unix.c

这是用C编写IMAP源代码

/* Internal routines */


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

void unix_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->line) fs_give ((void **) &LOCAL->line);
				/* nuke the local data */
    fs_give ((void **) &stream->local);
    stream->dtb = NIL;		/* log out the DTB */
  }
}

/* UNIX 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 unix_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);
      else dotlock_unlock (lock); /* open failed, free the dotlock */
    }
    else flock (fd,op);		/* paranoid way failed, just flock() it */
  }
  (*bn) (BLOCK_NONE,NIL);
  return fd;
}


/* UNIX unlock and close mailbox
 * Accepts: file descriptor
 *	    (optional) mailbox stream to check atime/mtime
 *	    (optional) lock file name
 */

void unix_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 */
}

/* UNIX 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 unix_parse (MAILSTREAM *stream,DOTLOCK *lock,int op)
{
  int zn;
  unsigned long i,j,k,m;
  unsigned char c,*s,*t,*u,tmp[MAILTMPLEN],date[30];
  int ti = 0,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 = unix_lock (stream->mailbox,(LOCAL->ld >= 0) ?
			      O_RDWR : O_RDONLY,NIL,lock,op)) < 0) {
    sprintf (tmp,"Mailbox open failed, aborted: %s",strerror (errno));
    MM_LOG (tmp,ERROR);
    unix_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 */
    unix_unlock (LOCAL->fd,stream,lock);
    unix_abort (stream);
    mail_unlock (stream);
    MM_NOCRITICAL (stream);	/* done with critical */
    return NIL;
  }

				/* new data? */
  else if (i = sbuf.st_size - LOCAL->filesize) {
    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 = CHUNK;	/* 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 = unix_mbxline (stream,&bs,&i);
      t = NIL,zn = 0;
      if (i) VALID (s,t,ti,zn);	/* see if valid From line */
      if (!ti) {		/* someone pulled the rug from under us */
	sprintf (tmp,"Unexpected changes to mailbox (try restarting): %.20s",
		 (char *) s);
	MM_LOG (tmp,ERROR);
	unix_unlock (LOCAL->fd,stream,lock);
	unix_abort (stream);
	mail_unlock (stream);
				/* done with critical */
	MM_NOCRITICAL (stream);
	return NIL;
      }
      stream->silent = T;	/* quell main program new message events */
      do {			/* found a message */
				/* 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.msg.header.offset = elt->private.special.text.size = i;

				/* generate plausible IMAPish date string */
	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);
	}

	do {			/* look for message body */
	  s = t = unix_mbxline (stream,&bs,&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;
	      }

				/* 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 ((k = (u - s)) && j < NUSERFLAGS) {
			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;
	      }

				/* 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);
				/* 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);
		  else {	/* normal UID case */
		    prevuid = elt->private.uid = j;
		    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 */

	  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;