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Merge of Breakpad Chrome Linux fork

Browse source 
A=agl, Lei Zhang
R=nealsid, agl



git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@384 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
nealsid 2009-08-17 23:12:53 +00:00
parent 7c48629d49
commit b0baafc4da
29 changed files with 6750 additions and 2288 deletions
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459
src/client/linux/handler/exception_handler.cc
View file

@ -1,8 +1,6 @@
// Copyright (c) 2006, Google Inc.
// Copyright (c) 2009, 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:
@ -29,48 +27,87 @@
// (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 <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
// The ExceptionHandler object installs signal handlers for a number of
// signals. We rely on the signal handler running on the thread which crashed
// in order to identify it. This is true of the synchronous signals (SEGV etc),
// but not true of ABRT. Thus, if you send ABRT to yourself in a program which
// uses ExceptionHandler, you need to use tgkill to direct it to the current
// thread.
//
// The signal flow looks like this:
//
// SignalHandler (uses a global stack of ExceptionHandler objects to find
// | one to handle the signal. If the first rejects it, try
// | the second etc...)
// V
// HandleSignal ----------------------------| (clones a new process which
// | | shares an address space with
// (wait for cloned | the crashed process. This
// process) | allows us to ptrace the crashed
// | | process)
// V V
// (set signal handler to ThreadEntry (static function to bounce
// SIG_DFL and rethrow, | back into the object)
// killing the crashed |
// process) V
// DoDump (writes minidump)
// |
// V
// sys_exit
//
#include <cassert>
#include <cstdlib>
#include <cstdio>
#include <ctime>
#include <linux/limits.h>
// This code is a little fragmented. Different functions of the ExceptionHandler
// class run in a number of different contexts. Some of them run in a normal
// context and are easy to code, others run in a compromised context and the
// restrictions at the top of minidump_writer.cc apply: no libc and use the
// alternative malloc. Each function should have comment above it detailing the
// context which it runs in.
#include "client/linux/handler/exception_handler.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/limits.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/signal.h>
#include <sys/syscall.h>
#include <sys/ucontext.h>
#include <sys/user.h>
#include <sys/wait.h>
#include <unistd.h>
#include "common/linux/linux_libc_support.h"
#include "common/linux/linux_syscall_support.h"
#include "common/linux/memory.h"
#include "client/linux/minidump_writer//minidump_writer.h"
#include "common/linux/guid_creator.h"
#include "google_breakpad/common/minidump_format.h"
// A wrapper for the tgkill syscall: send a signal to a specific thread.
static int tgkill(pid_t tgid, pid_t tid, int sig) {
syscall(__NR_tgkill, tgid, tid, sig);
}
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
// The list of signals which we consider to be crashes. The default action for
// all these signals must be Core (see man 7 signal) because we rethrow the
// signal after handling it and expect that it'll be fatal.
static const int kExceptionSignals[] = {
SIGSEGV, SIGABRT, SIGFPE, SIGILL, SIGBUS, -1
};
std::vector<ExceptionHandler*> *ExceptionHandler::handler_stack_ = NULL;
int ExceptionHandler::handler_stack_index_ = 0;
// We can stack multiple exception handlers. In that case, this is the global
// which holds the stack.
std::vector<ExceptionHandler*>* ExceptionHandler::handler_stack_ = NULL;
unsigned ExceptionHandler::handler_stack_index_ = 0;
pthread_mutex_t ExceptionHandler::handler_stack_mutex_ =
PTHREAD_MUTEX_INITIALIZER;
PTHREAD_MUTEX_INITIALIZER;
ExceptionHandler::ExceptionHandler(const string &dump_path,
// Runs before crashing: normal context.
ExceptionHandler::ExceptionHandler(const std::string &dump_path,
FilterCallback filter,
MinidumpCallback callback,
void *callback_context,
@ -79,212 +116,76 @@ ExceptionHandler::ExceptionHandler(const string &dump_path,
callback_(callback),
callback_context_(callback_context),
dump_path_(),
installed_handler_(install_handler) {
handler_installed_(install_handler),
crash_handler_(NULL) {
set_dump_path(dump_path);
act_.sa_handler = HandleException;
act_.sa_flags = SA_ONSTACK;
sigemptyset(&act_.sa_mask);
// now, make sure we're blocking all the signals we are handling
// when we're handling any of them
for ( size_t i = 0; i < sizeof(SigTable) / sizeof(SigTable[0]); ++i) {
sigaddset(&act_.sa_mask, SigTable[i]);
}
if (install_handler) {
SetupHandler();
InstallHandlers();
pthread_mutex_lock(&handler_stack_mutex_);
if (handler_stack_ == NULL)
handler_stack_ = new std::vector<ExceptionHandler *>;
handler_stack_->push_back(this);
if (handler_stack_ == NULL)
handler_stack_ = new std::vector<ExceptionHandler *>;
handler_stack_->push_back(this);
pthread_mutex_unlock(&handler_stack_mutex_);
}
}
// Runs before crashing: normal context.
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_);
UninstallHandlers();
}
bool ExceptionHandler::WriteMinidump() {
bool success = InternalWriteMinidump(0, 0, NULL);
UpdateNextID();
return success;
}
// Runs before crashing: normal context.
bool ExceptionHandler::InstallHandlers() {
// We run the signal handlers on an alternative stack because we might have
// crashed because of a stack overflow.
// 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, 0, NULL);
}
// We use this value rather than SIGSTKSZ because we would end up overrunning
// such a small stack.
static const unsigned kSigStackSize = 8192;
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;
signal_stack = malloc(kSigStackSize);
stack_t stack;
memset(&stack, 0, sizeof(stack));
stack.ss_sp = signal_stack;
stack.ss_size = kSigStackSize;
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) {
// We're storing pointers to the old signal action
// structure, rather than copying the structure
// because we can't count on the sa_mask field to
// be scalar.
struct sigaction *old_act = &old_actions_[signo];
if (sigaction(signo, &act_, old_act) < 0)
return;
}
void ExceptionHandler::TeardownHandler(int signo) {
TeardownHandler(signo, NULL);
}
void ExceptionHandler::TeardownHandler(int signo, struct sigaction *final_handler) {
if (old_actions_[signo].sa_handler) {
struct sigaction *act = &old_actions_[signo];
sigaction(signo, act, final_handler);
memset(&old_actions_[signo], 0x0, sizeof(struct sigaction));
}
}
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.
// However, if we are being called by another signal handler passing the
// signal up the chain, then we may not have this random extra parameter,
// so we may have to walk the stack to find it. We do the actual work
// on another thread, where it's a little safer, but we want the ebp
// from this frame to find it.
uintptr_t current_ebp = 0;
asm volatile ("movl %%ebp, %0"
:"=m"(current_ebp));
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.
struct sigaction old_action;
current_handler->TeardownHandler(signo, &old_action);
struct sigcontext *sig_ctx = NULL;
if (current_handler->InternalWriteMinidump(signo, current_ebp, &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.
if (old_action.sa_handler != NULL && sig_ctx != NULL) {
// Have our own typedef, because of the comment above w.r.t signal
// context on the stack
typedef void (*SignalHandler)(int signo, struct sigcontext);
SignalHandler old_handler =
reinterpret_cast<SignalHandler>(old_action.sa_handler);
sigset_t old_set;
// Use SIG_BLOCK here because we don't want to unblock a signal
// that the signal handler we're currently in needs to block
sigprocmask(SIG_BLOCK, &old_action.sa_mask, &old_set);
old_handler(signo, *sig_ctx);
sigprocmask(SIG_SETMASK, &old_set, NULL);
}
}
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,
uintptr_t sighandler_ebp,
struct sigcontext **sig_ctx) {
if (filter_ && !filter_(callback_context_))
if (sigaltstack(&stack, NULL) == -1)
return false;
bool success = false;
// Block all the signals we want to process when writting minidump.
// We don't want it to be interrupted.
sigset_t sig_blocked, sig_old;
bool blocked = true;
sigfillset(&sig_blocked);
for (size_t i = 0; i < sizeof(SigTable) / sizeof(SigTable[0]); ++i)
sigdelset(&sig_blocked, SigTable[i]);
if (sigprocmask(SIG_BLOCK, &sig_blocked, &sig_old) != 0) {
blocked = false;
fprintf(stderr, "google_breakpad::ExceptionHandler::HandleException: "
"failed to block signals.\n");
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
// mask all exception signals when we're handling one of them.
for (unsigned i = 0; kExceptionSignals[i] != -1; ++i)
sigaddset(&sa.sa_mask, kExceptionSignals[i]);
sa.sa_sigaction = SignalHandler;
sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
for (unsigned i = 0; kExceptionSignals[i] != -1; ++i) {
struct sigaction* old = new struct sigaction;
if (sigaction(kExceptionSignals[i], &sa, old) == -1)
return false;
old_handlers_.push_back(std::make_pair(kExceptionSignals[i], old));
}
success = minidump_generator_.WriteMinidumpToFile(
next_minidump_path_c_, signo, sighandler_ebp, sig_ctx);
// Unblock the signals.
if (blocked) {
sigprocmask(SIG_SETMASK, &sig_old, NULL);
}
if (callback_)
success = callback_(dump_path_c_, next_minidump_id_c_,
callback_context_, success);
return success;
}
// Runs before crashing: normal context.
void ExceptionHandler::UninstallHandlers() {
for (unsigned i = 0; i < old_handlers_.size(); ++i) {
struct sigaction *action =
reinterpret_cast<struct sigaction*>(old_handlers_[i].second);
sigaction(old_handlers_[i].first, action, NULL);
delete action;
}
old_handlers_.clear();
}
// Runs before crashing: normal context.
void ExceptionHandler::UpdateNextID() {
GUID guid;
char guid_str[kGUIDStringLength + 1];
@ -302,4 +203,120 @@ void ExceptionHandler::UpdateNextID() {
}
}
// This function runs in a compromised context: see the top of the file.
// Runs on the crashing thread.
// static
void ExceptionHandler::SignalHandler(int sig, siginfo_t* info, void* uc) {
// All the exception signals are blocked at this point.
pthread_mutex_lock(&handler_stack_mutex_);
if (!handler_stack_->size()) {
pthread_mutex_unlock(&handler_stack_mutex_);
return;
}
for (int i = handler_stack_->size() - 1; i >= 0; --i) {
if ((*handler_stack_)[i]->HandleSignal(sig, info, uc)) {
// successfully handled: We are in an invalid state since an exception
// signal has been delivered. We don't call the exit handlers because
// they could end up corrupting on-disk state.
break;
}
}
pthread_mutex_unlock(&handler_stack_mutex_);
// Terminate ourselves with the same signal so that our parent knows that we
// crashed. The default action for all the signals which we catch is Core, so
// this is the end of us.
signal(sig, SIG_DFL);
tgkill(getpid(), sys_gettid(), sig);
// not reached.
}
struct ThreadArgument {
pid_t pid; // the crashing process
ExceptionHandler* handler;
const void* context; // a CrashContext structure
size_t context_size;
};
// This is the entry function for the cloned process. We are in a compromised
// context here: see the top of the file.
// static
int ExceptionHandler::ThreadEntry(void *arg) {
const ThreadArgument *thread_arg = reinterpret_cast<ThreadArgument*>(arg);
return thread_arg->handler->DoDump(thread_arg->pid, thread_arg->context,
thread_arg->context_size) == false;
}
// This function runs in a compromised context: see the top of the file.
// Runs on the crashing thread.
bool ExceptionHandler::HandleSignal(int sig, siginfo_t* info, void* uc) {
if (filter_ && !filter_(callback_context_))
return false;
// Allow ourselves to be dumped.
sys_prctl(PR_SET_DUMPABLE, 1);
CrashContext context;
memcpy(&context.siginfo, info, sizeof(siginfo_t));
memcpy(&context.context, uc, sizeof(struct ucontext));
memcpy(&context.float_state, ((struct ucontext *)uc)->uc_mcontext.fpregs,
sizeof(context.float_state));
context.tid = sys_gettid();
if (crash_handler_ && crash_handler_(&context, sizeof(context),
callback_context_))
return true;
static const unsigned kChildStackSize = 8000;
PageAllocator allocator;
uint8_t* stack = (uint8_t*) allocator.Alloc(kChildStackSize);
if (!stack)
return false;
// clone() needs the top-most address. (scrub just to be safe)
stack += kChildStackSize;
my_memset(stack - 16, 0, 16);
ThreadArgument thread_arg;
thread_arg.handler = this;
thread_arg.pid = getpid();
thread_arg.context = &context;
thread_arg.context_size = sizeof(context);
const pid_t child = sys_clone(
ThreadEntry, stack, CLONE_FILES | CLONE_FS | CLONE_UNTRACED,
&thread_arg, NULL, NULL, NULL);
int r, status;
do {
r = sys_waitpid(child, &status, __WALL);
} while (r == -1 && errno == EINTR);
if (r == -1) {
static const char msg[] = "ExceptionHandler::HandleSignal: waitpid failed:";
sys_write(2, msg, sizeof(msg) - 1);
sys_write(2, strerror(errno), strlen(strerror(errno)));
sys_write(2, "\n", 1);
}
bool success = r != -1 && WIFEXITED(status) && WEXITSTATUS(status) == 0;
if (callback_)
success = callback_(dump_path_c_, next_minidump_id_c_,
callback_context_, success);
return success;
}
// This function runs in a compromised context: see the top of the file.
// Runs on the cloned process.
bool ExceptionHandler::DoDump(pid_t crashing_process, const void* context,
size_t context_size) {
return google_breakpad::WriteMinidump(
next_minidump_path_c_, crashing_process, context, context_size);
}
} // namespace google_breakpad