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/*
* 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 <stdlib.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <ucontext.h>
#include <unistd.h>
#include <string>
#include <backtrace/Backtrace.h>
#include <backtrace/BacktraceMap.h>
#include "BacktraceImpl.h"
#include "BacktraceLog.h"
#include "thread_utils.h"
//-------------------------------------------------------------------------
// Backtrace functions.
//-------------------------------------------------------------------------
Backtrace::Backtrace(BacktraceImpl* impl, pid_t pid, BacktraceMap* map)
: pid_(pid), tid_(-1), map_(map), map_shared_(true), impl_(impl) {
impl_->SetParent(this);
if (map_ == NULL) {
map_ = BacktraceMap::Create(pid);
map_shared_ = false;
}
}
Backtrace::~Backtrace() {
if (impl_) {
delete impl_;
impl_ = NULL;
}
if (map_ && !map_shared_) {
delete map_;
map_ = NULL;
}
}
bool Backtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
return impl_->Unwind(num_ignore_frames, ucontext);
}
extern "C" char* __cxa_demangle(const char* mangled, char* buf, size_t* len,
int* status);
std::string Backtrace::GetFunctionName(uintptr_t pc, uintptr_t* offset) {
std::string func_name = impl_->GetFunctionNameRaw(pc, offset);
if (!func_name.empty()) {
#if defined(__APPLE__)
// Mac OS' __cxa_demangle demangles "f" as "float"; last tested on 10.7.
if (func_name[0] != '_') {
return func_name;
}
#endif
char* name = __cxa_demangle(func_name.c_str(), 0, 0, 0);
if (name) {
func_name = name;
free(name);
}
}
return func_name;
}
bool Backtrace::VerifyReadWordArgs(uintptr_t ptr, word_t* out_value) {
if (ptr & (sizeof(word_t)-1)) {
BACK_LOGW("invalid pointer %p", (void*)ptr);
*out_value = (word_t)-1;
return false;
}
return true;
}
std::string Backtrace::FormatFrameData(size_t frame_num) {
if (frame_num >= frames_.size()) {
return "";
}
return FormatFrameData(&frames_[frame_num]);
}
std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) {
const char* map_name;
if (frame->map && !frame->map->name.empty()) {
map_name = frame->map->name.c_str();
} else {
map_name = "<unknown>";
}
uintptr_t relative_pc;
if (frame->map) {
relative_pc = frame->pc - frame->map->start;
} else {
relative_pc = frame->pc;
}
char buf[512];
if (!frame->func_name.empty() && frame->func_offset) {
snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s (%s+%" PRIuPTR ")",
frame->num, (int)sizeof(uintptr_t)*2, relative_pc, map_name,
frame->func_name.c_str(), frame->func_offset);
} else if (!frame->func_name.empty()) {
snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s (%s)", frame->num,
(int)sizeof(uintptr_t)*2, relative_pc, map_name, frame->func_name.c_str());
} else {
snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s", frame->num,
(int)sizeof(uintptr_t)*2, relative_pc, map_name);
}
return buf;
}
const backtrace_map_t* Backtrace::FindMap(uintptr_t pc) {
return map_->Find(pc);
}
//-------------------------------------------------------------------------
// BacktraceCurrent functions.
//-------------------------------------------------------------------------
BacktraceCurrent::BacktraceCurrent(
BacktraceImpl* impl, BacktraceMap* map) : Backtrace(impl, getpid(), map) {
}
BacktraceCurrent::~BacktraceCurrent() {
}
bool BacktraceCurrent::ReadWord(uintptr_t ptr, word_t* out_value) {
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
const backtrace_map_t* map = FindMap(ptr);
if (map && map->flags & PROT_READ) {
*out_value = *reinterpret_cast<word_t*>(ptr);
return true;
} else {
BACK_LOGW("pointer %p not in a readable map", reinterpret_cast<void*>(ptr));
*out_value = static_cast<word_t>(-1);
return false;
}
}
//-------------------------------------------------------------------------
// BacktracePtrace functions.
//-------------------------------------------------------------------------
BacktracePtrace::BacktracePtrace(
BacktraceImpl* impl, pid_t pid, pid_t tid, BacktraceMap* map)
: Backtrace(impl, pid, map) {
tid_ = tid;
}
BacktracePtrace::~BacktracePtrace() {
}
bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
// 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*>(ptr), NULL);
if (*out_value == static_cast<word_t>(-1) && errno) {
BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
reinterpret_cast<void*>(ptr), Tid(), strerror(errno));
return false;
}
return true;
#endif
}
Backtrace* Backtrace::Create(pid_t pid, pid_t tid, BacktraceMap* map) {
if (pid == BACKTRACE_CURRENT_PROCESS || pid == getpid()) {
if (tid == BACKTRACE_CURRENT_THREAD || tid == gettid()) {
return CreateCurrentObj(map);
} else {
return CreateThreadObj(tid, map);
}
} else if (tid == BACKTRACE_CURRENT_THREAD) {
return CreatePtraceObj(pid, pid, map);
} else {
return CreatePtraceObj(pid, tid, map);
}
}
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