* Implement a different way to delete a password from the cache.

[alpine.git] / imap / src / osdep / os2 / mtxnt.c

/* ========================================================================
 * Copyright 1988-2007 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:     MTX mail routines
 *
 * Author:      Mark Crispin
 *              Networks and Distributed Computing
 *              Computing & Communications
 *              University of Washington
 *              Administration Building, AG-44
 *              Seattle, WA  98195
 *              Internet: MRC@CAC.Washington.EDU
 *
 * Date:        22 May 1990
 * Last Edited: 15 June 2007
 */


/*                              FILE TIME SEMANTICS
 *
 * The atime is the last read time of the file.
 * The mtime is the last flags update time of the file.
 * The ctime is the last write time of the file.
 */

#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#ifndef errno
extern int errno;               /* just in case */
#endif
#include "mail.h"
#include "osdep.h"
#include <fcntl.h>
#include <time.h>
#include <sys/stat.h>
#include <sys/utime.h>
#include "misc.h"
#include "dummy.h"
#include "fdstring.h"
\f
/* MTX I/O stream local data */
        
typedef struct mtx_local {
  unsigned int shouldcheck: 1;  /* if ping should do a check instead */
  unsigned int mustcheck: 1;    /* if ping must do a check instead */
  int fd;                       /* file descriptor for I/O */
  off_t filesize;               /* file size parsed */
  time_t filetime;              /* last file time */
  time_t lastsnarf;             /* last snarf time */
  unsigned char *buf;           /* temporary buffer */
  unsigned long buflen;         /* current size of temporary buffer */
} MTXLOCAL;


/* Convenient access to local data */

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


/* Function prototypes */

DRIVER *mtx_valid (char *name);
int mtx_isvalid (char *name,char *file);
void *mtx_parameters (long function,void *value);
void mtx_scan (MAILSTREAM *stream,char *ref,char *pat,char *contents);
void mtx_list (MAILSTREAM *stream,char *ref,char *pat);
void mtx_lsub (MAILSTREAM *stream,char *ref,char *pat);
long mtx_create (MAILSTREAM *stream,char *mailbox);
long mtx_delete (MAILSTREAM *stream,char *mailbox);
long mtx_rename (MAILSTREAM *stream,char *old,char *newname);
long mtx_status (MAILSTREAM *stream,char *mbx,long flags);
MAILSTREAM *mtx_open (MAILSTREAM *stream);
void mtx_close (MAILSTREAM *stream,long options);
void mtx_flags (MAILSTREAM *stream,char *sequence,long flags);
char *mtx_header (MAILSTREAM *stream,unsigned long msgno,
                  unsigned long *length,long flags);
long mtx_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags);
void mtx_flag (MAILSTREAM *stream,char *sequence,char *flag,long flags);
void mtx_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt);
long mtx_ping (MAILSTREAM *stream);
void mtx_check (MAILSTREAM *stream);
void mtx_snarf (MAILSTREAM *stream);
long mtx_expunge (MAILSTREAM *stream,char *sequence,long options);
long mtx_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options);
long mtx_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);

long mtx_parse (MAILSTREAM *stream);
MESSAGECACHE *mtx_elt (MAILSTREAM *stream,unsigned long msgno);
void mtx_read_flags (MAILSTREAM *stream,MESSAGECACHE *elt);
void mtx_update_status (MAILSTREAM *stream,unsigned long msgno,long syncflag);
unsigned long mtx_hdrpos (MAILSTREAM *stream,unsigned long msgno,
                          unsigned long *size);

\f
/* MTX mail routines */


/* Driver dispatch used by MAIL */

DRIVER mtxdriver = {
  "mtx",                        /* driver name */
                                /* driver flags */
  DR_LOCAL|DR_MAIL|DR_CRLF|DR_NOSTICKY,
  (DRIVER *) NIL,               /* next driver */
  mtx_valid,                    /* mailbox is valid for us */
  mtx_parameters,               /* manipulate parameters */
  mtx_scan,                     /* scan mailboxes */
  mtx_list,                     /* list mailboxes */
  mtx_lsub,                     /* list subscribed mailboxes */
  NIL,                          /* subscribe to mailbox */
  NIL,                          /* unsubscribe from mailbox */
  mtx_create,                   /* create mailbox */
  mtx_delete,                   /* delete mailbox */
  mtx_rename,                   /* rename mailbox */
  mail_status_default,          /* status of mailbox */
  mtx_open,                     /* open mailbox */
  mtx_close,                    /* close mailbox */
  mtx_flags,                    /* fetch message "fast" attributes */
  mtx_flags,                    /* fetch message flags */
  NIL,                          /* fetch overview */
  NIL,                          /* fetch message envelopes */
  mtx_header,                   /* fetch message header */
  mtx_text,                     /* fetch message body */
  NIL,                          /* fetch partial message text */
  NIL,                          /* unique identifier */
  NIL,                          /* message number */
  mtx_flag,                     /* modify flags */
  mtx_flagmsg,                  /* per-message modify flags */
  NIL,                          /* search for message based on criteria */
  NIL,                          /* sort messages */
  NIL,                          /* thread messages */
  mtx_ping,                     /* ping mailbox to see if still alive */
  mtx_check,                    /* check for new messages */
  mtx_expunge,                  /* expunge deleted messages */
  mtx_copy,                     /* copy messages to another mailbox */
  mtx_append,                   /* append string message to mailbox */
  NIL                           /* garbage collect stream */
};

                                /* prototype stream */
MAILSTREAM mtxproto = {&mtxdriver};
\f
/* MTX mail validate mailbox
 * Accepts: mailbox name
 * Returns: our driver if name is valid, NIL otherwise
 */

DRIVER *mtx_valid (char *name)
{
  char tmp[MAILTMPLEN];
  return mtx_isvalid (name,tmp) ? &mtxdriver : NIL;
}


/* MTX mail test for valid mailbox
 * Accepts: mailbox name
 *          buffer to return file name
 * Returns: T if valid, NIL otherwise
 */

int mtx_isvalid (char *name,char *file)
{
  int fd;
  int ret = NIL;
  char *s,tmp[MAILTMPLEN];
  struct stat sbuf;
  struct utimbuf times;
  errno = EINVAL;               /* assume invalid argument */
                                /* if file, get its status */
  if ((s = dummy_file (file,name)) && !stat (s,&sbuf) &&
      ((sbuf.st_mode & S_IFMT) == S_IFREG)) {
    if (!sbuf.st_size)errno = 0;/* empty file */
    else if ((fd = open (file,O_BINARY|O_RDONLY,NIL)) >= 0) {
      memset (tmp,'\0',MAILTMPLEN);
      if ((read (fd,tmp,64) >= 0) && (s = strchr (tmp,'\015')) &&
          (s[1] == '\012')) {   /* valid format? */
        *s = '\0';              /* tie off header */
                                /* must begin with dd-mmm-yy" */
        ret = (((tmp[2] == '-' && tmp[6] == '-') ||
                (tmp[1] == '-' && tmp[5] == '-')) &&
               (s = strchr (tmp+18,',')) && strchr (s+2,';')) ? T : NIL;
      }
      else errno = -1;          /* bogus format */
      close (fd);               /* close the file */
                                /* \Marked status? */
      if (sbuf.st_ctime > sbuf.st_atime) {
                                /* preserve atime and mtime */
        times.actime = sbuf.st_atime;
        times.modtime = sbuf.st_mtime;
        utime (file,&times);    /* set the times */
      }
    }
  }
                                /* in case INBOX but not mtx format */
  else if ((errno == ENOENT) && !compare_cstring (name,"INBOX")) errno = -1;
  return ret;                   /* return what we should */
}


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

void *mtx_parameters (long function,void *value)
{
  return NIL;
}
\f
/* MTX mail scan mailboxes
 * Accepts: mail stream
 *          reference
 *          pattern to search
 *          string to scan
 */

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


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

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


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

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

long mtx_create (MAILSTREAM *stream,char *mailbox)
{
  char *s,mbx[MAILTMPLEN];
  if (s = dummy_file (mbx,mailbox)) return dummy_create (stream,s);
  sprintf (mbx,"Can't create %.80s: invalid name",mailbox);
  mm_log (mbx,ERROR);
  return NIL;
}


/* MTX mail delete mailbox
 * Accepts: MAIL stream
 *          mailbox name to delete
 * Returns: T on success, NIL on failure
 */

long mtx_delete (MAILSTREAM *stream,char *mailbox)
{
  return mtx_rename (stream,mailbox,NIL);
}
\f
/* MTX mail rename mailbox
 * Accepts: MAIL stream
 *          old mailbox name
 *          new mailbox name (or NIL for delete)
 * Returns: T on success, NIL on failure
 */

long mtx_rename (MAILSTREAM *stream,char *old,char *newname)
{
  long ret = LONGT;
  char c,*s,tmp[MAILTMPLEN],file[MAILTMPLEN],lock[MAILTMPLEN];
  int fd,ld;
  struct stat sbuf;
  if (!dummy_file (file,old) ||
      (newname && (!((s = mailboxfile (tmp,newname)) && *s) ||
                   ((s = strrchr (tmp,'\\')) && !s[1])))) {
    sprintf (tmp,newname ?
             "Can't rename mailbox %.80s to %.80s: invalid name" :
             "Can't delete mailbox %.80s: invalid name",
             old,newname);
    mm_log (tmp,ERROR);
    return NIL;
  }
  if ((fd = open (file,O_BINARY|O_RDWR,NIL)) < 0) {
    sprintf (tmp,"Can't open mailbox %.80s: %s",old,strerror (errno));
    mm_log (tmp,ERROR);
    return NIL;
  }
                                /* get exclusive parse/append permission */
  if ((ld = lockname (lock,file,LOCK_EX)) < 0) {
    mm_log ("Unable to lock rename mailbox",ERROR);
    return NIL;
  }
                                /* lock out other users */
  if (flock (fd,LOCK_EX|LOCK_NB)) {
    close (fd);                 /* couldn't lock, give up on it then */
    sprintf (tmp,"Mailbox %.80s is in use by another process",old);
    mm_log (tmp,ERROR);
    unlockfd (ld,lock);         /* release exclusive parse/append permission */
    return NIL;
  }
\f
  if (newname) {                /* want rename? */
                                /* found superior to destination name? */
    if ((s = strrchr (tmp,'\\')) && (s != tmp) &&
        ((tmp[1] != ':') || (s != tmp + 2))) {
      c = s[1];                 /* remember character after delimiter */
      *s = s[1] = '\0';         /* tie off name at delimiter */
                                /* name doesn't exist, create it */
      if (stat (tmp,&sbuf) || ((sbuf.st_mode & S_IFMT) != S_IFDIR)) {
        *s = '\\';              /* restore delimiter */
        if (!dummy_create (stream,tmp)) ret = NIL;
      }
      else *s = '\\';           /* restore delimiter */
      s[1] = c;                 /* restore character after delimiter */
    }
    flock (fd,LOCK_UN);         /* release lock on the file */
    close (fd);                 /* pacify NTFS */
                                /* rename the file */
    if (ret && rename (file,tmp)) {
      sprintf (tmp,"Can't rename mailbox %.80s to %.80s: %s",old,newname,
               strerror (errno));
      mm_log (tmp,ERROR);
      ret = NIL;                /* set failure */
    }
  }
  else {
    flock (fd,LOCK_UN);         /* release lock on the file */
    close (fd);                 /* pacify NTFS */
    if (unlink (file)) {
      sprintf (tmp,"Can't delete mailbox %.80s: %.80s",old,strerror (errno));
      mm_log (tmp,ERROR);
      ret = NIL;                /* set failure */
    }
  }
  unlockfd (ld,lock);           /* release exclusive parse/append permission */
  return ret;                   /* return success */
}
\f
/* MTX mail open
 * Accepts: stream to open
 * Returns: stream on success, NIL on failure
 */

MAILSTREAM *mtx_open (MAILSTREAM *stream)
{
  int fd,ld;
  char tmp[MAILTMPLEN];
                                /* return prototype for OP_PROTOTYPE call */
  if (!stream) return &mtxproto;
  if (stream->local) fatal ("mtx recycle stream");
                                /* canonicalize the mailbox name */
  if (!dummy_file (tmp,stream->mailbox)) {
    sprintf (tmp,"Can't open - invalid name: %.80s",stream->mailbox);
    mm_log (tmp,ERROR);
  }
  if (stream->rdonly ||
      (fd = open (tmp,O_BINARY|O_RDWR,NIL)) < 0) {
    if ((fd = open (tmp,O_BINARY|O_RDONLY,NIL)) < 0) {
      sprintf (tmp,"Can't open mailbox: %.80s",strerror (errno));
      mm_log (tmp,ERROR);
      return NIL;
    }
    else if (!stream->rdonly) { /* got it, but readonly */
      mm_log ("Can't get write access to mailbox, access is readonly",WARN);
      stream->rdonly = T;
    }
  }
  stream->local = fs_get (sizeof (MTXLOCAL));
  LOCAL->fd = fd;               /* bind the file */
  LOCAL->buf = (char *) fs_get (CHUNKSIZE);
  LOCAL->buflen = CHUNKSIZE - 1;
                                /* note if an INBOX or not */
  stream->inbox = !compare_cstring (stream->mailbox,"INBOX");
  fs_give ((void **) &stream->mailbox);
  stream->mailbox = cpystr (tmp);
                                /* get shared parse permission */
  if ((ld = lockname (tmp,stream->mailbox,LOCK_SH)) < 0) {
    mm_log ("Unable to lock open mailbox",ERROR);
    return NIL;
  }
  flock (LOCAL->fd,LOCK_SH);    /* lock the file */
  unlockfd (ld,tmp);            /* release shared parse permission */
  LOCAL->filesize = 0;          /* initialize parsed file size */
  LOCAL->filetime = 0;          /* time not set up yet */
  LOCAL->mustcheck = LOCAL->shouldcheck = NIL;
  stream->sequence++;           /* bump sequence number */
  stream->uid_validity = (unsigned long) time (0);
                                /* parse mailbox */
  stream->nmsgs = stream->recent = 0;
  if (mtx_ping (stream) && !stream->nmsgs)
    mm_log ("Mailbox is empty",(long) NIL);
  if (!LOCAL) return NIL;       /* failure if stream died */
  stream->perm_seen = stream->perm_deleted =
    stream->perm_flagged = stream->perm_answered = stream->perm_draft =
      stream->rdonly ? NIL : T;
  stream->perm_user_flags = stream->rdonly ? NIL : 0xffffffff;
  return stream;                /* return stream to caller */
}
\f
/* MTX mail close
 * Accepts: MAIL stream
 *          close options
 */

void mtx_close (MAILSTREAM *stream,long options)
{
  if (stream && LOCAL) {        /* only if a file is open */
    int silent = stream->silent;
    stream->silent = T;         /* note this stream is dying */
    if (options & CL_EXPUNGE) mtx_expunge (stream,NIL,NIL);
    stream->silent = silent;    /* restore previous status */
    flock (LOCAL->fd,LOCK_UN);  /* unlock local file */
    close (LOCAL->fd);          /* close the local file */
                                /* free local text buffer */
    if (LOCAL->buf) fs_give ((void **) &LOCAL->buf);
                                /* nuke the local data */
    fs_give ((void **) &stream->local);
    stream->dtb = NIL;          /* log out the DTB */
  }
}


/* MTX mail fetch flags
 * Accepts: MAIL stream
 *          sequence
 *          option flags
 * Sniffs at file to see if some other process changed the flags
 */

void mtx_flags (MAILSTREAM *stream,char *sequence,long flags)
{
  unsigned long i;
  if (mtx_ping (stream) &&      /* ping mailbox, get new status for messages */
      ((flags & FT_UID) ? mail_uid_sequence (stream,sequence) :
       mail_sequence (stream,sequence)))
    for (i = 1; i <= stream->nmsgs; i++) 
      if (mail_elt (stream,i)->sequence) mtx_elt (stream,i);
}
\f
/* MTX mail fetch message header
 * Accepts: MAIL stream
 *          message # to fetch
 *          pointer to returned header text length
 *          option flags
 * Returns: message header in RFC822 format
 */

char *mtx_header (MAILSTREAM *stream,unsigned long msgno,unsigned long *length,
                  long flags)
{
  *length = 0;                  /* default to empty */
  if (flags & FT_UID) return "";/* UID call "impossible" */
                                /* get to header position */
  lseek (LOCAL->fd,mtx_hdrpos (stream,msgno,length),L_SET);
                                /* is buffer big enough? */
  if (*length > LOCAL->buflen) {
    fs_give ((void **) &LOCAL->buf);
    LOCAL->buf = (char *) fs_get ((LOCAL->buflen = *length) + 1);
  }
  LOCAL->buf[*length] = '\0';   /* tie off string */
                                /* slurp the data */
  read (LOCAL->fd,LOCAL->buf,*length);
  return LOCAL->buf;
}
\f
/* MTX mail fetch message text (body only)
 * Accepts: MAIL stream
 *          message # to fetch
 *          pointer to returned header text length
 *          option flags
 * Returns: T, always
 */

long mtx_text (MAILSTREAM *stream,unsigned long msgno,STRING *bs,long flags)
{
  FDDATA d;
  unsigned long i,j;
  MESSAGECACHE *elt;
                                /* UID call "impossible" */
  if (flags & FT_UID) return NIL;
  elt = mtx_elt (stream,msgno); /* get message status */
                                /* if message not seen */
  if (!(flags & FT_PEEK) && !elt->seen) {
    elt->seen = T;              /* mark message as seen */
                                /* recalculate status */
    mtx_update_status (stream,msgno,NIL);
    mm_flags (stream,msgno);
  }
                                /* find header position */
  i = mtx_hdrpos (stream,msgno,&j);
  d.fd = LOCAL->fd;             /* set up file descriptor */
  d.pos = i + j;
  d.chunk = LOCAL->buf; /* initial buffer chunk */
  d.chunksize = CHUNKSIZE;
  INIT (bs,fd_string,&d,elt->rfc822_size - j);
  return T;                     /* success */
}
\f
/* MTX mail modify flags
 * Accepts: MAIL stream
 *          sequence
 *          flag(s)
 *          option flags
 */

void mtx_flag (MAILSTREAM *stream,char *sequence,char *flag,long flags)
{
  struct utimbuf times;
  struct stat sbuf;
  if (!stream->rdonly) {        /* make sure the update takes */
    fsync (LOCAL->fd);
    fstat (LOCAL->fd,&sbuf);    /* get current write time */
    times.modtime = LOCAL->filetime = sbuf.st_mtime;
    times.actime = time (0);    /* make sure read comes after all that */
    utime (stream->mailbox,&times);
  }
}


/* MTX mail per-message modify flags
 * Accepts: MAIL stream
 *          message cache element
 */

void mtx_flagmsg (MAILSTREAM *stream,MESSAGECACHE *elt)
{
  struct stat sbuf;
                                /* maybe need to do a checkpoint? */
  if (LOCAL->filetime && !LOCAL->shouldcheck) {
    fstat (LOCAL->fd,&sbuf);    /* get current write time */
    if (LOCAL->filetime < sbuf.st_mtime) LOCAL->shouldcheck = T;
    LOCAL->filetime = 0;        /* don't do this test for any other messages */
  }
                                /* recalculate status */
  mtx_update_status (stream,elt->msgno,NIL);
}
\f
/* MTX mail ping mailbox
 * Accepts: MAIL stream
 * Returns: T if stream still alive, NIL if not
 */

long mtx_ping (MAILSTREAM *stream)
{
  unsigned long i = 1;
  long r = T;
  int ld;
  char lock[MAILTMPLEN];
  struct stat sbuf;
  if (stream && LOCAL) {        /* only if stream already open */
    fstat (LOCAL->fd,&sbuf);    /* get current file poop */
    if (LOCAL->filetime && !(LOCAL->mustcheck || LOCAL->shouldcheck) &&
        (LOCAL->filetime < sbuf.st_mtime)) LOCAL->shouldcheck = T;
                                /* check for changed message status */
    if (LOCAL->mustcheck || LOCAL->shouldcheck) {
      LOCAL->filetime = sbuf.st_mtime;
      if (LOCAL->shouldcheck)   /* babble when we do this unilaterally */
        mm_notify (stream,"[CHECK] Checking for flag updates",NIL);
      while (i <= stream->nmsgs) mtx_elt (stream,i++);
      LOCAL->mustcheck = LOCAL->shouldcheck = NIL;
    }
                                /* get shared parse/append permission */
    if ((sbuf.st_size != LOCAL->filesize) &&
        ((ld = lockname (lock,stream->mailbox,LOCK_SH)) >= 0)) {
                                /* parse resulting mailbox */
      r = (mtx_parse (stream)) ? T : NIL;
      unlockfd (ld,lock);       /* release shared parse/append permission */
    }
  }
  return r;                     /* return result of the parse */
}


/* MTX mail check mailbox (reparses status too)
 * Accepts: MAIL stream
 */

void mtx_check (MAILSTREAM *stream)
{
                                /* mark that a check is desired */
  if (LOCAL) LOCAL->mustcheck = T;
  if (mtx_ping (stream)) mm_log ("Check completed",(long) NIL);
}
\f
/* MTX mail expunge mailbox
 *          sequence to expunge if non-NIL
 *          expunge options
 * Returns: T, always
 */

long mtx_expunge (MAILSTREAM *stream,char *sequence,long options)
{
  long ret;
  struct utimbuf times;
  struct stat sbuf;
  off_t pos = 0;
  int ld;
  unsigned long i = 1;
  unsigned long j,k,m,recent;
  unsigned long n = 0;
  unsigned long delta = 0;
  char lock[MAILTMPLEN];
  MESSAGECACHE *elt;
  if (!(ret = (sequence ? ((options & EX_UID) ?
                           mail_uid_sequence (stream,sequence) :
                           mail_sequence (stream,sequence)) : LONGT) &&
        mtx_ping (stream)));    /* parse sequence if given, ping stream */
  else if (stream->rdonly) mm_log ("Expunge ignored on readonly mailbox",WARN);
  else {
    if (LOCAL->filetime && !LOCAL->shouldcheck) {
      fstat (LOCAL->fd,&sbuf);  /* get current write time */
      if (LOCAL->filetime < sbuf.st_mtime) LOCAL->shouldcheck = T;
    }
                                /* get exclusive parse/append permission */
    if ((ld = lockname (lock,stream->mailbox,LOCK_EX)) < 0)
      mm_log ("Unable to lock expunge mailbox",ERROR);
                                /* make sure see any newly-arrived messages */
    else if (!mtx_parse (stream));
                                /* get exclusive access */
    else if (flock (LOCAL->fd,LOCK_EX|LOCK_NB)) {
      flock (LOCAL->fd,LOCK_SH);/* recover previous lock */
      mm_log ("Can't expunge because mailbox is in use by another process",
              ERROR);
      unlockfd (ld,lock);       /* release exclusive parse/append permission */
    }
\f
    else {
      mm_critical (stream);     /* go critical */
      recent = stream->recent;  /* get recent now that pinged and locked */
                                /* for each message */
      while (i <= stream->nmsgs) {
                                /* get cache element */
        elt = mtx_elt (stream,i);
                                /* number of bytes to smash or preserve */
        k = elt->private.special.text.size + elt->rfc822_size;
                                /* if need to expunge this message */
        if (elt->deleted && (sequence ? elt->sequence : T)) {
                                /* if recent, note one less recent message */
          if (elt->recent) --recent;
          delta += k;           /* number of bytes to delete */
                                /* notify upper levels */
          mail_expunged (stream,i);
          n++;                  /* count up one more expunged message */
        }
        else if (i++ && delta) {/* preserved message */
                                /* first byte to preserve */
          j = elt->private.special.offset;
          do {                  /* read from source position */
            m = min (k,LOCAL->buflen);
            lseek (LOCAL->fd,j,L_SET);
            read (LOCAL->fd,LOCAL->buf,m);
            pos = j - delta;    /* write to destination position */
            while (T) {
              lseek (LOCAL->fd,pos,L_SET);
              if (write (LOCAL->fd,LOCAL->buf,m) > 0) break;
              mm_notify (stream,strerror (errno),WARN);
              mm_diskerror (stream,errno,T);
            }
            pos += m;           /* new position */
            j += m;             /* next chunk, perhaps */
          } while (k -= m);     /* until done */
                                /* note the new address of this text */
          elt->private.special.offset -= delta;
        }
                                /* preserved but no deleted messages */
        else pos = elt->private.special.offset + k;
      }
      if (n) {                  /* truncate file after last message */
        if (pos != (LOCAL->filesize -= delta)) {
          sprintf (LOCAL->buf,
                   "Calculated size mismatch %lu != %lu, delta = %lu",
                   (unsigned long) pos,(unsigned long) LOCAL->filesize,delta);
          mm_log (LOCAL->buf,WARN);
          LOCAL->filesize = pos;/* fix it then */
        }
        ftruncate (LOCAL->fd,LOCAL->filesize);
        sprintf (LOCAL->buf,"Expunged %lu messages",n);
                                /* output the news */
        mm_log (LOCAL->buf,(long) NIL);
      }
      else mm_log ("No messages deleted, so no update needed",(long) NIL);
      fsync (LOCAL->fd);        /* force disk update */
      fstat (LOCAL->fd,&sbuf);  /* get new write time */
      times.modtime = LOCAL->filetime = sbuf.st_mtime;
      times.actime = time (0);  /* reset atime to now */
      utime (stream->mailbox,&times);
      mm_nocritical (stream);   /* release critical */
                                /* notify upper level of new mailbox size */
      mail_exists (stream,stream->nmsgs);
      mail_recent (stream,recent);
      flock (LOCAL->fd,LOCK_SH);/* allow sharers again */
      unlockfd (ld,lock);       /* release exclusive parse/append permission */
    }
  }
  return ret;
}
\f
/* MTX mail copy message(s)
 * Accepts: MAIL stream
 *          sequence
 *          destination mailbox
 *          copy options
 * Returns: T if success, NIL if failed
 */

long mtx_copy (MAILSTREAM *stream,char *sequence,char *mailbox,long options)
{
  struct stat sbuf;
  struct utimbuf times;
  MESSAGECACHE *elt;
  unsigned long i,j,k;
  long ret = LONGT;
  int fd,ld;
  char file[MAILTMPLEN],lock[MAILTMPLEN];
  mailproxycopy_t pc =
    (mailproxycopy_t) mail_parameters (stream,GET_MAILPROXYCOPY,NIL);
                                /* make sure valid mailbox */
  if (!mtx_isvalid (mailbox,file)) switch (errno) {
  case ENOENT:                  /* no such file? */
    mm_notify (stream,"[TRYCREATE] Must create mailbox before copy",NIL);
    return NIL;
  case 0:                       /* merely empty file? */
    break;
  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 MTX-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 MTX-format mailbox: %.80s",mailbox);
    mm_log (LOCAL->buf,ERROR);
    return NIL;
  }
  if (!((options & CP_UID) ? mail_uid_sequence (stream,sequence) :
        mail_sequence (stream,sequence))) return NIL;
                                /* got file? */
  if ((fd = open (file,O_BINARY|O_RDWR|O_CREAT,S_IREAD|S_IWRITE)) < 0) {
    sprintf (LOCAL->buf,"Unable to open copy mailbox: %.80s",strerror (errno));
    mm_log (LOCAL->buf,ERROR);
    return NIL;
  }
  mm_critical (stream);         /* go critical */
                                /* get exclusive parse/append permission */
  if (flock (fd,LOCK_SH) || ((ld = lockname (lock,file,LOCK_EX)) < 0)) {
    mm_log ("Unable to lock copy mailbox",ERROR);
    mm_nocritical (stream);
    return NIL;
  }
  fstat (fd,&sbuf);             /* get current file size */
  lseek (fd,sbuf.st_size,L_SET);/* move to end of file */
\f
                                /* for each requested message */
  for (i = 1; ret && (i <= stream->nmsgs); i++) 
    if ((elt = mail_elt (stream,i))->sequence) {
      lseek (LOCAL->fd,elt->private.special.offset,L_SET);
                                /* number of bytes to copy */
      k = elt->private.special.text.size + elt->rfc822_size;
      do {                      /* read from source position */
        j = min (k,LOCAL->buflen);
        read (LOCAL->fd,LOCAL->buf,j);
        if (write (fd,LOCAL->buf,j) < 0) ret = NIL;
      } while (ret && (k -= j));/* until done */
    }
                                /* make sure all the updates take */
  if (!(ret && (ret = !fsync (fd)))) {
    sprintf (LOCAL->buf,"Unable to write message: %s",strerror (errno));
    mm_log (LOCAL->buf,ERROR);
    ftruncate (fd,sbuf.st_size);
  }
                                /* set atime to now-1 if successful copy */
  if (ret) times.actime = time (0) - 1;
                                /* else preserved \Marked status */
  else times.actime = (sbuf.st_ctime > sbuf.st_atime) ?
         sbuf.st_atime : time (0);
  times.modtime = sbuf.st_mtime;/* preserve mtime */
  utime (file,&times);          /* set the times */
  unlockfd (ld,lock);           /* release exclusive parse/append permission */
  close (fd);                   /* close the file */
  mm_nocritical (stream);       /* release critical */
                                /* delete all requested messages */
  if (ret && (options & CP_MOVE)) {
    for (i = 1; i <= stream->nmsgs; i++)
      if ((elt = mtx_elt (stream,i))->sequence) {
        elt->deleted = T;       /* mark message deleted */
                                /* recalculate status */
        mtx_update_status (stream,i,NIL);
      }
    if (!stream->rdonly) {      /* make sure the update takes */
      fsync (LOCAL->fd);
      fstat (LOCAL->fd,&sbuf);  /* get current write time */
      times.modtime = LOCAL->filetime = sbuf.st_mtime;
      times.actime = time (0);  /* make sure atime remains greater */
      utime (stream->mailbox,&times);
    }
  }
  if (ret && mail_parameters (NIL,GET_COPYUID,NIL))
    mm_log ("Can not return meaningful COPYUID with this mailbox format",WARN);
  return ret;
}
\f
/* MTX mail append message from stringstruct
 * Accepts: MAIL stream
 *          destination mailbox
 *          append callback
 *          data for callback
 * Returns: T if append successful, else NIL
 */

long mtx_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data)
{
  struct stat sbuf;
  int fd,ld,c;
  char *flags,*date,tmp[MAILTMPLEN],file[MAILTMPLEN],lock[MAILTMPLEN];
  struct utimbuf times;
  FILE *df;
  MESSAGECACHE elt;
  long f;
  unsigned long i,uf;
  STRING *message;
  long ret = LONGT;
                                /* default stream to prototype */
  if (!stream) stream = &mtxproto;
                                /* make sure valid mailbox */
  if (!mtx_isvalid (mailbox,file)) switch (errno) {
  case ENOENT:                  /* no such file? */
    if (!compare_cstring (mailbox,"INBOX")) mtx_create (NIL,"INBOX");
    else {
      mm_notify (stream,"[TRYCREATE] Must create mailbox before append",NIL);
      return NIL;
    }
                                /* falls through */
  case 0:                       /* merely empty file? */
    break;
  case EACCES:                  /* file protected */
    sprintf (tmp,"Can't access destination: %.80s",mailbox);
    MM_LOG (tmp,ERROR);
    return NIL;
  case EINVAL:
    sprintf (tmp,"Invalid MTX-format mailbox name: %.80s",mailbox);
    mm_log (tmp,ERROR);
    return NIL;
  default:
    sprintf (tmp,"Not a MTX-format mailbox: %.80s",mailbox);
    mm_log (tmp,ERROR);
    return NIL;
  }
                                /* get first message */
  if (!(*af) (stream,data,&flags,&date,&message)) return NIL;
\f
                                /* open destination mailbox */
  if (((fd = open (file,O_BINARY|O_WRONLY|O_APPEND|O_CREAT,S_IREAD|S_IWRITE))
       < 0) || !(df = fdopen (fd,"ab"))) {
    sprintf (tmp,"Can't open append mailbox: %s",strerror (errno));
    mm_log (tmp,ERROR);
    return NIL;
  }
                                /* get parse/append permission */
  if (flock (fd,LOCK_SH) || ((ld = lockname (lock,file,LOCK_EX)) < 0)) {
    mm_log ("Unable to lock append mailbox",ERROR);
    close (fd);
    return NIL;
  }
  mm_critical (stream);         /* go critical */
  fstat (fd,&sbuf);             /* get current file size */
  errno = 0;
  do {                          /* parse flags */
    if (!SIZE (message)) {      /* guard against zero-length */
      mm_log ("Append of zero-length message",ERROR);
      ret = NIL;
      break;
    }
    f = mail_parse_flags (stream,flags,&i);
                                /* reverse bits (dontcha wish we had CIRC?) */
    for (uf = 0; i; uf |= 1 << (29 - find_rightmost_bit (&i)));
    if (date) {                 /* parse date if given */
      if (!mail_parse_date (&elt,date)) {
        sprintf (tmp,"Bad date in append: %.80s",date);
        mm_log (tmp,ERROR);
        ret = NIL;              /* mark failure */
        break;
      }
      mail_date (tmp,&elt);     /* write preserved date */
    }
    else internal_date (tmp);   /* get current date in IMAP format */
                                /* write header */
    if (fprintf (df,"%s,%lu;%010lo%02lo\015\012",tmp,i = SIZE (message),uf,
                 (unsigned long) f) < 0) ret = NIL;
    else {                      /* write message */
      if (i) do c = 0xff & SNX (message);
      while ((putc (c,df) != EOF) && --i);
                                /* get next message */
      if (i || !(*af) (stream,data,&flags,&date,&message)) ret = NIL;
    }
  } while (ret && message);
                                /* if error... */
  if (!ret || (fflush (df) == EOF)) {
    ftruncate (fd,sbuf.st_size);/* revert file */
    close (fd);                 /* make sure fclose() doesn't corrupt us */
    if (errno) {
      sprintf (tmp,"Message append failed: %s",strerror (errno));
      mm_log (tmp,ERROR);
    }
    ret = NIL;
  }
  if (ret) times.actime = time (0) - 1;
                                /* else preserved \Marked status */
  else times.actime = (sbuf.st_ctime > sbuf.st_atime) ?
         sbuf.st_atime : time (0);
  times.modtime = sbuf.st_mtime;/* preserve mtime */
  utime (file,&times);          /* set the times */
  fclose (df);                  /* close the file */
  unlockfd (ld,lock);           /* release exclusive parse/append permission */
  mm_nocritical (stream);       /* release critical */
  if (ret && mail_parameters (NIL,GET_APPENDUID,NIL))
    mm_log ("Can not return meaningful APPENDUID with this mailbox format",
            WARN);
  return ret;
}
\f
/* Internal routines */


/* MTX mail parse mailbox
 * Accepts: MAIL stream
 * Returns: T if parse OK
 *          NIL if failure, stream aborted
 */

long mtx_parse (MAILSTREAM *stream)
{
  struct stat sbuf;
  MESSAGECACHE *elt = NIL;
  unsigned char c,*s,*t,*x;
  char tmp[MAILTMPLEN];
  unsigned long i,j;
  long curpos = LOCAL->filesize;
  long nmsgs = stream->nmsgs;
  long recent = stream->recent;
  short added = NIL;
  short silent = stream->silent;
  fstat (LOCAL->fd,&sbuf);      /* get status */
  if (sbuf.st_size < curpos) {  /* sanity check */
    sprintf (tmp,"Mailbox shrank from %ld to %ld!",curpos,sbuf.st_size);
    mm_log (tmp,ERROR);
    mtx_close (stream,NIL);
    return NIL;
  }
  stream->silent = T;           /* don't pass up mm_exists() events yet */
  while (sbuf.st_size - curpos){/* while there is stuff to parse */
                                /* get to that position in the file */
    lseek (LOCAL->fd,curpos,L_SET);
    if ((i = read (LOCAL->fd,LOCAL->buf,64)) <= 0) {
      sprintf (tmp,"Unable to read internal header at %lu, size = %lu: %s",
               (unsigned long) curpos,(unsigned long) sbuf.st_size,
               i ? strerror (errno) : "no data read");
      mm_log (tmp,ERROR);
      mtx_close (stream,NIL);
      return NIL;
    }
    LOCAL->buf[i] = '\0';       /* tie off buffer just in case */
    if (!((s = strchr (LOCAL->buf,'\015')) && (s[1] == '\012'))) {
      sprintf (tmp,"Unable to find CRLF at %lu in %lu bytes, text: %s",
               (unsigned long) curpos,i,(char *) LOCAL->buf);
      mm_log (tmp,ERROR);
      mtx_close (stream,NIL);
      return NIL;
    }
    *s = '\0';                  /* tie off header line */
    i = (s + 2) - LOCAL->buf;   /* note start of text offset */
    if (!((s = strchr (LOCAL->buf,',')) && (t = strchr (s+1,';')))) {
      sprintf (tmp,"Unable to parse internal header at %lu: %s",
               (unsigned long) curpos,(char *) LOCAL->buf);
      mm_log (tmp,ERROR);
      mtx_close (stream,NIL);
      return NIL;
    }
    *s++ = '\0'; *t++ = '\0';   /* tie off fields */
\f
    added = T;                  /* note that a new message was added */
                                /* swell the cache */
    mail_exists (stream,++nmsgs);
                                /* instantiate an elt for this message */
    (elt = mail_elt (stream,nmsgs))->valid = T;
    elt->private.uid = ++stream->uid_last;
                                /* note file offset of header */
    elt->private.special.offset = curpos;
                                /* in case error */
    elt->private.special.text.size = 0;
                                /* header size not known yet */
    elt->private.msg.header.text.size = 0;
    x = s;                      /* parse the header components */
    if (mail_parse_date (elt,LOCAL->buf) &&
        (elt->rfc822_size = strtoul (s,(char **) &s,10)) && (!(s && *s)) &&
        isdigit (t[0]) && isdigit (t[1]) && isdigit (t[2]) &&
        isdigit (t[3]) && isdigit (t[4]) && isdigit (t[5]) &&
        isdigit (t[6]) && isdigit (t[7]) && isdigit (t[8]) &&
        isdigit (t[9]) && isdigit (t[10]) && isdigit (t[11]) && !t[12])
      elt->private.special.text.size = i;
    else {                      /* oops */
      sprintf (tmp,"Unable to parse internal header elements at %ld: %s,%s;%s",
               curpos,(char *) LOCAL->buf,(char *) x,(char *) t);
      mm_log (tmp,ERROR);
      mtx_close (stream,NIL);
      return NIL;
    }
                                /* make sure didn't run off end of file */
    if ((curpos += (elt->rfc822_size + i)) > sbuf.st_size) {
      sprintf (tmp,"Last message (at %lu) runs past end of file (%lu > %lu)",
               elt->private.special.offset,(unsigned long) curpos,
               (unsigned long) sbuf.st_size);
      mm_log (tmp,ERROR);
      mtx_close (stream,NIL);
      return NIL;
    }
    c = t[10];                  /* remember first system flags byte */
    t[10] = '\0';               /* tie off flags */
    j = strtoul (t,NIL,8);      /* get user flags value */
    t[10] = c;                  /* restore first system flags byte */
                                /* set up all valid user flags (reversed!) */
    while (j) if (((i = 29 - find_rightmost_bit (&j)) < NUSERFLAGS) &&
                  stream->user_flags[i]) elt->user_flags |= 1 << i;
                                /* calculate system flags */
    if ((j = ((t[10]-'0') * 8) + t[11]-'0') & fSEEN) elt->seen = T;
    if (j & fDELETED) elt->deleted = T;
    if (j & fFLAGGED) elt->flagged = T;
    if (j & fANSWERED) elt->answered = T;
    if (j & fDRAFT) elt->draft = T;
    if (!(j & fOLD)) {          /* newly arrived message? */
      elt->recent = T;
      recent++;                 /* count up a new recent message */
                                /* mark it as old */
      mtx_update_status (stream,nmsgs,NIL);
    }
  }
  fsync (LOCAL->fd);            /* make sure all the fOLD flags take */
                                /* update parsed file size and time */
  LOCAL->filesize = sbuf.st_size;
  fstat (LOCAL->fd,&sbuf);      /* get status again to ensure time is right */
  LOCAL->filetime = sbuf.st_mtime;
  if (added && !stream->rdonly){/* make sure atime updated */
    struct utimbuf times;
    times.actime = time (0);
    times.modtime = LOCAL->filetime;
    utime (stream->mailbox,&times);
  }
  stream->silent = silent;      /* can pass up events now */
  mail_exists (stream,nmsgs);   /* notify upper level of new mailbox size */
  mail_recent (stream,recent);  /* and of change in recent messages */
  return LONGT;                 /* return the winnage */
}
\f
/* MTX get cache element with status updating from file
 * Accepts: MAIL stream
 *          message number
 * Returns: cache element
 */

MESSAGECACHE *mtx_elt (MAILSTREAM *stream,unsigned long msgno)
{
  MESSAGECACHE *elt = mail_elt (stream,msgno);
  struct {                      /* old flags */
    unsigned int seen : 1;
    unsigned int deleted : 1;
    unsigned int flagged : 1;
    unsigned int answered : 1;
    unsigned int draft : 1;
    unsigned long user_flags;
  } old;
  old.seen = elt->seen; old.deleted = elt->deleted; old.flagged = elt->flagged;
  old.answered = elt->answered; old.draft = elt->draft;
  old.user_flags = elt->user_flags;
  mtx_read_flags (stream,elt);
  if ((old.seen != elt->seen) || (old.deleted != elt->deleted) ||
      (old.flagged != elt->flagged) || (old.answered != elt->answered) ||
      (old.draft != elt->draft) || (old.user_flags != elt->user_flags))
    mm_flags (stream,msgno);    /* let top level know */
  return elt;
}
\f
/* MTX read flags from file
 * Accepts: MAIL stream
 * Returns: cache element
 */

void mtx_read_flags (MAILSTREAM *stream,MESSAGECACHE *elt)
{
  unsigned long i,j;
                                /* noop if readonly and have valid flags */
  if (stream->rdonly && elt->valid) return;
                                /* set the seek pointer */
  lseek (LOCAL->fd,(off_t) elt->private.special.offset +
         elt->private.special.text.size - 14,L_SET);
                                /* read the new flags */
  if (read (LOCAL->fd,LOCAL->buf,12) < 0) {
    sprintf (LOCAL->buf,"Unable to read new status: %s",strerror (errno));
    fatal (LOCAL->buf);
  }
                                /* calculate system flags */
  i = (((LOCAL->buf[10]-'0') * 8) + LOCAL->buf[11]-'0');
  elt->seen = i & fSEEN ? T : NIL; elt->deleted = i & fDELETED ? T : NIL;
  elt->flagged = i & fFLAGGED ? T : NIL;
  elt->answered = i & fANSWERED ? T : NIL; elt->draft = i & fDRAFT ? T : NIL;
  LOCAL->buf[10] = '\0';        /* tie off flags */
  j = strtoul(LOCAL->buf,NIL,8);/* get user flags value */
                                /* set up all valid user flags (reversed!) */
  while (j) if (((i = 29 - find_rightmost_bit (&j)) < NUSERFLAGS) &&
                stream->user_flags[i]) elt->user_flags |= 1 << i;
  elt->valid = T;               /* have valid flags now */
}
\f
/* MTX update status string
 * Accepts: MAIL stream
 *          message number
 *          flag saying whether or not to sync
 */

void mtx_update_status (MAILSTREAM *stream,unsigned long msgno,long syncflag)
{
  struct utimbuf times;
  struct stat sbuf;
  MESSAGECACHE *elt = mail_elt (stream,msgno);
  unsigned long j,k = 0;
                                /* readonly */
  if (stream->rdonly || !elt->valid) mtx_read_flags (stream,elt);
  else {                        /* readwrite */
    j = elt->user_flags;        /* get user flags */
                                /* reverse bits (dontcha wish we had CIRC?) */
    while (j) k |= 1 << (29 - find_rightmost_bit (&j));
                                /* print new flag string */
    sprintf (LOCAL->buf,"%010lo%02o",k,(unsigned)
             (fOLD + (fSEEN * elt->seen) + (fDELETED * elt->deleted) +
              (fFLAGGED * elt->flagged) + (fANSWERED * elt->answered) +
              (fDRAFT * elt->draft)));
    while (T) {                 /* get to that place in the file */
      lseek (LOCAL->fd,(off_t) elt->private.special.offset +
             elt->private.special.text.size - 14,L_SET);
                                /* write new flags */
      if (write (LOCAL->fd,LOCAL->buf,12) > 0) break;
      mm_notify (stream,strerror (errno),WARN);
      mm_diskerror (stream,errno,T);
    }
    if (syncflag) {             /* sync if requested */
      fsync (LOCAL->fd);
      fstat (LOCAL->fd,&sbuf);  /* get new write time */
      times.modtime = LOCAL->filetime = sbuf.st_mtime;
      times.actime = time (0);  /* make sure read is later */
      utime (stream->mailbox,&times);
    }
  }
}
\f
/* MTX locate header for a message
 * Accepts: MAIL stream
 *          message number
 *          pointer to returned header size
 * Returns: position of header in file
 */

unsigned long mtx_hdrpos (MAILSTREAM *stream,unsigned long msgno,
                          unsigned long *size)
{
  unsigned long siz;
  long i = 0;
  int q = 0;
  char *s,tmp[MAILTMPLEN];
  MESSAGECACHE *elt = mtx_elt (stream,msgno);
  unsigned long ret = elt->private.special.offset +
    elt->private.special.text.size;
                                /* is header size known? */
  if (!(*size = elt->private.msg.header.text.size)) {
    lseek (LOCAL->fd,ret,L_SET);/* get to header position */
                                /* search message for CRLF CRLF */
    for (siz = 1,s = tmp; siz <= elt->rfc822_size; siz++) {
                                /* read another buffer as necessary */
      if ((--i <= 0) &&         /* buffer empty? */
          (read (LOCAL->fd,s = tmp,
                 i = min (elt->rfc822_size - siz,(long) MAILTMPLEN)) < 0))
        return ret;             /* I/O error? */
      switch (q) {              /* sniff at buffer */
      case 0:                   /* first character */
        q = (*s++ == '\015') ? 1 : 0;
        break;
      case 1:                   /* second character */
        q = (*s++ == '\012') ? 2 : 0;
        break;
      case 2:                   /* third character */
        q = (*s++ == '\015') ? 3 : 0;
        break;
      case 3:                   /* fourth character */
        if (*s++ == '\012') {   /* have the sequence? */
                                /* yes, note for later */
          elt->private.msg.header.text.size = *size = siz;
          return ret;
        }
        q = 0;                  /* lost... */
        break;
      }
    }
                                /* header consumes entire message */
    elt->private.msg.header.text.size = *size = elt->rfc822_size;
  }
  return ret;
}