lib: fix static analysis issues, use regfree()

* Fix potential NULL dereference
* Fix use of uninitialized value
* Fix leaking memory by not freeing regex_t
* Fix extra \n when using empty regex filter
* Clean up still-reachable hook memory
* Handle nonexistent pager

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

lib/command.c

@@ -1198,16 +1198,22 @@ static int handle_pipe_action(struct vty *vty, const char *cmd_in,
 	if (strmatch(token, "include")) {
 		/* the remaining text should be a regexp */
 		char *regexp = working;
+
+		if (!regexp) {
+			vty_out(vty, "%% Need a regexp to filter with\n");
+			goto fail;
+		}
+
 		bool succ = vty_set_include(vty, regexp);
 
 		if (!succ) {
-			vty_out(vty, "%% Bad regexp '%s'", regexp);
+			vty_out(vty, "%% Bad regexp '%s'\n", regexp);
 			goto fail;
 		}
 		*cmd_out = XSTRDUP(MTYPE_TMP, cmd_in);
 		*(strstr(*cmd_out, "|")) = '\0';
 	} else {
-		vty_out(vty, "%% Unknown action '%s'", token);
+		vty_out(vty, "%% Unknown action '%s'\n", token);
 		goto fail;
 	}
 
@@ -2892,6 +2898,9 @@ void cmd_terminate()
 {
 	struct cmd_node *cmd_node;
 
+	hook_unregister(cmd_execute, handle_pipe_action);
+	hook_unregister(cmd_execute_done, handle_pipe_action_done);
+
 	if (cmdvec) {
 		for (unsigned int i = 0; i < vector_active(cmdvec); i++)
 			if ((cmd_node = vector_slot(cmdvec, i)) != NULL) {

lib/frrstr.c

@@ -58,6 +58,9 @@ vector frrstr_split_vec(const char *string, const char *delimiter)
 	char **result;
 	int argc;
 
+	if (!string)
+		return NULL;
+
 	frrstr_split(string, delimiter, &result, &argc);
 
 	vector v = array_to_vector((void **)result, argc);
@@ -89,7 +92,7 @@ char *frrstr_join(const char **parts, int argc, const char *join)
 
 		memcpy(p, parts[i], arglen);
 		p += arglen;
-		if (i + 1 != argc) {
+		if (i + 1 != argc && join) {
 			memcpy(p, join, joinlen);
 			p += joinlen;
 		}

lib/vty.c

@@ -119,8 +119,8 @@ bool vty_set_include(struct vty *vty, const char *regexp)
 	bool ret = true;
 	char errbuf[256];
 
-	if (!regexp) {
+	if (!regexp && vty->filter) {
-		memset(&vty->include, 0x00, sizeof(vty->include));
+		regfree(&vty->include);
 		vty->filter = false;
 		return true;
 	}
@@ -188,8 +188,26 @@ int vty_out(struct vty *vty, const char *format, ...)
 		vector lines = frrstr_split_vec(buf, "\n");
 
 		frrstr_filter_vec(lines, &vty->include);
-		if (buf[strlen(buf) - 1] == '\n' && vector_active(lines) > 0)
+
+		/*
+		 * Consider the string "foo\n". If the regex is an empty string
+		 * and the line ended with a newline, then the vector will look
+		 * like:
+		 *
+		 * [0]: 'foo'
+		 * [1]: ''
+		 *
+		 * If the regex isn't empty, the vector will look like:
+		 *
+		 * [0]: 'foo'
+		 *
+		 * In this case we'd like to preserve the newline, so we add
+		 * the empty string [1] as in the first example.
+		 */
+		if (buf[strlen(buf) - 1] == '\n' && vector_active(lines) > 0
+		    && strlen(vector_slot(lines, vector_active(lines) - 1)))
 			vector_set(lines, XSTRDUP(MTYPE_TMP, ""));
+
 		filtered = frrstr_join_vec(lines, "\n");
 		frrstr_strvec_free(lines);
 	} else {

vtysh/vtysh.c

@@ -70,6 +70,9 @@ static FILE *vty_open_pager(struct vty *vty)
 	if (vty->is_paged)
 		return vty->of;
 
+	if (!vtysh_pager_name)
+		return NULL;
+
 	vty->of_saved = vty->of;
 	vty->of = popen(vtysh_pager_name, "w");
 	if (vty->of == NULL) {