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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "nsShmImage.h"
#ifdef MOZ_HAVE_SHMIMAGE
# include "mozilla/X11Util.h"
# include "mozilla/gfx/gfxVars.h"
# include "mozilla/ipc/SharedMemory.h"
# include "gfxPlatform.h"
# include "nsPrintfCString.h"
# include "nsTArray.h"
# include <dlfcn.h>
# include <errno.h>
# include <string.h>
# include <sys/ipc.h>
# include <sys/shm.h>
extern "C" {
# include <X11/ImUtil.h>
}
using namespace mozilla::ipc;
using namespace mozilla::gfx;
nsShmImage::nsShmImage(Display* aDisplay, Drawable aWindow, Visual* aVisual,
unsigned int aDepth)
: mDisplay(aDisplay),
mConnection(XGetXCBConnection(aDisplay)),
mWindow(aWindow),
mVisual(aVisual),
mDepth(aDepth),
mFormat(mozilla::gfx::SurfaceFormat::UNKNOWN),
mSize(0, 0),
mStride(0),
mPixmap(XCB_NONE),
mGC(XCB_NONE),
mRequestPending(false),
mShmSeg(XCB_NONE),
mShmId(-1),
mShmAddr(nullptr) {
mozilla::PodZero(&mSyncRequest);
}
nsShmImage::~nsShmImage() { DestroyImage(); }
// If XShm isn't available to our client, we'll try XShm once, fail,
// set this to false and then never try again.
static bool gShmAvailable = true;
bool nsShmImage::UseShm() { return gShmAvailable; }
bool nsShmImage::CreateShmSegment() {
size_t size = SharedMemory::PageAlignedSize(mStride * mSize.height);
# if defined(__OpenBSD__) && defined(MOZ_SANDBOX)
static mozilla::LazyLogModule sPledgeLog("SandboxPledge");
MOZ_LOG(sPledgeLog, mozilla::LogLevel::Debug,
("%s called when pledged, returning false\n", __func__));
return false;
# endif
mShmId = shmget(IPC_PRIVATE, size, IPC_CREAT | 0600);
if (mShmId == -1) {
return false;
}
mShmAddr = (uint8_t*)shmat(mShmId, nullptr, 0);
mShmSeg = xcb_generate_id(mConnection);
// Mark the handle removed so that it will destroy the segment when unmapped.
shmctl(mShmId, IPC_RMID, nullptr);
if (mShmAddr == (void*)-1) {
// Since mapping failed, the segment is already destroyed.
mShmId = -1;
nsPrintfCString warning("shmat(): %s (%d)\n", strerror(errno), errno);
NS_WARNING(warning.get());
return false;
}
# ifdef DEBUG
struct shmid_ds info;
if (shmctl(mShmId, IPC_STAT, &info) < 0) {
return false;
}
MOZ_ASSERT(size <= info.shm_segsz, "Segment doesn't have enough space!");
# endif
return true;
}
void nsShmImage::DestroyShmSegment() {
if (mShmId != -1) {
shmdt(mShmAddr);
mShmId = -1;
}
}
static bool gShmInitialized = false;
static bool gUseShmPixmaps = false;
bool nsShmImage::InitExtension() {
if (gShmInitialized) {
return gShmAvailable;
}
gShmInitialized = true;
// Bugs 1397918, 1293474 - race condition in libxcb fixed upstream as of
// version 1.11. Since we can't query libxcb's version directly, the only
// other option is to check for symbols that were added after 1.11.
// xcb_discard_reply64 was added in 1.11.1, so check for existence of
// that to verify we are using a version of libxcb with the bug fixed.
// Otherwise, we can't risk using libxcb due to aforementioned crashes.
if (!dlsym(RTLD_DEFAULT, "xcb_discard_reply64")) {
gShmAvailable = false;
return false;
}
const xcb_query_extension_reply_t* extReply;
extReply = xcb_get_extension_data(mConnection, &xcb_shm_id);
if (!extReply || !extReply->present) {
gShmAvailable = false;
return false;
}
xcb_shm_query_version_reply_t* shmReply = xcb_shm_query_version_reply(
mConnection, xcb_shm_query_version(mConnection), nullptr);
if (!shmReply) {
gShmAvailable = false;
return false;
}
gUseShmPixmaps = shmReply->shared_pixmaps &&
shmReply->pixmap_format == XCB_IMAGE_FORMAT_Z_PIXMAP;
free(shmReply);
return true;
}
bool nsShmImage::CreateImage(const IntSize& aSize) {
MOZ_ASSERT(mConnection && mVisual);
if (!InitExtension()) {
return false;
}
mSize = aSize;
BackendType backend = gfxVars::ContentBackend();
mFormat = SurfaceFormat::UNKNOWN;
switch (mDepth) {
case 32:
if (mVisual->red_mask == 0xff0000 && mVisual->green_mask == 0xff00 &&
mVisual->blue_mask == 0xff) {
mFormat = SurfaceFormat::B8G8R8A8;
}
break;
case 24:
// Only support the BGRX layout, and report it as BGRA to the compositor.
// The alpha channel will be discarded when we put the image.
// Cairo/pixman lacks some fast paths for compositing BGRX onto BGRA, so
// just report it as BGRX directly in that case.
if (mVisual->red_mask == 0xff0000 && mVisual->green_mask == 0xff00 &&
mVisual->blue_mask == 0xff) {
mFormat = backend == BackendType::CAIRO ? SurfaceFormat::B8G8R8X8
: SurfaceFormat::B8G8R8A8;
}
break;
case 16:
if (mVisual->red_mask == 0xf800 && mVisual->green_mask == 0x07e0 &&
mVisual->blue_mask == 0x1f) {
mFormat = SurfaceFormat::R5G6B5_UINT16;
}
break;
}
if (mFormat == SurfaceFormat::UNKNOWN) {
NS_WARNING("Unsupported XShm Image format!");
gShmAvailable = false;
return false;
}
// Round up stride to the display's scanline pad (in bits) as XShm expects.
int scanlinePad = _XGetScanlinePad(mDisplay, mDepth);
int bitsPerPixel = _XGetBitsPerPixel(mDisplay, mDepth);
int bitsPerLine =
((bitsPerPixel * aSize.width + scanlinePad - 1) / scanlinePad) *
scanlinePad;
mStride = bitsPerLine / 8;
if (!CreateShmSegment()) {
DestroyImage();
return false;
}
xcb_generic_error_t* error;
xcb_void_cookie_t cookie;
cookie = xcb_shm_attach_checked(mConnection, mShmSeg, mShmId, 0);
if ((error = xcb_request_check(mConnection, cookie))) {
NS_WARNING("Failed to attach MIT-SHM segment.");
DestroyImage();
gShmAvailable = false;
free(error);
return false;
}
if (gUseShmPixmaps) {
mPixmap = xcb_generate_id(mConnection);
cookie = xcb_shm_create_pixmap_checked(mConnection, mPixmap, mWindow,
aSize.width, aSize.height, mDepth,
mShmSeg, 0);
if ((error = xcb_request_check(mConnection, cookie))) {
// Disable shared pixmaps permanently if creation failed.
mPixmap = XCB_NONE;
gUseShmPixmaps = false;
free(error);
}
}
return true;
}
void nsShmImage::DestroyImage() {
if (mGC) {
xcb_free_gc(mConnection, mGC);
mGC = XCB_NONE;
}
if (mPixmap != XCB_NONE) {
xcb_free_pixmap(mConnection, mPixmap);
mPixmap = XCB_NONE;
}
if (mShmSeg != XCB_NONE) {
xcb_shm_detach_checked(mConnection, mShmSeg);
mShmSeg = XCB_NONE;
}
DestroyShmSegment();
// Avoid leaking any pending reply. No real need to wait but CentOS 6 build
// machines don't have xcb_discard_reply().
WaitIfPendingReply();
}
// Wait for any in-flight shm-affected requests to complete.
// Typically X clients would wait for a XShmCompletionEvent to be received,
// but this works as it's sent immediately after the request is sent.
void nsShmImage::WaitIfPendingReply() {
if (mRequestPending) {
xcb_get_input_focus_reply_t* reply =
xcb_get_input_focus_reply(mConnection, mSyncRequest, nullptr);
free(reply);
mRequestPending = false;
}
}
already_AddRefed<DrawTarget> nsShmImage::CreateDrawTarget(
const mozilla::LayoutDeviceIntRegion& aRegion) {
WaitIfPendingReply();
// query window size. Instead we just track the largest offset within the
// image we are drawing to and grow the image to accomodate it. Since usually
// the entire window is invalidated on the first paint to it, this should grow
// the image to the necessary size quickly without many intermediate
// reallocations.
IntRect bounds = aRegion.GetBounds().ToUnknownRect();
IntSize size(bounds.XMost(), bounds.YMost());
if (size.width > mSize.width || size.height > mSize.height) {
DestroyImage();
if (!CreateImage(size)) {
return nullptr;
}
}
return gfxPlatform::CreateDrawTargetForData(
reinterpret_cast<unsigned char*>(mShmAddr) + bounds.y * mStride +
bounds.x * BytesPerPixel(mFormat),
bounds.Size(), mStride, mFormat);
}
void nsShmImage::Put(const mozilla::LayoutDeviceIntRegion& aRegion) {
AutoTArray<xcb_rectangle_t, 32> xrects;
xrects.SetCapacity(aRegion.GetNumRects());
for (auto iter = aRegion.RectIter(); !iter.Done(); iter.Next()) {
const mozilla::LayoutDeviceIntRect& r = iter.Get();
xcb_rectangle_t xrect = {(short)r.x, (short)r.y, (unsigned short)r.width,
(unsigned short)r.height};
xrects.AppendElement(xrect);
}
if (!mGC) {
mGC = xcb_generate_id(mConnection);
xcb_create_gc(mConnection, mGC, mWindow, 0, nullptr);
}
xcb_set_clip_rectangles(mConnection, XCB_CLIP_ORDERING_YX_BANDED, mGC, 0, 0,
xrects.Length(), xrects.Elements());
if (mPixmap != XCB_NONE) {
xcb_copy_area(mConnection, mPixmap, mWindow, mGC, 0, 0, 0, 0, mSize.width,
mSize.height);
} else {
xcb_shm_put_image(mConnection, mWindow, mGC, mSize.width, mSize.height, 0,
0, mSize.width, mSize.height, 0, 0, mDepth,
XCB_IMAGE_FORMAT_Z_PIXMAP, 0, mShmSeg, 0);
}
// Send a request that returns a response so that we don't have to start a
// sync in nsShmImage::CreateDrawTarget.
mSyncRequest = xcb_get_input_focus(mConnection);
mRequestPending = true;
xcb_flush(mConnection);
}
#endif // MOZ_HAVE_SHMIMAGE