js/xpconnect/loader/mozJSLoaderUtils.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/scache/StartupCache.h"
   8
   9 #include "jsapi.h"
  10 #include "jsfriendapi.h"
  11 #include "js/CompileOptions.h"
  12 #include "js/Transcoding.h"
  13 #include "js/experimental/JSStencil.h"
  14
  15 #include "mozilla/BasePrincipal.h"
  16 #include "mozilla/Span.h"
  17
  18 using namespace JS;
  19 using namespace mozilla::scache;
  20 using mozilla::UniquePtr;
  21
  22 static nsresult HandleTranscodeResult(JSContext* cx,
  23                                       JS::TranscodeResult result) {
  24   if (result == JS::TranscodeResult::Ok) {
  25     return NS_OK;
  26   }
  27
  28   if (result == JS::TranscodeResult::Throw) {
  29     JS_ClearPendingException(cx);
  30     return NS_ERROR_OUT_OF_MEMORY;
  31   }
  32
  33   MOZ_ASSERT(IsTranscodeFailureResult(result));
  34   return NS_ERROR_FAILURE;
  35 }
  36
  37 nsresult ReadCachedStencil(StartupCache* cache, nsACString& cachePath,
  38                            JSContext* cx,
  39                            const JS::ReadOnlyDecodeOptions& options,
  40                            JS::Stencil** stencilOut) {
  41   MOZ_ASSERT(options.borrowBuffer);
  42   MOZ_ASSERT(!options.usePinnedBytecode);
  43
  44   const char* buf;
  45   uint32_t len;
  46   nsresult rv =
  47       cache->GetBuffer(PromiseFlatCString(cachePath).get(), &buf, &len);
  48   if (NS_FAILED(rv)) {
  49     return rv;  // don't warn since NOT_AVAILABLE is an ok error
  50   }
  51
  52   JS::TranscodeRange range(AsBytes(mozilla::Span(buf, len)));
  53   JS::TranscodeResult code = JS::DecodeStencil(cx, options, range, stencilOut);
  54   return HandleTranscodeResult(cx, code);
  55 }
  56
  57 nsresult WriteCachedStencil(StartupCache* cache, nsACString& cachePath,
  58                             JSContext* cx, JS::Stencil* stencil) {
  59   JS::TranscodeBuffer buffer;
  60   JS::TranscodeResult code = JS::EncodeStencil(cx, stencil, buffer);
  61   if (code != JS::TranscodeResult::Ok) {
  62     return HandleTranscodeResult(cx, code);
  63   }
  64
  65   size_t size = buffer.length();
  66   if (size > UINT32_MAX) {
  67     return NS_ERROR_FAILURE;
  68   }
  69
  70   // Move the vector buffer into a unique pointer buffer.
  71   mozilla::UniqueFreePtr<char[]> buf(
  72       reinterpret_cast<char*>(buffer.extractOrCopyRawBuffer()));
  73   nsresult rv = cache->PutBuffer(PromiseFlatCString(cachePath).get(),
  74                                  std::move(buf), size);
  75   return rv;
  76 }