loadfile: avoid infinite playlist loading loops

There are a number of ways one can craft a playlist file that refers to
itself or cleverly goes around in a loop to other playlist files. There
is obviously no use for this, but mpv spins around forever trying to
load the files so you have to just SIGTERM/SIGKILL it. We can be smarter
about this and attempt to detect it. The condition for detecting this is
surprisingly simple: the filename of the first entry in the playlist
must match a previous playlist path we stored. If we get this, we can
then log an error and stop playback. If there is a "real" file loaded at
any point in time, then we know it's not an infinite loop and clear out
the saved playlist paths. Fixes #3967.

1 files changed, 2 insertions, 0 deletions

diff --git a/player/core.h b/player/core.h
index 3ea862462d..9b60add51d 100644
--- a/player/core.h
+++ b/player/core.h
@@ -275,6 +275,8 @@ typedef struct MPContext {
     struct playlist_entry *playing; // currently playing file
     char *filename; // immutable copy of playing->filename (or NULL)
     char *stream_open_filename;
+    char **playlist_paths; // used strictly for playlist validation
+    int playlist_paths_len;
     enum stop_play_reason stop_play;
     bool playback_initialized; // playloop can be run/is running
     int error_playing;