Base: Change ReadPlatformFile to perform a best

base/platform_file_posix.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/platform_file.h"
 
 #include <fcntl.h>
 #include <errno.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ skipping 129 matching lines @@
   }
 
   return descriptor;
 }
 
 bool ClosePlatformFile(PlatformFile file) {
   return !HANDLE_EINTR(close(file));
 }
 
 int ReadPlatformFile(PlatformFile file, int64 offset, char* data, int size) {
+  if (file < 0 || size < 0)
+    return -1;
+
+  int bytes_read = 0;
+  int rv;
+  do {
+    rv = HANDLE_EINTR(pread(file, data + bytes_read,
+                            size - bytes_read, offset + bytes_read));
+    if (rv <= 0)
+      break;
+
+    bytes_read += rv;
+  } while (bytes_read < size);
+
+  return bytes_read ? bytes_read : rv;
+}
+
+int ReadPlatformFileNoBestEffort(PlatformFile file, int64 offset,
+                                 char* data, int size) {
   if (file < 0)
     return -1;
 
   return HANDLE_EINTR(pread(file, data, size, offset));
 }
 
 int WritePlatformFile(PlatformFile file, int64 offset,
                       const char* data, int size) {
   if (file < 0 || size < 0)
     return -1;
@@ skipping 42 matching lines @@
   info->is_directory = S_ISDIR(file_info.st_mode);
   info->is_symbolic_link = S_ISLNK(file_info.st_mode);
   info->size = file_info.st_size;
   info->last_modified = base::Time::FromTimeT(file_info.st_mtime);
   info->last_accessed = base::Time::FromTimeT(file_info.st_atime);
   info->creation_time = base::Time::FromTimeT(file_info.st_ctime);
   return true;
 }
 
 }  // namespace base