From 6b32d195e88fc51289a317ee7e43fe642ef6b49f Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Mon, 16 Dec 2024 09:13:09 +0000
Subject: [PATCH] Add a nesting limit to source-file, from Fadi Afani in GitHub
 issue 4223.

---
 cmd-source-file.c | 30 ++++++++++++++++++++++++++++++
 tmux.h            |  1 +
 2 files changed, 31 insertions(+)

diff --git a/cmd-source-file.c b/cmd-source-file.c
index 67f353b9..7696dc92 100644
--- a/cmd-source-file.c
+++ b/cmd-source-file.c
@@ -30,6 +30,9 @@
  * Sources a configuration file.
  */
 
+#define CMD_SOURCE_FILE_DEPTH_LIMIT 50
+static u_int cmd_source_file_depth;
+
 static enum cmd_retval	cmd_source_file_exec(struct cmd *, struct cmdq_item *);
 
 const struct cmd_entry cmd_source_file_entry = {
@@ -60,6 +63,16 @@ struct cmd_source_file_data {
 static enum cmd_retval
 cmd_source_file_complete_cb(struct cmdq_item *item, __unused void *data)
 {
+	struct client	*c = cmdq_get_client(item);
+
+	if (c == NULL) {
+		cmd_source_file_depth--;
+		log_debug("%s: depth now %u", __func__, cmd_source_file_depth);
+	} else {
+		c->source_file_depth--;
+		log_debug("%s: depth now %u", __func__, c->source_file_depth);
+	}
+
 	cfg_print_causes(item);
 	return (CMD_RETURN_NORMAL);
 }
@@ -131,6 +144,7 @@ cmd_source_file_add(struct cmd_source_file_data *cdata, const char *path)
 		path = resolved;
 
 	log_debug("%s: %s", __func__, path);
+
 	cdata->files = xreallocarray(cdata->files, cdata->nfiles + 1,
 	    sizeof *cdata->files);
 	cdata->files[cdata->nfiles++] = xstrdup(path);
@@ -149,6 +163,22 @@ cmd_source_file_exec(struct cmd *self, struct cmdq_item *item)
 	int				 result;
 	u_int				 i, j;
 
+	if (c == NULL) {
+		if (cmd_source_file_depth >= CMD_SOURCE_FILE_DEPTH_LIMIT) {
+			cmdq_error(item, "too many nested files");
+			return (CMD_RETURN_ERROR);
+		}
+		cmd_source_file_depth++;
+		log_debug("%s: depth now %u", __func__, cmd_source_file_depth);
+	} else {
+		if (c->source_file_depth >= CMD_SOURCE_FILE_DEPTH_LIMIT) {
+			cmdq_error(item, "too many nested files");
+			return (CMD_RETURN_ERROR);
+		}
+		c->source_file_depth++;
+		log_debug("%s: depth now %u", __func__, c->source_file_depth);
+	}
+
 	cdata = xcalloc(1, sizeof *cdata);
 	cdata->item = item;
 
diff --git a/tmux.h b/tmux.h
index bc4df764..7077f9b1 100644
--- a/tmux.h
+++ b/tmux.h
@@ -2013,6 +2013,7 @@ struct client {
 	struct event		 overlay_timer;
 
 	struct client_files	 files;
+	u_int			 source_file_depth;
 
 	u_int			*clipboard_panes;
 	u_int			 clipboard_npanes;