From 1e6063f6fc9fa02bd2f12ad9e60cbc2529fc0377 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Sat, 1 Jul 2017 19:08:46 -0700
Subject: [PATCH] QWaylandShmBuffer: use a memfd if we can for a simple memory
buffer
which has a file descriptor we can also use to share with
Change-Id: I8d96dea9955d4c749b99fffd14cd61628c616b30
Reviewed-by: Johan Helsing <johan.helsing@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
src/client/qwaylandshmbackingstore.cpp | 35 ++++++++++++++++++++------
1 file changed, 28 insertions(+), 7 deletions(-)
diff --git a/src/client/qwaylandshmbackingstore.cpp b/src/client/qwaylandshmbackingstore.cpp
index 4c7c53b2..2085bc59 100644
--- a/src/client/qwaylandshmbackingstore.cpp
+++ b/src/client/qwaylandshmbackingstore.cpp
@@ -55,6 +55,13 @@
#include <unistd.h>
#include <sys/mman.h>
+
+#ifdef Q_OS_LINUX
+# include <sys/syscall.h>
+// from linux/memfd.h:
+# define MFD_CLOEXEC 0x0001U
+#endif
+
QT_BEGIN_NAMESPACE
namespace QtWaylandClient {
@@ -71,15 +78,29 @@ QWaylandShmBuffer::QWaylandShmBuffer(QWaylandDisplay *display,
{
int stride = size.width() * 4;
int alloc = stride * size.height();
- int fd;
-
- QTemporaryFile tmp(QStandardPaths::writableLocation(QStandardPaths::RuntimeLocation) +
- QLatin1String("/wayland-shm-XXXXXX"));
- if (!tmp.open() || !tmp.resize(alloc)) {
- qWarning("QWaylandShmBuffer: failed: %s", qUtf8Printable(tmp.errorString()));
+ int fd = -1;
+
+#ifdef SYS_memfd_create
+ fd = syscall(SYS_memfd_create, "wayland-shm", MFD_CLOEXEC);
+#endif
+
+ QScopedPointer<QFile> filePointer;
+
+ if (fd == -1) {
+ auto tmpFile = new QTemporaryFile (QStandardPaths::writableLocation(QStandardPaths::RuntimeLocation) +
+ QLatin1String("/wayland-shm-XXXXXX"));
+ tmpFile->open();
+ filePointer.reset(tmpFile);
+ } else {
+ auto file = new QFile;
+ file->open(fd, QIODevice::ReadWrite | QIODevice::Unbuffered, QFile::AutoCloseHandle);
+ filePointer.reset(file);
+ }
+ if (!filePointer->isOpen() || !filePointer->resize(alloc)) {
+ qWarning("QWaylandShmBuffer: failed: %s", qUtf8Printable(filePointer->errorString()));
return;
}
- fd = tmp.handle();
+ fd = filePointer->handle();
// map ourselves: QFile::map() will unmap when the object is destroyed,
// but we want this mapping to persist (unmapping in destructor)
--
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