stream: change open code, add stream filter concept

Add a stream filter concept, in which streams can be opened on top of
an underlying "source" stream. Change the open code to make this
easier, and also to account for some mechanisms that will be needed
for this.

The following commit will add stream_rar, which contains such a stream
filter.

1 files changed, 75 insertions, 54 deletions

diff --git a/stream/stream.c b/stream/stream.c
index e1b8efee83..474e46d96a 100644
--- a/stream/stream.c
+++ b/stream/stream.c
@@ -76,7 +76,7 @@ extern const stream_info_t stream_info_ifo;
 extern const stream_info_t stream_info_dvd;
 extern const stream_info_t stream_info_bluray;
 
-static const stream_info_t *const auto_open_streams[] = {
+static const stream_info_t *const stream_list[] = {
 #ifdef CONFIG_VCD
     &stream_info_vcd,
 #endif
@@ -210,15 +210,48 @@ static stream_t *new_stream(void)
     return s;
 }
 
-static stream_t *open_stream_plugin(const stream_info_t *sinfo,
-                                    const char *url, const char *path, int mode,
-                                    struct MPOpts *options, int *ret)
+static const char *match_proto(const char *url, const char *proto)
+{
+    int l = strlen(proto);
+    if (l > 0) {
+        if (strncasecmp(url, proto, l) == 0 && strncmp("://", url + l, 3) == 0)
+            return url + l + 3;
+    } else {
+        // pure filenames (including "/path" and "./path")
+        if (url[0] == '/' || url[0] == '.' || !strstr(url, "://"))
+            return url;
+    }
+    return NULL;
+}
+
+static int open_internal(const stream_info_t *sinfo, struct stream *underlying,
+                         const char *url, int flags, struct MPOpts *options,
+                         struct stream **ret)
 {
+    if (sinfo->stream_filter != !!underlying)
+        return STREAM_NO_MATCH;
+    if (sinfo->stream_filter && (flags & STREAM_NO_FILTERS))
+        return STREAM_NO_MATCH;
+
+    const char *path = NULL;
+    // Stream filters use the original URL, with no protocol matching at all.
+    if (!sinfo->stream_filter) {
+        for (int n = 0; sinfo->protocols && sinfo->protocols[n]; n++) {
+            path = match_proto(url, sinfo->protocols[n]);
+            if (path)
+                break;
+        }
+
+        if (!path)
+            return STREAM_NO_MATCH;
+    }
+
     stream_t *s = new_stream();
     s->info = sinfo;
     s->opts = options;
     s->url = talloc_strdup(s, url);
     s->path = talloc_strdup(s, path);
+    s->source = underlying;
 
     // Parse options
     if (sinfo->priv_size) {
@@ -232,17 +265,16 @@ static stream_t *open_stream_plugin(const stream_info_t *sinfo,
         if (s->info->url_options && !parse_url(s, config)) {
             mp_tmsg(MSGT_OPEN, MSGL_ERR, "URL parsing failed on url %s\n", url);
             talloc_free(s);
-            *ret = STREAM_ERROR;
-            return NULL;
+            return STREAM_ERROR;
         }
     }
 
     s->flags = 0;
-    s->mode = mode;
-    *ret = sinfo->open(s, mode);
-    if ((*ret) != STREAM_OK) {
+    s->mode = flags & (STREAM_READ | STREAM_WRITE);
+    int r = sinfo->open(s, s->mode);
+    if (r != STREAM_OK) {
         talloc_free(s);
-        return NULL;
+        return r;
     }
 
     if (!s->read_chunk)
@@ -256,8 +288,6 @@ static stream_t *open_stream_plugin(const stream_info_t *sinfo,
     if (s->flags & MP_STREAM_FAST_SKIPPING)
         s->flags |= MP_STREAM_SEEK_FW;
 
-    s->mode = mode;
-
     s->uncached_type = s->type;
 
     mp_msg(MSGT_OPEN, MSGL_V, "[stream] [%s] %s\n", sinfo->name, url);
@@ -265,67 +295,57 @@ static stream_t *open_stream_plugin(const stream_info_t *sinfo,
     if (s->mime_type)
         mp_msg(MSGT_OPEN, MSGL_V, "Mime-type: '%s'\n", s->mime_type);
 
-    return s;
+    *ret = s;
+    return STREAM_OK;
 }
 
-static const char *match_proto(const char *url, const char *proto)
+struct stream *stream_create(const char *url, int flags, struct MPOpts *options)
 {
-    int l = strlen(proto);
-    if (l > 0) {
-        if (strncasecmp(url, proto, l) == 0 && strncmp("://", url + l, 3) == 0)
-            return url + l + 3;
-    } else {
-        // pure filenames
-        if (!strstr(url, "://"))
-            return url;
-    }
-    return NULL;
-}
-
-static stream_t *open_stream_full(const char *url, int mode,
-                                  struct MPOpts *options)
-{
-    int i, j, r;
-    const stream_info_t *sinfo;
-    stream_t *s;
-
+    struct stream *s = NULL;
     assert(url);
 
-    for (i = 0; auto_open_streams[i]; i++) {
-        sinfo = auto_open_streams[i];
-        if (!sinfo->protocols) {
-            mp_msg(MSGT_OPEN, MSGL_WARN,
-                   "Stream type %s has protocols == NULL, it's a bug\n",
-                   sinfo->name);
+    // Open stream proper
+    for (int i = 0; stream_list[i]; i++) {
+        int r = open_internal(stream_list[i], NULL, url, flags, options, &s);
+        if (r == STREAM_OK)
+            break;
+        if (r == STREAM_NO_MATCH || r == STREAM_UNSUPPORTED)
             continue;
+        if (r != STREAM_OK) {
+            mp_tmsg(MSGT_OPEN, MSGL_ERR, "Failed to open %s.\n", url);
+            return NULL;
         }
-        for (j = 0; sinfo->protocols[j]; j++) {
-            const char *path = match_proto(url, sinfo->protocols[j]);
-            if (path) {
-                s = open_stream_plugin(sinfo, url, path, mode, options, &r);
-                if (s)
-                    return s;
-                if (r != STREAM_UNSUPPORTED) {
-                    mp_tmsg(MSGT_OPEN, MSGL_ERR, "Failed to open %s.\n", url);
-                    return NULL;
-                }
+    }
+
+    if (!s) {
+        mp_tmsg(MSGT_OPEN, MSGL_ERR, "No stream found to handle url %s\n", url);
+        return NULL;
+    }
+
+    // Open stream filters
+    for (;;) {
+        struct stream *new = NULL;
+        for (int i = 0; stream_list[i]; i++) {
+            int r = open_internal(stream_list[i], s, s->url, flags, options, &new);
+            if (r == STREAM_OK)
                 break;
-            }
         }
+        if (!new)
+            break;
+        s = new;
     }
 
-    mp_tmsg(MSGT_OPEN, MSGL_ERR, "No stream found to handle url %s\n", url);
-    return NULL;
+    return s;
 }
 
 struct stream *stream_open(const char *filename, struct MPOpts *options)
 {
-    return open_stream_full(filename, STREAM_READ, options);
+    return stream_create(filename, STREAM_READ, options);
 }
 
 stream_t *open_output_stream(const char *filename, struct MPOpts *options)
 {
-    return open_stream_full(filename, STREAM_WRITE, options);
+    return stream_create(filename, STREAM_WRITE, options);
 }
 
 static int stream_reconnect(stream_t *s)
@@ -673,6 +693,7 @@ void free_stream(stream_t *s)
     if (s->close)
         s->close(s);
     free_stream(s->uncached_stream);
+    free_stream(s->source);
     talloc_free(s);
 }