[FFmpeg-cvslog] url: Document the expected behaviour of url_read

[Nicolas George]

ffmpeg | branch: master | Nicolas George <nicolas.george at normalesup.org> | Thu Mar 15 12:16:54 2012 +0100| [01b0ade665b94749d82061b6b7dee8863a2b1536] | committer: Martin Storsjö

url: Document the expected behaviour of url_read

Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=01b0ade665b94749d82061b6b7dee8863a2b1536
---

 libavformat/url.h |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/libavformat/url.h b/libavformat/url.h
index 265a8ab..bf8b6ed 100644
--- a/libavformat/url.h
+++ b/libavformat/url.h
@@ -59,6 +59,19 @@ typedef struct URLProtocol {
      * for those nested protocols.
      */
     int     (*url_open2)(URLContext *h, const char *url, int flags, AVDictionary **options);
+
+    /**
+     * Read data from the protocol.
+     * If data is immediately available (even less than size), EOF is
+     * reached or an error occurs (including EINTR), return immediately.
+     * Otherwise:
+     * In non-blocking mode, return AVERROR(EAGAIN) immediately.
+     * In blocking mode, wait for data/EOF/error with a short timeout (0.1s),
+     * and return AVERROR(EAGAIN) on timeout.
+     * Checking interrupt_callback, looping on EINTR and EAGAIN and until
+     * enough data has been read is left to the calling function; see
+     * retry_transfer_wrapper in avio.c.
+     */
     int     (*url_read)( URLContext *h, unsigned char *buf, int size);
     int     (*url_write)(URLContext *h, const unsigned char *buf, int size);
     int64_t (*url_seek)( URLContext *h, int64_t pos, int whence);