On Sun, 26 Jan 2020 at 21:22, Marton Balint <c...@passwd.hu> wrote:
>
> recvfrom() is not a cancellation point in pthreads-win32, see
> https://sourceware.org/pthreads-win32/manual/pthread_cancel.html
>
> In order to be able to cancel the reader thread on Win32 properly we first
> shutdown the socket then call CancelIoEx to abort pending IO. Subsequent
> recvfrom() calls will fail with WSAESHUTDOWN causing the thread to exit.
>
> Fixes ticket #5717.
>
> Signed-off-by: Marton Balint <c...@passwd.hu>
> ---
> libavformat/udp.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/udp.c b/libavformat/udp.c
> index 85c9e3a900..23c3773c64 100644
> --- a/libavformat/udp.c
> +++ b/libavformat/udp.c
> @@ -1069,8 +1069,17 @@ static int udp_close(URLContext *h)
> if (s->thread_started) {
> int ret;
> // Cancel only read, as write has been signaled as success to the
> user
> - if (h->flags & AVIO_FLAG_READ)
> + if (h->flags & AVIO_FLAG_READ) {
> +#ifdef _WIN32
> + /* recvfrom() is not a cancellation point for win32, so we
> shutdown
> + * the socket and abort pending IO, subsequent recvfrom() calls
> + * will fail with WSAESHUTDOWN causing the thread to exit. */
> + shutdown(s->udp_fd, SD_RECEIVE);
> + CancelIoEx((HANDLE)(SOCKET)s->udp_fd, NULL);
> +#else
> pthread_cancel(s->circular_buffer_thread);
> +#endif
> + }
> ret = pthread_join(s->circular_buffer_thread, NULL);
> if (ret != 0)
> av_log(h, AV_LOG_ERROR, "pthread_join(): %s\n", strerror(ret));
> --
> 2.16.4
This was applied as 53aa76686e7ff4f1f6625502503d7923cec8c10e, but that
commit fails to compile in my mingw cross-compile build.
x86_64-w64-mingw32-gcc -I. -I./ --static -DPTW32_STATIC_LIB
-D_WIN32_WINNT=0x0501 -I/opt/ffbuild/include -D_ISOC99_SOURCE
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -U__STRICT_ANSI__
-D__USE_MINGW_ANSI_STDIO=1 -D__printf__=__gnu_printf__
-D_WIN32_WINNT=0x0600 -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
-DPIC -DOPJ_STATIC -DZLIB_CONST -DHAVE_AV_CONFIG_H -DBUILDING_avformat
--static -DPTW32_STATIC_LIB -D_WIN32_WINNT=0x0501
-I/opt/ffbuild/include --static -DPTW32_STATIC_LIB
-D_WIN32_WINNT=0x0501 -std=c11 -fomit-frame-pointer -pthread
-I/opt/ffbuild/include -I/opt/ffbuild/include -I/opt/ffbuild/include
-I/opt/ffbuild/include/openjpeg-2.3 -I/opt/ffbuild/include/opus
-I/opt/ffbuild/include/opus -I/opt/ffbuild/include
-I/opt/ffbuild/include -I/opt/ffbuild/include -I/opt/ffbuild/include
-I/opt/ffbuild/include -I/opt/ffbuild/include -I/opt/ffbuild/include
-I/opt/ffbuild/include -I/opt/ffbuild/include -DLIBXML_STATIC
-I/opt/ffbuild/include/libxml2 -I/opt/ffbuild/include -g
-Wdeclaration-after-statement -Wall -Wdisabled-optimization
-Wpointer-arith -Wredundant-decls -Wwrite-strings -Wtype-limits
-Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast
-Wstrict-prototypes -Wempty-body -Wno-parentheses -Wno-switch
-Wno-format-zero-length -Wno-pointer-sign -Wno-char-subscripts -O3
-fno-math-errno -fno-signed-zeros -fno-tree-vectorize
-Werror=format-security -Werror=implicit-function-declaration
-Werror=missing-prototypes -Werror=return-type -Werror=vla -Wformat
-fdiagnostics-color=auto -Wno-maybe-uninitialized -MMD -MF
libavformat/udp.d -MT libavformat/udp.o -c -o libavformat/udp.o
libavformat/udp.c
In file included from libavformat/udp.c:65:0:
/opt/ffbuild/include/pthread.h:108:0: warning: "PTW32_LEVEL" redefined
#define PTW32_LEVEL PTW32_LEVEL_MAX
^
/opt/ffbuild/include/pthread.h:95:0: note: this is the location of the
previous definition
#define PTW32_LEVEL 1
^
In file included from /opt/ffbuild/include/pthread.h:299:0,
from libavformat/udp.c:65:
/opt/ffbuild/include/sched.h:64:0: warning: "PTW32_SCHED_LEVEL" redefined
#define PTW32_SCHED_LEVEL PTW32_SCHED_LEVEL_MAX
^
/opt/ffbuild/include/sched.h:51:0: note: this is the location of the
previous definition
#define PTW32_SCHED_LEVEL 1
^
libavformat/udp.c: In function 'udp_close':
libavformat/udp.c:1078:13: error: implicit declaration of function
'CancelIoEx' [-Werror=implicit-function-declaration]
CancelIoEx((HANDLE)(SOCKET)s->udp_fd, NULL);
^
cc1: some warnings being treated as errors
ffbuild/common.mak:59: recipe for target 'libavformat/udp.o' failed
make: *** [libavformat/udp.o] Error 1
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Mark Himsley
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