fd (int fd,char *tmp);
void *mmdf_parameters (long function,void *value);
void mmdf_scan (MAILSTREAM *stream,char *ref,char *pat,char *contents);
void mmdf_list (MAILSTREAM *stream,char *ref,char *pat);
void mmdf_lsub (MAILSTREAM *stream,char *ref,char *pat);
long mmdf_create (MAILSTREAM *stream,char *mailbox);
long mmdf_delete (MAILSTREAM *stream,char *mailbox);
long mmdf_rename (MAILSTREAM *stream,char *old,char *newname);
MAILSTREAM *mmdf_open (MAILSTREAM *stream);
void mmdf_close (MAILSTREAM *stream,long options);
char *mmdf_header (MAILSTREAM *stream,unsigned long msgno,
                   unsigned long *length,long flags);
long mmdf_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags);
char *mmdf_text_work (MAILSTREAM *stream,MESSAGECACHE *elt,
                      unsigned long *length,long flags);
void mmdf_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt);
long mmdf_ping (MAILSTREAM *stream);
void mmdf_check (MAILSTREAM *stream);
long mmdf_expunge (MAILSTREAM *stream,char *sequence,long options);
long mmdf_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options);
long mmdf_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);
int mmdf_collect_msg (MAILSTREAM *stream,FILE *sf,char *flags,char *date,
                     STRING *msg);
int mmdf_append_msgs (MAILSTREAM *stream,FILE *sf,FILE *df,SEARCHSET *set);

void mmdf_abort (MAILSTREAM *stream);
char *mmdf_file (char *dst,char *name);
int mmdf_lock (char *file,int flags,int mode,DOTLOCK *lock,int op);
void mmdf_unlock (int fd,MAILSTREAM *stream,DOTLOCK *lock);
int mmdf_parse (MAILSTREAM *stream,DOTLOCK *lock,int op);
char *mmdf_mbxline (MAILSTREAM *stream,STRING *bs,unsigned long *size);
unsigned long mmdf_pseudo (MAILSTREAM *stream,char *hdr);
unsigned long mmdf_xstatus (MAILSTREAM *stream,char *status,MESSAGECACHE *elt,
                            unsigned long uid,long flag);
long mmdf_rewrite (MAILSTREAM *stream,unsigned long *nexp,DOTLOCK *lock,
                   long flags);
long mmdf_extend (MAILSTREAM *stream,unsigned long size);
void mmdf_write (MMDFFILE *f,char *s,unsigned long i);
void mmdf_phys_write (MMDFFILE *f,char *buf,size_t size);
\f
/* MMDF mail routines */


/* Driver dispatch used by MAIL */

DRIVER mmdfdriver = {
  "mmdf",                       /* driver name */
                                /* driver flags */
  DR_LOCAL|DR_MAIL|DR_LOCKING|DR_NONEWMAILRONLY|DR_XPOINT,
  (DRIVER *) NIL,               /* next driver */
  mmdf_valid,                   /* mailbox is valid for us */
  mmdf_parameters,              /* manipulate parameters */
  mmdf_scan,                    /* scan mailboxes */
  mmdf_list,                    /* list mailboxes */
  mmdf_lsub,                    /* list subscribed mailboxes */
  NIL,                          /* subscribe to mailbox */
  NIL,                          /* unsubscribe from mailbox */
  mmdf_create,                  /* create mailbox */
  mmdf_delete,                  /* delete mailbox */
  mmdf_rename,                  /* rename mailbox */
  mail_status_default,          /* status of mailbox */
  mmdf_open,                    /* open mailbox */
  mmdf_close,                   /* close mailbox */
  NIL,                          /* fetch message "fast" attributes */
  NIL,                          /* fetch message flags */
  NIL,                          /* fetch overview */
  NIL,                          /* fetch message envelopes */
  mmdf_header,                  /* fetch message header */
  mmdf_text,                    /* fetch message text */
  NIL,                          /* fetch partial message text */
  NIL,                          /* unique identifier */
  NIL,                          /* message number */
  NIL,                          /* modify flags */
  mmdf_flagmsg,                 /* per-message modify flags */
  NIL,                          /* search for message based on criteria */
  NIL,                          /* sort messages */
  NIL,                          /* thread messages */
  mmdf_ping,                    /* ping mailbox to see if still alive */
  mmdf_check,                   /* check for new messages */
  mmdf_expunge,                 /* expunge deleted messages */
  mmdf_copy,                    /* copy messages to another mailbox */
  mmdf_append,                  /* append string message to mailbox */
  NIL                           /* garbage collect stream */
};

                                /* prototype stream */
MAILSTREAM mmdfproto = {&mmdfdriver};

char *mmdfhdr = MMDFHDRTXT;     /* MMDF header */
\f
/* MMDF mail validate mailbox
 * Accepts: mailbox name
 * Returns: our driver if name is valid, NIL otherwise
 */

DRIVER *mmdf_valid (char *name)
{
  char tmp[MAILTMPLEN];
  return mmdf_isvalid (name,tmp) ? &mmdfdriver : NIL;
}


/* MMDF mail test for valid mailbox name
 * Accepts: mailbox name
 *          scratch buffer
 * Returns: T if valid, NIL otherwise
 */

long mmdf_isvalid (char *name,char *tmp)
{
  int fd;
  int ret = NIL;
  char *t,file[MAILTMPLEN];
  struct stat sbuf;
  time_t tp[2];
  errno = EINVAL;               /* assume invalid argument */
                                /* must be non-empty file */
  if ((t = dummy_file (file,name)) && !stat (t,&sbuf)) {
    if (!sbuf.st_size)errno = 0;/* empty file */
    else if ((fd = open (file,O_RDONLY,NIL)) >= 0) {
                                /* error -1 for invalid format */
      if (!(ret = mmdf_isvalid_fd (fd,tmp))) errno = -1;
      close (fd);               /* close the file */
                                /* \Marked status? */
      if ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) {
        tp[0] = sbuf.st_atime;  /* preserve atime and mtime */
        tp[1] = sbuf.st_mtime;
        utime (file,tp);        /* set the times */
      }
    }
  }
  return ret;                   /* return what we should */
}
\f
/* MMDF mail test for valid mailbox
 * Accepts: file descriptor
 *          scratch buffer
 * Returns: T if valid, NIL otherwise
 */

long mmdf_isvalid_fd (int fd,char *tmp)
{
  int ret = NIL;
  memset (tmp,'\0',MAILTMPLEN);
  if (read (fd,tmp,MAILTMPLEN-1) >= 0) ret = ISMMDF (tmp) ? T : NIL;
  return ret;                   /* return what we should */
}


/* MMDF manipulate driver parameters
 * Accepts: function code
 *          function-dependent value
 * Returns: function-dependent return value
 */

void *mmdf_parameters (long function,void *value)
{
  void *ret = NIL;
  switch ((int) function) {
  case GET_INBOXPATH:
    if (value) ret = dummy_file ((char *) value,"INBOX");
    break;
  }
  return ret;
}
\f
/* MMDF mail scan mailboxes
 * Accepts: mail stream
 *          reference
 *          pattern to search
 *          string to scan
 */

void mmdf_scan (MAILSTREAM *stream,char *ref,char *pat,char *contents)
{
  if (stream) dummy_scan (NIL,ref,pat,contents);
}


/* MMDF mail list mailboxes
 * Accepts: mail stream
 *          reference
 *          pattern to search
 */

void mmdf_list (MAILSTREAM *stream,char *ref,char *pat)
{
  if (stream) dummy_list (NIL,ref,pat);
}


/* MMDF mail list subscribed mailboxes
 * Accepts: mail stream
 *          reference
 *          pattern to search
 */

void mmdf_lsub (MAILSTREAM *stream,char *ref,char *pat)
{
  if (stream) dummy_lsub (NIL,ref,pat);
}
\f
/* MMDF mail create mailbox
 * Accepts: MAIL stream
 *          mailbox name to create
 * Returns: T on success, NIL on failure
 */

long mmdf_create (MAILSTREAM *stream,char *mailbox)
{
  char *s,mbx[MAILTMPLEN],tmp[MAILTMPLEN];
  long ret = NIL;
  int i,fd;
  time_t ti = time (0);
  if (!(s = dummy_file (mbx,mailbox))) {
    sprintf (tmp,"Can't create %.80s: invalid name",mailbox);
    MM_LOG (tmp,ERROR);
  }
                                /* create underlying file */
  else if (dummy_create_path (stream,s,get_dir_protection (mailbox))) {
                                /* done if dir-only or whiner */
    if (((s = strrchr (s,'/')) && !s[1]) ||
        mail_parameters (NIL,GET_USERHASNOLIFE,NIL)) ret = T;
    else if ((fd = open (mbx,O_WRONLY,
                    (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL))) < 0) {
      sprintf (tmp,"Can't reopen mailbox node %.80s: %s",mbx,strerror (errno));
      MM_LOG (tmp,ERROR);
      unlink (mbx);             /* delete the file */
    }
    else {                      /* initialize header */
      memset (tmp,'\0',MAILTMPLEN);
      sprintf (tmp,"%sFrom %s %sDate: ",mmdfhdr,pseudo_from,ctime (&ti));
      rfc822_date (s = tmp + strlen (tmp));
      sprintf (s += strlen (s), /* write the pseudo-header */
               "\nFrom: %s <%s@%s>\nSubject: %s\nX-IMAP: %010lu 0000000000",
               pseudo_name,pseudo_from,mylocalhost (),pseudo_subject,
               (unsigned long) ti);
      for (i = 0; i < NUSERFLAGS; ++i) if (default_user_flag (i))
        sprintf (s += strlen (s)," %s",default_user_flag (i));
      sprintf (s += strlen (s),"\nStatus: RO\n\n%s\n%s",pseudo_msg,mmdfhdr);
      if (write (fd,tmp,strlen (tmp)) > 0) ret = T;
      else {
        sprintf (tmp,"Can't initialize mailbox node %.80s: %s",mbx,
                 strerror (errno));
        MM_LOG (tmp,ERROR);
        unlink (mbx);           /* delete the file */
      }
      close (fd);               /* close file */
    }
  }
                                /* set proper protections */
  return ret ? set_mbx_protections (mailbox,mbx) : NIL;
}
\f
/* MMDF mail delete mailbox
 * Accepts: MAIL stream
 *          mailbox name to delete
 * Returns: T on success, NIL on failure
 */

long mmdf_delete (MAILSTREAM *stream,char *mailbox)
{
  return mmdf_rename (stream,mailbox,NIL);
}


/* MMDF mail rename mailbox
 * Accepts: MAIL stream
 *          old mailbox name
 *          new mailbox name (or NIL for delete)
 * Returns: T on success, NIL on failure
 */

long mmdf_rename (MAILSTREAM *stream,char *old,char *newname)
{
  long ret = NIL;
  char c,*s = NIL;
  char tmp[MAILTMPLEN],file[MAILTMPLEN],lock[MAILTMPLEN];
  DOTLOCK lockx;
  int fd,ld;
  long i;
  struct stat sbuf;
  MM_CRITICAL (stream); /* get the c-client lock */
  if (!dummy_file (file,old) ||
      (newname && (!((s = mailboxfile (tmp,newname)) && *s) ||
                   ((s = strrchr (tmp,'/')) && !s[1])))){
    if(newname) sprintf (tmp,
        "Can't rename mailbox %.80s to %.80s: invalid name",
        old,newname);
    else
       sprintf (tmp, "Can't delete mailbox %.80s: invalid name", old);
  }                             /* lock out other c-clients */
  else if ((ld = lockname (lock,file,LOCK_EX|LOCK_NB,&i)) < 0)
    sprintf (tmp,"Mailbox %.80s is in use by another process",old);
\f
  else {
    if ((fd = mmdf_lock (file,O_RDWR,
                         (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
                         &lockx,LOCK_EX)) < 0)
       sprintf (tmp,"Can't lock mailbox %.80s: %s",old,strerror (errno));
    else {
      if (newname) {            /* want rename? */
                                /* found superior to destination name? */
        if ((s = strrchr (s,'/')) != NULL) {
          c = *++s;             /* remember first character of inferior */
          *s = '\0';            /* tie off to get just superior */
                                /* name doesn't exist, create it */
          if ((stat (tmp,&sbuf) || ((sbuf.st_mode & S_IFMT) != S_IFDIR)) &&
              !dummy_create_path (stream,tmp,get_dir_protection (newname))) {
            mmdf_unlock (fd,NIL,&lockx);
            mmdf_unlock (ld,NIL,NIL);
            unlink (lock);
            MM_NOCRITICAL (stream);
            return ret;         /* return success or failure */
          }
          *s = c;               /* restore full name */
        }
        if (rename (file,tmp))
          sprintf (tmp,"Can't rename mailbox %.80s to %.80s: %s",old,newname,
                   strerror (errno));
        else ret = T;           /* set success */
      }
      else if (unlink (file))
        sprintf (tmp,"Can't delete mailbox %.80s: %s",old,strerror (errno));
      else ret = T;             /* set success */
      mmdf_unlock (fd,NIL,&lockx);
    }
    mmdf_unlock (ld,NIL,NIL);   /* flush the lock */
    unlink (lock);
  }
  MM_NOCRITICAL (stream);       /* no longer critical */
  if (!ret) MM_LOG (tmp,ERROR); /* log error */
  return ret;                   /* return success or failure */
}
\f
/* MMDF mail open
 * Accepts: Stream to open
 * Returns: Stream on success, NIL on failure
 */

MAILSTREAM *mmdf_open (MAILSTREAM *stream)
{
  long i;
  int fd;
  char tmp[MAILTMPLEN];
  DOTLOCK lock;
  long retry;
                                /* return prototype for OP_PROTOTYPE call */
  if (!stream) return user_flags (&mmdfproto);
  retry = stream->silent ? 1 : KODRETRY;
  if (stream->local) fatal ("mmdf recycle stream");
  stream->local = memset (fs_get (sizeof (MMDFLOCAL)),0,sizeof (MMDFLOCAL));
                                /* note if an INBOX or not */
  stream->inbox = !compare_cstring (stream->mailbox,"INBOX");
                                /* canonicalize the stream mailbox name */
  if (!dummy_file (tmp,stream->mailbox)) {
    sprintf (tmp,"Can't open - invalid name: %.80s",stream->mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }
                                /* flush old name */
  fs_give ((void **) &stream->mailbox);
                                /* save canonical name */
  stream->mailbox = cpystr (tmp);
  LOCAL->fd = LOCAL->ld = -1;   /* no file or state locking yet */
  LOCAL->buf = (char *) fs_get (CHUNKSIZE);
  LOCAL->buflen = CHUNKSIZE - 1;
  LOCAL->text.data = (unsigned char *) fs_get (CHUNKSIZE);
  LOCAL->text.size = CHUNKSIZE - 1;
  LOCAL->linebuf = (char *) fs_get (CHUNKSIZE);
  LOCAL->linebuflen = CHUNKSIZE - 1;
  stream->sequence++;           /* bump sequence number */
\f
                                /* make lock for read/write access */
  if (!stream->rdonly) while (retry) {
                                /* try to lock file */
    if ((fd = lockname (tmp,stream->mailbox,LOCK_EX|LOCK_NB,&i)) < 0) {
                                /* suppressing kiss-of-death? */
      if (stream->nokod) retry = 0;
                                /* no, first time through? */
      else if (retry-- == KODRETRY) {
                                /* learned other guy's PID and can signal? */
        if (i && !kill ((int) i,SIGUSR2)) {
          sprintf (tmp,"Trying to get mailbox lock from process %ld",i);
          MM_LOG (tmp,WARN);
        }
        else retry = 0;         /* give up */
      }
      if (!stream->silent) {    /* nothing if silent stream */
        if (retry) sleep (1);   /* wait a second before trying again */
        else MM_LOG ("Mailbox is open by another process, access is readonly",
                     WARN);
      }
    }
    else {                      /* got the lock, nobody else can alter state */
      LOCAL->ld = fd;           /* note lock's fd and name */
      LOCAL->lname = cpystr (tmp);
                                /* make sure mode OK (don't use fchmod()) */
      chmod (LOCAL->lname,(long) mail_parameters (NIL,GET_LOCKPROTECTION,NIL));
      if (stream->silent) i = 0;/* silent streams won't accept KOD */
      else {                    /* note our PID in the lock */
        sprintf (tmp,"%d",getpid ());
        write (fd,tmp,(i = strlen (tmp))+1);
      }
      ftruncate (fd,i);         /* make sure tied off */
      fsync (fd);               /* make sure it's available */
      retry = 0;                /* no more need to try */
    }
  }
\f
                                /* parse mailbox */
  stream->nmsgs = stream->recent = 0;
                                /* will we be able to get write access? */
  if ((LOCAL->ld >= 0) && access (stream->mailbox,W_OK) && (errno == EACCES)) {
    MM_LOG ("Can't get write access to mailbox, access is readonly",WARN);
    flock (LOCAL->ld,LOCK_UN);  /* release the lock */
    close (LOCAL->ld);          /* close the lock file */
    LOCAL->ld = -1;             /* no more lock fd */
    unlink (LOCAL->lname);      /* delete it */
  }
                                /* reset UID validity */
  stream->uid_validity = stream->uid_last = 0;
  if (stream->silent && !stream->rdonly && (LOCAL->ld < 0))
    mmdf_abort (stream);        /* abort if can't get RW silent stream */
                                /* parse mailbox */
  else if (mmdf_parse (stream,&lock,LOCK_SH)) {
    mmdf_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);     /* done with critical */
  }
  if (!LOCAL) return NIL;       /* failure if stream died */
                                /* make sure upper level knows readonly */
  stream->rdonly = (LOCAL->ld < 0);
                                /* notify about empty mailbox */
  if (!(stream->nmsgs || stream->silent)) MM_LOG ("Mailbox is empty",NIL);
  if (!stream->rdonly) {        /* flags stick if readwrite */
    stream->perm_seen = stream->perm_deleted =
      stream->perm_flagged = stream->perm_answered = stream->perm_draft = T;
    if (!stream->uid_nosticky) {/* users with lives get permanent keywords */
      stream->perm_user_flags = 0xffffffff;
                                /* and maybe can create them too! */
      stream->kwd_create = stream->user_flags[NUSERFLAGS-1] ? NIL : T;
    }
  }
  return stream;                /* return stream alive to caller */
}


/* MMDF mail close
 * Accepts: MAIL stream
 *          close options
 */

void mmdf_close (MAILSTREAM *stream,long options)
{
  int silent = stream->silent;
  stream->silent = T;           /* go silent */
                                /* expunge if requested */
  if (options & CL_EXPUNGE) mmdf_expunge (stream,NIL,NIL);
                                /* else dump final checkpoint */
  else if (LOCAL->dirty) mmdf_check (stream);
  stream->silent = silent;      /* restore old silence state */
  mmdf_abort (stream);          /* now punt the file and local data */
}
\f
/* MMDF mail fetch message header
 * Accepts: MAIL stream
 *          message # to fetch
 *          pointer to returned header text length
 *          option flags
 * Returns: message header in RFC822 format
 */

                                /* lines to filter from header */
static STRINGLIST *mmdf_hlines = NIL;

char *mmdf_header (MAILSTREAM *stream,unsigned long msgno,
                   unsigned long *length,long flags)
{
  MESSAGECACHE *elt;
  unsigned char *s,*t,*tl;
  *length = 0;                  /* default to empty */
  if (flags & FT_UID) return "";/* UID call "impossible" */
  elt = mail_elt (stream,msgno);/* get cache */
  if (!mmdf_hlines) {           /* once only code */
    STRINGLIST *lines = mmdf_hlines = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "Status"));
    lines = lines->next = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "X-Status"));
    lines = lines->next = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "X-Keywords"));
    lines = lines->next = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "X-UID"));
    lines = lines->next = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "X-IMAP"));
    lines = lines->next = mail_newstringlist ();
    lines->text.size = strlen ((char *) (lines->text.data =
                                         (unsigned char *) "X-IMAPbase"));
  }
                                /* go to header position */
  lseek (LOCAL->fd,elt->private.special.offset +
         elt->private.msg.header.offset,L_SET);
\f
  if (flags & FT_INTERNAL) {    /* initial data OK? */
    if (elt->private.msg.header.text.size > LOCAL->buflen) {
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen =
                                     elt->private.msg.header.text.size) + 1);
    }
                                /* read message */
    read (LOCAL->fd,LOCAL->buf,elt->private.msg.header.text.size);
                                /* got text, tie off string */
    LOCAL->buf[*length = elt->private.msg.header.text.size] = '\0';
                                /* squeeze out CRs (in case from PC) */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if (*t != '\r') *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;   /* adjust length */
  }
  else {                        /* need to make a CRLF version */
    read (LOCAL->fd,s = (char *) fs_get (elt->private.msg.header.text.size+1),
          elt->private.msg.header.text.size);
                                /* tie off string, and convert to CRLF */
    s[elt->private.msg.header.text.size] = '\0';
    *length = strcrlfcpy (&LOCAL->buf,&LOCAL->buflen,s,
                          elt->private.msg.header.text.size);
    fs_give ((void **) &s);     /* free readin buffer */
                                /* squeeze out spurious CRs */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if ((*t != '\r') || (t[1] == '\n')) *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;   /* adjust length */
  }
  *length = mail_filter (LOCAL->buf,*length,mmdf_hlines,FT_NOT);
  return (char *) LOCAL->buf;   /* return processed copy */
}
\f
/* MMDF mail fetch message text
 * Accepts: MAIL stream
 *          message # to fetch
 *          pointer to returned stringstruct
 *          option flags
 * Returns: T on success, NIL if failure
 */

long mmdf_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags)
{
  char *s;
  unsigned long i;
  MESSAGECACHE *elt;
                                /* UID call "impossible" */
  if (flags & FT_UID) return NIL;
  elt = mail_elt (stream,msgno);/* get cache element */
                                /* if message not seen */
  if (!(flags & FT_PEEK) && !elt->seen) {
                                /* mark message seen and dirty */
    elt->seen = elt->private.dirty = LOCAL->dirty = T;
    MM_FLAGS (stream,msgno);
  }
  s = mmdf_text_work (stream,elt,&i,flags);
  INIT (bs,mail_string,s,i);    /* set up stringstruct */
  return T;                     /* success */
}
\f
/* MMDF mail fetch message text worker routine
 * Accepts: MAIL stream
 *          message cache element
 *          pointer to returned header text length
 *          option flags
 */

char *mmdf_text_work (MAILSTREAM *stream,MESSAGECACHE *elt,
                      unsigned long *length,long flags)
{
  FDDATA d;
  STRING bs;
  unsigned char c,*s,*t,*tl,tmp[CHUNKSIZE];
                                /* go to text position */
  lseek (LOCAL->fd,elt->private.special.offset +
         elt->private.msg.text.offset,L_SET);
  if (flags & FT_INTERNAL) {    /* initial data OK? */
    if (elt->private.msg.text.text.size > LOCAL->buflen) {
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen =
                                     elt->private.msg.text.text.size) + 1);
    }
                                /* read message */
    read (LOCAL->fd,LOCAL->buf,elt->private.msg.text.text.size);
                                /* got text, tie off string */
    LOCAL->buf[*length = elt->private.msg.text.text.size] = '\0';
                                /* squeeze out CRs (in case from PC) */
    for (s = t = LOCAL->buf,tl = LOCAL->buf + *length; t < tl; t++)
      if (*t != '\r') *s++ = *t;
    *s = '\0';
    *length = s - LOCAL->buf;   /* adjust length */
    return (char *) LOCAL->buf;
  }
\f
                                /* have it cached already? */
  if (elt->private.uid != LOCAL->uid) {
                                /* not cached, cache it now */
    LOCAL->uid = elt->private.uid;
                                /* is buffer big enough? */
    if (elt->rfc822_size > LOCAL->text.size) {
      /* excessively conservative, but the right thing is too hard to do */
      fs_give ((void **) &LOCAL->text.data);
      LOCAL->text.data = (unsigned char *)
        fs_get ((LOCAL->text.size = elt->rfc822_size) + 1);
    }
    d.fd = LOCAL->fd;           /* yes, set up file descriptor */
    d.pos = elt->private.special.offset + elt->private.msg.text.offset;
    d.chunk = tmp;              /* initial buffer chunk */
    d.chunksize = CHUNKSIZE;    /* file chunk size */
    INIT (&bs,fd_string,&d,elt->private.msg.text.text.size);
    for (s = (char *) LOCAL->text.data; SIZE (&bs);) switch (c = SNX (&bs)) {
    case '\r':                  /* carriage return seen */
      break;
    case '\n':
      *s++ = '\r';              /* insert a CR */
    default:
      *s++ = c;                 /* copy characters */
    }
    *s = '\0';                  /* tie off buffer */
                                /* calculate length of cached data */
    LOCAL->textlen = s - LOCAL->text.data;
  }
  *length = LOCAL->textlen;     /* return from cache */
  return (char *) LOCAL->text.data;
}
\f
/* MMDF per-message modify flag
 * Accepts: MAIL stream
 *          message cache element
 */

void mmdf_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt)
{
                                /* only after finishing */
  if (elt->valid) elt->private.dirty = LOCAL->dirty = T;
}


/* MMDF mail ping mailbox
 * Accepts: MAIL stream
 * Returns: T if stream alive, else NIL
 */

long mmdf_ping (MAILSTREAM *stream)
{
  DOTLOCK lock;
  struct stat sbuf;
  long reparse;
                                /* big no-op if not readwrite */
  if (LOCAL && (LOCAL->ld >= 0) && !stream->lock) {
    if (stream->rdonly) {       /* does he want to give up readwrite? */
                                /* checkpoint if we changed something */
      if (LOCAL->dirty) mmdf_check (stream);
      flock (LOCAL->ld,LOCK_UN);/* release readwrite lock */
      close (LOCAL->ld);        /* close the readwrite lock file */
      LOCAL->ld = -1;           /* no more readwrite lock fd */
      unlink (LOCAL->lname);    /* delete the readwrite lock file */
    }
    else {                      /* see if need to reparse */
      if (!(reparse = (long) mail_parameters (NIL,GET_NETFSSTATBUG,NIL))) {
                                /* get current mailbox size */
        if (LOCAL->fd >= 0) fstat (LOCAL->fd,&sbuf);
        else if (stat (stream->mailbox,&sbuf)) {
          sprintf (LOCAL->buf,"Mailbox stat failed, aborted: %s",
                   strerror (errno));
          MM_LOG (LOCAL->buf,ERROR);
          mmdf_abort (stream);
          return NIL;
        }
        reparse = (sbuf.st_size != LOCAL->filesize);
      }
                                /* parse if mailbox changed */
      if ((LOCAL->ddirty || reparse) && mmdf_parse (stream,&lock,LOCK_EX)) {
                                /* force checkpoint if double-dirty */
        if (LOCAL->ddirty) mmdf_rewrite (stream,NIL,&lock,NIL);
                                /* unlock mailbox */
        else mmdf_unlock (LOCAL->fd,stream,&lock);
        mail_unlock (stream);   /* and stream */
                                /* done with critical */
        MM_NOCRITICAL (stream);
      }
    }
  }
  return LOCAL ? LONGT : NIL;   /* return if still alive */
}
\f
/* MMDF mail check mailbox
 * Accepts: MAIL stream
 */

void mmdf_check (MAILSTREAM *stream)
{
  DOTLOCK lock;
                                /* parse and lock mailbox */
  if (LOCAL && (LOCAL->ld >= 0) && !stream->lock &&
      mmdf_parse (stream,&lock,LOCK_EX)) {
                                /* any unsaved changes? */
    if (LOCAL->dirty && mmdf_rewrite (stream,NIL,&lock,NIL)) {
      if (!stream->silent) MM_LOG ("Checkpoint completed",NIL);
    }
                                /* no checkpoint needed, just unlock */
    else mmdf_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);       /* unlock the stream */
    MM_NOCRITICAL (stream);     /* done with critical */
  }
}


/* MMDF mail expunge mailbox
 * Accepts: MAIL stream
 *          sequence to expunge if non-NIL
 *          expunge options
 * Returns: T, always
 */

long mmdf_expunge (MAILSTREAM *stream,char *sequence,long options)
{
  long ret;
  unsigned long i;
  DOTLOCK lock;
  char *msg = NIL;
  if ((ret = (sequence ? ((options & EX_UID) ?
                         mail_uid_sequence (stream,sequence) :
                         mail_sequence (stream,sequence)) : LONGT) != 0L) &&
      LOCAL && (LOCAL->ld >= 0) && !stream->lock &&
      mmdf_parse (stream,&lock,LOCK_EX)) {
                                /* check expunged messages if not dirty */
    for (i = 1; !LOCAL->dirty && (i <= stream->nmsgs); i++) {
      MESSAGECACHE *elt = mail_elt (stream,i);
      if (mail_elt (stream,i)->deleted) LOCAL->dirty = T;
    }
    if (!LOCAL->dirty) {        /* not dirty and no expunged messages */
      mmdf_unlock (LOCAL->fd,stream,&lock);
      msg = "No messages deleted, so no update needed";
    }
    else if (mmdf_rewrite (stream,&i,&lock,sequence ? LONGT : NIL)) {
      if (i) sprintf (msg = LOCAL->buf,"Expunged %lu messages",i);
      else msg = "Mailbox checkpointed, but no messages expunged";
    }
                                /* rewrite failed */
    else mmdf_unlock (LOCAL->fd,stream,&lock);
    mail_unlock (stream);       /* unlock the stream */
    MM_NOCRITICAL (stream);     /* done with critical */
    if (msg && !stream->silent) MM_LOG (msg,NIL);
  }
  else if (!stream->silent)
    MM_LOG ("Expunge ignored on readonly mailbox",WARN);
  return ret;
}
\f
/* MMDF mail copy message(s)
 * Accepts: MAIL stream
 *          sequence
 *          destination mailbox
 *          copy options
 * Returns: T if copy successful, else NIL
 */

long mmdf_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options)
{
  struct stat sbuf;
  int fd;
  char *s,file[MAILTMPLEN];
  DOTLOCK lock;
  time_t tp[2];
  unsigned long i,j;
  MESSAGECACHE *elt;
  long ret = T;
  mailproxycopy_t pc =
    (mailproxycopy_t) mail_parameters (stream,GET_MAILPROXYCOPY,NIL);
  copyuid_t cu = (copyuid_t) (mail_parameters (NIL,GET_USERHASNOLIFE,NIL) ?
                              NIL : mail_parameters (NIL,GET_COPYUID,NIL));
  SEARCHSET *source = cu ? mail_newsearchset () : NIL;
  SEARCHSET *dest = cu ? mail_newsearchset () : NIL;
  MAILSTREAM *tstream = NIL;
  if (!((options & CP_UID) ? mail_uid_sequence (stream,sequence) :
        mail_sequence (stream,sequence))) return NIL;
                                /* make sure destination is valid */
  if (!(mmdf_valid (mailbox) || !errno))
    switch (errno) {
    case ENOENT:                /* no such file? */
      if (compare_cstring (mailbox,"INBOX")) {
        MM_NOTIFY (stream,"[TRYCREATE] Must create mailbox before copy",NIL);
        return NIL;
      }
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      mmdf_create (NIL,"INBOX");/* create empty INBOX */
    case EACCES:                /* file protected */
      sprintf (LOCAL->buf,"Can't access destination: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    case EINVAL:
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      sprintf (LOCAL->buf,"Invalid MMDF-format mailbox name: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    default:
      if (pc) return (*pc) (stream,sequence,mailbox,options);
      sprintf (LOCAL->buf,"Not a MMDF-format mailbox: %.80s",mailbox);
      MM_LOG (LOCAL->buf,ERROR);
      return NIL;
    }
\f
                                /* try to open rewrite for UIDPLUS */
  if ((tstream = mail_open_work (&mmdfdriver,NIL,mailbox,
                                 OP_SILENT|OP_NOKOD)) && tstream->rdonly)
    tstream = mail_close (tstream);
  if (cu && !tstream) {         /* wanted a COPYUID? */
    sprintf (LOCAL->buf,"Unable to write-open mailbox for COPYUID: %.80s",
             mailbox);
    MM_LOG (LOCAL->buf,WARN);
    cu = NIL;                   /* don't try to do COPYUID */
  }
  LOCAL->buf[0] = '\0';
  MM_CRITICAL (stream);         /* go critical */
  if ((fd = mmdf_lock (dummy_file (file,mailbox),O_WRONLY|O_APPEND,
                       (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
                       &lock,LOCK_EX)) < 0) {
    MM_NOCRITICAL (stream);     /* done with critical */
    sprintf (LOCAL->buf,"Can't open destination mailbox: %s",strerror (errno));
    MM_LOG (LOCAL->buf,ERROR);  /* log the error */
    return NIL;                 /* failed */
  }
  fstat (fd,&sbuf);             /* get current file size */
                                /* write all requested messages to mailbox */
  for (i = 1; ret && (i <= stream->nmsgs); i++)
    if ((elt = mail_elt (stream,i))->sequence) {
      lseek (LOCAL->fd,elt->private.special.offset,L_SET);
      read (LOCAL->fd,LOCAL->buf,elt->private.special.text.size);
      if (write (fd,LOCAL->buf,elt->private.special.text.size) < 0) ret = NIL;
      else {                    /* internal header succeeded */
        s = mmdf_header (stream,i,&j,FT_INTERNAL);
                                /* header size, sans trailing newline */
        if (j && (s[j - 2] == '\n')) j--;
        if (write (fd,s,j) < 0) ret = NIL;
        else {                  /* message header succeeded */
          j = tstream ?         /* write UIDPLUS data if have readwrite */
            mmdf_xstatus (stream,LOCAL->buf,elt,++(tstream->uid_last),LONGT) :
            mmdf_xstatus (stream,LOCAL->buf,elt,NIL,NIL);
          if (write (fd,LOCAL->buf,j) < 0) ret = NIL;
          else {                /* message status succeeded */
            s = mmdf_text_work (stream,elt,&j,FT_INTERNAL);
            if ((write (fd,s,j) < 0) || (write (fd,mmdfhdr,MMDFHDRLEN) < 0))
              ret = NIL;
            else if (cu) {      /* need to pass back new UID? */
              mail_append_set (source,mail_uid (stream,i));
              mail_append_set (dest,tstream->uid_last);
            }
          }
        }
      }
    }
\f
  if (!ret || fsync (fd)) {     /* force out the update */
    sprintf (LOCAL->buf,"Message copy failed: %s",strerror (errno));
    ftruncate (fd,sbuf.st_size);
    ret = NIL;
  }
                                /* force UIDVALIDITY assignment now */
  if (tstream && !tstream->uid_validity) tstream->uid_validity = time (0);
                                /* return sets if doing COPYUID */
  if (cu && ret) (*cu) (stream,mailbox,tstream->uid_validity,source,dest);
  else {                        /* flush any sets we may have built */
    mail_free_searchset (&source);
    mail_free_searchset (&dest);
  }
  tp[1] = time (0);             /* set mtime to now */
  if (ret) tp[0] = tp[1] - 1;   /* set atime to now-1 if successful copy */
  else tp[0] =                  /* else preserve \Marked status */
         ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) ?
         sbuf.st_atime : tp[1];
  utime (file,tp);              /* set the times */
  mmdf_unlock (fd,NIL,&lock);   /* unlock and close mailbox */
  if (tstream) {                /* update last UID if we can */
    MMDFLOCAL *local = (MMDFLOCAL *) tstream->local;
    local->dirty = T;           /* do a rewrite */
    local->appending = T;       /* but not at the cost of marking as old */
    tstream = mail_close (tstream);
  }
                                /* log the error */
  if (!ret) MM_LOG (LOCAL->buf,ERROR);
                                /* delete if requested message */
  else if (options & CP_MOVE) for (i = 1; i <= stream->nmsgs; i++)
    if ((elt = mail_elt (stream,i))->sequence)
      elt->deleted = elt->private.dirty = LOCAL->dirty = T;
  MM_NOCRITICAL (stream);       /* release critical */
  return ret;
}
\f
/* MMDF mail append message from stringstruct
 * Accepts: MAIL stream
 *          destination mailbox
 *          append callback
 *          data for callback
 * Returns: T if append successful, else NIL
 */

#define BUFLEN 8*MAILTMPLEN

long mmdf_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data)
{
  struct stat sbuf;
  int fd;
  unsigned long i;
  char *flags,*date,buf[BUFLEN],tmp[MAILTMPLEN],file[MAILTMPLEN];
  time_t tp[2];
  FILE *sf,*df;
  MESSAGECACHE elt;
  DOTLOCK lock;
  STRING *message;
  unsigned long uidlocation = 0;
  appenduid_t au = (appenduid_t)
    (mail_parameters (NIL,GET_USERHASNOLIFE,NIL) ? NIL :
     mail_parameters (NIL,GET_APPENDUID,NIL));
  SEARCHSET *dst = au ? mail_newsearchset () : NIL;
  long ret = LONGT;
  MAILSTREAM *tstream = NIL;
                                /* default stream to prototype */
  if (!stream) {                /* stream specified? */
    stream = &mmdfproto;        /* no, default stream to prototype */
    for (i = 0; i < NUSERFLAGS && stream->user_flags[i]; ++i)
      fs_give ((void **) &stream->user_flags[i]);
  }
  if (!mmdf_valid (mailbox)) switch (errno) {
  case ENOENT:                  /* no such file? */
    if (compare_cstring (mailbox,"INBOX")) {
      MM_NOTIFY (stream,"[TRYCREATE] Must create mailbox before append",NIL);
      return NIL;
    }
    mmdf_create (NIL,"INBOX");  /* create empty INBOX */
  case 0:                       /* merely empty file? */
    tstream = stream;
    break;
  case EACCES:                  /* file protected */
    sprintf (tmp,"Can't access destination: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  case EINVAL:
    sprintf (tmp,"Invalid MMDF-format mailbox name: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  default:
    sprintf (tmp,"Not a MMDF-format mailbox: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }
                                /* get sniffing stream for keywords */
  else if (!(tstream = mail_open (NIL,mailbox,
                                  OP_READONLY|OP_SILENT|OP_NOKOD|OP_SNIFF))) {
    sprintf (tmp,"Unable to examine mailbox for APPEND: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  }
\f
                                /* get first message */
  if (!MM_APPEND (af) (tstream,data,&flags,&date,&message)) return NIL;
  if (!(sf = tmpfile ())) {     /* must have scratch file */
    sprintf (tmp,".%lx.%lx",(unsigned long) time (0),(unsigned long)getpid ());
    if (!stat (tmp,&sbuf) || !(sf = fopen (tmp,"wb+"))) {
      sprintf (tmp,"Unable to create scratch file: %.80s",strerror (errno));
      MM_LOG (tmp,ERROR);
      return NIL;
    }
    unlink (tmp);
  }
  do {                          /* parse date */
    if (!date) rfc822_date (date = tmp);
    if (!mail_parse_date (&elt,date)) {
      sprintf (tmp,"Bad date in append: %.80s",date);
      MM_LOG (tmp,ERROR);
    }
    else {                      /* user wants to suppress time zones? */
      if (mail_parameters (NIL,GET_NOTIMEZONES,NIL)) {
        time_t when = mail_longdate (&elt);
        date = ctime (&when);   /* use traditional date */
      }
                                /* use POSIX-style date */
      else date = mail_cdate (tmp,&elt);
      if (!SIZE (message)) MM_LOG ("Append of zero-length message",ERROR);
      else if (!mmdf_collect_msg (tstream,sf,flags,date,message)) {
        sprintf (tmp,"Error writing scratch file: %.80s",strerror (errno));
        MM_LOG (tmp,ERROR);
      }
                                /* get next message */
      else if (MM_APPEND (af) (tstream,data,&flags,&date,&message)) continue;
    }
    fclose (sf);                /* punt scratch file */
    return NIL;                 /* give up */
  } while (message);            /* until no more messages */
  if (fflush (sf)) {
    sprintf (tmp,"Error finishing scratch file: %.80s",strerror (errno));
    MM_LOG (tmp,ERROR);
    fclose (sf);                /* punt scratch file */
    return NIL;                 /* give up */
  }
  i = ftell (sf);               /* size of scratch file */
  if (tstream != stream) tstream = mail_close (tstream);
\f
  MM_CRITICAL (stream);         /* go critical */
                                /* try to open readwrite for UIDPLUS */
  if ((tstream = mail_open_work (&mmdfdriver,NIL,mailbox,
                                 OP_SILENT|OP_NOKOD)) && tstream->rdonly)
    tstream = mail_close (tstream);
  if (au && !tstream) {         /* wanted an APPENDUID? */
    sprintf (tmp,"Unable to re-open mailbox for APPENDUID: %.80s",mailbox);
    MM_LOG (tmp,WARN);
    au = NIL;
  }
  if (((fd = mmdf_lock (dummy_file (file,mailbox),O_WRONLY|O_APPEND,
                        (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL),
                        &lock,LOCK_EX)) < 0) ||
      !(df = fdopen (fd,"ab"))) {
    MM_NOCRITICAL (stream);     /* done with critical */
    sprintf (tmp,"Can't open append mailbox: %s",strerror (errno));
    MM_LOG (tmp,ERROR);
    return NIL;
  }
  fstat (fd,&sbuf);             /* get current file size */
  rewind (sf);
  tp[1] = time (0);             /* set mtime to now */
                                /* write all messages */
  if (!mmdf_append_msgs (tstream,sf,df,au ? dst : NIL) ||
      (fflush (df) == EOF) || fsync (fd)) {
    sprintf (buf,"Message append failed: %s",strerror (errno));
    MM_LOG (buf,ERROR);
    ftruncate (fd,sbuf.st_size);
    tp[0] =                     /* preserve \Marked status */
      ((sbuf.st_ctime > sbuf.st_atime) || (sbuf.st_mtime > sbuf.st_atime)) ?
      sbuf.st_atime : tp[1];
    ret = NIL;                  /* return error */
  }
  else tp[0] = tp[1] - 1;       /* set atime to now-1 if successful copy */
  utime (file,tp);              /* set the times */
  fclose (sf);                  /* done with scratch file */
                                /* force UIDVALIDITY assignment now */
  if (tstream && !tstream->uid_validity) tstream->uid_validity = time (0);
                                /* return sets if doing APPENDUID */
  if (au && ret) (*au) (mailbox,tstream->uid_validity,dst);
  else mail_free_searchset (&dst);
  mmdf_unlock (fd,NIL,&lock);   /* unlock and close mailbox */
  fclose (df);
  if (tstream) {                /* update last UID if we can */
    MMDFLOCAL *local = (MMDFLOCAL *) tstream->local;
    local->dirty = T;           /* do a rewrite */
    local->appending = T;       /* but not at the cost of marking as old */
    tstream = mail_close (tstream);
  }
  MM_NOCRITICAL (stream);       /* release critical */
  return ret;
}
\f
/* Collect and write single message to append scratch file
 * Accepts: MAIL stream
 *          scratch file
 *          flags
 *          date
 *          message stringstruct
 * Returns: NIL if write error, else T
 */

int mmdf_collect_msg (MAILSTREAM *stream,FILE *sf,char *flags,char *date,
                     STRING *msg)
{
  unsigned char *s,*t;
  unsigned long uf;
  long f = mail_parse_flags (stream,flags,&uf);
                                /* write metadata, note date ends with NL */
  if (fprintf (sf,"%ld %lu %s",f,SIZE (msg) + 1,date) < 0) return NIL;
  while (uf)                    /* write user flags */    
    if ((s = stream->user_flags[find_rightmost_bit (&uf)]) &&
        (fprintf (sf," %s",s) < 0)) return NIL;
  if (putc ('\n',sf) == EOF) return NIL;
  while (SIZE (msg)) {          /* copy text to scratch file */
    for (s = (unsigned char *) msg->curpos, t = s + msg->cursize; s < t; ++s)
      if (!*s) *s = 0x80;       /* disallow NUL */
                                /* write buffered text */
    if (fwrite (msg->curpos,1,msg->cursize,sf) == msg->cursize)
      SETPOS (msg,GETPOS (msg) + msg->cursize);
    else return NIL;            /* failed */
  }
                                /* write trailing newline and return */
  return (putc ('\n',sf) == EOF) ? NIL : T;
}
\f
/* Append messages from scratch file to mailbox
 * Accepts: MAIL stream
 *          source file
 *          destination file
 *          uidset to update if non-NIL
 * Returns: T if success, NIL if failure
 */

int mmdf_append_msgs (MAILSTREAM *stream,FILE *sf,FILE *df,SEARCHSET *set)
{
  int c;
  long f;
  unsigned long i,j;
  char *x,tmp[MAILTMPLEN];
  int hdrp = T;
                                /* get message metadata line */
  while (fgets (tmp,MAILTMPLEN,sf)) {
    if (!(isdigit (tmp[0]) && strchr (tmp,'\n'))) return NIL;
    f = strtol (tmp,&x,10);     /* get flags */
    if (!((*x++ == ' ') && isdigit (*x))) return NIL;
    i = strtoul (x,&x,10);      /* get message size */
    if ((*x++ != ' ') ||        /* build initial header */
        (fprintf (df,"%sFrom %s@%s %sStatus: ",mmdfhdr,myusername(),
                  mylocalhost(),x) < 0) ||
        (f&fSEEN && (putc ('R',df) == EOF)) ||
        (fputs ("\nX-Status: ",df) == EOF) ||
        (f&fDELETED && (putc ('D',df) == EOF)) ||
        (f&fFLAGGED && (putc ('F',df) == EOF)) ||
        (f&fANSWERED && (putc ('A',df) == EOF)) ||
        (f&fDRAFT && (putc ('T',df) == EOF)) ||
        (fputs ("\nX-Keywords:",df) == EOF)) return NIL;
                                /* copy keywords */
    while ((c = getc (sf)) != '\n') switch (c) {
    case EOF:
      return NIL;
    default:
      if (putc (c,df) == EOF) return NIL;
    }
    if ((putc ('\n',df) == EOF) ||
        (set && (fprintf (df,"X-UID: %lu\n",++(stream->uid_last)) < 0)))
      return NIL;
\f
    for (c = '\n'; i && fgets (tmp,MAILTMPLEN,sf); c = tmp[j-1]) {
                                /* get read line length */
      if (i < (j = strlen (tmp))) fatal ("mmdf_append_msgs overrun");
      i -= j;                   /* number of bytes left */
                                /* squish out ^A and CRs (note copies NUL) */
      for (x = tmp; (x = strpbrk (x,"\01\r")) != NULL; --j) memmove (x,x+1,j-(x-tmp));
      if (!j) continue;         /* do nothing if line emptied */
                                /* start of line? */
      if (c == '\n') switch (tmp[0]) {
      case 'S': case 's':       /* possible "Status:" */
        if (hdrp && (j > 6) && ((tmp[1] == 't') || (tmp[1] == 'T')) &&
            ((tmp[2] == 'a') || (tmp[2] == 'A')) &&
            ((tmp[3] == 't') || (tmp[3] == 'T')) &&
            ((tmp[4] == 'u') || (tmp[4] == 'U')) &&
            ((tmp[5] == 's') || (tmp[5] == 'S')) && (tmp[6] == ':') &&
            (fputs ("X-Original-",df) == EOF)) return NIL;
        break;
      case 'X': case 'x':       /* possible X-??? header */
        if (hdrp && (tmp[1] == '-') &&
                                /* possible X-UID: */
            (((j > 5) && ((tmp[2] == 'U') || (tmp[2] == 'u')) &&
              ((tmp[3] == 'I') || (tmp[3] == 'i')) &&
              ((tmp[4] == 'D') || (tmp[4] == 'd')) && (tmp[5] == ':')) ||
                                /* possible X-IMAP: */
             ((j > 6) && ((tmp[2] == 'I') || (tmp[2] == 'i')) &&
              ((tmp[3] == 'M') || (tmp[3] == 'm')) &&
              ((tmp[4] == 'A') || (tmp[4] == 'a')) &&
              ((tmp[5] == 'P') || (tmp[5] == 'p')) &&
              ((tmp[6] == ':') ||
                                /* or X-IMAPbase: */
               ((j > 10) && ((tmp[6] == 'b') || (tmp[6] == 'B')) &&
                ((tmp[7] == 'a') || (tmp[7] == 'A')) &&
                ((tmp[8] == 's') || (tmp[8] == 'S')) &&
                ((tmp[9] == 'e') || (tmp[9] == 'E')) && (tmp[10] == ':')))) ||
                                /* possible X-Status: */
             ((j > 8) && ((tmp[2] == 'S') || (tmp[2] == 's')) &&
              ((tmp[3] == 't') || (tmp[3] == 'T')) &&
              ((tmp[4] == 'a') || (tmp[4] == 'A')) &&
              ((tmp[5] == 't') || (tmp[5] == 'T')) &&
              ((tmp[6] == 'u') || (tmp[6] == 'U')) &&
              ((tmp[7] == 's') || (tmp[7] == 'S')) && (tmp[8] == ':')) ||
                                /* possible X-Keywords: */
             ((j > 10) && ((tmp[2] == 'K') || (tmp[2] == 'k')) &&
              ((tmp[3] == 'e') || (tmp[3] == 'E')) &&
              ((tmp[4] == 'y') || (tmp[4] == 'Y')) &&
              ((tmp[5] == 'w') || (tmp[5] == 'W')) &&
              ((tmp[6] == 'o') || (tmp[6] == 'O')) &&
              ((tmp[7] == 'r') || (tmp[7] == 'R')) &&
              ((tmp[8] == 'd') || (tmp[8] == 'D')) &&
              ((tmp[9] == 's') || (tmp[9] == 'S')) && (tmp[10] == ':'))) &&
            (fputs ("X-Original-",df) == EOF)) return NIL;
        break;
      case '\n':                /* blank line */
        hdrp = NIL;
        break;
      default:                  /* nothing to do */
        break;
      }
                                /* just write the line */
      if (fwrite (tmp,1,j,df) != j) return NIL;
    }
                                /* make sure read entire msg & wrote trailer */
    if (i || (fputs (mmdfhdr,df) == EOF)) return NIL;
                                /* update set */
    if (stream) mail_append_set (set,stream->uid_last);
  }
  return T;
}
\f
/* Internal routines */


/* MMDF mail abort stream
 * Accepts: MAIL stream
 */

void mmdf_abort (MAILSTREAM *stream)
{
  if (LOCAL) {                  /* only if a file is open */
    if (LOCAL->fd >= 0) close (LOCAL->fd);
    if (LOCAL->ld >= 0) {       /* have a mailbox lock? */
      flock (LOCAL->ld,LOCK_UN);/* yes, release the lock */
      close (LOCAL->ld);        /* close the lock file */
      unlink (LOCAL->lname);    /* and delete it */
    }
    if (LOCAL->lname) fs_give ((void **) &LOCAL->lname);
                                /* free local text buffers */
    if (LOCAL->buf) fs_give ((void **) &LOCAL->buf);
    if (LOCAL->text.data) fs_give ((void **) &LOCAL->text.data);
    if (LOCAL->linebuf) fs_give ((void **) &LOCAL->linebuf);
    if (LOCAL->line) fs_give ((void **) &LOCAL->line);
                                /* nuke the local data */
    fs_give ((void **) &stream->local);
    stream->dtb = NIL;          /* log out the DTB */
  }
}
\f
/* MMDF open and lock mailbox
 * Accepts: file name to open/lock
 *          file open mode
 *          destination buffer for lock file name
 *          type of locking operation (LOCK_SH or LOCK_EX)
 */

int mmdf_lock (char *file,int flags,int mode,DOTLOCK *lock,int op)
{
  int fd;
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  (*bn) (BLOCK_FILELOCK,NIL);
                                /* try locking the easy way */
  if (dotlock_lock (file,lock,-1)) {
                                /* got dotlock file, easy open */
    if ((fd = open (file,flags,mode)) >= 0) flock (fd,op);
    else dotlock_unlock (lock); /* open failed, free the dotlock */
  }
                                /* no dot lock file, open file now */
  else if ((fd = open (file,flags,mode)) >= 0) {
                                /* try paranoid way to make a dot lock file */
    if (dotlock_lock (file,lock,fd)) {
      close (fd);               /* get fresh fd in case of timing race */
      if ((fd = open (file,flags,mode)) >= 0) flock (fd,op);
                                /* open failed, free the dotlock */
      else dotlock_unlock (lock);
    }
    else flock (fd,op);         /* paranoid way failed, just flock() it */
  }
  (*bn) (BLOCK_NONE,NIL);
  return fd;
}
\f
/* MMDF unlock and close mailbox
 * Accepts: file descriptor
 *          (optional) mailbox stream to check atime/mtime
 *          (optional) lock file name
 */

void mmdf_unlock (int fd,MAILSTREAM *stream,DOTLOCK *lock)
{
  if (stream) {                 /* need to muck with times? */
    struct stat sbuf;
    time_t tp[2];
    time_t now = time (0);
    fstat (fd,&sbuf);           /* get file times */
    if (LOCAL->ld >= 0) {       /* yes, readwrite session? */
      tp[0] = now;              /* set atime to now */
                                /* set mtime to (now - 1) if necessary */
      tp[1] = (now > sbuf.st_mtime) ? sbuf.st_mtime : now - 1;
    }
    else if (stream->recent) {  /* readonly with recent messages */
      if ((sbuf.st_atime >= sbuf.st_mtime) ||
          (sbuf.st_atime >= sbuf.st_ctime))
                                /* keep past mtime, whack back atime */
        tp[0] = (tp[1] = (sbuf.st_mtime < now) ? sbuf.st_mtime : now) - 1;
      else now = 0;             /* no time change needed */
    }
                                /* readonly with no recent messages */
    else if ((sbuf.st_atime < sbuf.st_mtime) ||
             (sbuf.st_atime < sbuf.st_ctime)) {
      tp[0] = now;              /* set atime to now */
                                /* set mtime to (now - 1) if necessary */
      tp[1] = (now > sbuf.st_mtime) ? sbuf.st_mtime : now - 1;
    }
    else now = 0;               /* no time change needed */
                                /* set the times, note change */
    if (now && !utime (stream->mailbox,tp)) LOCAL->filetime = tp[1];
  }
  flock (fd,LOCK_UN);           /* release flock'ers */
  if (!stream) close (fd);      /* close the file if no stream */
  dotlock_unlock (lock);        /* flush the lock file if any */
}
\f
/* MMDF mail parse and lock mailbox
 * Accepts: MAIL stream
 *          space to write lock file name
 *          type of locking operation
 * Returns: T if parse OK, critical & mailbox is locked shared; NIL if failure
 */

int mmdf_parse (MAILSTREAM *stream,DOTLOCK *lock,int op)
{
  int ti,zn,m;
  unsigned long i,j,k;
  unsigned char c,*s,*t,*u,tmp[MAILTMPLEN],date[30];
  int retain = T;
  unsigned long nmsgs = stream->nmsgs;
  unsigned long prevuid = nmsgs ? mail_elt (stream,nmsgs)->private.uid : 0;
  unsigned long recent = stream->recent;
  unsigned long oldnmsgs = stream->nmsgs;
  short silent = stream->silent;
  short pseudoseen = NIL;
  struct stat sbuf;
  STRING bs;
  FDDATA d;
  MESSAGECACHE *elt;
  mail_lock (stream);           /* guard against recursion or pingers */
                                /* toss out previous descriptor */
  if (LOCAL->fd >= 0) close (LOCAL->fd);
  MM_CRITICAL (stream);         /* open and lock mailbox (shared OK) */
  if ((LOCAL->fd = mmdf_lock (stream->mailbox,(LOCAL->ld >= 0) ?
                              O_RDWR : O_RDONLY,
                              (long)mail_parameters(NIL,GET_MBXPROTECTION,NIL),
                              lock,op)) < 0) {
    sprintf (tmp,"Mailbox open failed, aborted: %s",strerror (errno));
    MM_LOG (tmp,ERROR);
    mmdf_abort (stream);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);     /* done with critical */
    return NIL;
  }
  fstat (LOCAL->fd,&sbuf);      /* get status */
                                /* validate change in size */
  if (sbuf.st_size < LOCAL->filesize) {
    sprintf (tmp,"Mailbox shrank from %lu to %lu bytes, aborted",
             (unsigned long) LOCAL->filesize,(unsigned long) sbuf.st_size);
    MM_LOG (tmp,ERROR);         /* this is pretty bad */
    mmdf_unlock (LOCAL->fd,stream,lock);
    mmdf_abort (stream);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);     /* done with critical */
    return NIL;
  }
\f
                                /* new data? */
  else if ((i = sbuf.st_size - LOCAL->filesize) != 0L) {
    d.fd = LOCAL->fd;           /* yes, set up file descriptor */
    d.pos = LOCAL->filesize;    /* get to that position in the file */
    d.chunk = LOCAL->buf;       /* initial buffer chunk */
    d.chunksize = CHUNKSIZE;    /* file chunk size */
    INIT (&bs,fd_string,&d,i);  /* initialize stringstruct */
                                /* skip leading whitespace for broken MTAs */
    while (((c = CHR (&bs)) == '\n') || (c == '\r') ||
           (c == ' ') || (c == '\t')) SNX (&bs);
    if (SIZE (&bs)) {           /* read new data */
                                /* remember internal header position */
      j = LOCAL->filesize + GETPOS (&bs);
      s = mmdf_mbxline (stream,&bs,&i);
      stream->silent = T;       /* quell main program new message events */
      do {                      /* read MMDF header */
        if (!(i && ISMMDF (s))){/* see if valid MMDF header */
          sprintf (tmp,"Unexpected changes to mailbox (try restarting): %.20s",
                   (char *) s);
                                /* see if we can back up to a line */
          if (i && (j > MMDFHDRLEN)) {
            SETPOS (&bs,j -= MMDFHDRLEN);
                                /* read previous line */
            s = mmdf_mbxline (stream,&bs,&i);
                                /* kill the error if it looks good */
            if (i && ISMMDF (s)) tmp[0] = '\0';
          }
          if (tmp[0]) {
            MM_LOG (tmp,ERROR);
            mmdf_unlock (LOCAL->fd,stream,lock);
            mmdf_abort (stream);
            mail_unlock (stream);
            MM_NOCRITICAL (stream);
            return NIL;
          }
        }
                                /* instantiate first new message */
        mail_exists (stream,++nmsgs);
        (elt = mail_elt (stream,nmsgs))->valid = T;
        recent++;               /* assume recent by default */
        elt->recent = T;
                                /* note position/size of internal header */
        elt->private.special.offset = j;
        elt->private.special.text.size = i;
\f
        s = mmdf_mbxline (stream,&bs,&i);
        ti = 0;                 /* assume not a valid date */
        zn = 0,t = NIL;
        if (i) VALID (s,t,ti,zn);
        if (ti) {               /* generate plausible IMAPish date string */
                                /* this is also part of header */
          elt->private.special.text.size += i;
          date[2] = date[6] = date[20] = '-'; date[11] = ' ';
          date[14] = date[17] = ':';
                                /* dd */
          date[0] = t[ti - 2]; date[1] = t[ti - 1];
                                /* mmm */
          date[3] = t[ti - 6]; date[4] = t[ti - 5]; date[5] = t[ti - 4];
                                /* hh */
          date[12] = t[ti + 1]; date[13] = t[ti + 2];
                                /* mm */
          date[15] = t[ti + 4]; date[16] = t[ti + 5];
          if (t[ti += 6]==':'){ /* ss */
            date[18] = t[++ti]; date[19] = t[++ti];
            ti++;               /* move to space */
          }
          else date[18] = date[19] = '0';
                                /* yy -- advance over timezone if necessary */
          if (zn == ti) ti += (((t[zn+1] == '+') || (t[zn+1] == '-')) ? 6 : 4);
          date[7] = t[ti + 1]; date[8] = t[ti + 2];
          date[9] = t[ti + 3]; date[10] = t[ti + 4];
                                /* zzz */
          t = zn ? (t + zn + 1) : (unsigned char *) "LCL";
          date[21] = *t++; date[22] = *t++; date[23] = *t++;
          if ((date[21] != '+') && (date[21] != '-')) date[24] = '\0';
          else {                /* numeric time zone */
            date[24] = *t++; date[25] = *t++;
            date[26] = '\0'; date[20] = ' ';
          }
                                /* set internal date */
          if (!mail_parse_date (elt,date)) {
            sprintf (tmp,"Unable to parse internal date: %s",(char *) date);
            MM_LOG (tmp,WARN);
          }
        }
        else {                  /* make date from file date */
          struct tm *tm = gmtime (&sbuf.st_mtime);
          elt->day = tm->tm_mday; elt->month = tm->tm_mon + 1;
          elt->year = tm->tm_year + 1900 - BASEYEAR;
          elt->hours = tm->tm_hour; elt->minutes = tm->tm_min;
          elt->seconds = tm->tm_sec;
          elt->zhours = 0; elt->zminutes = 0;
          t = NIL;              /* suppress line read */
        }
                                /* header starts here */
        elt->private.msg.header.offset = elt->private.special.text.size;
\f
        do {                    /* look for message body */
          j = GETPOS (&bs);     /* note position before line */
          if (t) s = t = mmdf_mbxline (stream,&bs,&i);
          else t = s;           /* this line read was suppressed */
          if (ISMMDF (s)) {     /* found terminator in header? */
            SETPOS (&bs,j);     /* oops, back up before line */
                                /* must insert a newline */
            elt->private.spare.data++;
            break;              /* punt */
          }
                                /* this line is part of header */
          elt->private.msg.header.text.size += i;
          if (i) switch (*s) {  /* check header lines */
          case 'X':             /* possible X-???: line */
            if (s[1] == '-') {  /* must be immediately followed by hyphen */
                                /* X-Status: becomes Status: in S case */
              if (s[2] == 'S' && s[3] == 't' && s[4] == 'a' && s[5] == 't' &&
                  s[6] == 'u' && s[7] == 's' && s[8] == ':') s += 2;
                                /* possible X-Keywords */
              else if (s[2] == 'K' && s[3] == 'e' && s[4] == 'y' &&
                       s[5] == 'w' && s[6] == 'o' && s[7] == 'r' &&
                       s[8] == 'd' && s[9] == 's' && s[10] == ':') {
                SIZEDTEXT uf;
                retain = NIL;   /* don't retain continuation */
                s += 11;        /* flush leading whitespace */
                while (*s && (*s != '\n') && ((*s != '\r') || (s[1] != '\n'))){
                  while (*s == ' ') s++;
                                /* find end of keyword */
                  if (!(u = strpbrk (s," \n\r"))) u = s + strlen (s);
                                /* got a keyword? */
                  if ((k = (u - s)) && (k <= MAXUSERFLAG)) {
                    uf.data = (unsigned char *) s;
                    uf.size = k;
                    for (j = 0; (j < NUSERFLAGS) && stream->user_flags[j]; ++j)
                      if (!compare_csizedtext (stream->user_flags[j],&uf)) {
                        elt->user_flags |= ((long) 1) << j;
                        break;
                      }
                  }
                  s = u;        /* advance to next keyword */
                }
                break;
              }
\f
                                /* possible X-IMAP */
              else if ((s[2] == 'I') && (s[3] == 'M') && (s[4] == 'A') &&
                       (s[5] == 'P') && ((m = (s[6] == ':')) ||
                                         ((s[6] == 'b') && (s[7] == 'a') &&
                                          (s[8] == 's') && (s[9] == 'e') &&
                                          (s[10] == ':')))) {
                retain = NIL;   /* don't retain continuation */
                if ((nmsgs == 1) && !stream->uid_validity) {
                                /* advance to data */
                  s += m ? 7 : 11;
                                /* flush whitespace */
                  while (*s == ' ') s++;
                  j = 0;        /* slurp UID validity */
                                /* found a digit? */
                  while (isdigit (*s)) {
                    j *= 10;    /* yes, add it in */
                    j += *s++ - '0';
                  }
                                /* flush whitespace */
                  while (*s == ' ') s++;
                                /* must have valid UID validity and UID last */
                  if (j && isdigit (*s)) {
                                /* pseudo-header seen if X-IMAP */
                    if (m) pseudoseen = LOCAL->pseudo = T;
                                /* save UID validity */
                    stream->uid_validity = j;
                    j = 0;      /* slurp UID last */
                    while (isdigit (*s)) {
                      j *= 10;  /* yes, add it in */
                      j += *s++ - '0';
                    }
                                /* save UID last */
                    stream->uid_last = j;
                                /* process keywords */
                    for (j = 0; (*s != '\n') && ((*s != '\r')||(s[1] != '\n'));
                         s = u,j++) {
                                /* flush leading whitespace */
                      while (*s == ' ') s++;
                      u = strpbrk (s," \n\r");
                                /* got a keyword? */
                      if ((j < NUSERFLAGS) && (k = (u - s)) &&
                          (k <= MAXUSERFLAG)) {
                        if (stream->user_flags[j])
                          fs_give ((void **) &stream->user_flags[j]);
                        stream->user_flags[j] = (char *) fs_get (k + 1);
                        strncpy (stream->user_flags[j],s,k);
                        stream->user_flags[j][k] = '\0';
                      }
                    }
                  }
                }
                break;
              }
\f
                                /* possible X-UID */
              else if (s[2] == 'U' && s[3] == 'I' && s[4] == 'D' &&
                       s[5] == ':') {
                retain = NIL;   /* don't retain continuation */
                                /* only believe if have a UID validity */
                if (stream->uid_validity && ((nmsgs > 1) || !pseudoseen)) {
                  s += 6;       /* advance to UID value */
                                /* flush whitespace */
                  while (*s == ' ') s++;
                  j = 0;
                                /* found a digit? */
                  while (isdigit (*s)) {
                    j *= 10;    /* yes, add it in */
                    j += *s++ - '0';
                  }
                                /* flush remainder of line */
                  while (*s != '\n') s++;
                                /* make sure not duplicated */
                  if (elt->private.uid)
                    sprintf (tmp,"Message %lu UID %lu already has UID %lu",
                             pseudoseen ? elt->msgno - 1 : elt->msgno,
                             j,elt->private.uid);
                                /* make sure UID doesn't go backwards */
                  else if (j <= prevuid)
                    sprintf (tmp,"Message %lu UID %lu less than %lu",
                             pseudoseen ? elt->msgno - 1 : elt->msgno,
                             j,prevuid + 1);
#if 0   /* this is currently broken by UIDPLUS */
                                /* or skip by mailbox's recorded last */
                  else if (j > stream->uid_last)
                    sprintf (tmp,"Message %lu UID %lu greater than last %lu",
                             pseudoseen ? elt->msgno - 1 : elt->msgno,
                             j,stream->uid_last);
#endif
                  else {        /* normal UID case */
                    prevuid = elt->private.uid = j;
#if 1   /* temporary kludge for UIDPLUS */
                    if (prevuid > stream->uid_last) {
                      stream->uid_last = prevuid;
                      LOCAL->ddirty = LOCAL->dirty = T;
                    }               
#endif
                    break;      /* exit this cruft */
                  }
                  MM_LOG (tmp,WARN);
                                /* invalidate UID validity */
                  stream->uid_validity = 0;
                  elt->private.uid = 0;
                }
                break;
              }
            }
                                /* otherwise fall into S case */
\f
          case 'S':             /* possible Status: line */
            if (s[0] == 'S' && s[1] == 't' && s[2] == 'a' && s[3] == 't' &&
                s[4] == 'u' && s[5] == 's' && s[6] == ':') {
              retain = NIL;     /* don't retain continuation */
              s += 6;           /* advance to status flags */
              do switch (*s++) {/* parse flags */
              case 'R':         /* message read */
                elt->seen = T;
                break;
              case 'O':         /* message old */
                if (elt->recent) {
                  elt->recent = NIL;
                  recent--;     /* it really wasn't recent */
                }
                break;
              case 'D':         /* message deleted */
                elt->deleted = T;
                break;
              case 'F':         /* message flagged */
                elt->flagged = T;
                break;
              case 'A':         /* message answered */
                elt->answered = T;
                break;
              case 'T':         /* message is a draft */
                elt->draft = T;
                break;
              default:          /* some other crap */
                break;
              } while (*s && (*s != '\n') && ((*s != '\r') || (s[1] != '\n')));
              break;            /* all done */
            }
                                /* otherwise fall into default case */
\f
          default:              /* ordinary header line */
            if ((*s == 'S') || (*s == 's') ||
                (((*s == 'X') || (*s == 'x')) && (s[1] == '-'))) {
              unsigned char *e,*v;
                                /* must match what mail_filter() does */
              for (u = s,v = tmp,e = u + min (i,MAILTMPLEN - 1);
                   (u < e) && ((c = (*u ? *u : (*u = ' '))) != ':') &&
                   ((c > ' ') || ((c != ' ') && (c != '\t') &&
                                  (c != '\r') && (c != '\n')));
                   *v++ = *u++);
              *v = '\0';        /* tie off */
                                /* matches internal header? */
              if (!compare_cstring (tmp,"STATUS") ||
                  !compare_cstring (tmp,"X-STATUS") ||
                  !compare_cstring (tmp,"X-KEYWORDS") ||
                  !compare_cstring (tmp,"X-UID") ||
                  !compare_cstring (tmp,"X-IMAP") ||
                  !compare_cstring (tmp,"X-IMAPBASE")) {
                char err[MAILTMPLEN];
                sprintf (err,"Discarding bogus %s header in message %lu",
                         (char *) tmp,elt->msgno);
                MM_LOG (err,WARN);
                retain = NIL;   /* don't retain continuation */
                break;          /* different case or something */
              }
            }
                                /* retain or non-continuation? */
            if (retain || ((*s != ' ') && (*s != '\t'))) {
              retain = T;       /* retaining continuation now */
                                /* line length in LF format newline */
              for (j = k = 0; j < i; ++j) if (s[j] != '\r') ++k;
                                /* "internal" header size */
              elt->private.spare.data += k;
                                /* message size */
              elt->rfc822_size += k + 1;
            }
            else {
              char err[MAILTMPLEN];
              sprintf (err,"Discarding bogus continuation in msg %lu: %.80s",
                      elt->msgno,(char *) s);
              if ((u = strpbrk (err,"\r\n")) != NULL) *u = '\0';
              MM_LOG (err,WARN);
              break;            /* different case or something */
            }
            break;
          }
        } while (i && (*t != '\n') && ((*t != '\r') || (t[1] != '\n')));
                                /* "internal" header sans trailing newline */
        if (i) elt->private.spare.data--;
                                /* assign a UID if none found */
        if (((nmsgs > 1) || !pseudoseen) && !elt->private.uid) {
          prevuid = elt->private.uid = ++stream->uid_last;
          elt->private.dirty = T;
        }
        else elt->private.dirty = elt->recent;
\f
                                /* note size of header, location of text */
        elt->private.msg.header.text.size =
          (elt->private.msg.text.offset =
           (LOCAL->filesize + GETPOS (&bs)) - elt->private.special.offset) -
             elt->private.special.text.size;
                                /* note current position */
        j = LOCAL->filesize + GETPOS (&bs);
        if (i) do {             /* look for next message */
          s = mmdf_mbxline (stream,&bs,&i);
          if (i) {              /* got new data? */
            if (ISMMDF (s)) break;
            else {              /* not a header line, add it to message */
              elt->rfc822_size += i;
              for (j = 0; j < i; ++j) switch (s[j]) {
              case '\r':        /* squeeze out CRs */
                elt->rfc822_size -= 1;
                break;
              case '\n':        /* LF becomes CRLF */
                elt->rfc822_size += 1;
                break;
              default:
                break;
              }
                                /* update current position */
              j = LOCAL->filesize + GETPOS (&bs);
            }
          }
        } while (i);            /* until found a header */
        elt->private.msg.text.text.size = j -
          (elt->private.special.offset + elt->private.msg.text.offset);
        if (i) {                /* get next header line */
                                /* remember first internal header position */
          j = LOCAL->filesize + GETPOS (&bs);
          s = mmdf_mbxline (stream,&bs,&i);
        }
                                /* until end of buffer */
      } while (!stream->sniff && i);
      if (pseudoseen) {         /* flush pseudo-message if present */
                                /* decrement recent count */
        if (mail_elt (stream,1)->recent) recent--;
                                /* and the exists count */
        mail_exists (stream,nmsgs--);
        mail_expunged(stream,1);/* fake an expunge of that message */
      }
                                /* need to start a new UID validity? */
      if (!stream->uid_validity) {
        stream->uid_validity = time (0);
                                /* in case a whiner with no life */
        if (mail_parameters (NIL,GET_USERHASNOLIFE,NIL))
          stream->uid_nosticky = T;
        else if (nmsgs) {       /* don't bother if empty file */
                                /* make dirty to restart UID epoch */
          LOCAL->ddirty = LOCAL->dirty = T;
                                /* need to rewrite msg 1 if not pseudo */
          if (!LOCAL->pseudo) mail_elt (stream,1)->private.dirty = T;
          MM_LOG ("Assigning new unique identifiers to all messages",NIL);
        }
      }
      stream->nmsgs = oldnmsgs; /* whack it back down */
      stream->silent = silent;  /* restore old silent setting */
                                /* notify upper level of new mailbox sizes */
      mail_exists (stream,nmsgs);
      mail_recent (stream,recent);
                                /* mark dirty so O flags are set */
      if (recent) LOCAL->dirty = T;
    }
  }
                                /* no change, don't babble if never got time */
  else if (LOCAL->filetime && LOCAL->filetime != sbuf.st_mtime)
    MM_LOG ("New mailbox modification time but apparently no changes",WARN);
                                /* update parsed file size and time */
  LOCAL->filesize = sbuf.st_size;
  LOCAL->filetime = sbuf.st_mtime;
  return T;                     /* return the winnage */
}
\f
/* MMDF read line from mailbox
 * Accepts: mail stream
 *          stringstruct
 *          pointer to line size
 * Returns: pointer to input line
 */

char *mmdf_mbxline (MAILSTREAM *stream,STRING *bs,unsigned long *size)
{
  unsigned long i,j,k,m;
  char *s,*t,*te;
  char *ret = "";
                                /* flush old buffer */
  if (LOCAL->line) fs_give ((void **) &LOCAL->line);
                                /* if buffer needs refreshing */
  if (!bs->cursize) SETPOS (bs,GETPOS (bs));
  if (SIZE (bs)) {              /* find newline */
                                /* end of fast scan */
    te = (t = (s = bs->curpos) + bs->cursize) - 12;
    while (s < te) if ((*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                       (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n')) {
      --s;                      /* back up */
      break;                    /* exit loop */
    }
                                /* final character-at-a-time scan */
    while ((s < t) && (*s != '\n')) ++s;
                                /* difficult case if line spans buffer */
    if ((i = s - bs->curpos) == bs->cursize) {
                                /* have space in line buffer? */
      if (i > LOCAL->linebuflen) {
        fs_give ((void **) &LOCAL->linebuf);
        LOCAL->linebuf = (char *) fs_get (LOCAL->linebuflen = i);
      }
                                /* remember what we have so far */
      memcpy (LOCAL->linebuf,bs->curpos,i);
                                /* load next buffer */
      SETPOS (bs,k = GETPOS (bs) + i);
                                /* end of fast scan */
      te = (t = (s = bs->curpos) + bs->cursize) - 12;
                                /* fast scan in overlap buffer */
      while (s < te) if ((*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                         (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                         (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n') ||
                         (*s++ == '\n') || (*s++ == '\n') || (*s++ == '\n')) {
        --s;                    /* back up */
        break;                  /* exit loop */
      }
\f
                                /* final character-at-a-time scan */
      while ((s < t) && (*s != '\n')) ++s;
                                /* huge line? */
      if ((j = s - bs->curpos) == bs->cursize) {
        SETPOS (bs,GETPOS (bs) + j);
                                /* look for end of line (s-l-o-w!!) */
        for (m = SIZE (bs); m && (SNX (bs) != '\n'); --m,++j);
        SETPOS (bs,k);          /* go back to where it started */
      }
                                /* got size of data, make buffer for return */
      ret = LOCAL->line = (char *) fs_get (i + j + 2);
                                /* copy first chunk */
      memcpy (ret,LOCAL->linebuf,i);
      while (j) {               /* copy remainder */
        if (!bs->cursize) SETPOS (bs,GETPOS (bs));
        memcpy (ret + i,bs->curpos,k = min (j,bs->cursize));
        i += k;                 /* account for this much read in */
        j -= k;
        bs->curpos += k;        /* increment new position */
        bs->cursize -= k;       /* eat that many bytes */
      }
                                /* read newline at end */
      if (SIZE (bs)) ret[i++] = SNX (bs);
      ret[i] = '\0';            /* makes debugging easier */
    }
    else {                      /* this is easy */
      ret = bs->curpos;         /* string it at this position */
      bs->curpos += ++i;        /* increment new position */
      bs->cursize -= i;         /* eat that many bytes */
    }
    *size = i;                  /* return that to user */
  }
  else *size = 0;               /* end of data, return empty */
                                /* embedded MMDF header at end of line? */
  if ((*size > sizeof (MMDFHDRTXT)) &&
      (s = ret + *size - (i = sizeof (MMDFHDRTXT) - 1)) && ISMMDF (s)) {
    SETPOS (bs,GETPOS (bs) - i);/* back up to start of MMDF header */
    *size -= i;                 /* reduce length of line */
    ret[*size - 1] = '\n';      /* force newline at end */
  }
  return ret;
}
\f
/* MMDF make pseudo-header
 * Accepts: MAIL stream
 *          buffer to write pseudo-header
 * Returns: length of pseudo-header
 */

unsigned long mmdf_pseudo (MAILSTREAM *stream,char *hdr)
{
  int i;
  char *s,tmp[MAILTMPLEN];
  time_t now = time (0);
  rfc822_fixed_date (tmp);
  sprintf (hdr,"%sFrom %s %.24s\nDate: %s\nFrom: %s <%s@%.80s>\nSubject: %s\nMessage-ID: <%lu@%.80s>\nX-IMAP: %010lu %010lu",
           mmdfhdr,pseudo_from,ctime (&now),
           tmp,pseudo_name,pseudo_from,mylocalhost (),pseudo_subject,
           (unsigned long) now,mylocalhost (),stream->uid_validity,
           stream->uid_last);
  for (s = hdr + strlen (hdr),i = 0; i < NUSERFLAGS; ++i)
    if (stream->user_flags[i])
      sprintf (s += strlen (s)," %s",stream->user_flags[i]);
  sprintf (s += strlen (s),"\nStatus: RO\n\n%s\n%s",pseudo_msg,mmdfhdr);
  return strlen (hdr);
}
\f
/* MMDF make status string
 * Accepts: MAIL stream
 *          destination string to write
 *          message cache entry
 *          UID to write if non-zero (else use elt->private.uid)
 *          non-zero flag to write UID (.LT. 0 to write UID base info too)
 * Returns: length of string
 */

unsigned long mmdf_xstatus (MAILSTREAM *stream,char *status,MESSAGECACHE *elt,
                            unsigned long uid,long flag)
{
  char *t,stack[64];
  char *s = status;
  unsigned long n;
  int pad = 50;
  int sticky = uid ? T : !stream->uid_nosticky;
  /* This used to use sprintf(), but thanks to certain cretinous C libraries
     with horribly slow implementations of sprintf() I had to change it to this
     mess.  At least it should be fast. */
  if ((flag < 0) && sticky) {   /* need to write X-IMAPbase: header? */
    *s++ = 'X'; *s++ = '-'; *s++ = 'I'; *s++ = 'M'; *s++ = 'A'; *s++ = 'P';
    *s++ = 'b'; *s++ = 'a'; *s++ = 's'; *s++ = 'e'; *s++ = ':'; *s++ = ' ';
    t = stack;
    n = stream->uid_validity;   /* push UID validity digits on the stack */
    do *t++ = (char) (n % 10) + '0';
    while (n /= 10);
                                /* pop UID validity digits from stack */
    while (t > stack) *s++ = *--t;
   *s++ = ' ';
    n = stream->uid_last;       /* push UID last digits on the stack */
    do *t++ = (char) (n % 10) + '0';
    while (n /= 10);
                                /* pop UID last digits from stack */
    while (t > stack) *s++ = *--t;
    for (n = 0; n < NUSERFLAGS; ++n) if ((t = stream->user_flags[n]) != NULL)
      for (*s++ = ' '; *t; *s++ = *t++);
    *s++ = '\n';
    pad += 30;                  /* increased padding if have IMAPbase */
  }
  *s++ = 'S'; *s++ = 't'; *s++ = 'a'; *s++ = 't'; *s++ = 'u'; *s++ = 's';
  *s++ = ':'; *s++ = ' ';
  if (elt->seen) *s++ = 'R';
                                /* only write O if have a UID */
  if (flag && (!elt->recent || !LOCAL->appending)) *s++ = 'O';
  *s++ = '\n';
  *s++ = 'X'; *s++ = '-'; *s++ = 'S'; *s++ = 't'; *s++ = 'a'; *s++ = 't';
  *s++ = 'u'; *s++ = 's'; *s++ = ':'; *s++ = ' ';
  if (elt->deleted) *s++ = 'D';
  if (elt->flagged) *s++ = 'F';
  if (elt->answered) *s++ = 'A';
  if (elt->draft) *s++ = 'T';
    *s++ = '\n';
\f
  if (sticky) {                 /* only do this if UIDs sticky */
    *s++ = 'X'; *s++ = '-'; *s++ = 'K'; *s++ = 'e'; *s++ = 'y'; *s++ = 'w';
    *s++ = 'o'; *s++ = 'r'; *s++ = 'd'; *s++ = 's'; *s++ = ':';
    if ((n = elt->user_flags) != 0L) do {
      *s++ = ' ';
      for (t = stream->user_flags[find_rightmost_bit (&n)]; *t; *s++ = *t++);
    } while (n);
    n = s - status;             /* get size of stuff so far */
                                /* pad X-Keywords to make size constant */
    if (n < pad) for (n = pad - n; n > 0; --n) *s++ = ' ';
    *s++ = '\n';
    if (flag) {                 /* want to include UID? */
      t = stack;
                                /* push UID digits on the stack */
      n = uid ? uid : elt->private.uid;
      do *t++ = (char) (n % 10) + '0';
      while (n /= 10);
      *s++ = 'X'; *s++ = '-'; *s++ = 'U'; *s++ = 'I'; *s++ = 'D'; *s++ = ':';
      *s++ = ' ';
                                /* pop UID from stack */
      while (t > stack) *s++ = *--t;
      *s++ = '\n';
    }
  }
  *s++ = '\n'; *s = '\0';       /* end of extended message status */
  return s - status;            /* return size of resulting string */
}
\f
/* Rewrite mailbox file
 * Accepts: MAIL stream, must be critical and locked
 *          return pointer to number of expunged messages if want expunge
 *          lock file name
 *          expunge sequence, not deleted flag
 * Returns: T if success and mailbox unlocked, NIL if failure
 */

#define OVERFLOWBUFLEN 8192     /* initial overflow buffer length */

long mmdf_rewrite (MAILSTREAM *stream,unsigned long *nexp,DOTLOCK *lock,
                   long flags)
{
  MESSAGECACHE *elt;
  MMDFFILE f;
  char *s;
  time_t tp[2];
  long ret,flag;
  unsigned long i,j;
  unsigned long recent = stream->recent;
  unsigned long size = LOCAL->pseudo ? mmdf_pseudo (stream,LOCAL->buf) : 0;
  if (nexp) *nexp = 0;          /* initially nothing expunged */
                                /* calculate size of mailbox after rewrite */
  for (i = 1,flag = LOCAL->pseudo ? 1 : -1; i <= stream->nmsgs; i++) {
    elt = mail_elt (stream,i);  /* get cache */
    if (!(nexp && elt->deleted && (flags ? elt->sequence : T))) {
                                /* add RFC822 size of this message */
      size += elt->private.special.text.size + elt->private.spare.data +
        mmdf_xstatus (stream,LOCAL->buf,elt,NIL,flag) +
          elt->private.msg.text.text.size + MMDFHDRLEN;
      flag = 1;                 /* only count X-IMAPbase once */
    }
  }
                                /* no messages, has a life, and no pseudo */
  if (!size && !mail_parameters (NIL,GET_USERHASNOLIFE,NIL)) {
    LOCAL->pseudo = T;          /* so make a pseudo-message now */
    size = mmdf_pseudo (stream,LOCAL->buf);
  }
                                /* extend the file as necessary */
  if ((ret = mmdf_extend (stream,size)) != 0L){
    /* Set up buffered I/O file structure
     * curpos   current position being written through buffering
     * filepos  current position being written physically to the disk
     * bufpos   current position being written in the buffer
     * protect  current maximum position that can be written to the disk
     *          before buffering is forced
     * The code tries to buffer so that that disk is written in multiples of
     * OVERBLOWBUFLEN bytes.
     */
    f.stream = stream;          /* note mail stream */
    f.curpos = f.filepos = 0;   /* start of file */
    f.protect = stream->nmsgs ? /* initial protection pointer */
    mail_elt (stream,1)->private.special.offset : 8192;
    f.bufpos = f.buf = (char *) fs_get (f.buflen = OVERFLOWBUFLEN);
\f
    if (LOCAL->pseudo)          /* update pseudo-header */
      mmdf_write (&f,LOCAL->buf,mmdf_pseudo (stream,LOCAL->buf));
                                /* loop through all messages */
    for (i = 1,flag = LOCAL->pseudo ? 1 : -1; i <= stream->nmsgs;) {
      elt = mail_elt (stream,i);/* get cache */
                                /* expunge this message? */
      if (nexp && elt->deleted && (flags ? elt->sequence : T)) {
                                /* one less recent message */
        if (elt->recent) --recent;
        mail_expunged(stream,i);/* notify upper levels */
        ++*nexp;                /* count up one more expunged message */
      }
      else {                    /* preserve this message */
        i++;                    /* advance to next message */
        if ((flag < 0) ||       /* need to rewrite message? */
            elt->private.dirty || (f.curpos != elt->private.special.offset) ||
            (elt->private.msg.header.text.size !=
             (elt->private.spare.data +
              mmdf_xstatus (stream,LOCAL->buf,elt,NIL,flag)))) {
          unsigned long newoffset = f.curpos;
                                /* yes, seek to internal header */
          lseek (LOCAL->fd,elt->private.special.offset,L_SET);
          read (LOCAL->fd,LOCAL->buf,elt->private.special.text.size);
                                /* see if need to squeeze out a CR */
          if (LOCAL->buf[elt->private.special.text.size - 2] == '\r') {
            LOCAL->buf[--elt->private.special.text.size - 1] = '\n';
            --size;             /* squeezed out a CR from PC */
          }
                                /* protection pointer moves to RFC822 header */
          f.protect = elt->private.special.offset +
            elt->private.msg.header.offset;
                                /* write internal header */
          mmdf_write (&f,LOCAL->buf,elt->private.special.text.size);
                                /* get RFC822 header */
          s = mmdf_header (stream,elt->msgno,&j,FT_INTERNAL);
                                /* in case this got decremented */
          elt->private.msg.header.offset = elt->private.special.text.size;
                                /* header size, sans trailing newline */
          if ((j < 2) || (s[j - 2] == '\n')) j--;
                                /* this can happen if CRs were squeezed */
          if (j < elt->private.spare.data) {
                                /* so fix up counts */
            size -= elt->private.spare.data - j;
            elt->private.spare.data = j;
          }
          else if (j != elt->private.spare.data)
            fatal ("header size inconsistent");
                                /* protection pointer moves to RFC822 text */
          f.protect = elt->private.special.offset +
            elt->private.msg.text.offset;
          mmdf_write (&f,s,j);  /* write RFC822 header */
                                /* write status and UID */
          mmdf_write (&f,LOCAL->buf,
                      j = mmdf_xstatus (stream,LOCAL->buf,elt,NIL,flag));
          flag = 1;             /* only write X-IMAPbase once */
                                /* new file header size */
          elt->private.msg.header.text.size = elt->private.spare.data + j;
\f
                                /* did text move? */
          if (f.curpos != f.protect) {
                                /* get message text */
            s = mmdf_text_work (stream,elt,&j,FT_INTERNAL);
                                /* this can happen if CRs were squeezed */
            if (j < elt->private.msg.text.text.size) {
                                /* so fix up counts */
              size -= elt->private.msg.text.text.size - j;
              elt->private.msg.text.text.size = j;
            }
                                /* can't happen it says here */
            else if (j > elt->private.msg.text.text.size)
              fatal ("text size inconsistent");
                                /* new text offset, status/UID may change it */
            elt->private.msg.text.offset = f.curpos - newoffset;
                                /* protection pointer moves to next message */
            f.protect = (i <= stream->nmsgs) ?
              mail_elt (stream,i)->private.special.offset :
                (f.curpos + j + MMDFHDRLEN);
            mmdf_write (&f,s,j);/* write text */
                                /* write trailing newline */
            mmdf_write (&f,mmdfhdr,MMDFHDRLEN);
          }
          else {                /* tie off header and status */
            mmdf_write (&f,NIL,NIL);
            f.curpos = f.protect =/* restart everything at end of message */
              f.filepos += elt->private.msg.text.text.size + MMDFHDRLEN;
          }
                                /* new internal header offset */
          elt->private.special.offset = newoffset;
          elt->private.dirty =NIL;/* message is now clean */
        }
        else {                  /* no need to rewrite this message */
                                /* tie off previous message if needed */
          mmdf_write (&f,NIL,NIL);
          f.curpos = f.protect =/* restart everything at end of message */
            f.filepos += elt->private.special.text.size +
              elt->private.msg.header.text.size +
                elt->private.msg.text.text.size + MMDFHDRLEN;
        }
      }
    }
\f
    mmdf_write (&f,NIL,NIL);    /* tie off final message */
    if (size != f.filepos) fatal ("file size inconsistent");
    fs_give ((void **) &f.buf); /* free buffer */
                                /* make sure tied off */
    ftruncate (LOCAL->fd,LOCAL->filesize = size);
    fsync (LOCAL->fd);          /* make sure the updates take */
    if (size && (flag < 0)) fatal ("lost UID base information");
                                /* no longer dirty */
    LOCAL->ddirty = LOCAL->dirty = NIL;
                                /* notify upper level of new mailbox sizes */
    mail_exists (stream,stream->nmsgs);
    mail_recent (stream,recent);
                                /* set atime to now, mtime a second earlier */
    tp[1] = (tp[0] = time (0)) - 1;
                                /* set the times, note change */
    if (!utime (stream->mailbox,tp)) LOCAL->filetime = tp[1];
    close (LOCAL->fd);          /* close and reopen file */
    if ((LOCAL->fd = open (stream->mailbox,O_RDWR,
                           (long) mail_parameters (NIL,GET_MBXPROTECTION,NIL)))
        < 0) {
      sprintf (LOCAL->buf,"Mailbox open failed, aborted: %s",strerror (errno));
      MM_LOG (LOCAL->buf,ERROR);
      mmdf_abort (stream);
    }
    dotlock_unlock (lock);      /* flush the lock file */
  }
  return ret;                   /* return state from algorithm */
}
\f
/* Extend MMDF mailbox file
 * Accepts: MAIL stream
 *          new desired size
 * Return: T if success, else NIL
 */

long mmdf_extend (MAILSTREAM *stream,unsigned long size)
{
  unsigned long i = (size > LOCAL->filesize) ? size - LOCAL->filesize : 0;
  if (i) {                      /* does the mailbox need to grow? */
    if (i > LOCAL->buflen) {    /* make sure have enough space */
                                /* this user won the lottery all right */
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen = i) + 1);
    }
    memset (LOCAL->buf,'\0',i); /* get a block of nulls */
    while (T) {                 /* until write successful or punt */
      lseek (LOCAL->fd,LOCAL->filesize,L_SET);
      if ((write (LOCAL->fd,LOCAL->buf,i) >= 0) && !fsync (LOCAL->fd)) break;
      else {
        long e = errno;         /* note error before doing ftruncate */
        ftruncate (LOCAL->fd,LOCAL->filesize);
        if (MM_DISKERROR (stream,e,NIL)) {
          fsync (LOCAL->fd);    /* user chose to punt */
          sprintf (LOCAL->buf,"Unable to extend mailbox: %s",strerror (e));
          if (!stream->silent) MM_LOG (LOCAL->buf,ERROR);
          return NIL;
        }
      }
    }
  }
  return LONGT;
}
\f
/* Write data to buffered file
 * Accepts: buffered file pointer
 *          file data or NIL to indicate "flush buffer"
 *          date size (ignored for "flush buffer")
 * Does not return until success
 */

void mmdf_write (MMDFFILE *f,char *buf,unsigned long size)
{
  unsigned long i,j,k;
  if (buf) {                    /* doing buffered write? */
    i = f->bufpos - f->buf;     /* yes, get size of current buffer data */
                                /* yes, have space in current buffer chunk? */
    if ((j = i ? ((f->buflen - i) % OVERFLOWBUFLEN) : f->buflen) != 0L) {
                                /* yes, fill up buffer as much as we can */
      memcpy (f->bufpos,buf,k = min (j,size));
      f->bufpos += k;           /* new buffer position */
      f->curpos += k;           /* new current position */
      if (j -= k) return;       /* all done if still have buffer free space */
      buf += k;                 /* full, get new unwritten data pointer */
      size -= k;                /* new data size */
      i += k;                   /* new buffer data size */
    }
    /* This chunk of the buffer is full.  See if can make some space by
     * writing to the disk, if there's enough unprotected space to do so.
     * Try to fill out any unaligned chunk, along with any subsequent full
     * chunks that will fit in unprotected space.
     */
                                /* any unprotected space we can write to? */
    if ((j = min (i,f->protect - f->filepos)) != 0L) {
                                /* yes, filepos not at chunk boundary? */
      if ((k = f->filepos % OVERFLOWBUFLEN) && ((k = OVERFLOWBUFLEN - k) < j))
        j -= k;                 /* yes, and can write out partial chunk */
      else k = 0;               /* no partial chunk to write */
                                /* if at least a chunk free, write that too */
      if (j > OVERFLOWBUFLEN) k += j - (j % OVERFLOWBUFLEN);
      if (k) {                  /* write data if there is anything we can */
        mmdf_phys_write (f,f->buf,k);
                                /* slide buffer */
        if (i -= k) memmove (f->buf,f->buf + k,i);
        f->bufpos = f->buf + i; /* new end of buffer */
      }
    }
\f
    /* Have flushed the buffer as best as possible.  All done if no more
     * data to write.  Otherwise, if the buffer is empty AND if the unwritten
     * data is larger than a chunk AND the unprotected space is also larger
     * than a chunk, then write as many chunks as we can directly from the
     * data.  Buffer the rest, expanding the buffer as needed.
     */
    if (size) {                 /* have more data that we need to buffer? */
                                /* can write any of it to disk instead? */
      if ((f->bufpos == f->buf) && 
          ((j = min (f->protect - f->filepos,size)) > OVERFLOWBUFLEN)) {
                                /* write as much as we can right now */
        mmdf_phys_write (f,buf,j -= (j % OVERFLOWBUFLEN));
        buf += j;               /* new data pointer */
        size -= j;              /* new data size */
        f->curpos += j;         /* advance current pointer */
      }
      if (size) {               /* still have data that we need to buffer? */
                                /* yes, need to expand the buffer? */
        if ((i = ((f->bufpos + size) - f->buf)) > f->buflen) {
                                /* note current position in buffer */
          j = f->bufpos - f->buf;
          i += OVERFLOWBUFLEN;  /* yes, grow another chunk */
          fs_resize ((void **) &f->buf,f->buflen = i - (i % OVERFLOWBUFLEN));
                                /* in case buffer relocated */
          f->bufpos = f->buf + j;
        }
                                /* buffer remaining data */
        memcpy (f->bufpos,buf,size);
        f->bufpos += size;      /* new end of buffer */
        f->curpos += size;      /* advance current pointer */
      }
    }
  }
  else {                        /* flush buffer to disk */
    mmdf_phys_write (f,f->buf,i = f->bufpos - f->buf);
    f->bufpos = f->buf;         /* reset buffer */
                                /* update positions */
    f->curpos = f->protect = f->filepos;
  }
}
\f
/* Physical disk write
 * Accepts: buffered file pointer
 *          buffer address
 *          buffer size
 * Does not return until success
 */

void mmdf_phys_write (MMDFFILE *f,char *buf,size_t size)
{
  MAILSTREAM *stream = f->stream;
                                /* write data at desired position */
  while (size && ((lseek (LOCAL->fd,f->filepos,L_SET) < 0) ||
                  (write (LOCAL->fd,buf,size) < 0))) {
    int e;
    char tmp[MAILTMPLEN];
    sprintf (tmp,"Unable to write to mailbox: %s",strerror (e = errno));
    MM_LOG (tmp,ERROR);
    MM_DISKERROR (NIL,e,T);     /* serious problem, must retry */
  }
  f->filepos += size;           /* update file position */
}