tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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BuildId.h (2747B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this
      4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 /**
      7 * Embedding-provided build ID information, used by SpiderMonkey to tag cached
      8 * compilation data so that cached data can be reused when possible, or
      9 * discarded and regenerated if necessary.
     10 */
     11 
     12 #ifndef js_BuildId_h
     13 #define js_BuildId_h
     14 
     15 #include "jstypes.h"  // JS_PUBLIC_API
     16 
     17 #include "js/Vector.h"  // js::Vector
     18 
     19 namespace js {
     20 
     21 class SystemAllocPolicy;
     22 
     23 }  // namespace js
     24 
     25 namespace JS {
     26 
     27 /** Vector of characters used for holding build ids. */
     28 using BuildIdCharVector = js::Vector<char, 0, js::SystemAllocPolicy>;
     29 
     30 /**
     31 * Return the buildId (represented as a sequence of characters) associated with
     32 * the currently-executing build. If the JS engine is embedded such that a
     33 * single cache entry can be observed by different compiled versions of the JS
     34 * engine, it is critical that the buildId shall change for each new build of
     35 * the JS engine.
     36 */
     37 using BuildIdOp = bool (*)(BuildIdCharVector* buildId);
     38 
     39 /**
     40 * Embedder hook to set the buildId-generating function.
     41 */
     42 extern JS_PUBLIC_API void SetProcessBuildIdOp(BuildIdOp buildIdOp);
     43 
     44 /**
     45 * Some cached data is, in addition to being build-specific, CPU-specific: the
     46 * cached data depends on CPU features like a particular level of SSE support.
     47 *
     48 * This function produces a buildId that includes:
     49 *
     50 *   * the buildId defined by the embedder-provided BuildIdOp set by
     51 *     JS::SetProcessBuildIdOp, and
     52 *   * CPU feature information for the current CPU.
     53 *
     54 * Embedders may use this function to tag cached data whose validity depends
     55 * on having consistent buildId *and* on the CPU supporting features identical
     56 * to those in play when the cached data was computed.
     57 */
     58 [[nodiscard]] extern JS_PUBLIC_API bool GetOptimizedEncodingBuildId(
     59    BuildIdCharVector* buildId);
     60 
     61 /**
     62 * Script bytecode is dependent on the buildId and a few other things.
     63 *
     64 * This function produces a buildId that includes:
     65 *
     66 *   * The buildId defined by the embedder-provided BuildIdOp set by
     67 *     JS::SetProcessBuildIdOp.
     68 *   * Additional bytes describing things like endianness, pointer size and
     69 *     other state XDR buffers depend on.
     70 *
     71 * Note: this value may depend on runtime preferences so isn't guaranteed to be
     72 * stable across restarts.
     73 *
     74 * Embedders should use this function to tag transcoded bytecode.
     75 * See Transcoding.h.
     76 */
     77 [[nodiscard]] extern JS_PUBLIC_API bool GetScriptTranscodingBuildId(
     78    BuildIdCharVector* buildId);
     79 
     80 }  // namespace JS
     81 
     82 #endif /* js_BuildId_h */