[FFmpeg-devel] [PATCH 1/2] avformat/file: Add a specialized url_check callback for pipe protocol
Neil Roberts
bpeeluk at yahoo.co.uk
Mon Aug 29 17:43:19 EEST 2022
Using file_check for the pipe protocol doesn't make sense. For example,
for a URL like “pipe:0” it would end up checking whether the “pipe:0”
file exists. This patch instead makes it check the access modes on the
corresponding file descriptor using fcntl.
Signed-off-by: Neil Roberts <bpeeluk at yahoo.co.uk>
---
libavformat/file.c | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)
diff --git a/libavformat/file.c b/libavformat/file.c
index 98c9e81bcb..f17d219cb2 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -375,9 +375,8 @@ const URLProtocol ff_file_protocol = {
#if CONFIG_PIPE_PROTOCOL
-static int pipe_open(URLContext *h, const char *filename, int flags)
+static int pipe_get_fd(const char *filename, int flags)
{
- FileContext *c = h->priv_data;
int fd;
char *final;
av_strstart(filename, "pipe:", &filename);
@@ -390,6 +389,14 @@ static int pipe_open(URLContext *h, const char *filename, int flags)
fd = 0;
}
}
+
+ return fd;
+}
+
+static int pipe_open(URLContext *h, const char *filename, int flags)
+{
+ FileContext *c = h->priv_data;
+ int fd = pipe_get_fd(filename, flags);
#if HAVE_SETMODE
setmode(fd, O_BINARY);
#endif
@@ -398,13 +405,40 @@ static int pipe_open(URLContext *h, const char *filename, int flags)
return 0;
}
+static int pipe_check(URLContext *h, int mask)
+{
+ int fd = pipe_get_fd(h->filename, mask);
+ int status_flags = fcntl(fd, F_GETFL);
+ int access;
+
+ if (status_flags == -1)
+ return AVERROR(errno);
+
+ switch (status_flags & O_ACCMODE) {
+ case O_RDONLY:
+ access = AVIO_FLAG_READ;
+ break;
+ case O_WRONLY:
+ access = AVIO_FLAG_WRITE;
+ break;
+ case O_RDWR:
+ access = AVIO_FLAG_READ | AVIO_FLAG_WRITE;
+ break;
+ default:
+ access = 0;
+ break;
+ }
+
+ return access & mask;
+}
+
const URLProtocol ff_pipe_protocol = {
.name = "pipe",
.url_open = pipe_open,
.url_read = file_read,
.url_write = file_write,
.url_get_file_handle = file_get_handle,
- .url_check = file_check,
+ .url_check = pipe_check,
.priv_data_size = sizeof(FileContext),
.priv_data_class = &pipe_class,
.default_whitelist = "crypto,data"
--
2.37.2
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