histogram_shared_memory.cc | Explore in Territory

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/metrics/histogram_shared_memory.h"

#include <string_view>

#include "base/base_switches.h"
#include "base/debug/crash_logging.h"
#include "base/memory/shared_memory_mapping.h"
#include "base/memory/shared_memory_switch.h"
#include "base/memory/writable_shared_memory_region.h"
#include "base/metrics/histogram_macros_local.h"
#include "base/metrics/persistent_histogram_allocator.h"
#include "base/metrics/persistent_memory_allocator.h"
#include "base/process/launch.h"
#include "base/process/process_handle.h"
#include "base/process/process_info.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/unguessable_token.h"

// On Apple platforms, the shared memory handle is shared using a Mach port
// rendezvous key.
#if BUILDFLAG(IS_APPLE)
#include "base/mac/mach_port_rendezvous.h"
#endif

// On POSIX, the shared memory handle is a file_descriptor mapped in the
// GlobalDescriptors table.
#if BUILDFLAG(IS_POSIX)
#include "base/posix/global_descriptors.h"
#endif

#if BUILDFLAG(IS_WIN)
#include <windows.h>

#include "base/win/win_util.h"
#endif

#if BUILDFLAG(IS_FUCHSIA)
#include <lib/zx/vmo.h>
#include <zircon/process.h>

#include "base/fuchsia/fuchsia_logging.h"
#endif

// This file supports passing a read/write histogram shared memory region
// between a parent process and child process. The information about the
// shared memory region is encoded into a command-line switch value.
//
// Format: "handle,[irp],guid-high,guid-low,size".
//
// The switch value is composed of 5 segments, separated by commas:
//
// 1. The platform-specific handle id for the shared memory as a string.
// 2. [irp] to indicate whether the handle is inherited (i, most platforms),
//    sent via rendezvous (r, MacOS), or should be queried from the parent
//    (p, Windows).
// 3. The high 64 bits of the shared memory block GUID.
// 4. The low 64 bits of the shared memory block GUID.
// 5. The size of the shared memory segment as a string.
//
// TODO(crbug.com/40109064): Refactor the common logic here and in
// base/metrics/field_trial.cc
namespace base {

BASE_FEATURE(…);

#if BUILDFLAG(IS_APPLE)
const MachPortsForRendezvous::key_type HistogramSharedMemory::kRendezvousKey =
    'hsmr';
#endif

HistogramSharedMemory::SharedMemory::SharedMemory(
    UnsafeSharedMemoryRegion r,
    std::unique_ptr<PersistentMemoryAllocator> a)
    : … { … }

HistogramSharedMemory::SharedMemory::~SharedMemory() = default;

HistogramSharedMemory::SharedMemory::SharedMemory(
    HistogramSharedMemory::SharedMemory&&) = default;

HistogramSharedMemory::SharedMemory&
HistogramSharedMemory::SharedMemory::operator=(
    HistogramSharedMemory::SharedMemory&&) = default;

// static
std::optional<HistogramSharedMemory::SharedMemory>
HistogramSharedMemory::Create(int process_id,
                              const HistogramSharedMemory::Config& config) { … }

// static
bool HistogramSharedMemory::PassOnCommandLineIsEnabled(
    std::string_view process_type) { … }

// static
void HistogramSharedMemory::AddToLaunchParameters(
    UnsafeSharedMemoryRegion histogram_shmem_region,
#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_APPLE)
    GlobalDescriptors::Key descriptor_key,
    ScopedFD& descriptor_to_share,
#endif
    CommandLine* command_line,
    LaunchOptions* launch_options) { … }

// static
void HistogramSharedMemory::InitFromLaunchParameters(
    const CommandLine& command_line) { … }

}  // namespace base
chromium/base/metrics/histogram_shared_memory.cc
