mbx.c

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 * Accepts: MAIL stream
 *	    cache element
 * Returns: non-NIL if message expunged
 */

unsigned long mbx_read_flags (MAILSTREAM *stream,MESSAGECACHE *elt)
{
  unsigned long i;
  struct stat sbuf;
  fstat (LOCAL->fd,&sbuf);	/* get status */
				/* make sure file size is good */
  if (sbuf.st_size < LOCAL->filesize) {
    sprintf (LOCAL->buf,"Mailbox shrank from %lu to %lu in flag read!",
	     (unsigned long) LOCAL->filesize,(unsigned long) sbuf.st_size);
    fatal (LOCAL->buf);
  }
				/* set the seek pointer */
  lseek (LOCAL->fd,(off_t) elt->private.special.offset +
	 elt->private.special.text.size - 24,L_SET);
				/* read the new flags */
  if (read (LOCAL->fd,LOCAL->buf,14) < 0) {
    sprintf (LOCAL->buf,"Unable to read new status: %s",strerror (errno));
    fatal (LOCAL->buf);
  }
  if ((LOCAL->buf[0] != ';') || (LOCAL->buf[13] != '-')) {
    LOCAL->buf[14] = '\0';	/* tie off buffer for error message */
    sprintf (LOCAL->buf+50,"Invalid flags for message %lu (%lu %lu): %s",
	     elt->msgno,elt->private.special.offset,
	     elt->private.special.text.size,(char *) LOCAL->buf);
    fatal (LOCAL->buf+50);
  }
  LOCAL->buf[13] = '\0';	/* tie off buffer */
				/* calculate system flags */
  i = strtoul (LOCAL->buf+9,NIL,16);
  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->expunged |= i & fEXPUNGED ? T : NIL;
  LOCAL->buf[9] = '\0';		/* tie off flags */
				/* get user flags value */
  elt->user_flags = strtoul (LOCAL->buf+1,NIL,16);
  elt->valid = T;		/* have valid flags now */
  return i & fEXPUNGED;
}

/* MBX update header
 * Accepts: MAIL stream
 */

#ifndef CYGKLUDGEOFFSET
#define CYGKLUDGEOFFSET 0
#endif

void mbx_update_header (MAILSTREAM *stream)
{
  int i;
  char *s = LOCAL->buf;
  memset (s,'\0',HDRSIZE);	/* initialize header */
  sprintf (s,"*mbx*\015\012%08lx%08lx\015\012",
	   stream->uid_validity,stream->uid_last);
  for (i = 0; (i < NUSERFLAGS) && stream->user_flags[i]; ++i)
    sprintf (s += strlen (s),"%s\015\012",stream->user_flags[i]);
  LOCAL->ffuserflag = i;	/* first free user flag */
				/* can we create more user flags? */
  stream->kwd_create = (i < NUSERFLAGS) ? T : NIL;
				/* write reserved lines */
  while (i++ < NUSERFLAGS) strcat (s,"\015\012");
  sprintf (LOCAL->buf + HDRSIZE - 10,"%08lx\015\012",LOCAL->lastpid);
  while (T) {			/* rewind file */
    lseek (LOCAL->fd,CYGKLUDGEOFFSET,L_SET);
				/* write new header */
    if (write (LOCAL->fd,LOCAL->buf + CYGKLUDGEOFFSET,
	       HDRSIZE - CYGKLUDGEOFFSET) > 0) break;
    MM_NOTIFY (stream,strerror (errno),WARN);
    MM_DISKERROR (stream,errno,T);
  }
}

/* MBX update status string
 * Accepts: MAIL stream
 *	    message number
 *	    flags
 */

void mbx_update_status (MAILSTREAM *stream,unsigned long msgno,long flags)
{
  struct stat sbuf;
  MESSAGECACHE *elt = mail_elt (stream,msgno);
				/* readonly */
  if (stream->rdonly || !elt->valid) mbx_read_flags (stream,elt);
  else {			/* readwrite */
    fstat (LOCAL->fd,&sbuf);	/* get status */
				/* make sure file size is good */
    if (sbuf.st_size < LOCAL->filesize) {
      sprintf (LOCAL->buf,"Mailbox shrank from %lu to %lu in flag update!",
	       (unsigned long) LOCAL->filesize,(unsigned long) sbuf.st_size);
      fatal (LOCAL->buf);
    }
				/* set the seek pointer */
    lseek (LOCAL->fd,(off_t) elt->private.special.offset +
	   elt->private.special.text.size - 24,L_SET);
				/* read the new flags */
    if (read (LOCAL->fd,LOCAL->buf,14) < 0) {
      sprintf (LOCAL->buf,"Unable to read old status: %s",strerror (errno));
      fatal (LOCAL->buf);
    }
    if ((LOCAL->buf[0] != ';') || (LOCAL->buf[13] != '-')) {
      LOCAL->buf[14] = '\0';	/* tie off buffer for error message */
      sprintf (LOCAL->buf+50,"Invalid flags for message %lu (%lu %lu): %s",
	       elt->msgno,elt->private.special.offset,
	       elt->private.special.text.size,(char *) LOCAL->buf);
      fatal (LOCAL->buf+50);
    }
				/* print new flag string */
    sprintf (LOCAL->buf,"%08lx%04x-%08lx",elt->user_flags,(unsigned)
	     (((elt->deleted && flags) ?
	       fEXPUNGED : (strtoul (LOCAL->buf+9,NIL,16)) & fEXPUNGED) +
	      (fSEEN * elt->seen) + (fDELETED * elt->deleted) +
	      (fFLAGGED * elt->flagged) + (fANSWERED * elt->answered) +
	      (fDRAFT * elt->draft) + fOLD),elt->private.uid);
    while (T) {			/* get to that place in the file */
      lseek (LOCAL->fd,(off_t) elt->private.special.offset +
	     elt->private.special.text.size - 23,L_SET);
				/* write new flags and UID */
      if (write (LOCAL->fd,LOCAL->buf,21) > 0) break;
      MM_NOTIFY (stream,strerror (errno),WARN);
      MM_DISKERROR (stream,errno,T);
    }
  }
}

/* MBX locate header for a message
 * Accepts: MAIL stream
 *	    message number
 *	    pointer to returned header size
 *	    pointer to possible returned header
 * Returns: position of header in file
 */

#define HDRBUFLEN 16384		/* good enough for most headers */
#define SLOP 4			/* CR LF CR LF */

unsigned long mbx_hdrpos (MAILSTREAM *stream,unsigned long msgno,
			  unsigned long *size,char **hdr)
{
  unsigned long siz,done;
  long i;
  unsigned char *s,*t,*te;
  MESSAGECACHE *elt = mail_elt (stream,msgno);
  unsigned long ret = elt->private.special.offset +
    elt->private.special.text.size;
  if (hdr) *hdr = NIL;		/* assume no header returned */
				/* is header size known? */ 
  if (*size = elt->private.msg.header.text.size) return ret;
				/* paranoia check */
  if (LOCAL->buflen < (HDRBUFLEN + SLOP))
    fatal ("LOCAL->buf smaller than HDRBUFLEN");
  lseek (LOCAL->fd,ret,L_SET);	/* get to header position */
				/* read HDRBUFLEN chunks with 4 byte slop */
  for (done = siz = 0, s = LOCAL->buf;
       (i = min ((long) (elt->rfc822_size - done),(long) HDRBUFLEN)) &&
       (read (LOCAL->fd,s,i) == i);
       done += i, siz += (t - LOCAL->buf) - SLOP, s = LOCAL->buf + SLOP) {
    te = (t = s + i) - 12;	/* calculate end of fast scan */
				/* fast scan for CR */
    for (s = LOCAL->buf; s < te;)
      if (((*s++ == '\015') || (*s++ == '\015') || (*s++ == '\015') ||
	   (*s++ == '\015') || (*s++ == '\015') || (*s++ == '\015') ||
	   (*s++ == '\015') || (*s++ == '\015') || (*s++ == '\015') ||
	   (*s++ == '\015') || (*s++ == '\015') || (*s++ == '\015')) &&
	  (*s == '\012') && (*++s == '\015') && (*++s == '\012')) {
	*size = elt->private.msg.header.text.size = siz + (++s - LOCAL->buf);
	if (hdr) *hdr = LOCAL->buf;
	return ret;
      }
    for (te = t - 3; (s < te);)	/* final character-at-a-time scan */
      if ((*s++ == '\015') && (*s == '\012') && (*++s == '\015') &&
	  (*++s == '\012')) {
	*size = elt->private.msg.header.text.size = siz + (++s - LOCAL->buf);
	if (hdr) *hdr = LOCAL->buf;
	return ret;
      }
    if (i <= SLOP) break;	/* end of data */
				/* slide over last 4 bytes */
    memmove (LOCAL->buf,t - SLOP,SLOP);
    hdr = NIL;			/* can't return header this way */
  }
				/* not found: header consumes entire message */
  elt->private.msg.header.text.size = *size = elt->rfc822_size;
  if (hdr) *hdr = LOCAL->buf;	/* possibly return header too */
  return ret;
}

/* MBX mail rewrite mailbox
 * Accepts: MAIL stream
 *	    pointer to return reclaimed size
 *	    flags (0 = no expunge, 1 = expunge deleted, -1 = expunge sequence)
 * Returns: number of expunged messages
 */

unsigned long mbx_rewrite (MAILSTREAM *stream,unsigned long *reclaimed,
			   long flags)
{
  time_t tp[2];
  struct stat sbuf;
  off_t pos,ppos;
  int ld;
  unsigned long i,j,k,m,delta;
  unsigned long n = *reclaimed = 0;
  unsigned long recent = 0;
  char lock[MAILTMPLEN];
  MESSAGECACHE *elt;
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  /* The cretins who designed flock() created a window of vulnerability in
   * upgrading locks from shared to exclusive or downgrading from exclusive
   * to shared.  Rather than maintain the lock at shared status at a minimum,
   * flock() actually *releases* the former lock.  Obviously they never talked
   * to any database guys.  Fortunately, we have the parse/append permission
   * lock.  If we require this lock before going exclusive on the mailbox,
   * another process can not sneak in and steal the exclusive mailbox lock on
   * us, because it will block on trying to get parse/append permission first.
   */
				/* get parse/append permission */
  if ((ld = lockfd (LOCAL->fd,lock,LOCK_EX)) < 0) {
    MM_LOG ("Unable to lock mailbox for rewrite",ERROR);
    return 0;
  }
  fstat (LOCAL->fd,&sbuf);	/* get current write time */
  if (LOCAL->filetime && !LOCAL->flagcheck &&
      (LOCAL->filetime < sbuf.st_mtime)) LOCAL->flagcheck = T;
  if (!mbx_parse (stream)) {	/* make sure see any newly-arrived messages */
    unlockfd (ld,lock);		/* failed?? */
    return 0;
  }
  if (LOCAL->flagcheck) {	/* sweep flags if need flagcheck */
    LOCAL->filetime = sbuf.st_mtime;
    for (i = 1; i <= stream->nmsgs; ++i) mbx_elt (stream,i,NIL);
    LOCAL->flagcheck = NIL;
  }

				/* get exclusive access */
  if (!flock (LOCAL->fd,LOCK_EX|LOCK_NB)) {
    MM_CRITICAL (stream);	/* go critical */
    for (i = 1,delta = 0,pos = ppos = HDRSIZE; i <= stream->nmsgs; ) {
				/* note if message not at predicted location */
      if (m = (elt = mbx_elt (stream,i,NIL))->private.special.offset - ppos) {
	ppos = elt->private.special.offset;
	*reclaimed += m;	/* note reclaimed message space */
	delta += m;		/* and as expunge delta  */
      }
				/* number of bytes to smash or preserve */
      ppos += (k = elt->private.special.text.size + elt->rfc822_size);
				/* if need to expunge this message*/
      if (flags && elt->deleted && ((flags > 0) || elt->sequence)) {
	delta += k;		/* number of bytes to delete */
	mail_expunged(stream,i);/* notify upper levels */
	n++;			/* count up one more expunged message */
      }
      else {			/* preserved message */
	i++;			/* count this message */
	if (elt->recent) ++recent;
	if (delta) {		/* moved, note 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 yet */
	else pos = elt->private.special.offset + k;
      }
    }
				/* deltaed file size match position? */
    if (m = (LOCAL->filesize -= delta) - pos) {
      *reclaimed += m;		/* probably an fEXPUNGED msg */
      LOCAL->filesize = pos;	/* set correct size */
    }
				/* truncate file after last message */
    ftruncate (LOCAL->fd,LOCAL->filesize);
    fsync (LOCAL->fd);		/* force disk update */
    MM_NOCRITICAL (stream);	/* release critical */
    (*bn) (BLOCK_FILELOCK,NIL);
    flock (LOCAL->fd,LOCK_SH);	/* allow sharers again */
    (*bn) (BLOCK_NONE,NIL);
  }

  else {			/* can't get exclusive */
    (*bn) (BLOCK_FILELOCK,NIL);
    flock (LOCAL->fd,LOCK_SH);	/* recover previous shared mailbox lock */
    (*bn) (BLOCK_NONE,NIL);
				/* do hide-expunge when shared */
    if (flags) for (i = 1; i <= stream->nmsgs; ) {
      if (elt = mbx_elt (stream,i,T)) {
				/* make the message invisible */
	if (elt->deleted && ((flags > 0) || elt->sequence)) {
	  mbx_update_status (stream,elt->msgno,LONGT);
				/* notify upper levels */
	  mail_expunged (stream,i);
	  n++;			/* count up one more expunged message */
	}
	else {
	  i++;			/* preserved message */
	  if (elt->recent) ++recent;
	}
      }
      else n++;			/* count up one more expunged message */
    }
    fsync (LOCAL->fd);		/* force disk update */
  }
  fstat (LOCAL->fd,&sbuf);	/* get new write time */
  tp[1] = LOCAL->filetime = sbuf.st_mtime;
  tp[0] = time (0);		/* reset atime to now */
  utime (stream->mailbox,tp);
  unlockfd (ld,lock);		/* release exclusive parse/append permission */
				/* notify upper level of new mailbox size */
  mail_exists (stream,stream->nmsgs);
  mail_recent (stream,recent);
  return n;			/* return number of expunged messages */
}

/* MBX mail lock for flag updating
 * Accepts: stream
 * Returns: T if successful, NIL if failure
 */

long mbx_flaglock (MAILSTREAM *stream)
{
  struct stat sbuf;
  unsigned long i;
  int ld;
  char lock[MAILTMPLEN];
				/* no-op if readonly or already locked */
  if (!stream->rdonly && LOCAL && (LOCAL->fd >= 0) && (LOCAL->ld < 0)) {
				/* lock now */
    if ((ld = lockfd (LOCAL->fd,lock,LOCK_EX)) < 0) return NIL;
    if (!LOCAL->flagcheck) {	/* don't do this if flagcheck already needed */
      if (LOCAL->filetime) {	/* know previous time? */
	fstat (LOCAL->fd,&sbuf);/* get current write time */
	if (LOCAL->filetime < sbuf.st_mtime) LOCAL->flagcheck = T;
	LOCAL->filetime = 0;	/* don't do this test for any other messages */
      }
      if (!mbx_parse (stream)) {/* parse mailbox */
	unlockfd (ld,lock);	/* shouldn't happen */
	return NIL;
      }
      if (LOCAL->flagcheck)	/* invalidate cache if flagcheck */
	for (i = 1; i <= stream->nmsgs; ++i) mail_elt (stream,i)->valid = NIL;
    }
    LOCAL->ld = ld;		/* copy to stream for subsequent calls */
    memcpy (LOCAL->lock,lock,MAILTMPLEN);
  }
  return LONGT;
}