crashpad/util/ios/scoped_vm_read.cc
Ben Hamilton 28354d11c3 [ios] New class ScopedVMMap
This CL introduces a new class ScopedVMMap, a fork of ScopedVMRead
which maps the memory using vm_remap() instead of reading it.

This is useful for Annotations which use ScopedSpinGuard to
protect reads from simultaneous writes; the in-process intermediate
dump handler can try to take the spin guard when reading such
an Annotation and skip reading it if it the spin guard could not
be obtained.

Change-Id: I60d7a48d1ba4e5d2dfdb44307b78b4d9ffb73560
Bug: crashpad:437
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4114550
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Ben Hamilton <benhamilton@google.com>
2023-01-30 22:19:37 +00:00

71 lines
2.1 KiB
C++

// Copyright 2021 The Crashpad Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "util/ios/scoped_vm_read.h"
#include "util/ios/raw_logging.h"
namespace crashpad {
namespace internal {
ScopedVMReadInternal::ScopedVMReadInternal()
: data_(0), region_start_(0), region_size_(0) {}
ScopedVMReadInternal::~ScopedVMReadInternal() {
Reset();
}
bool ScopedVMReadInternal::Read(const void* data, const size_t data_length) {
Reset();
vm_address_t data_address = reinterpret_cast<vm_address_t>(data);
vm_address_t page_region_address = trunc_page(data_address);
vm_size_t page_region_size =
round_page(data_address - page_region_address + data_length);
if (page_region_size < data_length) {
CRASHPAD_RAW_LOG("ScopedVMRead data_length overflow");
return false;
}
kern_return_t kr = vm_read(mach_task_self(),
page_region_address,
page_region_size,
&region_start_,
&region_size_);
if (kr != KERN_SUCCESS) {
// It's expected that this will sometimes fail. Don't log here.
return false;
}
data_ = region_start_ + (data_address - page_region_address);
return true;
}
void ScopedVMReadInternal::Reset() {
if (!region_start_) {
return;
}
kern_return_t kr =
vm_deallocate(mach_task_self(), region_start_, region_size_);
if (kr != KERN_SUCCESS) {
CRASHPAD_RAW_LOG_ERROR(kr, "vm_deallocate");
}
region_start_ = 0;
region_size_ = 0;
data_ = 0;
}
} // namespace internal
} // namespace crashpad