stream_env: add new stream to read from environment variables

DOCS/man/mpv.rst

@@ -1492,6 +1492,10 @@ PROTOCOLS
 
         This will play ``video.mkv`` in the archive file ``file.zip``.
 
+``env://variable``
+
+    Read the environment variable ``variable`` as source data.
+
 PSEUDO GUI MODE
 ===============
 

meson.build

@@ -200,6 +200,7 @@ sources = files(
     'stream/stream_null.c',
     'stream/stream_slice.c',
     'stream/stream_bstr.c',
+    'stream/stream_env.c',
 
     ## Subtitles
     'sub/ass_mp.c',

stream/stream.c

@@ -62,6 +62,7 @@ extern const stream_info_t stream_info_edl;
 extern const stream_info_t stream_info_libarchive;
 extern const stream_info_t stream_info_cb;
 extern const stream_info_t stream_info_curl;
+extern const stream_info_t stream_info_env;
 
 static const stream_info_t *const stream_list[] = {
     &stream_info_mpv,
@@ -96,6 +97,7 @@ static const stream_info_t *const stream_list[] = {
 #endif
     &stream_info_ffmpeg,
     &stream_info_ffmpeg_unsafe,
+    &stream_info_env,
 };
 
 // Because of guarantees documented on STREAM_BUFFER_SIZE.

stream/stream_env.c

@@ -0,0 +1,47 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+
+#include "common/common.h"
+#include "stream_bstr.h"
+
+static int open2(stream_t *stream, const struct stream_open_args *args)
+{
+    bstr data = bstr0(stream->url);
+    bstr_eatstart0(&data, "env://");
+
+    char *name = bstrdup0(stream, data);
+    char *val = getenv(name);
+    talloc_free(name);
+
+    if (!val) {
+        MP_FATAL(stream, "Could not read from environment variable '%.*s'\n",
+                 BSTR_P(data));
+        return STREAM_ERROR;
+    }
+
+    data = bstrdup(stream, bstr0(val));
+    return stream_bstr_open2(stream, args, data);
+}
+
+const stream_info_t stream_info_env = {
+    .name = "env",
+    .open2 = open2,
+    .protocols = (const char*const[]){ "env", NULL },
+    .stream_origin = STREAM_ORIGIN_DIRECT,
+};