pty.c: Don't attempt to write 0 bytes to node.

For non-ANSI nodes, we call bbs_ansi_strip to
remove all the escape sequences from the buffer
before we write it to the node. However, in the
case that this actually results in an empty
buffer, don't attempt to write it. No nasty
side effects will happen, but a warning will be
thrown otherwise since we shouldn't be attempting
to write 0 bytes.

bbs/node.c

@@ -661,7 +661,7 @@ static int cli_nodes(struct bbs_cli_args *a)
 	int c = 0;
 	time_t now = time(NULL);
 
-	bbs_dprintf(a->fdout, "%3s %8s %9s %7s %-15s %-25s %15s %5s %1s %1s %7s %3s %3s %3s %3s %3s %3s %s\n", "#", "PROTOCOL", "ELAPSED", "TRM SZE", "USER", "MENU/PAGE", "IP ADDRESS", "RPORT", "E", "B", "TID", "FD", "RFD", "WFD", "MST", "SLV", "SPY", "SLV NAME");
+	bbs_dprintf(a->fdout, "%3s %9s %9s %7s %-15s %-25s %15s %5s %1s %1s %7s %3s %3s %3s %3s %3s %3s %s\n", "#", "PROTOCOL", "ELAPSED", "TRM SZE", "USER", "MENU/PAGE", "IP ADDRESS", "RPORT", "E", "B", "TID", "FD", "RFD", "WFD", "MST", "SLV", "SPY", "SLV NAME");
 
 	RWLIST_RDLOCK(&nodes);
 	RWLIST_TRAVERSE(&nodes, n, entry) {
@@ -678,7 +678,7 @@ static int cli_nodes(struct bbs_cli_args *a)
 		print_time_elapsed(n->created, now, elapsed, sizeof(elapsed));
 		snprintf(menufull, sizeof(menufull), "%s%s%s%s", S_IF(n->menu), n->menuitem ? " (" : "", S_IF(n->menuitem), n->menuitem ? ")" : "");
 		lwp = bbs_pthread_tid(n->thread);
-		bbs_dprintf(a->fdout, "%3d %8s %9s %3dx%3d %-15s %-25s %15s %5u %1s %1s %7d %3d %3d %3d %3d %3d %3d %s\n",
+		bbs_dprintf(a->fdout, "%3d %9s %9s %3dx%3d %-15s %-25s %15s %5u %1s %1s %7d %3d %3d %3d %3d %3d %3d %s\n",
 			n->id, n->protname, elapsed, n->cols, n->rows, bbs_username(n->user), menufull, n->ip, n->rport, BBS_YN(n->echo), BBS_YN(n->buffered),
 			lwp, n->fd, n->rfd, n->wfd, n->amaster, n->slavefd, n->spyfd, n->slavename);
 		c++;

bbs/pty.c

@@ -707,6 +707,12 @@ void *pty_master(void *varg)
 				writebuf[bytes_read] = '\0'; /* NUL terminate for bbs_ansi_strip */
 				/*! \todo XXX This should always get smaller... so couldn't this be done in place? */
 				if (!bbs_ansi_strip(writebuf, (size_t) bytes_read, strippedbuf, sizeof(strippedbuf), &strippedlen)) {
+					if (strippedlen == 0) {
+						bbs_debug(9, "Reduced all %lu bytes to nothing after stripping escape sequences\n", bytes_read);
+						/* There is nothing to write, don't even bother calling bbs_write,
+						 * since we shouldn't call write with 0 bytes. */
+						continue;
+					}
 					bytes_read = strippedlen;
 					relaybuf = strippedbuf;
 				} /* else, failed to strip, just write the original data (possibly containing ANSI escape sequences) */

bbs/socket.c

@@ -2124,7 +2124,6 @@ static int bbs_node_ansi_write(struct bbs_node *node, const char *restrict buf,
 ssize_t bbs_node_write(struct bbs_node *node, const char *buf, size_t len)
 {
 	struct pollfd pfd;
-	size_t left = len;
 	ssize_t res;
 
 #ifdef DETECT_IMPROPER_NODE_WRITES
@@ -2147,28 +2146,27 @@ ssize_t bbs_node_write(struct bbs_node *node, const char *buf, size_t len)
 	/* So helgrind doesn't complain about data race if node is shut down
 	 * and slavefd closed during write */
 	bbs_node_lock(node);
-	res = full_write(&pfd, node->slavefd, buf, left);
+	res = full_write(&pfd, node->slavefd, buf, len);
 	if (res <= 0 || res != (ssize_t) len) {
 		bbs_debug(5, "Node %d: write returned %lu/%lu\n", node->id, res, len);
 	}
 	bbs_node_unlock(node);
-	return (int) res;
+	return res;
 }
 
 ssize_t bbs_write(int fd, const char *buf, size_t len)
 {
 	struct pollfd pfd;
-	size_t left = len;
 	ssize_t res;
 
 	pfd.fd = fd;
 	pfd.events = POLLOUT;
 
-	res = full_write(&pfd, fd, buf, left);
+	res = full_write(&pfd, fd, buf, len);
 	if (res <= 0) {
 		bbs_debug(5, "fd %d: write returned %ld: %s\n", fd, res, res ? strerror(errno) : "");
 	}
-	return (int) res;
+	return res;
 }
 
 ssize_t bbs_timed_write(int fd, const char *buf, size_t len, int ms)

include/ansi.h

@@ -20,5 +20,6 @@
  * \param out Buffer in which the stripped string will be placed
  * \param outlen Size of out. Should be at least inlen, but no more than it.
  * \param strippedlen Will be set to the actual length of the stripped output, not including null terminator.
+ * \retval 0 on success, -1 on failure
  */
 int bbs_ansi_strip(const char *restrict in, size_t inlen, char *restrict out, size_t outlen, int *restrict strippedlen);