Fix error handling in POSIX version of the base::File::GetLength.

net/disk_cache/simple/simple_test_util.cc

 // Copyright 2013 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 "net/disk_cache/simple/simple_test_util.h"
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "net/base/hash_value.h"
 #include "net/disk_cache/simple/simple_entry_format.h"
@@ skipping 21 matching lines @@
 bool RemoveKeySHA256FromEntry(const std::string& key,
                               const FilePath& cache_path) {
   FilePath entry_file_path = cache_path.AppendASCII(
       disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
   int flags = File::FLAG_OPEN | File::FLAG_READ | File::FLAG_WRITE;
   File entry_file(entry_file_path, flags);
   if (!entry_file.IsValid())
     return false;
   int file_length = entry_file.GetLength();
   SimpleFileEOF eof_record;
+  if (file_length < sizeof(eof_record))
+    return false;
   if (entry_file.Read(file_length - sizeof(eof_record),
                       reinterpret_cast<char*>(&eof_record),
                       sizeof(eof_record)) != sizeof(eof_record)) {
     return false;
   }
   if (eof_record.final_magic_number != disk_cache::kSimpleFinalMagicNumber ||
       (eof_record.flags & SimpleFileEOF::FLAG_HAS_KEY_SHA256) !=
           SimpleFileEOF::FLAG_HAS_KEY_SHA256) {
     return false;
   }
@@ skipping 14 matching lines @@
 }
 
 bool CorruptKeySHA256FromEntry(const std::string& key,
                                const base::FilePath& cache_path) {
   FilePath entry_file_path = cache_path.AppendASCII(
       disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
   int flags = File::FLAG_OPEN | File::FLAG_READ | File::FLAG_WRITE;
   File entry_file(entry_file_path, flags);
   if (!entry_file.IsValid())
     return false;
-  int file_length = entry_file.GetLength();
+  int64_t file_length = entry_file.GetLength();
   SimpleFileEOF eof_record;
+  if (file_length < sizeof(eof_record))
+    return false;
   if (entry_file.Read(file_length - sizeof(eof_record),
                       reinterpret_cast<char*>(&eof_record),
                       sizeof(eof_record)) != sizeof(eof_record)) {
     return false;
   }
   if (eof_record.final_magic_number != disk_cache::kSimpleFinalMagicNumber ||
       (eof_record.flags & SimpleFileEOF::FLAG_HAS_KEY_SHA256) !=
           SimpleFileEOF::FLAG_HAS_KEY_SHA256) {
     return false;
   }
@@ skipping 10 matching lines @@
 }
 
 bool CorruptStream0LengthFromEntry(const std::string& key,
                                    const base::FilePath& cache_path) {
   FilePath entry_file_path = cache_path.AppendASCII(
       disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
   int flags = File::FLAG_OPEN | File::FLAG_READ | File::FLAG_WRITE;
   File entry_file(entry_file_path, flags);
   if (!entry_file.IsValid())
     return false;
-  int file_length = entry_file.GetLength();
+  int64_t file_length = entry_file.GetLength();
   SimpleFileEOF eof_record;
+  if (file_length < sizeof(eof_record))
+    return false;
   if (entry_file.Read(file_length - sizeof(eof_record),
                       reinterpret_cast<char*>(&eof_record),
                       sizeof(eof_record)) != sizeof(eof_record)) {
     return false;
   }
   if (eof_record.final_magic_number != disk_cache::kSimpleFinalMagicNumber)
     return false;
 
   // Set the stream size to a clearly invalidly large value.
   eof_record.stream_size = std::numeric_limits<uint32_t>::max() - 50;
   if (entry_file.Write(file_length - sizeof(eof_record),
                        reinterpret_cast<char*>(&eof_record),
                        sizeof(eof_record)) != sizeof(eof_record)) {
     return false;
   }
   return true;
 }
 
 }  // namespace simple_util
 }  // namespace disk_cache