libbacktrace/BacktraceImpl.cpp - platform/system/core - Git at Google

 /*
  * 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/param.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 (BacktraceMap::IsValid(frame->map) && !frame->map.name.empty()) {
     map_name = frame->map.name.c_str();
   } else {
     map_name = "<unknown>";
   }

   uintptr_t relative_pc;
   if (BacktraceMap::IsValid(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;
 }

 void Backtrace::FillInMap(uintptr_t pc, backtrace_map_t* map) {
   map_->FillIn(pc, map);
 }

 //-------------------------------------------------------------------------
 // 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;
   }

   backtrace_map_t map;
   FillInMap(ptr, &map);
   if (BacktraceMap::IsValid(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;
   }
 }

 size_t BacktraceCurrent::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
   backtrace_map_t map;
   FillInMap(addr, &map);
   if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
     return 0;
   }
   bytes = MIN(map.end - addr, bytes);
   memcpy(buffer, reinterpret_cast<uint8_t*>(addr), bytes);
   return bytes;
 }

 //-------------------------------------------------------------------------
 // BacktracePtrace functions.
 //-------------------------------------------------------------------------
 BacktracePtrace::BacktracePtrace(
     BacktraceImpl* impl, pid_t pid, pid_t tid, BacktraceMap* map)
     : Backtrace(impl, pid, map) {
   tid_ = tid;
 }

 BacktracePtrace::~BacktracePtrace() {
 }

 #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), 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*>(addr), tid, strerror(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);
   size_t bytes_read = 0;
   word_t data_word;
   size_t align_bytes = addr & (sizeof(word_t) - 1);
   if (align_bytes != 0) {
     if (!PtraceRead(Tid(), addr & ~(sizeof(word_t) - 1), &data_word)) {
       return 0;
     }
     align_bytes = sizeof(word_t) - align_bytes;
     memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + sizeof(word_t) - align_bytes,
            align_bytes);
     addr += align_bytes;
     buffer += align_bytes;
     bytes -= align_bytes;
     bytes_read += align_bytes;
   }

   size_t num_words = bytes / sizeof(word_t);
   for (size_t i = 0; i < num_words; i++) {
     if (!PtraceRead(Tid(), addr, &data_word)) {
       return bytes_read;
     }
     memcpy(buffer, &data_word, sizeof(word_t));
     buffer += sizeof(word_t);
     addr += sizeof(word_t);
     bytes_read += sizeof(word_t);
   }

   size_t left_over = bytes & (sizeof(word_t) - 1);
   if (left_over) {
     if (!PtraceRead(Tid(), addr, &data_word)) {
       return bytes_read;
     }
     memcpy(buffer, &data_word, left_over);
     bytes_read += left_over;
   }
   return bytes_read;
 #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);
   }
 }
	/*
	* 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/param.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 (BacktraceMap::IsValid(frame->map) && !frame->map.name.empty()) {
	map_name = frame->map.name.c_str();
	} else {
	map_name = "<unknown>";
	}

	uintptr_t relative_pc;
	if (BacktraceMap::IsValid(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;
	}

	void Backtrace::FillInMap(uintptr_t pc, backtrace_map_t* map) {
	map_->FillIn(pc, map);
	}

	//-------------------------------------------------------------------------
	// 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;
	}

	backtrace_map_t map;
	FillInMap(ptr, &map);
	if (BacktraceMap::IsValid(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;
	}
	}

	size_t BacktraceCurrent::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
	backtrace_map_t map;
	FillInMap(addr, &map);
	if (!BacktraceMap::IsValid(map) \|\| !(map.flags & PROT_READ)) {
	return 0;
	}
	bytes = MIN(map.end - addr, bytes);
	memcpy(buffer, reinterpret_cast<uint8_t*>(addr), bytes);
	return bytes;
	}

	//-------------------------------------------------------------------------
	// BacktracePtrace functions.
	//-------------------------------------------------------------------------
	BacktracePtrace::BacktracePtrace(
	BacktraceImpl* impl, pid_t pid, pid_t tid, BacktraceMap* map)
	: Backtrace(impl, pid, map) {
	tid_ = tid;
	}

	BacktracePtrace::~BacktracePtrace() {
	}

	#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), 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*>(addr), tid, strerror(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);
	size_t bytes_read = 0;
	word_t data_word;
	size_t align_bytes = addr & (sizeof(word_t) - 1);
	if (align_bytes != 0) {
	if (!PtraceRead(Tid(), addr & ~(sizeof(word_t) - 1), &data_word)) {
	return 0;
	}
	align_bytes = sizeof(word_t) - align_bytes;
	memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + sizeof(word_t) - align_bytes,
	align_bytes);
	addr += align_bytes;
	buffer += align_bytes;
	bytes -= align_bytes;
	bytes_read += align_bytes;
	}

	size_t num_words = bytes / sizeof(word_t);
	for (size_t i = 0; i < num_words; i++) {
	if (!PtraceRead(Tid(), addr, &data_word)) {
	return bytes_read;
	}
	memcpy(buffer, &data_word, sizeof(word_t));
	buffer += sizeof(word_t);
	addr += sizeof(word_t);
	bytes_read += sizeof(word_t);
	}

	size_t left_over = bytes & (sizeof(word_t) - 1);
	if (left_over) {
	if (!PtraceRead(Tid(), addr, &data_word)) {
	return bytes_read;
	}
	memcpy(buffer, &data_word, left_over);
	bytes_read += left_over;
	}
	return bytes_read;
	#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);
	}
	}