platform_system_core/libbacktrace/BacktracePtrace.cpp

93 lines
2.5 KiB
C++

/*
* Copyright (C) 2013 The Android Open Source Project
*
* 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 <errno.h>
#include <stdint.h>
#include <string.h>
#include <sys/uio.h>
#include <sys/param.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <ucontext.h>
#include <unistd.h>
#include <backtrace/Backtrace.h>
#include <backtrace/BacktraceMap.h>
#include "BacktraceLog.h"
#include "BacktracePtrace.h"
#include "thread_utils.h"
#if !defined(__APPLE__)
static bool PtraceRead(pid_t tid, uintptr_t addr, word_t* out_value) {
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, tid, reinterpret_cast<void*>(addr), nullptr);
if (*out_value == static_cast<word_t>(-1) && errno) {
return false;
}
return true;
}
#endif
bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
backtrace_map_t map;
FillInMap(ptr, &map);
if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
return false;
}
return PtraceRead(Tid(), ptr, out_value);
#endif
}
size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return 0;
#else
backtrace_map_t map;
FillInMap(addr, &map);
if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
return 0;
}
bytes = MIN(map.end - addr, bytes);
struct iovec local_io;
local_io.iov_base = buffer;
local_io.iov_len = bytes;
struct iovec remote_io;
remote_io.iov_base = reinterpret_cast<void*>(addr);
remote_io.iov_len = bytes;
ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0);
if (bytes_read == -1) {
return 0;
}
return static_cast<size_t>(bytes_read);
#endif
}