accept zero-sized messages from IMAP

while such a thing is rather pointless, completely empty messages are
not forbidden. consequently, we should be able to deal with them, and
above all not crash.

mbsync-get-cert

@@ -9,9 +9,25 @@
 # from a trusted source.
 #
 
-if [ $# != 1 ]; then
+usage() {
-	echo "Usage: $0 <host>" >&2
+	echo "Usage: $0 [-s] <host>" >&2
+	echo "  -s        Use IMAP+STARTTLS (port 143) instead of IMAPS (port 993)" >&2
 	exit 1
+}
+
+STARTTLS=false
+
+while getopts "s" opt; do
+	case $opt in
+	s) STARTTLS=true ;;
+	*) usage ;;
+	esac
+done
+
+shift `expr $OPTIND - 1`
+
+if [ $# -ne 1 ]; then
+	usage
 fi
 
 HOST=$1
@@ -33,7 +49,15 @@ TMPFILE=$TMPDIR/get-cert
 ERRFILE=$TMPDIR/get-cert-err
 CERTFILE=$TMPDIR/cert
 
-echo QUIT | openssl s_client -connect $HOST:993 -showcerts \
+if $STARTTLS; then
+	FLAGS="-starttls imap"
+	PORT=143
+else
+	FLAGS=
+	PORT=993
+fi
+
+echo QUIT | openssl s_client $FLAGS -connect $HOST:$PORT -showcerts \
 	> $TMPFILE 2> $ERRFILE
 sed -e '1,/^-----BEGIN CERTIFICATE-----/d' \
 	-e '/^-----END CERTIFICATE-----/,$d' < $TMPFILE > $CERTFILE

src/drv_imap.c

@@ -780,6 +780,8 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 				if (sts->callback->atom( ctx, NULL, bytes, AtomChunkedLiteral ) != LIST_OK)
 					goto bail;
 				sts->in_literal = ChunkedLiteral;
+				if (!bytes)
+					goto nobytes;
 				sts->big_literal = 1;
 			  get_chunked:
 				n = 1;
@@ -806,7 +808,7 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 				} else if (DFlags & DEBUG_NET_ALL) {
 					printf( "%s=========\n", ctx->label );
 					fwrite( p, n, 1, stdout );
-					if (p[n - 1] != '\n')
+					if (n && p[n - 1] != '\n')
 						fputs( "\n(no-nl) ", stdout );
 					printf( "%s=========\n", ctx->label );
 				} else {
@@ -819,6 +821,7 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 			bytes -= n;
 			if (bytes > 0)
 				goto postpone;
+		  nobytes:
 			if (sts->in_literal == ChunkedLiteral && sts->callback->atom( ctx, NULL, 0, AtomLiteral ) != LIST_OK)
 				goto bail;
 		  getline:

src/main_sync.c

@@ -9,7 +9,6 @@
 
 #define nz(a, b) ((a) ? (a) : (b))
 
-static int ops_any[2], trash_any[2], expunge_any[2];
 static int chans_total, chans_done;
 static int boxes_total, boxes_done;
 
@@ -84,25 +83,10 @@ summary( void )
 	if (!boxes_done)
 		return;  // Shut up if we errored out early.
 
-	printf( "Processed %d box(es) in %d channel(s)", boxes_done, chans_done );
+	printf( "Channels: %d    Boxes: %d    Far: +%d *%d #%d -%d    Near: +%d *%d #%d -%d\n",
-	for (int t = 2; --t >= 0; ) {
+	        chans_done, boxes_done,
-		if (ops_any[t])
+	        new_done[F], flags_done[F], trash_done[F], expunge_done[F],
-			printf( (DFlags & DRYRUN) ?
+	        new_done[N], flags_done[N], trash_done[N], expunge_done[N] );
-			            ",\nwould %s %d new message(s) and %d flag update(s)" :
-			            ",\n%sed %d new message(s) and %d flag update(s)",
-			        str_hl[t], new_done[t], flags_done[t] );
-		if (trash_any[t])
-			printf( (DFlags & DRYRUN) ?
-			            ",\nwould move %d %s message(s) to trash" :
-			            ",\nmoved %d %s message(s) to trash",
-			        trash_done[t], str_fn[t] );
-		if (expunge_any[t])
-			printf( (DFlags & DRYRUN) ?
-			            ",\nwould expunge %d message(s) from %s" :
-			            ",\nexpunged %d message(s) from %s",
-			        expunge_done[t], str_fn[t] );
-	}
-	puts( "." );
 }
 
 static int
@@ -244,14 +228,6 @@ add_channel( chan_ent_t ***chanapp, channel_conf_t *chan, int ops[] )
 			free( ce );
 			return NULL;
 		}
-		if (chan->ops[t] & OP_MASK_TYPE)
-			ops_any[t] = 1;
-		if (chan->ops[t] & (OP_EXPUNGE | OP_EXPUNGE_SOLO)) {
-			expunge_any[t] = 1;
-			if (chan->stores[t]->trash ||
-			    (chan->stores[t^1]->trash && chan->stores[t^1]->trash_remote_new))
-				trash_any[t] = 1;
-		}
 	}
 
 	**chanapp = ce;

src/mbsync.1.in

@@ -802,7 +802,7 @@ No attempt is made to calculate the totals in advance, so they grow over
 time as more information is gathered.
 .P
 Irrespective of output redirection, \fBmbsync\fR will print a summary
-of the above in plain language upon completion, except in quiet mode.
+of the above upon completion, except in quiet mode.
 .
 .SH RECOMMENDATIONS
 Make sure your IMAP server does not auto-expunge deleted messages - it is

src/socket.c

@@ -952,7 +952,6 @@ socket_expect_bytes( conn_t *conn, uint len )
 char *
 socket_read( conn_t *conn, uint min_len, uint max_len, uint *out_len )
 {
-	assert( min_len > 0 );
 	assert( min_len <= sizeof(conn->buf) );
 	assert( min_len <= max_len );
 

src/sync.c

@@ -511,7 +511,7 @@ box_opened2( sync_vars_t *svars, int t )
 	channel_conf_t *chan;
 	sync_rec_t *srec;
 	uint_array_alloc_t mexcs;
-	uint opts[2], fails, minwuid;
+	uint opts[2], minwuid;
 
 	svars->state[t] |= ST_SELECTED;
 	if (!(svars->state[t^1] & ST_SELECTED))
@@ -520,23 +520,13 @@ box_opened2( sync_vars_t *svars, int t )
 	ctx[1] = svars->ctx[1];
 	chan = svars->chan;
 
-	fails = 0;
+	if (!lock_state( svars )) {
-	for (t = 0; t < 2; t++)
-		if (svars->uidval[t] != UIDVAL_BAD && svars->uidval[t] != svars->newuidval[t])
-			fails++;
-	// If only one side changed UIDVALIDITY, we will try to re-approve it further down.
-	if (fails == 2) {
-		error( "Error: channel %s: UIDVALIDITY of both far side %s and near side %s changed.\n",
-		       svars->chan->name, svars->orig_name[F], svars->orig_name[N]);
 	  bail:
 		svars->ret = SYNC_FAIL;
 		sync_bail( svars );
 		return;
 	}
 
-	if (!lock_state( svars ))
-		goto bail;
-
 	int any_dummies[2] = { 0, 0 };
 	int any_purges[2] = { 0, 0 };
 	int any_upgrades[2] = { 0, 0 };
@@ -574,9 +564,11 @@ box_opened2( sync_vars_t *svars, int t )
 	}
 
 	opts[F] = opts[N] = 0;
-	if (fails)
-		opts[F] = opts[N] = OPEN_PAIRED | OPEN_PAIRED_IDS;
 	for (t = 0; t < 2; t++) {
+		if (svars->uidval[t] != UIDVAL_BAD && svars->uidval[t] != svars->newuidval[t]) {
+			opts[F] |= OPEN_PAIRED | OPEN_PAIRED_IDS;
+			opts[N] |= OPEN_PAIRED | OPEN_PAIRED_IDS;
+		}
 		if (any_purges[t]) {
 			debug( "resuming %d %s purge(s)\n", any_purges[t], str_fn[t] );
 			opts[t] |= OPEN_SETFLAGS;
@@ -859,8 +851,15 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 				if (!srec->msg[t^1])
 					continue;  // Partner disappeared.
 				if (!srec->msg[t^1]->msgid || strcmp( srec->msg[F]->msgid, srec->msg[N]->msgid )) {
-					error( "Error: channel %s, %s box %s: UIDVALIDITY genuinely changed (at UID %u).\n",
+					if (svars->uidval[t^1] != svars->newuidval[t^1]) {
+						error( "Error: channel %s, %s box %s (at UID %u):"
+						       " Unable to recover from both-sided UIDVALIDITY change,"
+						       " as it is genuine on at least one side.\n",
 						       svars->chan->name, str_fn[t], svars->orig_name[t], srec->uid[t] );
+					} else {
+						error( "Error: channel %s, %s box %s (at UID %u): UIDVALIDITY genuinely changed.\n",
+						       svars->chan->name, str_fn[t], svars->orig_name[t], srec->uid[t] );
+					}
 				  uvchg:
 					svars->ret |= SYNC_FAIL;
 					cancel_sync( svars );
@@ -1014,7 +1013,7 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 						sflags = sanitize_flags( sflags, svars, t );
 						if ((t != xt) && (srec->status & (S_EXPIRE | S_EXPIRED))) {
 							/* Don't propagate deletion resulting from expiration. */
-							debug( "  near side expiring\n" );
+							debug( "  %s side expiring\n", str_fn[xt] );
 							sflags &= ~F_DELETED;
 						}
 						if (srec->status & S_DUMMY(t^1)) {
@@ -1205,7 +1204,7 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 			if (!srec->uid[xt^1])
 				continue;
 			if (!(srec->status & S_PENDING)) {
-				// We ignore unpaired far-side messages, as there is obviously nothing
+				// We ignore unpaired keep-side messages, as there is obviously nothing
 				// to expire in the first place.
 				if (!srec->msg[xt])
 					continue;
@@ -1230,6 +1229,8 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 					// but we may be pulling in the real ones.
 					nflags = (srec->pflags | srec->aflags[xt]) & ~srec->dflags[xt];
 				} else {
+					if (!srec->msg[xt^1])
+						continue;
 					nflags = srec->msg[xt^1]->flags;
 				}
 			}

src/util.c

@@ -637,6 +637,11 @@ nfmalloc( size_t sz )
 {
 	void *ret;
 
+#ifndef __GLIBC__
+	// The C standard allows NULL returns for zero-sized allocations.
+	if (!sz)
+		sz = 1;
+#endif
 	if (!(ret = malloc( sz )))
 		oom();
 	return ret;