Base: Change ReadPlatformFile to perform a best

base/platform_file_unittest.cc

 // Copyright (c) 2011 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 "base/file_util.h"
 #include "base/platform_file.h"
 #include "base/scoped_temp_dir.h"
 #include "base/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 // Reads from a file the given number of bytes, or until EOF is reached.
 // Returns the number of bytes read.
 int ReadFully(base::PlatformFile file, int64 offset, char* data, int size) {
-  int total_bytes_read = 0;
-  int bytes_read;
-  while (total_bytes_read < size) {
-    bytes_read = base::ReadPlatformFile(
-        file, offset + total_bytes_read, &data[total_bytes_read],
-        size - total_bytes_read);
-
-    // If we reached EOF, bytes_read will be 0.
-    if (bytes_read == 0)
-      return total_bytes_read;
-
-    if ((bytes_read < 0) || (bytes_read > size - total_bytes_read))
-      return -1;
-
-    total_bytes_read += bytes_read;
-  }
-
-  return total_bytes_read;
+  return base::ReadPlatformFile(file, offset, data, size);
 }
 
 // Writes the given number of bytes to a file.
 // Returns the number of bytes written.
 int WriteFully(base::PlatformFile file, int64 offset,
                const char* data, int size) {
   return base::WritePlatformFile(file, offset, data, size);
 }
 
 } // namespace
@@ skipping 141 matching lines @@
   // Read 0 bytes.
   bytes_read = ReadFully(file, 0, data_read_1, 0);
   EXPECT_EQ(0, bytes_read);
 
   // Read the entire file.
   bytes_read = ReadFully(file, 0, data_read_1, kTestDataSize);
   EXPECT_EQ(kTestDataSize, bytes_read);
   for (int i = 0; i < bytes_read; i++)
     EXPECT_EQ(data_to_write[i], data_read_1[i]);
 
+  // Read again, but using the trivial native wrapper.
+  bytes_read = base::ReadPlatformFileNoBestEffort(file, 0, data_read_1,
+                                                  kTestDataSize);
+  EXPECT_LE(bytes_read, kTestDataSize);
+  for (int i = 0; i < bytes_read; i++)
+    EXPECT_EQ(data_to_write[i], data_read_1[i]);
+
   // Write past the end of the file.
   const int kOffsetBeyondEndOfFile = 10;
   const int kPartialWriteLength = 2;
   bytes_written = WriteFully(file, kOffsetBeyondEndOfFile,
                              data_to_write, kPartialWriteLength);
   EXPECT_EQ(kPartialWriteLength, bytes_written);
 
   // Make sure the file was extended.
   int64 file_size = 0;
   EXPECT_TRUE(file_util::GetFileSize(file_path, &file_size));
@@ skipping 132 matching lines @@
   EXPECT_EQ(info.last_modified.ToInternalValue(),
             new_last_modified.ToInternalValue());
 #endif
 
   EXPECT_EQ(info.creation_time.ToInternalValue(),
             creation_time.ToInternalValue());
 
   // Close the file handle to allow the temp directory to be deleted.
   base::ClosePlatformFile(file);
 }