player: strip 'file://' from filenames on playback start

This fixes two things:

1. Dropping files on the VO window will auto-load subtitles (since most
   drag & drop code prefixes the filenames with 'file://', and the
   subtitle auto-load code considers 'file://' non-local)
2. Fix behavior of the %x screenshot filename template (similar problem)

One could force all that code to special-case 'file://' URLs, but just
replacing the filename on playback start is simpler.

player/loadfile.c

@@ -1029,6 +1029,7 @@ static void load_per_file_options(m_config_t *conf,
 static void play_current_file(struct MPContext *mpctx)
 {
     struct MPOpts *opts = mpctx->opts;
+    void *tmp = talloc_new(NULL);
     double playback_start = -1e100;
 
     mpctx->initialized_flags |= INITIALIZED_PLAYBACK;
@@ -1047,6 +1048,10 @@ static void play_current_file(struct MPContext *mpctx)
     if (!mpctx->filename)
         goto terminate_playback;
 
+    char *local_filename = mp_file_url_to_filename(tmp, bstr0(mpctx->filename));
+    if (local_filename)
+        mpctx->filename = local_filename;
+
 #if HAVE_ENCODING
     encode_lavc_discontinuity(mpctx->encode_lavc_ctx);
 #endif
@@ -1096,6 +1101,7 @@ static void play_current_file(struct MPContext *mpctx)
     char *stream_filename = mpctx->filename;
     mpctx->resolve_result = resolve_url(stream_filename, mpctx->global);
     if (mpctx->resolve_result) {
+        talloc_steal(tmp, mpctx->resolve_result);
         print_resolve_contents(mpctx->log, mpctx->resolve_result);
         if (mpctx->resolve_result->playlist) {
             transfer_playlist(mpctx, mpctx->resolve_result->playlist);
@@ -1370,8 +1376,8 @@ terminate_playback:  // don't jump here after ao/vo/getch initialization!
         getch2_enable();
 
     mpctx->filename = NULL;
-    talloc_free(mpctx->resolve_result);
     mpctx->resolve_result = NULL;
+    talloc_free(tmp);
 
     // Played/paused for longer than 3 seconds -> ok
     bool playback_short = mpctx->stop_play == AT_END_OF_FILE &&

stream/stream.h

@@ -281,4 +281,7 @@ typedef struct {
 void mp_url_unescape_inplace(char *buf);
 char *mp_url_escape(void *talloc_ctx, const char *s, const char *ok);
 
+// stream_file.c
+char *mp_file_url_to_filename(void *talloc_ctx, bstr url);
+
 #endif /* MPLAYER_STREAM_H */

stream/stream_file.c

@@ -32,6 +32,7 @@
 #include "common/msg.h"
 #include "stream.h"
 #include "options/m_option.h"
+#include "options/path.h"
 
 struct priv {
     int fd;
@@ -91,10 +92,25 @@ static void s_close(stream_t *s)
         close(p->fd);
 }
 
+// If url is a file:// URL, return the local filename, otherwise return NULL.
+char *mp_file_url_to_filename(void *talloc_ctx, bstr url)
+{
+    bstr proto = mp_split_proto(url, &url);
+    if (bstrcasecmp0(proto, "file") != 0)
+        return NULL;
+    char *filename = bstrto0(talloc_ctx, url);
+    mp_url_unescape_inplace(filename);
+#if HAVE_DOS_PATHS
+    // extract '/' from '/x:/path'
+    if (filename[0] == '/' && filename[1] && filename[2] == ':')
+        memmove(filename, filename + 1, strlen(filename)); // including \0
+#endif
+    return filename;
+}
+
 static int open_f(stream_t *stream, int mode)
 {
     int fd;
-    char *filename = stream->path;
     struct priv *priv = talloc_ptrtype(stream, priv);
     *priv = (struct priv) {
         .fd = -1
@@ -111,15 +127,12 @@ static int open_f(stream_t *stream, int mode)
         return STREAM_UNSUPPORTED;
     }
 
-    // "file://" prefix -> decode URL-style escapes
+    char *filename = mp_file_url_to_filename(stream, bstr0(stream->url));
-    if (strlen(stream->url) > strlen(stream->path))
+    if (filename) {
-        mp_url_unescape_inplace(stream->path);
+        stream->path = filename;
-
+    } else {
-#if HAVE_DOS_PATHS
+        filename = stream->path;
-    // extract '/' from '/x:/path'
+    }
-    if (filename[0] == '/' && filename[1] && filename[2] == ':')
-        filename++;
-#endif
 
     if (!strcmp(filename, "-")) {
         if (mode == STREAM_READ) {
@@ -151,8 +164,7 @@ static int open_f(stream_t *stream, int mode)
 #ifndef __MINGW32__
         struct stat st;
         if (fstat(fd, &st) == 0 && S_ISDIR(st.st_mode)) {
-            MP_ERR(stream, "File is a directory: '%s'\n",
+            MP_ERR(stream, "File is a directory: '%s'\n", filename);
-                    filename);
             close(fd);
             return STREAM_ERROR;
         }