Linux video capture, invoking mmap() with both READ and WRITE.

media/video/capture/linux/video_capture_device_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/video/capture/linux/video_capture_device_linux.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #if defined(OS_OPENBSD)
 #include <sys/videoio.h>
@@ skipping 450 matching lines @@
     v4l2_buffer buffer;
     memset(&buffer, 0, sizeof(buffer));
     buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
     buffer.memory = V4L2_MEMORY_MMAP;
     buffer.index = i;
 
     if (ioctl(device_fd_, VIDIOC_QUERYBUF, &buffer) < 0) {
       return false;
     }
 
-    buffer_pool_[i].start = mmap(NULL, buffer.length, PROT_READ,
+    // Some devices require mmap() to be called with both READ and WRITE.
+    // See crbug.com/178582.
+    buffer_pool_[i].start = mmap(NULL, buffer.length, PROT_READ | PROT_WRITE,
                                  MAP_SHARED, device_fd_, buffer.m.offset);
     if (buffer_pool_[i].start == MAP_FAILED) {
       return false;
     }
     buffer_pool_[i].length = buffer.length;
     // Enqueue the buffer in the drivers incoming queue.
     if (ioctl(device_fd_, VIDIOC_QBUF, &buffer) < 0) {
       return false;
     }
   }
@@ skipping 23 matching lines @@
   buffer_pool_size_ = 0;
 }
 
 void VideoCaptureDeviceLinux::SetErrorState(const std::string& reason) {
   DVLOG(1) << reason;
   state_ = kError;
   observer_->OnError();
 }
 
 }  // namespace media