core: add a playlist demuxer

Modeled after the old playlist_parser.c, but actually new code, and it
works a bit differently.

Demuxers (and sometimes streams) are the component that should be used
to open files and to determine the file format. This was already done
for subtitles, but playlists still use a separate code path.

DOCS/man/en/options.rst

@@ -1198,6 +1198,22 @@
 ``--list-properties``
     Print a list of the available properties.
 
+``--load-unsafe-playlists``
+    Normally, something like ``mpv playlist.m3u`` won't load the playlist. This
+    is because the playlist code is unsafe. (This is the same in all other
+    variations of MPlayer.)
+
+    See ``--playlist`` for details.
+
+    Note: this option will allow opening playlists using the ``playlist``
+    special demuxer. The ``--playlist`` uses different code, and supports more
+    playlist formats than the playlist demuxer. This means that for now, the
+    ``--playlist`` option should always be used if you intend to open playlists.
+    Background: the special demuxer contains newly written code, while the
+    ``--playlist`` option uses the old MPlayer code. Adding support for more
+    playlist formats to the special demuxer is work in progress, and eventually
+    the old code should disappear.
+
 ``--loop=<number|inf|no>``
     Loops playback ``<number>`` times. ``inf`` means forever and ``no`` disables
     looping. If several files are specified on command line, the entire playlist

Makefile

@@ -171,8 +171,9 @@ SOURCES = talloc.c \
           demux/demux_lavf.c \
           demux/demux_mf.c \
           demux/demux_mkv.c \
-          demux/demux_subreader.c \
+          demux/demux_playlist.c \
           demux/demux_raw.c \
+          demux/demux_subreader.c \
           demux/ebml.c \
           demux/mf.c \
           mpvcore/asxparser.c \

demux/demux.c

@@ -59,6 +59,7 @@ extern const demuxer_desc_t demuxer_desc_lavf;
 extern const demuxer_desc_t demuxer_desc_mng;
 extern const demuxer_desc_t demuxer_desc_libass;
 extern const demuxer_desc_t demuxer_desc_subreader;
+extern const demuxer_desc_t demuxer_desc_playlist;
 
 /* Please do not add any new demuxers here. If you want to implement a new
  * demuxer, add it to libavformat, except for wrappers around external
@@ -81,6 +82,7 @@ const demuxer_desc_t *const demuxer_list[] = {
 #ifdef CONFIG_MNG
     &demuxer_desc_mng,
 #endif
+    &demuxer_desc_playlist,
     // Pretty aggressive, so should be last.
     &demuxer_desc_subreader,
     /* Please do not add any new demuxers here. If you want to implement a new
@@ -309,6 +311,8 @@ static void free_sh_stream(struct sh_stream *sh)
 
 void free_demuxer(demuxer_t *demuxer)
 {
+    if (!demuxer)
+        return;
     if (demuxer->desc->close)
         demuxer->desc->close(demuxer);
     // free streams:

demux/demux.h

@@ -182,6 +182,9 @@ typedef struct demuxer {
     // for trivial demuxers which just read the whole file for codec to use
     struct bstr file_contents;
 
+    // If the file is a playlist file
+    struct playlist *playlist;
+
     void *priv;   // demuxer-specific internal data
     char **info;  // metadata
     struct MPOpts *opts;

demux/demux_playlist.c

@@ -0,0 +1,136 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mpvcore/mp_common.h"
+#include "mpvcore/options.h"
+#include "mpvcore/mp_msg.h"
+#include "mpvcore/playlist.h"
+#include "mpvcore/path.h"
+#include "stream/stream.h"
+#include "demux.h"
+
+#define PROBE_SIZE (8 * 1024)
+
+struct pl_parser {
+    struct stream *s;
+    char buffer[8 * 1024];
+    int utf16;
+    struct playlist *pl;
+    bool probing;
+};
+
+static char *pl_get_line0(struct pl_parser *p)
+{
+    char *res = stream_read_line(p->s, p->buffer, sizeof(p->buffer), p->utf16);
+    if (res) {
+        int len = strlen(res);
+        if (len > 0 && res[len - 1] == '\n')
+            res[len - 1] = '\0';
+    }
+    return res;
+}
+
+static bstr pl_get_line(struct pl_parser *p)
+{
+    return bstr0(pl_get_line0(p));
+}
+
+static void pl_add(struct pl_parser *p, bstr entry)
+{
+    char *s = bstrto0(NULL, entry);
+    playlist_add_file(p->pl, s);
+    talloc_free(s);
+}
+
+static bool pl_eof(struct pl_parser *p)
+{
+    return p->s->eof;
+}
+
+static int parse_m3u(struct pl_parser *p)
+{
+    bstr line = bstr_strip(pl_get_line(p));
+    if (!bstr_equals0(line, "#EXTM3U"))
+        return -1;
+    if (p->probing)
+        return 0;
+    while (!pl_eof(p)) {
+        line = bstr_lstrip(pl_get_line(p));
+        if (line.len == 0 || bstr_startswith0(line, "#"))
+            continue;
+        pl_add(p, line);
+    }
+    return 0;
+}
+
+struct pl_format {
+    const char *name;
+    int (*parse)(struct pl_parser *p);
+};
+
+static const struct pl_format formats[] = {
+    {"m3u", parse_m3u},
+};
+
+static const struct pl_format *probe_pl(struct pl_parser *p, bool force)
+{
+    int64_t start = stream_tell(p->s);
+    for (int n = 0; n < MP_ARRAY_SIZE(formats); n++) {
+        const struct pl_format *fmt = &formats[n];
+        stream_seek(p->s, start);
+        if (fmt->parse(p) >= 0)
+            return fmt;
+    }
+    return NULL;
+}
+
+static int open_file(struct demuxer *demuxer, enum demux_check check)
+{
+    bool force = check < DEMUX_CHECK_UNSAFE || check == DEMUX_CHECK_REQUEST;
+
+    struct pl_parser *p = talloc_zero(NULL, struct pl_parser);
+    p->pl = talloc_zero(p, struct playlist);
+
+    bstr probe_buf = stream_peek(demuxer->stream, PROBE_SIZE);
+    p->s = open_memory_stream(probe_buf.start, probe_buf.len);
+    p->utf16 = stream_skip_bom(p->s);
+    p->probing = true;
+    const struct pl_format *fmt = probe_pl(p, force);
+    free_stream(p->s);
+    playlist_clear(p->pl);
+    if (!fmt) {
+        talloc_free(p);
+        return -1;
+    }
+
+    p->probing = false;
+    p->s = demuxer->stream;
+    p->utf16 = stream_skip_bom(p->s);
+    bool ok = fmt->parse(p) >= 0;
+    if (ok)
+        playlist_add_base_path(p->pl, mp_dirname(demuxer->filename));
+    demuxer->playlist = talloc_steal(demuxer, p->pl);
+    demuxer->filetype = fmt->name;
+    talloc_free(p);
+    return ok ? 0 : -1;
+}
+
+const struct demuxer_desc demuxer_desc_playlist = {
+    .name = "playlist",
+    .desc = "Playlist file",
+    .open = open_file,
+};

mpvcore/asxparser.c

@@ -449,7 +449,6 @@ asx_parse_ref(ASX_Parser_t* parser, char** attribs) {
 
 static void asx_parse_entryref(ASX_Parser_t* parser,char* buffer,char** _attribs) {
   char *href;
-  stream_t* stream;
 
   if(parser->deep > 0)
     return;
@@ -459,16 +458,8 @@ static void asx_parse_entryref(ASX_Parser_t* parser,char* buffer,char** _attribs
     asx_warning_attrib_required(parser,"ENTRYREF" ,"HREF" );
     return;
   }
-  stream=stream_open(href, NULL);
+  mp_msg(MSGT_PLAYTREE,MSGL_ERR,"Recursive playlist %s\n", href);
-  if(!stream) {
+  playlist_add_file(parser->pl, href);
-    mp_msg(MSGT_PLAYTREE,MSGL_WARN,"Can't open playlist %s\n",href);
-    free(href);
-    return;
-  }
-
-  mp_msg(MSGT_PLAYTREE,MSGL_ERR,"Not recursively loading playlist %s\n",href);
-
-  free_stream(stream);
   free(href);
   //mp_msg(MSGT_PLAYTREE,MSGL_INFO,"Need to implement entryref\n");
 }

mpvcore/command.c

@@ -2319,7 +2319,7 @@ void run_command(MPContext *mpctx, mp_cmd_t *cmd)
     case MP_CMD_LOADLIST: {
         char *filename = cmd->args[0].v.s;
         bool append = cmd->args[1].v.i;
-        struct playlist *pl = playlist_parse_file(filename);
+        struct playlist *pl = playlist_parse_file(filename, opts);
         if (pl) {
             if (!append)
                 playlist_clear(mpctx->playlist);

mpvcore/mplayer.c

@@ -4133,6 +4133,19 @@ static void stream_dump(struct MPContext *mpctx)
     }
 }
 
+// Replace the current playlist entry with playlist contents. Moves the entries
+// from the given playlist pl, so the entries don't actually need to be copied.
+static void transfer_playlist(struct MPContext *mpctx, struct playlist *pl)
+{
+    if (mpctx->demuxer->playlist->first) {
+        playlist_transfer_entries(mpctx->playlist, mpctx->demuxer->playlist);
+        if (mpctx->playlist->current)
+            playlist_remove(mpctx->playlist, mpctx->playlist->current);
+    } else {
+        MP_WARN(mpctx, "Empty playlist!\n");
+    }
+}
+
 // Start playing the current playlist entry.
 // Handle initialization and deinitialization.
 static void play_current_file(struct MPContext *mpctx)
@@ -4213,11 +4226,7 @@ static void play_current_file(struct MPContext *mpctx)
     mpctx->resolve_result = resolve_url(stream_filename, opts);
     if (mpctx->resolve_result) {
         if (mpctx->resolve_result->playlist) {
-            // Replace entry with playlist contents
+            transfer_playlist(mpctx, mpctx->resolve_result->playlist);
-            playlist_transfer_entries(mpctx->playlist,
-                                      mpctx->resolve_result->playlist);
-            if (mpctx->playlist->current)
-                playlist_remove(mpctx->playlist, mpctx->playlist->current);
             goto terminate_playback;
         }
         stream_filename = mpctx->resolve_result->url;
@@ -4258,12 +4267,29 @@ goto_reopen_demuxer: ;
 
     mpctx->demuxer = demux_open(mpctx->stream, opts->demuxer_name, NULL, opts);
     mpctx->master_demuxer = mpctx->demuxer;
-
     if (!mpctx->demuxer) {
         mp_tmsg(MSGT_CPLAYER, MSGL_ERR, "Failed to recognize file format.\n");
         goto terminate_playback;
     }
 
+    MP_TARRAY_APPEND(NULL, mpctx->sources, mpctx->num_sources, mpctx->demuxer);
+
+    mpctx->initialized_flags |= INITIALIZED_DEMUXER;
+
+    if (mpctx->demuxer->playlist) {
+        if (mpctx->demuxer->stream->safe_origin || opts->load_unsafe_playlists) {
+            transfer_playlist(mpctx, mpctx->demuxer->playlist);
+        } else {
+            MP_ERR(mpctx, "\nThis looks like a playlist, but playlist support "
+                   "will not be used automatically.\nThe main problem with "
+                   "playlist safety is that playlist entries can be arbitrary,\n"
+                   "and an attacker could make mpv poke around in your local "
+                   "filesystem or network.\nUse --playlist=file or the "
+                   "--load-unsafe-playlists option to load them anyway.\n");
+        }
+        goto terminate_playback;
+    }
+
     if (mpctx->demuxer->matroska_data.ordered_chapters)
         build_ordered_chapter_timeline(mpctx);
 
@@ -4275,11 +4301,6 @@ goto_reopen_demuxer: ;
 
     print_timeline(mpctx);
 
-    if (!mpctx->num_sources) {
-        MP_TARRAY_APPEND(NULL, mpctx->sources, mpctx->num_sources,
-                         mpctx->demuxer);
-    }
-
     if (mpctx->timeline) {
         // With Matroska, the "master" file usually dictates track layout etc.
         // On the contrary, the EDL and CUE demuxers are empty wrappers, as
@@ -4298,8 +4319,6 @@ goto_reopen_demuxer: ;
     if (mpctx->timeline)
         timeline_set_part(mpctx, mpctx->timeline_part, true);
 
-    mpctx->initialized_flags |= INITIALIZED_DEMUXER;
-
     add_subtitle_fonts_from_sources(mpctx);
 
     open_subtitles_from_options(mpctx);

mpvcore/options.c

@@ -669,6 +669,8 @@ const m_option_t mp_opts[] = {
 
     OPT_DOUBLE("chapter-seek-threshold", chapter_seek_threshold, 0),
 
+    OPT_FLAG("load-unsafe-playlists", load_unsafe_playlists, 0),
+
     // a-v sync stuff:
     OPT_FLAG("correct-pts", correct_pts, 0),
     OPT_CHOICE("pts-association-mode", user_pts_assoc_mode, 0,

mpvcore/options.h

@@ -87,6 +87,7 @@ typedef struct MPOpts {
     int ordered_chapters;
     int chapter_merge_threshold;
     double chapter_seek_threshold;
+    int load_unsafe_playlists;
     int quiet;
     int load_config;
     int use_filedir_conf;

mpvcore/parser-mpcmd.c

@@ -114,6 +114,7 @@ static bool split_opt(struct parse_state *p)
 int m_config_parse_mp_command_line(m_config_t *config, struct playlist *files,
                                    int argc, char **argv)
 {
+    struct MPOpts *opts = config->optstruct;
     int ret = M_OPT_UNKNOWN;
     int mode = 0;
     struct playlist_entry *local_start = NULL;
@@ -187,7 +188,7 @@ int m_config_parse_mp_command_line(m_config_t *config, struct playlist *files,
             if (bstrcmp0(p.arg, "playlist") == 0) {
                 // append the playlist to the local args
                 char *param0 = bstrdup0(NULL, p.param);
-                struct playlist *pl = playlist_parse_file(param0);
+                struct playlist *pl = playlist_parse_file(param0, opts);
                 talloc_free(param0);
                 if (!pl) {
                     mp_tmsg(MSGT_CFGPARSER, MSGL_FATAL,

mpvcore/playlist_parser.c

@@ -16,6 +16,11 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+/*
+ * Warning: this is outdated, crappy code. It is used only for --playlist.
+ * New or cleaned up code should be added to demux_playlist.c instead.
+ */
+
 #include "config.h"
 #include <stdlib.h>
 #include <stdio.h>
@@ -406,43 +411,6 @@ static bool parse_ref_ini(play_tree_parser_t* p) {
   return true;
 }
 
-static bool parse_m3u(play_tree_parser_t* p) {
-  char* line;
-
-  mp_msg(MSGT_PLAYTREE,MSGL_V,"Trying extended m3u playlist...\n");
-  if (!(line = play_tree_parser_get_line(p)))
-    return NULL;
-  strstrip(line);
-  if(strcasecmp(line,"#EXTM3U"))
-    return NULL;
-  mp_msg(MSGT_PLAYTREE,MSGL_V,"Detected extended m3u playlist format\n");
-  play_tree_parser_stop_keeping(p);
-
-  while((line = play_tree_parser_get_line(p)) != NULL) {
-    strstrip(line);
-    if(line[0] == '\0')
-      continue;
-    /* EXTM3U files contain such lines:
-     * #EXTINF:<seconds>, <title>
-     * followed by a line with the filename
-     * for now we have no place to put that
-     * so we just skip that extra-info ::atmos
-     */
-    if(line[0] == '#') {
-#if 0 /* code functional */
-      if(strncasecmp(line,"#EXTINF:",8) == 0) {
-        mp_msg(MSGT_PLAYTREE,MSGL_INFO,"[M3U] Duration: %dsec  Title: %s\n",
-          strtol(line+8,&line,10), line+2);
-      }
-#endif
-      continue;
-    }
-    playlist_add_file(p->pl, line);
-  }
-
-  return true;
-}
-
 static bool parse_smil(play_tree_parser_t* p) {
   int entrymode=0;
   char* line,source[512],*pos,*s_start,*s_end,*src_line;
@@ -697,9 +665,11 @@ err_out:
   return success;
 }
 
-struct playlist *playlist_parse_file(const char *file)
+static struct playlist *do_parse(struct stream* stream, bool forced);
+
+struct playlist *playlist_parse_file(const char *file, struct MPOpts *opts)
 {
-  stream_t *stream = stream_open(file, NULL);
+  stream_t *stream = stream_open(file, opts);
   if(!stream) {
       mp_msg(MSGT_PLAYTREE,MSGL_ERR,
              "Error while opening playlist file %s: %s\n",
@@ -710,7 +680,7 @@ struct playlist *playlist_parse_file(const char *file)
   mp_msg(MSGT_PLAYTREE, MSGL_V,
          "Parsing playlist file %s...\n", file);
 
-  struct playlist *ret = playlist_parse(stream);
+  struct playlist *ret = do_parse(stream, true);
   free_stream(stream);
 
   playlist_add_base_path(ret, mp_dirname(file));
@@ -723,7 +693,6 @@ typedef bool (*parser_fn)(play_tree_parser_t *);
 static const parser_fn pl_parsers[] = {
     parse_asx,
     parse_pls,
-    parse_m3u,
     parse_ref_ini,
     parse_smil,
     parse_nsc,
@@ -740,7 +709,13 @@ static struct playlist *do_parse(struct stream* stream, bool forced)
   };
 
   bool success = false;
-  if (play_tree_parser_get_line(&p) != NULL) {
+  struct demuxer *pl_demux = demux_open(stream, "playlist", NULL, stream->opts);
+  if (pl_demux && pl_demux->playlist) {
+    playlist_transfer_entries(p.pl, pl_demux->playlist);
+    success = true;
+  }
+  free_demuxer(pl_demux);
+  if (!success && play_tree_parser_get_line(&p) != NULL) {
     for (int n = 0; n < sizeof(pl_parsers) / sizeof(pl_parsers[0]); n++) {
       play_tree_parser_reset(&p);
       if (pl_parsers[n] == parse_textplain && !forced)
@@ -765,13 +740,3 @@ static struct playlist *do_parse(struct stream* stream, bool forced)
 
   return p.pl;
 }
-
-struct playlist *playlist_parse(struct stream* stream)
-{
-    return do_parse(stream, true);
-}
-
-struct playlist *playlist_probe_and_parse(struct stream* stream)
-{
-    return do_parse(stream, false);
-}

mpvcore/playlist_parser.h

@@ -21,14 +21,9 @@
 
 #include <stdbool.h>
 
-struct stream;
+struct MPOpts;
 struct playlist;
 
-// Parse the given stream as playlist. Append entries to pl. Return whether
+struct playlist *playlist_parse_file(const char *file, struct MPOpts *opts);
-// there was an error when parsing.
-// deep = Parser depth. Some formats allow including other files,
-struct playlist *playlist_parse(struct stream* stream);
-struct playlist *playlist_probe_and_parse(struct stream* stream);
-struct playlist *playlist_parse_file(const char *file);
 
 #endif

mpvcore/timeline/tl_cue.c

@@ -356,8 +356,6 @@ void build_cue_timeline(struct MPContext *mpctx)
         }
     }
 
-    add_source(mpctx, mpctx->demuxer);
-
     for (size_t i = 0; i < file_count; i++) {
         if (!open_source(mpctx, files[i]))
             goto out;

stream/stream.c

@@ -742,6 +742,7 @@ static int stream_enable_cache(stream_t **stream, int64_t size, int64_t min,
     cache->url = talloc_strdup(cache, orig->url);
     cache->mime_type = talloc_strdup(cache, orig->mime_type);
     cache->lavf_type = talloc_strdup(cache, orig->lavf_type);
+    cache->safe_origin = orig->safe_origin;
     cache->opts = orig->opts;
     cache->start_pos = orig->start_pos;
     cache->end_pos = orig->end_pos;
@@ -862,6 +863,8 @@ unsigned char *stream_read_line(stream_t *s, unsigned char *mem, int max,
     int len;
     const unsigned char *end;
     unsigned char *ptr = mem;
+    if (utf16 == -1)
+        utf16 = 0;
     if (max < 1)
         return NULL;
     max--; // reserve one for 0-termination
@@ -891,6 +894,21 @@ unsigned char *stream_read_line(stream_t *s, unsigned char *mem, int max,
     return mem;
 }
 
+static const char *bom[3] = {"\xEF\xBB\xBF", "\xFF\xFE", "\xFE\xFF"};
+
+// Return utf16 argument for stream_read_line
+int stream_skip_bom(struct stream *s)
+{
+    bstr data = stream_peek(s, 4);
+    for (int n = 0; n < 3; n++) {
+        if (bstr_startswith0(data, bom[n])) {
+            stream_skip(s, strlen(bom[n]));
+            return n;
+        }
+    }
+    return -1; // default to 8 bit codepages
+}
+
 // Read the rest of the stream into memory (current pos to EOF), and return it.
 //  talloc_ctx: used as talloc parent for the returned allocation
 //  max_size: must be set to >0. If the file is larger than that, it is treated

stream/stream.h

@@ -150,6 +150,7 @@ typedef struct stream {
     char *mime_type; // when HTTP streaming is used
     char *demuxer; // request demuxer to be used
     char *lavf_type; // name of expected demuxer type for lavf
+    bool safe_origin; // used for playlists that can be opened safely
     struct MPOpts *opts;
 
     FILE *capture_file;
@@ -208,6 +209,7 @@ inline static uint64_t stream_read_qword(stream_t *s)
 
 unsigned char *stream_read_line(stream_t *s, unsigned char *mem, int max,
                                 int utf16);
+int stream_skip_bom(struct stream *s);
 
 inline static int stream_eof(stream_t *s)
 {