[PR] avformat/file: add Windows handle protocol (PR #23678)

PR #23678 opened by felipdsa21
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23678
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23678.patch

On Windows, CRT file descriptors cannot be reliably passed to child processes, so HANDLEs need to be used instead. This adds a handle protocol so ffmpeg.exe can accept a HANDLE directly as input or output.

The new protocol duplicates the given handle, or falls back to the standard input or output handle, then converts it to a CRT fd, and reuses the existing fd/file protocol code for I/O.

Used the fd protocol's own addition as reference: https://code.ffmpeg.org/FFmpeg/FFmpeg/compare/e9fe1634d4...195ccf7ea8

Also includes a small fix removing pipe and fd's `url_check` hook, since it treated the URL as a filesystem path, which is incorrect for these protocols and gave bogus results.


From cc82b086e500947e69e184742136c7adc06300f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felipe=20Ara=C3=BAjo?= <[email protected]>
Date: Thu, 2 Jul 2026 02:05:58 -0300
Subject: [PATCH 1/3] avformat/file: remove broken url_check on pipe and fd
 protocols
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

file_check treats the URL as a file path, which is incorrect for the pipe and fd protocols.

Signed-off-by: Felipe Araújo <[email protected]>
---
 libavformat/file.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/libavformat/file.c b/libavformat/file.c
index 71d30a25c4..e58f00a9e5 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -481,7 +481,6 @@ const URLProtocol ff_pipe_protocol = {
     .url_write           = file_write,
     .url_close           = file_close,
     .url_get_file_handle = file_get_handle,
-    .url_check           = file_check,
     .priv_data_size      = sizeof(FileContext),
     .priv_data_class     = &pipe_class,
     .default_whitelist   = "crypto,data"
@@ -527,7 +526,6 @@ const URLProtocol ff_fd_protocol = {
     .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"
@@ -687,7 +685,6 @@ const URLProtocol ff_android_content_protocol = {
     .url_seek            = file_seek,
     .url_close           = file_close,
     .url_get_file_handle = file_get_handle,
-    .url_check           = NULL,
     .priv_data_size      = sizeof(FileContext),
     .priv_data_class     = &android_content_class,
 };
-- 
2.52.0


From 4700990c9bf56c299b3ae1f444e7afa627c1689b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felipe=20Ara=C3=BAjo?= <[email protected]>
Date: Thu, 2 Jul 2026 02:05:58 -0300
Subject: [PATCH 2/3] avformat/file: add Windows handle protocol
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Like the fd protocol, but takes a raw Windows HANDLE instead of a CRT file descriptor.

Signed-off-by: Felipe Araújo <[email protected]>
---
 configure               |  1 +
 doc/protocols.texi      | 26 ++++++++++++++
 libavformat/Makefile    |  1 +
 libavformat/file.c      | 79 +++++++++++++++++++++++++++++++++++++++++
 libavformat/protocols.c |  1 +
 libavformat/version.h   |  2 +-
 6 files changed, 109 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 4573d69f28..3fa3011798 100755
--- a/configure
+++ b/configure
@@ -4124,6 +4124,7 @@ unix_protocol_deps="sys_un_h"
 unix_protocol_select="network"
 ipfs_gateway_protocol_select="https_protocol"
 ipns_gateway_protocol_select="https_protocol"
+windows_handle_protocol_deps="windows_h"
 
 # external library protocols
 libamqp_protocol_deps="librabbitmq"
diff --git a/doc/protocols.texi b/doc/protocols.texi
index 5f8cc8094d..8ab61f4c08 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -419,6 +419,32 @@ Gophers protocol.
 
 The Gopher protocol with TLS encapsulation.
 
+@section handle
+
+Windows handle access protocol.
+
+The accepted syntax is:
+@example
+handle: -handle @var{handle}
+@end example
+
+If @option{handle} is not specified, by default the output handle will be
+used for writing, input handle for reading. This protocol is only available
+on Windows. It has seek support if the handle corresponds to a regular file.
+
+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.
+
+@item handle
+Set Windows handle.
+@end table
+
 @section http
 
 HTTP (Hyper Text Transfer Protocol).
diff --git a/libavformat/Makefile b/libavformat/Makefile
index b244eaabf9..d7d1046382 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -732,6 +732,7 @@ OBJS-$(CONFIG_DTLS_PROTOCOL)             += tls.o $(TLS-OBJS-yes)
 OBJS-$(CONFIG_UDP_PROTOCOL)              += udp.o ip.o
 OBJS-$(CONFIG_UDPLITE_PROTOCOL)          += udp.o ip.o
 OBJS-$(CONFIG_UNIX_PROTOCOL)             += unix.o
+OBJS-$(CONFIG_WINDOWS_HANDLE_PROTOCOL)   += file.o
 
 # external library protocols
 OBJS-$(CONFIG_LIBAMQP_PROTOCOL)          += libamqp.o
diff --git a/libavformat/file.c b/libavformat/file.c
index e58f00a9e5..6c80c4c815 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -103,6 +103,9 @@ typedef struct FileContext {
 #if HAVE_DIRENT_H
     DIR *dir;
 #endif
+#if CONFIG_WINDOWS_HANDLE_PROTOCOL
+    int64_t handle;
+#endif
 } FileContext;
 
 static const AVOption file_options[] = {
@@ -533,6 +536,82 @@ const URLProtocol ff_fd_protocol = {
 
 #endif /* CONFIG_FD_PROTOCOL */
 
+#if CONFIG_WINDOWS_HANDLE_PROTOCOL
+
+#include <windows.h>
+
+static const AVOption windows_handle_options[] = {
+    { "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 },
+    { "handle", "set Windows handle", offsetof(FileContext, handle), AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, AV_OPT_FLAG_ENCODING_PARAM },
+    { NULL }
+};
+
+static const AVClass windows_handle_class = {
+    .class_name = "windows_handle",
+    .item_name  = av_default_item_name,
+    .option     = windows_handle_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static int windows_handle_open(URLContext *h, const char *filename, int flags)
+{
+    FileContext *c = h->priv_data;
+    HANDLE handle = (HANDLE)(intptr_t)c->handle;
+    HANDLE dup_handle;
+    int fd;
+    struct stat st;
+
+    if (strcmp(filename, "handle:") != 0) {
+        av_log(h, AV_LOG_ERROR, "Doesn't support passing Windows handles via URL,"
+                                " please set it via -handle {num}\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (handle == INVALID_HANDLE_VALUE || !handle) {
+        if (flags & AVIO_FLAG_WRITE)
+            handle = GetStdHandle(STD_OUTPUT_HANDLE);
+        else
+            handle = GetStdHandle(STD_INPUT_HANDLE);
+    }
+
+    if (!DuplicateHandle(GetCurrentProcess(), handle,
+                         GetCurrentProcess(), &dup_handle,
+                         0, FALSE, DUPLICATE_SAME_ACCESS))
+        return AVERROR(EIO);
+
+    fd = _open_osfhandle((intptr_t)dup_handle, O_BINARY |
+                         ((flags & AVIO_FLAG_WRITE) ? O_RDWR : O_RDONLY));
+    if (fd == -1) {
+        CloseHandle(dup_handle);
+        return AVERROR(errno);
+    }
+
+    if (fstat(fd, &st) < 0) {
+        close(fd);
+        return AVERROR(errno);
+    }
+
+    c->fd = fd;
+    h->is_streamed = !(S_ISREG(st.st_mode) || S_ISBLK(st.st_mode));
+
+    return 0;
+}
+
+const URLProtocol ff_windows_handle_protocol = {
+    .name                = "handle",
+    .url_open            = windows_handle_open,
+    .url_read            = file_read,
+    .url_write           = file_write,
+    .url_seek            = file_seek,
+    .url_close           = file_close,
+    .url_get_file_handle = file_get_handle,
+    .priv_data_size      = sizeof(FileContext),
+    .priv_data_class     = &windows_handle_class,
+    .default_whitelist   = "crypto,data"
+};
+
+#endif /* CONFIG_WINDOWS_HANDLE_PROTOCOL */
+
 #if CONFIG_ANDROID_CONTENT_PROTOCOL
 #include <jni.h>
 #include "libavcodec/ffjni.h"
diff --git a/libavformat/protocols.c b/libavformat/protocols.c
index 257b41970a..db5bc37aef 100644
--- a/libavformat/protocols.c
+++ b/libavformat/protocols.c
@@ -79,6 +79,7 @@ extern const URLProtocol ff_libsmbclient_protocol;
 extern const URLProtocol ff_libzmq_protocol;
 extern const URLProtocol ff_ipfs_gateway_protocol;
 extern const URLProtocol ff_ipns_gateway_protocol;
+extern const URLProtocol ff_windows_handle_protocol;
 
 #include "libavformat/protocol_list.c"
 
diff --git a/libavformat/version.h b/libavformat/version.h
index 7ff1483912..af7d0a1024 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFORMAT_VERSION_MINOR   3
+#define LIBAVFORMAT_VERSION_MINOR   4
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
-- 
2.52.0


From 725c210f2d7f01d5ae53999ca76f5acf0873b819 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felipe=20Ara=C3=BAjo?= <[email protected]>
Date: Thu, 2 Jul 2026 02:05:59 -0300
Subject: [PATCH 3/3] fftools/ffmpeg_demux: disable stdin interaction for
 Windows handle protocol
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Felipe Araújo <[email protected]>
---
 fftools/ffmpeg_demux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index 38bd580bfc..cc98a0f8e0 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -2078,6 +2078,7 @@ int ifile_open(const OptionsContext *o, const char *filename, Scheduler *sch)
 
     stdin_interaction &= strncmp(filename, "pipe:", 5) &&
                          strcmp(filename, "fd:") &&
+                         strcmp(filename, "handle:") &&
                          strcmp(filename, "/dev/stdin");
 
     /* get default parameters from command line */
-- 
2.52.0

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