unix.c

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  LOCAL->fd = LOCAL->ld = -1;	/* no file or state locking yet */
  LOCAL->buf = (char *) fs_get ((LOCAL->buflen = CHUNK) + 1);
  stream->sequence++;		/* bump sequence number */

				/* 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) {
      if (retry-- == KODRETRY) {/* no, first time through? */
	if (i) {		/* learned the other guy's PID? */
	  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,(int) 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 */
    }
  }

				/* 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))
    unix_abort (stream);	/* abort if can't get RW silent stream */
				/* parse mailbox */
  else if (unix_parse (stream,&lock,LOCK_SH)) {
    unix_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 */
}


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

void unix_close (MAILSTREAM *stream,long options)
{
  int silent = stream->silent;
  stream->silent = T;		/* go silent */
				/* expunge if requested */
  if (options & CL_EXPUNGE) unix_expunge (stream);
				/* else dump final checkpoint */
  else if (LOCAL->dirty) unix_check (stream);
  stream->silent = silent;	/* restore old silence state */
  unix_abort (stream);		/* now punt the file and local data */
}

/* UNIX 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 *unix_hlines = NIL;

char *unix_header (MAILSTREAM *stream,unsigned long msgno,
		   unsigned long *length,long flags)
{
  MESSAGECACHE *elt;
  char *s;
  *length = 0;			/* default to empty */
  if (flags & FT_UID) return "";/* UID call "impossible" */
  elt = mail_elt (stream,msgno);/* get cache */
  if (!unix_hlines) {		/* once only code */
    STRINGLIST *lines = unix_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);

  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) */
    if (s = strchr (LOCAL->buf,'\r')) {
      char *t,*tl;
      for (t = s,tl = LOCAL->buf + *length; t <= tl; t++)
	if ((*t != '\r') || (t[1] != '\n')) *s++ = *t;
				/* adjust length */
      LOCAL->buf[*length = s - LOCAL->buf - 1] = '\0';
    }
  }
  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 */
  }
  *length = mail_filter (LOCAL->buf,*length,unix_hlines,FT_NOT);
  return LOCAL->buf;		/* return processed copy */
}

/* UNIX mail fetch message text
 * Accepts: MAIL stream
 *	    message # to fetch
 *	    pointer to returned stringstruct
 *	    option flags
 * Returns: T on success, NIL if failure
 */

long unix_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 = unix_text_work (stream,elt,&i,flags);
  INIT (bs,mail_string,s,i);	/* set up stringstruct */
  return T;			/* success */
}

/* UNIX mail fetch message text worker routine
 * Accepts: MAIL stream
 *	    message cache element
 *	    pointer to returned header text length
 *	    option flags
 */

char *unix_text_work (MAILSTREAM *stream,MESSAGECACHE *elt,
		      unsigned long *length,long flags)
{
  FDDATA d;
  STRING bs;
  char *s,tmp[CHUNK];
				/* 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) */
    if (s = strchr (LOCAL->buf,'\r')) {
      char *t,*tl;
      for (t = s,tl = LOCAL->buf + *length; t <= tl; t++)
	if ((*t != '\r') || (t[1] != '\n')) *s++ = *t;
				/* adjust length */
      *length = s - LOCAL->buf - 1;
    }
  }

  else {			/* need to make a CRLF version */
    if (elt->rfc822_size > LOCAL->buflen) {
      /* excessively conservative, but the right thing is too hard to do */
      fs_give ((void **) &LOCAL->buf);
      LOCAL->buf = (char *) fs_get ((LOCAL->buflen = 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 = CHUNK;	/* file chunk size */
    INIT (&bs,fd_string,&d,elt->private.msg.text.text.size);
    for (s = LOCAL->buf; SIZE (&bs);) switch (CHR (&bs)) {
    case '\r':			/* carriage return seen */
      *s++ = SNX (&bs);		/* copy it and any succeeding LF */
      if (SIZE (&bs) && (CHR (&bs) == '\n')) *s++ = SNX (&bs);
      break;
    case '\n':
      *s++ = '\r';		/* insert a CR */
    default:
      *s++ = SNX (&bs);		/* copy characters */
    }
    *s = '\0';			/* tie off buffer */
    *length = s - LOCAL->buf;	/* calculate length */
  }
  return LOCAL->buf;
}

/* UNIX per-message modify flag
 * Accepts: MAIL stream
 *	    message cache element
 */

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


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

long unix_ping (MAILSTREAM *stream)
{
  DOTLOCK lock;
  struct stat sbuf;
				/* 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) unix_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 {			/* get current mailbox size */
      if (LOCAL->fd >= 0) fstat (LOCAL->fd,&sbuf);
      else stat (stream->mailbox,&sbuf);
				/* parse if mailbox changed */
      if ((sbuf.st_size != LOCAL->filesize) &&
	  unix_parse (stream,&lock,LOCK_SH)) {
				/* unlock mailbox */
	unix_unlock (LOCAL->fd,stream,&lock);
	mail_unlock (stream);	/* and stream */
	mm_nocritical (stream);	/* done with critical */
      }
    }
  }
  return LOCAL ? LONGT : NIL;	/* return if still alive */
}

/* UNIX mail check mailbox
 * Accepts: MAIL stream
 */

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


/* UNIX mail expunge mailbox
 * Accepts: MAIL stream
 */

void unix_expunge (MAILSTREAM *stream)
{
  unsigned long i;
  DOTLOCK lock;
  char *msg = NIL;
				/* parse and lock mailbox */
  if (LOCAL && (LOCAL->ld >= 0) && !stream->lock &&
      unix_parse (stream,&lock,LOCK_EX)) {
				/* count expunged messages if not dirty */
    if (!LOCAL->dirty) for (i = 1; i <= stream->nmsgs; i++)
      if (mail_elt (stream,i)->deleted) LOCAL->dirty = T;
    if (!LOCAL->dirty) {	/* not dirty and no expunged messages */
      unix_unlock (LOCAL->fd,stream,&lock);
      msg = "No messages deleted, so no update needed";
    }
    else if (unix_rewrite (stream,&i,&lock)) {
      if (i) sprintf (msg = LOCAL->buf,"Expunged %lu messages",i);
      else msg = "Mailbox checkpointed, but no messages expunged";
    }
				/* rewrite failed */
    else unix_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);
}

/* UNIX mail copy message(s)
 * Accepts: MAIL stream
 *	    sequence
 *	    destination mailbox
 *	    copy options
 * Returns: T if copy successful, else NIL
 */

long unix_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;