From 6e1bfb96fb0340c812e2ad582e94de169d6cb6aa Mon Sep 17 00:00:00 2001
|
From: Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
|
Date: Tue, 15 Sep 2020 17:51:51 +0200
|
Subject: [PATCH 01/40] waylandsink: Use memfd_create() when available
|
MIME-Version: 1.0
|
Content-Type: text/plain; charset=UTF-8
|
Content-Transfer-Encoding: 8bit
|
|
This (so-far) Linux- and FreeBSD-only API lets users create file
|
descriptors purely in memory, without any backing file on the filesystem
|
and the race condition which could ensue when unlink()ing it.
|
|
It also allows seals to be placed on the file, ensuring to every other
|
process that we won’t be allowed to shrink the contents, potentially
|
causing a SIGBUS when they try reading it.
|
|
This patch is best viewed with the -w option of git log -p.
|
|
It is an almost exact copy of Wayland commit
|
6908c8c85a2e33e5654f64a55cd4f847bf385cae, see
|
https://gitlab.freedesktop.org/wayland/wayland/merge_requests/4
|
|
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1577>
|
(cherry picked from commit f97b718b4c7200b815026c03efc1074fd69912d4)
|
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
|
---
|
ext/wayland/wlshmallocator.c | 37 +++++++++++++++++++++++++-----------
|
meson.build | 1 +
|
2 files changed, 27 insertions(+), 11 deletions(-)
|
|
diff --git a/ext/wayland/wlshmallocator.c b/ext/wayland/wlshmallocator.c
|
index 8207113..0a82a35 100644
|
--- a/ext/wayland/wlshmallocator.c
|
+++ b/ext/wayland/wlshmallocator.c
|
@@ -49,16 +49,33 @@ gst_wl_shm_allocator_alloc (GstAllocator * allocator, gsize size,
|
|
/* TODO: make use of the allocation params, if necessary */
|
|
- /* allocate shm pool */
|
- snprintf (filename, 1024, "%s/%s-%d-%s", g_get_user_runtime_dir (),
|
- "wayland-shm", init++, "XXXXXX");
|
-
|
- fd = g_mkstemp (filename);
|
- if (fd < 0) {
|
- GST_ERROR_OBJECT (self, "opening temp file %s failed: %s", filename,
|
- strerror (errno));
|
- return NULL;
|
+#ifdef HAVE_MEMFD_CREATE
|
+ fd = memfd_create ("gst-wayland-shm", MFD_CLOEXEC | MFD_ALLOW_SEALING);
|
+ if (fd >= 0) {
|
+ /* We can add this seal before calling posix_fallocate(), as
|
+ * the file is currently zero-sized anyway.
|
+ *
|
+ * There is also no need to check for the return value, we
|
+ * couldn't do anything with it anyway.
|
+ */
|
+ fcntl (fd, F_ADD_SEALS, F_SEAL_SHRINK);
|
+ } else
|
+#endif
|
+ {
|
+ /* allocate shm pool */
|
+ snprintf (filename, 1024, "%s/%s-%d-%s", g_get_user_runtime_dir (),
|
+ "wayland-shm", init++, "XXXXXX");
|
+
|
+ fd = g_mkstemp (filename);
|
+ if (fd < 0) {
|
+ GST_ERROR_OBJECT (self, "opening temp file %s failed: %s", filename,
|
+ strerror (errno));
|
+ return NULL;
|
+ }
|
+
|
+ unlink (filename);
|
}
|
+
|
if (ftruncate (fd, size) < 0) {
|
GST_ERROR_OBJECT (self, "ftruncate failed: %s", strerror (errno));
|
close (fd);
|
@@ -84,8 +101,6 @@ gst_wl_shm_allocator_alloc (GstAllocator * allocator, gsize size,
|
* need it to release the miniobject lock */
|
gst_memory_unmap (mem, &info);
|
|
- unlink (filename);
|
-
|
return mem;
|
}
|
|
diff --git a/meson.build b/meson.build
|
index a124867..849aca7 100644
|
--- a/meson.build
|
+++ b/meson.build
|
@@ -158,6 +158,7 @@ check_functions = [
|
['HAVE_DCGETTEXT', 'dcgettext'],
|
['HAVE_GETPAGESIZE', 'getpagesize'],
|
['HAVE_GMTIME_R', 'gmtime_r'],
|
+ ['HAVE_MEMFD_CREATE', 'memfd_create'],
|
['HAVE_MMAP', 'mmap'],
|
['HAVE_PIPE2', 'pipe2'],
|
['HAVE_GETRUSAGE', 'getrusage', '#include<sys/resource.h>'],
|
--
|
2.17.1
|
