[FFmpeg-cvslog] file: Add an option for following a file that is being written

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Thu Feb  5 15:06:42 2015 +0200| [933dec0e29ec4d2cb83474279a6c52d62fdb7310] | committer: Martin Storsjö

file: Add an option for following a file that is being written

Using this requires setting the rw_timeout option to make it
terminate, alternatively using the interrupt callback (if used via
the API).

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=933dec0e29ec4d2cb83474279a6c52d62fdb7310
---

 doc/protocols.texi    |   11 +++++++++++
 libavformat/file.c    |    4 ++++
 libavformat/version.h |    2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/doc/protocols.texi b/doc/protocols.texi
index c0663ac..c136c74 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -69,6 +69,17 @@ The av* tools default to the file protocol, that is a resource
 specified with the name "FILE.mpeg" is interpreted as the URL
 "file:FILE.mpeg".
 
+This protocol accepts the following options:
+
+ at table @option
+ at item follow
+If set to 1, the protocol will retry reading at the end of the file, allowing
+reading files that still are being written. In order for this to terminate,
+you either need to use the rw_timeout option, or use the interrupt callback
+(for API users).
+
+ at end table
+
 @section gopher
 
 Gopher protocol.
diff --git a/libavformat/file.c b/libavformat/file.c
index 4f581cf..8683c1b 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -42,10 +42,12 @@ typedef struct FileContext {
     const AVClass *class;
     int fd;
     int trunc;
+    int follow;
 } FileContext;
 
 static const AVOption file_options[] = {
     { "truncate", "Truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
+    { "follow", "Follow a file as it is being written", offsetof(FileContext, follow), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
     { NULL }
 };
 
@@ -60,6 +62,8 @@ static int file_read(URLContext *h, unsigned char *buf, int size)
 {
     FileContext *c = h->priv_data;
     int ret = read(c->fd, buf, size);
+    if (ret == 0 && c->follow)
+        return AVERROR(EAGAIN);
     return (ret == -1) ? AVERROR(errno) : ret;
 }
 
diff --git a/libavformat/version.h b/libavformat/version.h
index 75d765b..aae1e23 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR 57
 #define LIBAVFORMAT_VERSION_MINOR  5
-#define LIBAVFORMAT_VERSION_MICRO  1
+#define LIBAVFORMAT_VERSION_MICRO  2
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \