1 files changed, 338 insertions, 0 deletions
diff --git a/widget/nsShmImage.cpp b/widget/nsShmImage.cpp
new file mode 100644
index 000000000..25d0a8c4b
--- /dev/null
+++ b/widget/nsShmImage.cpp
@@ -0,0 +1,338 @@
+/* -*- 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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#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 <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);
+
+  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;
+
+  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();
+
+  // Due to bug 1205045, we must avoid making GTK calls off the main thread to 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