[FFmpeg-devel] [PATCH v3 4/8] avformat/file: add fd protocol
Zhao Zhili
quinkblack at foxmail.com
Wed Dec 14 19:10:10 EET 2022
From: Zhao Zhili <zhilizhao at tencent.com>
Unlike the pipe protocol, fd protocol has seek support if it
corresponding to a regular file.
---
doc/protocols.texi | 27 +++++++++++++
libavformat/Makefile | 1 +
libavformat/file.c | 87 +++++++++++++++++++++++++++++++++--------
libavformat/protocols.c | 1 +
libavformat/version.h | 4 +-
5 files changed, 101 insertions(+), 19 deletions(-)
diff --git a/doc/protocols.texi b/doc/protocols.texi
index a686a7f0ac..21ae6181a0 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -275,6 +275,33 @@ For example, to convert a GIF file given inline with @command{ffmpeg}:
ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png
@end example
+ at section fd
+
+File descriptor access protocol.
+
+The accepted syntax is:
+ at example
+fd: -fd @var{file_descriptor}
+ at end example
+
+If @option{fd} is not specified, by default the stdout file descriptor will be
+used for writing, stdin for reading. Unlike the pipe protocol, fd protocol has
+seek support if it corresponding to a regular file. fd protocol doesn't support
+pass file descriptor via URL for security.
+
+This protocol accepts the following options:
+
+ at table @option
+ at item blocksize
+Set I/O operation maximum block size, in bytes. Default value is
+ at 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.
+
+ at item fd
+Set file descriptor.
+ at 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 878983a336..d20208e31f 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -110,6 +110,13 @@ 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;
@@ -197,6 +204,23 @@ static int file_close(URLContext *h)
return (ret == -1) ? AVERROR(errno) : 0;
}
+/* XXX: use llseek */
+static int64_t file_seek(URLContext *h, int64_t pos, int whence)
+{
+ FileContext *c = h->priv_data;
+ int64_t ret;
+
+ if (whence == AVSEEK_SIZE) {
+ struct stat st;
+ ret = fstat(c->fd, &st);
+ return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ? 0 : st.st_size);
+ }
+
+ ret = lseek(c->fd, pos, whence);
+
+ return ret < 0 ? AVERROR(errno) : ret;
+}
+
#if CONFIG_FILE_PROTOCOL
static int file_delete(URLContext *h)
@@ -276,23 +300,6 @@ static int file_open(URLContext *h, const char *filename, int flags)
return 0;
}
-/* XXX: use llseek */
-static int64_t file_seek(URLContext *h, int64_t pos, int whence)
-{
- FileContext *c = h->priv_data;
- int64_t ret;
-
- if (whence == AVSEEK_SIZE) {
- struct stat st;
- ret = fstat(c->fd, &st);
- return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ? 0 : st.st_size);
- }
-
- ret = lseek(c->fd, pos, whence);
-
- return ret < 0 ? AVERROR(errno) : ret;
-}
-
static int file_open_dir(URLContext *h)
{
#if HAVE_LSTAT
@@ -441,3 +448,49 @@ 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;
+ struct stat st;
+
+ if (strcmp(filename, "fd:") != 0) {
+ av_log(h, AV_LOG_ERROR, "Doesn't support pass file descriptor via URL,"
+ " please set it via -fd {num}\n");
+ return AVERROR(EINVAL);
+ }
+
+ if (c->fd < 0) {
+ if (flags & AVIO_FLAG_WRITE) {
+ c->fd = 1;
+ } else {
+ c->fd = 0;
+ }
+ }
+ if (fstat(c->fd, &st) < 0)
+ return AVERROR(errno);
+ h->is_streamed = !(S_ISREG(st.st_mode) || S_ISBLK(st.st_mode));
+ c->fd = fd_dup(h, c->fd);
+ if (c->fd == -1)
+ return AVERROR(errno);
+
+ return 0;
+}
+
+const URLProtocol ff_fd_protocol = {
+ .name = "fd",
+ .url_open = fd_open,
+ .url_read = file_read,
+ .url_write = file_write,
+ .url_seek = file_seek,
+ .url_close = file_close,
+ .url_get_file_handle = file_get_handle,
+ .url_check = file_check,
+ .priv_data_size = sizeof(FileContext),
+ .priv_data_class = &fd_class,
+ .default_whitelist = "crypto,data"
+};
+
+#endif /* CONFIG_FD_PROTOCOL */
diff --git a/libavformat/protocols.c b/libavformat/protocols.c
index 8b7d1b940f..82cb1033e4 100644
--- a/libavformat/protocols.c
+++ b/libavformat/protocols.c
@@ -29,6 +29,7 @@ extern const URLProtocol ff_concat_protocol;
extern const URLProtocol ff_concatf_protocol;
extern const URLProtocol ff_crypto_protocol;
extern const URLProtocol ff_data_protocol;
+extern const URLProtocol ff_fd_protocol;
extern const URLProtocol ff_ffrtmpcrypt_protocol;
extern const URLProtocol ff_ffrtmphttp_protocol;
extern const URLProtocol ff_file_protocol;
diff --git a/libavformat/version.h b/libavformat/version.h
index 63e753a3aa..f5a7f579b3 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,8 +31,8 @@
#include "version_major.h"
-#define LIBAVFORMAT_VERSION_MINOR 34
-#define LIBAVFORMAT_VERSION_MICRO 103
+#define LIBAVFORMAT_VERSION_MINOR 35
+#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
LIBAVFORMAT_VERSION_MINOR, \
--
2.25.1
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