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Fix potential crashes in the screen capturer on Mac

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ScreenCapturerMac wasn't handling the following two cases properly
which could cause crashes:
 1. CGDisplayCreateImage() returns image with depth other than 32-bit
 2. CGDisplayCreateImage() returns image with dimensions different
    from expected (e.g. when screen resolution is being changed).

I suspect that (2) was causing the linked bug.

BUG=crbug.com/504927
R=jiayl@webrtc.org

Review URL: https://codereview.webrtc.org/1816723002 .

Cr-Commit-Position: refs/heads/master@{#12077}
This commit is contained in:
Sergey Ulanov 2016-03-21 11:18:42 -07:00
parent 121ac122b9
commit 0c4de568a6
1 changed files with 50 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

93
webrtc/modules/desktop_capture/screen_capturer_mac.mm
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@ -168,8 +168,7 @@ DesktopRect GetExcludedWindowPixelBounds(CGWindowID window,
// pixels. The caller should release the returned CGImageRef and CFDataRef.
CGImageRef CreateExcludedWindowRegionImage(const DesktopRect& pixel_bounds,
float dip_to_pixel_scale,
CFArrayRef window_list,
CFDataRef* data_ref) {
CFArrayRef window_list) {
CGRect window_bounds;
// The origin is in DIP while the size is in physical pixels. That's what
// CGWindowListCreateImageFromArray expects.
@ -178,13 +177,8 @@ CGImageRef CreateExcludedWindowRegionImage(const DesktopRect& pixel_bounds,
window_bounds.size.width = pixel_bounds.width();
window_bounds.size.height = pixel_bounds.height();
CGImageRef excluded_image = CGWindowListCreateImageFromArray(
return CGWindowListCreateImageFromArray(
window_bounds, window_list, kCGWindowImageDefault);
CGDataProviderRef provider = CGImageGetDataProvider(excluded_image);
*data_ref = CGDataProviderCopyData(provider);
assert(*data_ref);
return excluded_image;
}
// A class to perform video frame capturing for mac.
@ -694,7 +688,6 @@ bool ScreenCapturerMac::CgBlitPostLion(const DesktopFrame& frame,
DesktopRect excluded_window_bounds;
CGImageRef excluded_image = NULL;
CFDataRef excluded_window_region_data = NULL;
if (excluded_window_ && window_list) {
// Get the region of the excluded window relative the primary display.
excluded_window_bounds = GetExcludedWindowPixelBounds(
@ -705,17 +698,30 @@ bool ScreenCapturerMac::CgBlitPostLion(const DesktopFrame& frame,
// than captuing the whole display.
if (!excluded_window_bounds.is_empty()) {
excluded_image = CreateExcludedWindowRegionImage(
excluded_window_bounds,
display_config.dip_to_pixel_scale,
window_list,
&excluded_window_region_data);
excluded_window_bounds, display_config.dip_to_pixel_scale,
window_list);
}
}
// Create an image containing a snapshot of the display.
CGImageRef image = CGDisplayCreateImage(display_config.id);
if (image == NULL)
if (image == NULL) {
if (excluded_image)
CFRelease(excluded_image);
continue;
}
// Verify that the image has 32-bit depth.
int bits_per_pixel = CGImageGetBitsPerPixel(image);
if (bits_per_pixel / 8 != DesktopFrame::kBytesPerPixel) {
LOG(LS_ERROR) << "CGDisplayCreateImage() returned imaged with "
<< bits_per_pixel
<< " bits per pixel. Only 32-bit depth is supported.";
CFRelease(image);
if (excluded_image)
CFRelease(excluded_image);
return false;
}
// Request access to the raw pixel data via the image's DataProvider.
CGDataProviderRef provider = CGImageGetDataProvider(image);
@ -724,50 +730,51 @@ bool ScreenCapturerMac::CgBlitPostLion(const DesktopFrame& frame,
const uint8_t* display_base_address = CFDataGetBytePtr(data);
int src_bytes_per_row = CGImageGetBytesPerRow(image);
int src_bytes_per_pixel = CGImageGetBitsPerPixel(image) / 8;
// Calculate where in the output buffer the display's origin is.
uint8_t* out_ptr = frame.data() +
(display_bounds.left() * src_bytes_per_pixel) +
(display_bounds.top() * frame.stride());
// |image| size may be different from display_bounds in case the screen was
// resized recently.
copy_region.IntersectWith(
DesktopRect::MakeWH(CGImageGetWidth(image), CGImageGetHeight(image)));
// Copy the dirty region from the display buffer into our desktop buffer.
uint8_t* out_ptr = frame.GetFrameDataAtPos(display_bounds.top_left());
for (DesktopRegion::Iterator i(copy_region); !i.IsAtEnd(); i.Advance()) {
CopyRect(display_base_address,
src_bytes_per_row,
out_ptr,
frame.stride(),
src_bytes_per_pixel,
i.rect());
CopyRect(display_base_address, src_bytes_per_row, out_ptr, frame.stride(),
DesktopFrame::kBytesPerPixel, i.rect());
}
// Copy the region of the excluded window to the frame.
CFRelease(data);
CFRelease(image);
if (excluded_image) {
assert(excluded_window_region_data);
display_base_address = CFDataGetBytePtr(excluded_window_region_data);
CGDataProviderRef provider = CGImageGetDataProvider(excluded_image);
CFDataRef excluded_image_data = CGDataProviderCopyData(provider);
assert(excluded_image_data);
display_base_address = CFDataGetBytePtr(excluded_image_data);
src_bytes_per_row = CGImageGetBytesPerRow(excluded_image);
// Translate the bounds relative to the desktop, because |frame| data
// starts from the desktop top-left corner.
DesktopRect window_bounds_relative_to_desktop(excluded_window_bounds);
window_bounds_relative_to_desktop.Translate(
-screen_pixel_bounds_.left(), -screen_pixel_bounds_.top());
out_ptr = frame.data() +
(window_bounds_relative_to_desktop.left() * src_bytes_per_pixel) +
(window_bounds_relative_to_desktop.top() * frame.stride());
window_bounds_relative_to_desktop.Translate(-screen_pixel_bounds_.left(),
-screen_pixel_bounds_.top());
CopyRect(display_base_address,
src_bytes_per_row,
out_ptr,
frame.stride(),
src_bytes_per_pixel,
DesktopRect::MakeSize(excluded_window_bounds.size()));
CFRelease(excluded_window_region_data);
DesktopRect rect_to_copy =
DesktopRect::MakeSize(excluded_window_bounds.size());
rect_to_copy.IntersectWith(DesktopRect::MakeWH(
CGImageGetWidth(excluded_image), CGImageGetHeight(excluded_image)));
if (CGImageGetBitsPerPixel(excluded_image) / 8 ==
DesktopFrame::kBytesPerPixel) {
CopyRect(display_base_address, src_bytes_per_row,
frame.GetFrameDataAtPos(
window_bounds_relative_to_desktop.top_left()),
frame.stride(), DesktopFrame::kBytesPerPixel, rect_to_copy);
}
CFRelease(excluded_image_data);
CFRelease(excluded_image);
}
CFRelease(data);
CFRelease(image);
}
if (window_list)
CFRelease(window_list);