Mojo: Implement passing of shared buffers across processes on POSIX.

mojo/system/raw_shared_buffer_posix.cc

 // Copyright 2014 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 "mojo/system/raw_shared_buffer.h"
 
 #include <stdint.h>
 #include <stdio.h>  // For |fileno()|.
 #include <sys/mman.h>  // For |mmap()|/|munmap()|.
+#include <sys/stat.h>
 #include <sys/types.h>  // For |off_t|.
 #include <unistd.h>
 
 #include <limits>
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 55 matching lines @@
 
   if (HANDLE_EINTR(ftruncate(fd.get(), static_cast<off_t>(num_bytes_))) != 0) {
     PLOG(ERROR) << "ftruncate";
     return false;
   }
 
   handle_.reset(embedder::PlatformHandle(fd.release()));
   return true;
 }
 
+bool RawSharedBuffer::InitFromPlatformHandleNoLock(
+    embedder::ScopedPlatformHandle platform_handle) {
+  DCHECK(!handle_.is_valid());
+
+  if (static_cast<uint64_t>(num_bytes_) >
+          static_cast<uint64_t>(std::numeric_limits<off_t>::max())) {
+    return false;
+  }
+
+  struct stat sb = {};
+  // Note: |fstat()| isn't interruptible.
+  if (fstat(platform_handle.get().fd, &sb) != 0) {
+    PLOG(ERROR) << "fstat";

[yzshen1, 2014/05/30 00:09:35]

nit: maybe also output the errno?

[viettrungluu, 2014/05/30 00:23:42]

That's what PLOG does.

[yzshen1, 2014/05/30 00:27:48]

Right. Didn't notice that. Thanks.

+    return false;
+  }
+
+  if (!S_ISREG(sb.st_mode)) {
+    LOG(ERROR) << "Platform handle not to a regular file";
+    return false;
+  }
+
+  if (sb.st_size != static_cast<off_t>(num_bytes_)) {
+    LOG(ERROR) << "Shared memory file has the wrong size";
+    return false;
+  }
+
+  // TODO(vtl): More checks?
+
+  handle_ = platform_handle.Pass();
+  return true;
+}
+
 scoped_ptr<RawSharedBufferMapping> RawSharedBuffer::MapImplNoLock(
     size_t offset,
     size_t length) {
   lock_.AssertAcquired();
 
   size_t offset_rounding = offset % base::SysInfo::VMAllocationGranularity();
   size_t real_offset = offset - offset_rounding;
   size_t real_length = length + offset_rounding;
 
   // This should hold (since we checked |num_bytes| versus the maximum value of
@@ skipping 17 matching lines @@
 
 // RawSharedBufferMapping ------------------------------------------------------
 
 void RawSharedBufferMapping::Unmap() {
   int result = munmap(real_base_, real_length_);
   PLOG_IF(ERROR, result != 0) << "munmap";
 }
 
 }  // namespace system
 }  // namespace mojo