Le sunnuntaina 11. joulukuuta 2022, 17.17.27 EET Zhao Zhili a écrit :
> From: Zhao Zhili <zhiliz...@tencent.com>
>
> Unlike the pipe protocol, fd protocol has seek support if it
> corresponding to a regular file.
> ---
> v2: dup the file descriptor for safety
>
> doc/protocols.texi | 24 ++++++++++++++++++
> libavformat/Makefile | 1 +
> libavformat/file.c | 55 +++++++++++++++++++++++++++++++++++++++++
> libavformat/protocols.c | 1 +
> libavformat/version.h | 4 +--
> 5 files changed, 83 insertions(+), 2 deletions(-)
>
> diff --git a/doc/protocols.texi b/doc/protocols.texi
> index 5e9198e67c..d9f2d2dec3 100644
> --- a/doc/protocols.texi
> +++ b/doc/protocols.texi
> @@ -275,6 +275,30 @@ For example, to convert a GIF file given inline with
> @command{ffmpeg}: ffmpeg -i
> "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywA
> AAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png @end example
>
> +@section fd
> +
> +File descriptor access protocol.
> +
> +The accepted syntax is:
> +@example
> +fd:[@var{number}]
> +@end example
> +
> +@var{number} is the number corresponding to a file descriptor. Unlike the
> pipe +protocol, fd protocol has seek support if it corresponding to a
> regular file. +If @var{number} is not specified, by default the stdout file
> descriptor will +be used for writing, stdin for reading.
> +
> +This protocol accepts the following options:
> +
> +@table @option
> +@item blocksize
> +Set I/O operation maximum block size, in bytes. Default value is
> +@code{INT_MAX}, which results in not limiting the requested block size.
> +Setting this value reasonably low improves user termination request
> reaction +time, which is valuable if data transmission is slow.
> +@end table
> +
> @section file
>
> File access protocol.
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index d7f198bf39..1452216e29 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -647,6 +647,7 @@ OBJS-$(CONFIG_DATA_PROTOCOL) += data_uri.o
> OBJS-$(CONFIG_FFRTMPCRYPT_PROTOCOL) += rtmpcrypt.o rtmpdigest.o
> rtmpdh.o OBJS-$(CONFIG_FFRTMPHTTP_PROTOCOL) += rtmphttp.o
> OBJS-$(CONFIG_FILE_PROTOCOL) += file.o
> +OBJS-$(CONFIG_FD_PROTOCOL) += file.o
> OBJS-$(CONFIG_FTP_PROTOCOL) += ftp.o urldecode.o
> OBJS-$(CONFIG_GOPHER_PROTOCOL) += gopher.o
> OBJS-$(CONFIG_GOPHERS_PROTOCOL) += gopher.o
> diff --git a/libavformat/file.c b/libavformat/file.c
> index 6103c37b34..b8725c1f48 100644
> --- a/libavformat/file.c
> +++ b/libavformat/file.c
> @@ -109,6 +109,13 @@ static const AVClass pipe_class = {
> .version = LIBAVUTIL_VERSION_INT,
> };
>
> +static const AVClass fd_class = {
> + .class_name = "fd",
> + .item_name = av_default_item_name,
> + .option = pipe_options,
> + .version = LIBAVUTIL_VERSION_INT,
> +};
> +
> static int file_read(URLContext *h, unsigned char *buf, int size)
> {
> FileContext *c = h->priv_data;
> @@ -412,3 +419,51 @@ const URLProtocol ff_pipe_protocol = {
> };
>
> #endif /* CONFIG_PIPE_PROTOCOL */
> +
> +#if CONFIG_FD_PROTOCOL
> +
> +static int fd_open(URLContext *h, const char *filename, int flags)
> +{
> + FileContext *c = h->priv_data;
> + int fd;
> + char *final;
> + struct stat st;
> +
> + av_strstart(filename, "fd:", &filename);
> +
> + fd = strtol(filename, &final, 10);
> + if ((filename == final) || *final ) {
> + if (flags & AVIO_FLAG_WRITE) {
> + fd = 1;
> + } else {
> + fd = 0;
> + }
> + }
> +#if HAVE_SETMODE
> + setmode(fd, O_BINARY);
> +#endif
> + if (fstat(fd, &st) < 0)
> + return AVERROR(errno);
> + h->is_streamed = !(S_ISREG(st.st_mode) || S_ISBLK(st.st_mode));
> + c->fd = dup(fd);
This leaks c->fd into child processes. You need atomic close-on-exec.
--
Реми Дёни-Курмон
http://www.remlab.net/
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