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// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// Author: Li Liu
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <asm/sigcontext.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <cassert>
#include <cstdlib>
#include <ctime>
#include "client/linux/handler/exception_handler.h"
#include "common/linux/guid_creator.h"
#include "google_breakpad/common/minidump_format.h"
namespace google_breakpad {
// Signals that we are interested.
int SigTable[] = {
#if defined(SIGSEGV)
SIGSEGV,
#endif
#ifdef SIGABRT
SIGABRT,
#endif
#ifdef SIGFPE
SIGFPE,
#endif
#ifdef SIGILL
SIGILL,
#endif
#ifdef SIGBUS
SIGBUS,
#endif
};
std::vector<ExceptionHandler*> *ExceptionHandler::handler_stack_ = NULL;
int ExceptionHandler::handler_stack_index_ = 0;
pthread_mutex_t ExceptionHandler::handler_stack_mutex_ =
PTHREAD_MUTEX_INITIALIZER;
ExceptionHandler::ExceptionHandler(const string &dump_path,
FilterCallback filter,
MinidumpCallback callback,
void *callback_context,
bool install_handler)
: filter_(filter),
callback_(callback),
callback_context_(callback_context),
dump_path_(),
installed_handler_(install_handler) {
set_dump_path(dump_path);
if (install_handler) {
SetupHandler();
pthread_mutex_lock(&handler_stack_mutex_);
if (handler_stack_ == NULL)
handler_stack_ = new std::vector<ExceptionHandler *>;
handler_stack_->push_back(this);
pthread_mutex_unlock(&handler_stack_mutex_);
}
}
ExceptionHandler::~ExceptionHandler() {
TeardownAllHandler();
pthread_mutex_lock(&handler_stack_mutex_);
if (handler_stack_->back() == this) {
handler_stack_->pop_back();
} else {
fprintf(stderr, "warning: removing Breakpad handler out of order\n");
for (std::vector<ExceptionHandler *>::iterator iterator =
handler_stack_->begin();
iterator != handler_stack_->end();
++iterator) {
if (*iterator == this) {
handler_stack_->erase(iterator);
}
}
}
if (handler_stack_->empty()) {
// When destroying the last ExceptionHandler that installed a handler,
// clean up the handler stack.
delete handler_stack_;
handler_stack_ = NULL;
}
pthread_mutex_unlock(&handler_stack_mutex_);
}
bool ExceptionHandler::WriteMinidump() {
return InternalWriteMinidump(0, NULL);
}
// static
bool ExceptionHandler::WriteMinidump(const string &dump_path,
MinidumpCallback callback,
void *callback_context) {
ExceptionHandler handler(dump_path, NULL, callback,
callback_context, false);
return handler.InternalWriteMinidump(0, NULL);
}
void ExceptionHandler::SetupHandler() {
// Signal on a different stack to avoid using the stack
// of the crashing thread.
struct sigaltstack sig_stack;
sig_stack.ss_sp = malloc(MINSIGSTKSZ);
if (sig_stack.ss_sp == NULL)
return;
sig_stack.ss_size = MINSIGSTKSZ;
sig_stack.ss_flags = 0;
if (sigaltstack(&sig_stack, NULL) < 0)
return;
for (size_t i = 0; i < sizeof(SigTable) / sizeof(SigTable[0]); ++i)
SetupHandler(SigTable[i]);
}
void ExceptionHandler::SetupHandler(int signo) {
struct sigaction act, old_act;
act.sa_handler = HandleException;
act.sa_flags = SA_ONSTACK;
if (sigaction(signo, &act, &old_act) < 0)
return;
old_handlers_[signo] = old_act.sa_handler;
}
void ExceptionHandler::TeardownHandler(int signo) {
if (old_handlers_.find(signo) != old_handlers_.end()) {
struct sigaction act;
act.sa_handler = old_handlers_[signo];
act.sa_flags = 0;
sigaction(signo, &act, 0);
}
}
void ExceptionHandler::TeardownAllHandler() {
for (size_t i = 0; i < sizeof(SigTable) / sizeof(SigTable[0]); ++i) {
TeardownHandler(SigTable[i]);
}
}
// static
void ExceptionHandler::HandleException(int signo) {
// In Linux, the context information about the signal is put on the stack of
// the signal handler frame as value parameter. For some reasons, the
// prototype of the handler doesn't declare this information as parameter, we
// will do it by hand. It is the second parameter above the signal number.
const struct sigcontext *sig_ctx =
reinterpret_cast<const struct sigcontext *>(&signo + 1);
pthread_mutex_lock(&handler_stack_mutex_);
ExceptionHandler *current_handler =
handler_stack_->at(handler_stack_->size() - ++handler_stack_index_);
pthread_mutex_unlock(&handler_stack_mutex_);
// Restore original handler.
current_handler->TeardownHandler(signo);
if (current_handler->InternalWriteMinidump(signo, sig_ctx)) {
// Fully handled this exception, safe to exit.
exit(EXIT_FAILURE);
} else {
// Exception not fully handled, will call the next handler in stack to
// process it.
typedef void (*SignalHandler)(int signo, struct sigcontext);
SignalHandler old_handler =
reinterpret_cast<SignalHandler>(current_handler->old_handlers_[signo]);
if (old_handler != NULL)
old_handler(signo, *sig_ctx);
}
pthread_mutex_lock(&handler_stack_mutex_);
current_handler->SetupHandler(signo);
--handler_stack_index_;
// All the handlers in stack have been invoked to handle the exception,
// normally the process should be terminated and should not reach here.
// In case we got here, ask the OS to handle it to avoid endless loop,
// normally the OS will generate a core and termiate the process. This
// may be desired to debug the program.
if (handler_stack_index_ == 0)
signal(signo, SIG_DFL);
pthread_mutex_unlock(&handler_stack_mutex_);
}
bool ExceptionHandler::InternalWriteMinidump(int signo,
const struct sigcontext *sig_ctx) {
if (filter_ && !filter_(callback_context_))
return false;
GUID guid;
bool success = false;;
char guid_str[kGUIDStringLength + 1];
if (CreateGUID(&guid) && GUIDToString(&guid, guid_str, sizeof(guid_str))) {
char minidump_path[PATH_MAX];
snprintf(minidump_path, sizeof(minidump_path), "%s/%s.dmp",
dump_path_c_,
guid_str);
success = minidump_generator_.WriteMinidumpToFile(
minidump_path, signo, sig_ctx);
if (callback_)
success = callback_(dump_path_c_, guid_str,
callback_context_, success);
}
return success;
}
} // namespace google_breakpad
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