Source/JavaScriptCore/runtime/JSCBytecodeCacheVersion.cpp

/*
 * Copyright (C) 2022-2024 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "JSCBytecodeCacheVersion.h"

#include <wtf/text/SuperFastHash.h>

#if OS(DARWIN)
#include <dlfcn.h>
#include <mach-o/dyld.h>
#include <uuid/uuid.h>
#include <wtf/DataLog.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/spi/darwin/dyldSPI.h>
#endif

namespace JSC {

#if OS(DARWIN)
namespace JSCBytecodeCacheVersionInternal {
static constexpr bool verbose = false;
}
#endif

uint32_t computeJSCBytecodeCacheVersion()
{
#if OS(DARWIN)
    static LazyNeverDestroyed<uint32_t> cacheVersion;
    static std::once_flag onceFlag;
    std::call_once(onceFlag, [] {
        void* jsFunctionAddr = bitwise_cast<void*>(&computeJSCBytecodeCacheVersion);

        uuid_t uuid;
        if (const mach_header* header = dyld_image_header_containing_address(jsFunctionAddr); header && _dyld_get_image_uuid(header, uuid)) {
            uuid_string_t uuidString = { };
            uuid_unparse(uuid, uuidString);
            cacheVersion.construct(SuperFastHash::computeHash(uuidString));
            dataLogLnIf(JSCBytecodeCacheVersionInternal::verbose, "UUID of JavaScriptCore.framework:", uuidString);
            return;
        }

        cacheVersion.construct(0);
        dataLogLnIf(JSCBytecodeCacheVersionInternal::verbose, "Failed to get UUID for JavaScriptCore framework");
    });
    return cacheVersion.get();
#else
    static constexpr uint32_t precomputedCacheVersion = SuperFastHash::computeHash(__TIMESTAMP__);
    return precomputedCacheVersion;
#endif
}

} // namespace JSC