[gin] Unify snapshot loading on Windows and other platforms.

Removes extra v8 snapshot and natives validation on Windows. All platforms
have the same validation henceforth.

BUG=501799

Review-Url: https://codereview.chromium.org/2103903002
Cr-Commit-Position: refs/heads/master@{#403430}

BUILD.gn

@@ -344,10 +344,6 @@ group("both_gn_and_gyp") {
     deps += [ "//components/policy:policy_templates" ]
   }
 
-  if (v8_use_external_startup_data) {
-    deps += [ "//gin:gin_v8_snapshot_fingerprint" ]
-  }
-
   if (is_win) {
     deps += [
       "//chrome/installer/gcapi",

build/gn_migration.gypi

@@ -55,7 +55,6 @@
         '../content/content_shell_and_tests.gyp:content_unittests',
         '../crypto/crypto.gyp:crypto_unittests',
         '../device/device_tests.gyp:device_unittests',
-        '../gin/gin.gyp:gin_v8_snapshot_fingerprint',
         '../gpu/gpu.gyp:angle_unittests',
         '../gpu/gpu.gyp:gl_tests',
         '../gpu/gpu.gyp:gpu_perftests',

gin/BUILD.gn

@@ -86,11 +86,6 @@ component("gin") {
     "//base/third_party/dynamic_annotations",
     "//crypto",
   ]
-  if (v8_use_external_startup_data && is_win) {
-    public_deps += [ ":gin_v8_snapshot_fingerprint" ]
-    sources += [ "$target_gen_dir/v8_snapshot_fingerprint.cc" ]
-    defines += [ "V8_VERIFY_EXTERNAL_STARTUP_DATA" ]
-  }
 
   if (is_mac) {
     libs = [ "CoreFoundation.framework" ]
@@ -99,36 +94,6 @@ component("gin") {
   configs += [ "//v8:external_startup_data" ]
 }
 
-if (v8_use_external_startup_data) {
-  action("gin_v8_snapshot_fingerprint") {
-    script = "//gin/fingerprint/fingerprint_v8_snapshot.py"
-
-    snapshot_file = "$root_out_dir/snapshot_blob.bin"
-    natives_file = "$root_out_dir/natives_blob.bin"
-    output_file = "$target_gen_dir/v8_snapshot_fingerprint.cc"
-
-    args = [
-      "--snapshot_file",
-      rebase_path(snapshot_file, root_build_dir),
-      "--natives_file",
-      rebase_path(natives_file, root_build_dir),
-      "--output_file",
-      rebase_path(output_file, root_build_dir),
-    ]
-    inputs = [
-      snapshot_file,
-      natives_file,
-    ]
-    outputs = [
-      output_file,
-    ]
-
-    deps = [
-      "//v8",
-    ]
-  }
-}
-
 executable("gin_shell") {
   sources = [
     "shell/gin_main.cc",

gin/gin.gyp

@@ -84,30 +84,6 @@
         'wrappable.h',
         'wrapper_info.cc',
       ],
-      'conditions': [
-        ['v8_use_external_startup_data==1 and OS=="win"', {
-          'dependencies': [
-            'gin_v8_snapshot_fingerprint',
-            '../crypto/crypto.gyp:crypto',
-          ],
-          'sources': [
-            '<(gin_gen_path)/v8_snapshot_fingerprint.cc',
-          ],
-          'defines': [
-            'V8_VERIFY_EXTERNAL_STARTUP_DATA',
-          ]
-        }],
-      ],
-    },
-    {
-      'target_name': 'gin_v8_snapshot_fingerprint',
-      'type': 'none',
-      'variables': {
-        'snapshot_file': '<(PRODUCT_DIR)/snapshot_blob.bin',
-        'natives_file': '<(PRODUCT_DIR)/natives_blob.bin',
-        'output_file': '<(gin_gen_path)/v8_snapshot_fingerprint.cc',
-      },
-      'includes': [ '../gin/fingerprint/fingerprint_v8_snapshot.gypi' ],
     },
     {
       'target_name': 'gin_shell',

gin/v8_initializer.cc

@@ -191,36 +191,6 @@ static const OpenedFileMap::mapped_type OpenFileIfNecessary(
   return opened;
 }
 
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-bool VerifyV8StartupFile(base::MemoryMappedFile** file,
-                         const unsigned char* fingerprint) {
-  unsigned char output[crypto::kSHA256Length];
-  crypto::SHA256HashString(
-      base::StringPiece(reinterpret_cast<const char*>((*file)->data()),
-                        (*file)->length()),
-      output, sizeof(output));
-  if (!memcmp(fingerprint, output, sizeof(output))) {
-    return true;
-  }
-
-  // TODO(oth): Remove this temporary diagnostics for http://crbug.com/501799
-  uint64_t input[sizeof(output)];
-  memcpy(input, fingerprint, sizeof(input));
-
-  base::debug::Alias(output);
-  base::debug::Alias(input);
-
-  const uint64_t* o64 = reinterpret_cast<const uint64_t*>(output);
-  const uint64_t* f64 = reinterpret_cast<const uint64_t*>(fingerprint);
-  LOG(FATAL) << "Natives length " << (*file)->length()
-             << " H(computed) " << o64[0] << o64[1] << o64[2] << o64[3]
-             << " H(expected) " << f64[0] << f64[1] << f64[2] << f64[3];
-
-  delete *file;
-  *file = NULL;
-  return false;
-}
-#endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 bool GenerateEntropy(unsigned char* buffer, size_t amount) {
@@ -243,47 +213,37 @@ bool ShouldUseIgnition() {
 }  // namespace
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-// Defined in gen/gin/v8_snapshot_fingerprint.cc
-extern const unsigned char g_natives_fingerprint[];
-extern const unsigned char g_snapshot_fingerprint[];
-#endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
+
+namespace {
 
 enum LoadV8FileResult {
   V8_LOAD_SUCCESS = 0,
   V8_LOAD_FAILED_OPEN,
   V8_LOAD_FAILED_MAP,
-  V8_LOAD_FAILED_VERIFY,
+  V8_LOAD_FAILED_VERIFY, // Deprecated.
   V8_LOAD_MAX_VALUE
 };
 
-static LoadV8FileResult MapVerify(const OpenedFileMap::mapped_type& file_region,
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-                                  const unsigned char* fingerprint,
-#endif
-                                  base::MemoryMappedFile** mmapped_file_out) {
+LoadV8FileResult MapOpenedFile(
+    const OpenedFileMap::mapped_type& file_region,
+    base::MemoryMappedFile** mmapped_file_out) {
   if (file_region.first == base::kInvalidPlatformFile)
     return V8_LOAD_FAILED_OPEN;
   if (!MapV8File(file_region.first, file_region.second, mmapped_file_out))
     return V8_LOAD_FAILED_MAP;
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-  if (!VerifyV8StartupFile(mmapped_file_out, fingerprint))
-    return V8_LOAD_FAILED_VERIFY;
-#endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
   return V8_LOAD_SUCCESS;
 }
 
+}  // namespace
+
 // static
 void V8Initializer::LoadV8Snapshot() {
   if (g_mapped_snapshot)
     return;
 
   OpenFileIfNecessary(kSnapshotFileName);
-  LoadV8FileResult result = MapVerify(GetOpenedFile(kSnapshotFileName),
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-                                      g_snapshot_fingerprint,
-#endif
-                                      &g_mapped_snapshot);
+  LoadV8FileResult result = MapOpenedFile(GetOpenedFile(kSnapshotFileName),
+                                          &g_mapped_snapshot);
   // V8 can't start up without the source of the natives, but it can
   // start up (slower) without the snapshot.
   UMA_HISTOGRAM_ENUMERATION("V8.Initializer.LoadV8Snapshot.Result", result,
@@ -295,10 +255,7 @@ void V8Initializer::LoadV8Natives() {
     return;
 
   OpenFileIfNecessary(kNativesFileName);
-  LoadV8FileResult result = MapVerify(GetOpenedFile(kNativesFileName),
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-                                      g_natives_fingerprint,
-#endif
+  LoadV8FileResult result = MapOpenedFile(GetOpenedFile(kNativesFileName),
                                       &g_mapped_natives);
   if (result != V8_LOAD_SUCCESS) {
     LOG(FATAL) << "Couldn't mmap v8 natives data file, status code is "
@@ -326,10 +283,6 @@ void V8Initializer::LoadV8SnapshotFromFD(base::PlatformFile snapshot_pf,
   LoadV8FileResult result = V8_LOAD_SUCCESS;
   if (!MapV8File(snapshot_pf, snapshot_region, &g_mapped_snapshot))
     result = V8_LOAD_FAILED_MAP;
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-  if (!VerifyV8StartupFile(&g_mapped_snapshot, g_snapshot_fingerprint))
-    result = V8_LOAD_FAILED_VERIFY;
-#endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
   if (result == V8_LOAD_SUCCESS) {
     g_opened_files.Get()[kSnapshotFileName] =
         std::make_pair(snapshot_pf, snapshot_region);
@@ -357,11 +310,6 @@ void V8Initializer::LoadV8NativesFromFD(base::PlatformFile natives_pf,
   if (!MapV8File(natives_pf, natives_region, &g_mapped_natives)) {
     LOG(FATAL) << "Couldn't mmap v8 natives data file";
   }
-#if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
-  if (!VerifyV8StartupFile(&g_mapped_natives, g_natives_fingerprint)) {
-    LOG(FATAL) << "Couldn't verify contents of v8 natives data file";
-  }
-#endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
   g_opened_files.Get()[kNativesFileName] =
       std::make_pair(natives_pf, natives_region);
 }