Merge commit '933dec0e29ec4d2cb83474279a6c52d62fdb7310'

* commit '933dec0e29ec4d2cb83474279a6c52d62fdb7310':
  file: Add an option for following a file that is being written

Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

doc/protocols.texi

@@ -224,6 +224,17 @@ it, unless special care is taken (tests, customized server configuration
 etc.). Different FTP servers behave in different way during seek
 operation. ff* tools may produce incomplete content due to server limitations.
 
+This protocol accepts the following options:
+
+@table @option
+@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).
+
+@end table
+
 @section gopher
 
 Gopher protocol.

libavformat/file.c

@@ -72,6 +72,7 @@ typedef struct FileContext {
     int fd;
     int trunc;
     int blocksize;
+    int follow;
 #if HAVE_DIRENT_H
     DIR *dir;
 #endif
@@ -80,6 +81,7 @@ typedef struct FileContext {
 static const AVOption file_options[] = {
     { "truncate", "truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
     { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, 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 }
 };
 
@@ -108,6 +110,8 @@ static int file_read(URLContext *h, unsigned char *buf, int size)
     int ret;
     size = FFMIN(size, c->blocksize);
     ret = read(c->fd, buf, size);
+    if (ret == 0 && c->follow)
+        return AVERROR(EAGAIN);
     return (ret == -1) ? AVERROR(errno) : ret;
 }
 

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR  57
 #define LIBAVFORMAT_VERSION_MINOR  34
-#define LIBAVFORMAT_VERSION_MICRO 102
+#define LIBAVFORMAT_VERSION_MICRO 103
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \