crashpad/util/linux/process_memory.cc
Joshua Peraza fa8ef92dc7 linux: Add ProcessMemory which reads another process' memory
Provides Read, ReadCString, and ReadCStringSizeLimited. Does not provide
ReadMapped because Linux does not support mmap on /proc/pid/mem.

Bug: crashpad:30
Change-Id: Ia319c0107b1f138aeb8e5d0ee480c77310df7202
Reviewed-on: https://chromium-review.googlesource.com/459700
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
2017-04-03 21:41:51 +00:00

124 lines
3.4 KiB
C++

// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// 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/linux/process_memory.h"
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <algorithm>
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
namespace crashpad {
ProcessMemory::ProcessMemory() : mem_fd_(), pid_(-1) {}
ProcessMemory::~ProcessMemory() {}
bool ProcessMemory::Initialize(pid_t pid) {
pid_ = pid;
char path[32];
snprintf(path, sizeof(path), "/proc/%d/mem", pid_);
mem_fd_.reset(HANDLE_EINTR(open(path, O_RDONLY | O_NOCTTY | O_CLOEXEC)));
if (!mem_fd_.is_valid()) {
PLOG(ERROR) << "open";
return false;
}
return true;
}
bool ProcessMemory::Read(LinuxVMAddress address,
size_t size,
void* buffer) const {
DCHECK(mem_fd_.is_valid());
char* buffer_c = static_cast<char*>(buffer);
while (size > 0) {
ssize_t bytes_read =
HANDLE_EINTR(pread(mem_fd_.get(), buffer_c, size, address));
if (bytes_read < 0) {
PLOG(ERROR) << "pread";
return false;
}
if (bytes_read == 0) {
LOG(ERROR) << "unexpected eof";
return false;
}
DCHECK_LE(static_cast<size_t>(bytes_read), size);
size -= bytes_read;
address += bytes_read;
buffer_c += bytes_read;
}
return true;
}
bool ProcessMemory::ReadCString(LinuxVMAddress address,
std::string* string) const {
return ReadCStringInternal(address, false, 0, string);
}
bool ProcessMemory::ReadCStringSizeLimited(LinuxVMAddress address,
size_t size,
std::string* string) const {
return ReadCStringInternal(address, true, size, string);
}
bool ProcessMemory::ReadCStringInternal(LinuxVMAddress address,
bool has_size,
size_t size,
std::string* string) const {
DCHECK(mem_fd_.is_valid());
string->clear();
char buffer[4096];
do {
size_t read_size;
if (has_size) {
read_size = std::min(sizeof(buffer), size);
} else {
read_size = sizeof(buffer);
}
ssize_t bytes_read;
bytes_read = HANDLE_EINTR(pread(mem_fd_.get(), buffer, read_size, address));
if (bytes_read < 0) {
PLOG(ERROR) << "pread";
return false;
}
if (bytes_read == 0) {
break;
}
DCHECK_LE(static_cast<size_t>(bytes_read), read_size);
char* nul = static_cast<char*>(memchr(buffer, '\0', bytes_read));
if (nul != nullptr) {
string->append(buffer, nul - buffer);
return true;
}
string->append(buffer, bytes_read);
address += bytes_read;
size -= bytes_read;
} while (!has_size || size > 0);
LOG(ERROR) << "unterminated string";
return false;
}
} // namespace crashpad