Source/bmalloc/bmalloc/Zone.cpp

/*
 * Copyright (C) 2014, 2015 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 "Sizes.h"
#include "Zone.h"

namespace bmalloc {

template<typename T> static void remoteRead(task_t task, memory_reader_t reader, vm_address_t remotePointer, T& result)
{
    void* tmp = nullptr;
    kern_return_t error = reader(task, remotePointer, sizeof(T), &tmp);

    // This read sometimes fails for unknown reasons (<rdar://problem/14093757>).
    // Avoid a crash by skipping the memcpy when this happens.
    if (error || !tmp) {
        fprintf(stderr, "bmalloc: error reading remote process: 0x%x\n", error);
        return;
    }

    memcpy(&result, tmp, sizeof(T));
}

// These function pointers are invoked unconditionally on all zones by various
// system tools. We don't support any of these features, but we provide
// just enough functionality not to crash.

static size_t good_size(malloc_zone_t*, size_t size)
{
    return size;
}

static boolean_t check(malloc_zone_t*)
{
    return true;
}

static void print(malloc_zone_t*, boolean_t)
{
}

static void log(malloc_zone_t*, void*)
{
}

static void force_lock(malloc_zone_t*)
{
}

static void force_unlock(malloc_zone_t*)
{
}

static void statistics(malloc_zone_t*, malloc_statistics_t* statistics)
{
    memset(statistics, 0, sizeof(malloc_statistics_t));
}

static size_t zoneSize(malloc_zone_t*, const void*)
{
    // Our zone is not public API, so no pointer can belong to us.
    return 0;
}

// This function runs inside the leaks process.
static kern_return_t enumerator(task_t task, void* context, unsigned type_mask, vm_address_t zone_address, memory_reader_t reader, vm_range_recorder_t recorder)
{
    Zone remoteZone(task, reader, zone_address);
    for (auto& range : remoteZone.ranges()) {
        vm_range_t vmRange = { reinterpret_cast<vm_address_t>(range.begin()), range.size() };

        if ((type_mask & MALLOC_PTR_REGION_RANGE_TYPE))
            (*recorder)(task, context, MALLOC_PTR_REGION_RANGE_TYPE, &vmRange, 1);

        if ((type_mask & MALLOC_PTR_IN_USE_RANGE_TYPE))
            (*recorder)(task, context, MALLOC_PTR_IN_USE_RANGE_TYPE, &vmRange, 1);
    }

    return 0;
}

// The memory analysis API requires the contents of this struct to be a static
// constant in the program binary. The leaks process will load this struct
// out of the program binary (and not out of the running process).
static const malloc_introspection_t zoneIntrospect = {
    .enumerator = bmalloc::enumerator,
    .good_size = bmalloc::good_size,
    .check = bmalloc::check,
    .print = bmalloc::print,
    .log = bmalloc::log,
    .force_lock = bmalloc::force_lock,
    .force_unlock = bmalloc::force_unlock,
    .statistics = bmalloc::statistics
};

Zone::Zone(const LockHolder&)
{
    malloc_zone_t::size = &bmalloc::zoneSize;
    malloc_zone_t::zone_name = "WebKit Malloc";
    malloc_zone_t::introspect = const_cast<malloc_introspection_t*>(&bmalloc::zoneIntrospect);
    malloc_zone_t::version = 4;
    malloc_zone_register(this);
}

Zone::Zone(task_t task, memory_reader_t reader, vm_address_t remotePointer)
{
    remoteRead(task, reader, remotePointer, *this);
}

} // namespace bmalloc