diff options
Diffstat (limited to 'Modules/faulthandler.c')
| -rw-r--r-- | Modules/faulthandler.c | 1329 |
1 files changed, 1329 insertions, 0 deletions
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c new file mode 100644 index 0000000000..51c66bdd65 --- /dev/null +++ b/Modules/faulthandler.c @@ -0,0 +1,1329 @@ +#include "Python.h" +#include "pythread.h" +#include <signal.h> +#include <object.h> +#include <frameobject.h> +#include <signal.h> +#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) +#include <pthread.h> +#endif + +/* Allocate at maximum 100 MB of the stack to raise the stack overflow */ +#define STACK_OVERFLOW_MAX_SIZE (100*1024*1024) + +#ifdef WITH_THREAD +# define FAULTHANDLER_LATER +# define FAULTHANDLER_WATCHDOG +#endif + +#ifndef MS_WINDOWS + /* register() is useless on Windows, because only SIGSEGV, SIGABRT and + SIGILL can be handled by the process, and these signals can only be used + with enable(), not using register() */ +# define FAULTHANDLER_USER +#endif + +#define PUTS(fd, str) write(fd, str, strlen(str)) + +#ifdef HAVE_SIGACTION +typedef struct sigaction _Py_sighandler_t; +#else +typedef PyOS_sighandler_t _Py_sighandler_t; +#endif + +typedef struct { + int signum; + int enabled; + const char* name; + _Py_sighandler_t previous; + int all_threads; +} fault_handler_t; + +static struct { + int enabled; + PyObject *file; + int fd; + int all_threads; + PyInterpreterState *interp; +} fatal_error = {0, NULL, -1, 0}; + +#ifdef FAULTHANDLER_LATER +static struct { + PyObject *file; + int fd; + PY_TIMEOUT_T timeout_us; /* timeout in microseconds */ + int repeat; + PyInterpreterState *interp; + int exit; + char *header; + size_t header_len; + /* The main thread always holds this lock. It is only released when + faulthandler_thread() is interrupted before this thread exits, or at + Python exit. */ + PyThread_type_lock cancel_event; + /* released by child thread when joined */ + PyThread_type_lock running; +} thread; +#endif + +#ifdef FAULTHANDLER_WATCHDOG +static struct { + int rfd; + int wfd; + PY_TIMEOUT_T period_us; /* period in microseconds */ + /* The main thread always holds this lock. It is only released when + faulthandler_watchdog() is interrupted before this thread exits, or at + Python exit. */ + PyThread_type_lock cancel_event; + /* released by child thread when joined */ + PyThread_type_lock running; +} watchdog; +#endif + +#ifdef FAULTHANDLER_USER +typedef struct { + int enabled; + PyObject *file; + int fd; + int all_threads; + int chain; + _Py_sighandler_t previous; + PyInterpreterState *interp; +} user_signal_t; + +static user_signal_t *user_signals; + +/* the following macros come from Python: Modules/signalmodule.c */ +#if defined(PYOS_OS2) && !defined(PYCC_GCC) +#define NSIG 12 +#endif +#ifndef NSIG +# if defined(_NSIG) +# define NSIG _NSIG /* For BSD/SysV */ +# elif defined(_SIGMAX) +# define NSIG (_SIGMAX + 1) /* For QNX */ +# elif defined(SIGMAX) +# define NSIG (SIGMAX + 1) /* For djgpp */ +# else +# define NSIG 64 /* Use a reasonable default value */ +# endif +#endif + +static void faulthandler_user(int signum); +#endif /* FAULTHANDLER_USER */ + + +static fault_handler_t faulthandler_handlers[] = { +#ifdef SIGBUS + {SIGBUS, 0, "Bus error", }, +#endif +#ifdef SIGILL + {SIGILL, 0, "Illegal instruction", }, +#endif + {SIGFPE, 0, "Floating point exception", }, + {SIGABRT, 0, "Aborted", }, + /* define SIGSEGV at the end to make it the default choice if searching the + handler fails in faulthandler_fatal_error() */ + {SIGSEGV, 0, "Segmentation fault", } +}; +static const unsigned char faulthandler_nsignals = \ + Py_ARRAY_LENGTH(faulthandler_handlers); + +#ifdef HAVE_SIGALTSTACK +static stack_t stack; +#endif + + +/* Get the file descriptor of a file by calling its fileno() method and then + call its flush() method. + + If file is NULL or Py_None, use sys.stderr as the new file. + + On success, return the new file and write the file descriptor into *p_fd. + On error, return NULL. */ + +static PyObject* +faulthandler_get_fileno(PyObject *file, int *p_fd) +{ + PyObject *result; + _Py_IDENTIFIER(fileno); + _Py_IDENTIFIER(flush); + long fd_long; + int fd; + + if (file == NULL || file == Py_None) { + file = PySys_GetObject("stderr"); + if (file == NULL) { + PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr"); + return NULL; + } + } + + result = _PyObject_CallMethodId(file, &PyId_fileno, ""); + if (result == NULL) + return NULL; + + fd = -1; + if (PyLong_Check(result)) { + fd_long = PyLong_AsLong(result); + if (0 <= fd_long && fd_long < INT_MAX) + fd = (int)fd_long; + } + Py_DECREF(result); + + if (fd == -1) { + PyErr_SetString(PyExc_RuntimeError, + "file.fileno() is not a valid file descriptor"); + return NULL; + } + + result = _PyObject_CallMethodId(file, &PyId_flush, ""); + if (result != NULL) + Py_DECREF(result); + else { + /* ignore flush() error */ + PyErr_Clear(); + } + *p_fd = fd; + return file; +} + +/* Get the state of the current thread: only call this function if the current + thread holds the GIL. Raise an exception on error. */ +static PyThreadState* +get_thread_state(void) +{ + PyThreadState *tstate = PyThreadState_Get(); + if (tstate == NULL) { + PyErr_SetString(PyExc_RuntimeError, + "unable to get the current thread state"); + return NULL; + } + return tstate; +} + +static PyObject* +faulthandler_dump_traceback_py(PyObject *self, + PyObject *args, PyObject *kwargs) +{ + static char *kwlist[] = {"file", "all_threads", NULL}; + PyObject *file = NULL; + int all_threads = 1; + PyThreadState *tstate; + const char *errmsg; + int fd; + + if (!PyArg_ParseTupleAndKeywords(args, kwargs, + "|Oi:dump_traceback", kwlist, + &file, &all_threads)) + return NULL; + + file = faulthandler_get_fileno(file, &fd); + if (file == NULL) + return NULL; + + tstate = get_thread_state(); + if (tstate == NULL) + return NULL; + + if (all_threads) { + errmsg = _Py_DumpTracebackThreads(fd, tstate->interp, tstate); + if (errmsg != NULL) { + PyErr_SetString(PyExc_RuntimeError, errmsg); + return NULL; + } + } + else { + _Py_DumpTraceback(fd, tstate); + } + Py_RETURN_NONE; +} + + +/* Handler for SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL signals. + + Display the current Python traceback, restore the previous handler and call + the previous handler. + + On Windows, don't explicitly call the previous handler, because the Windows + signal handler would not be called (for an unknown reason). The execution of + the program continues at faulthandler_fatal_error() exit, but the same + instruction will raise the same fault (signal), and so the previous handler + will be called. + + This function is signal-safe and should only call signal-safe functions. */ + +static void +faulthandler_fatal_error(int signum) +{ + const int fd = fatal_error.fd; + unsigned int i; + fault_handler_t *handler = NULL; + PyThreadState *tstate; + int save_errno = errno; + + if (!fatal_error.enabled) + return; + + for (i=0; i < faulthandler_nsignals; i++) { + handler = &faulthandler_handlers[i]; + if (handler->signum == signum) + break; + } + if (handler == NULL) { + /* faulthandler_nsignals == 0 (unlikely) */ + return; + } + + /* restore the previous handler */ +#ifdef HAVE_SIGACTION + (void)sigaction(signum, &handler->previous, NULL); +#else + (void)signal(signum, handler->previous); +#endif + handler->enabled = 0; + + PUTS(fd, "Fatal Python error: "); + PUTS(fd, handler->name); + PUTS(fd, "\n\n"); + +#ifdef WITH_THREAD + /* SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL are synchronous signals and + are thus delivered to the thread that caused the fault. Get the Python + thread state of the current thread. + + PyThreadState_Get() doesn't give the state of the thread that caused the + fault if the thread released the GIL, and so this function cannot be + used. Read the thread local storage (TLS) instead: call + PyGILState_GetThisThreadState(). */ + tstate = PyGILState_GetThisThreadState(); +#else + tstate = PyThreadState_Get(); +#endif + + if (fatal_error.all_threads) + _Py_DumpTracebackThreads(fd, fatal_error.interp, tstate); + else { + if (tstate != NULL) + _Py_DumpTraceback(fd, tstate); + } + + errno = save_errno; +#ifdef MS_WINDOWS + if (signum == SIGSEGV) { + /* don't explicitly call the previous handler for SIGSEGV in this signal + handler, because the Windows signal handler would not be called */ + return; + } +#endif + /* call the previous signal handler: it is called immediatly if we use + sigaction() thanks to SA_NODEFER flag, otherwise it is deferred */ + raise(signum); +} + +/* Install the handler for fatal signals, faulthandler_fatal_error(). */ + +static PyObject* +faulthandler_enable(PyObject *self, PyObject *args, PyObject *kwargs) +{ + static char *kwlist[] = {"file", "all_threads", NULL}; + PyObject *file = NULL; + int all_threads = 1; + unsigned int i; + fault_handler_t *handler; +#ifdef HAVE_SIGACTION + struct sigaction action; +#endif + int err; + int fd; + PyThreadState *tstate; + + if (!PyArg_ParseTupleAndKeywords(args, kwargs, + "|Oi:enable", kwlist, &file, &all_threads)) + return NULL; + + file = faulthandler_get_fileno(file, &fd); + if (file == NULL) + return NULL; + + tstate = get_thread_state(); + if (tstate == NULL) + return NULL; + + Py_XDECREF(fatal_error.file); + Py_INCREF(file); + fatal_error.file = file; + fatal_error.fd = fd; + fatal_error.all_threads = all_threads; + fatal_error.interp = tstate->interp; + + if (!fatal_error.enabled) { + fatal_error.enabled = 1; + + for (i=0; i < faulthandler_nsignals; i++) { + handler = &faulthandler_handlers[i]; +#ifdef HAVE_SIGACTION + action.sa_handler = faulthandler_fatal_error; + sigemptyset(&action.sa_mask); + /* Do not prevent the signal from being received from within + its own signal handler */ + action.sa_flags = SA_NODEFER; +#ifdef HAVE_SIGALTSTACK + if (stack.ss_sp != NULL) { + /* Call the signal handler on an alternate signal stack + provided by sigaltstack() */ + action.sa_flags |= SA_ONSTACK; + } +#endif + err = sigaction(handler->signum, &action, &handler->previous); +#else + handler->previous = signal(handler->signum, + faulthandler_fatal_error); + err = (handler->previous == SIG_ERR); +#endif + if (err) { + PyErr_SetFromErrno(PyExc_RuntimeError); + return NULL; + } + handler->enabled = 1; + } + } + Py_RETURN_NONE; +} + +static void +faulthandler_disable(void) +{ + unsigned int i; + fault_handler_t *handler; + + if (fatal_error.enabled) { + fatal_error.enabled = 0; + for (i=0; i < faulthandler_nsignals; i++) { + handler = &faulthandler_handlers[i]; + if (!handler->enabled) + continue; +#ifdef HAVE_SIGACTION + (void)sigaction(handler->signum, &handler->previous, NULL); +#else + (void)signal(handler->signum, handler->previous); +#endif + handler->enabled = 0; + } + } + + Py_CLEAR(fatal_error.file); +} + +static PyObject* +faulthandler_disable_py(PyObject *self) +{ + if (!fatal_error.enabled) { + Py_INCREF(Py_False); + return Py_False; + } + faulthandler_disable(); + Py_INCREF(Py_True); + return Py_True; +} + +static PyObject* +faulthandler_is_enabled(PyObject *self) +{ + return PyBool_FromLong(fatal_error.enabled); +} + +#ifdef FAULTHANDLER_LATER + +static void +faulthandler_thread(void *unused) +{ + PyLockStatus st; + const char* errmsg; + PyThreadState *current; + int ok; +#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) + sigset_t set; + + /* we don't want to receive any signal */ + sigfillset(&set); + pthread_sigmask(SIG_SETMASK, &set, NULL); +#endif + + do { + st = PyThread_acquire_lock_timed(thread.cancel_event, + thread.timeout_us, 0); + if (st == PY_LOCK_ACQUIRED) { + PyThread_release_lock(thread.cancel_event); + break; + } + /* Timeout => dump traceback */ + assert(st == PY_LOCK_FAILURE); + + /* get the thread holding the GIL, NULL if no thread hold the GIL */ + current = _Py_atomic_load_relaxed(&_PyThreadState_Current); + + write(thread.fd, thread.header, thread.header_len); + + errmsg = _Py_DumpTracebackThreads(thread.fd, thread.interp, current); + ok = (errmsg == NULL); + + if (thread.exit) + _exit(1); + } while (ok && thread.repeat); + + /* The only way out */ + PyThread_release_lock(thread.running); +} + +static void +cancel_dump_tracebacks_later(void) +{ + /* Notify cancellation */ + PyThread_release_lock(thread.cancel_event); + + /* Wait for thread to join */ + PyThread_acquire_lock(thread.running, 1); + PyThread_release_lock(thread.running); + + /* The main thread should always hold the cancel_event lock */ + PyThread_acquire_lock(thread.cancel_event, 1); + + Py_CLEAR(thread.file); + if (thread.header) { + free(thread.header); + thread.header = NULL; + } +} + +static char* +format_timeout(double timeout) +{ + unsigned long us, sec, min, hour; + double intpart, fracpart; + char buffer[100]; + + fracpart = modf(timeout, &intpart); + sec = (unsigned long)intpart; + us = (unsigned long)(fracpart * 1e6); + min = sec / 60; + sec %= 60; + hour = min / 60; + min %= 60; + + if (us != 0) + PyOS_snprintf(buffer, sizeof(buffer), + "Timeout (%lu:%02lu:%02lu.%06lu)!\n", + hour, min, sec, us); + else + PyOS_snprintf(buffer, sizeof(buffer), + "Timeout (%lu:%02lu:%02lu)!\n", + hour, min, sec); + + return strdup(buffer); +} + +static PyObject* +faulthandler_dump_tracebacks_later(PyObject *self, + PyObject *args, PyObject *kwargs) +{ + static char *kwlist[] = {"timeout", "repeat", "file", "exit", NULL}; + double timeout; + PY_TIMEOUT_T timeout_us; + int repeat = 0; + PyObject *file = NULL; + int fd; + int exit = 0; + PyThreadState *tstate; + char *header; + size_t header_len; + + if (!PyArg_ParseTupleAndKeywords(args, kwargs, + "d|iOi:dump_tracebacks_later", kwlist, + &timeout, &repeat, &file, &exit)) + return NULL; + if ((timeout * 1e6) >= (double) PY_TIMEOUT_MAX) { + PyErr_SetString(PyExc_OverflowError, "timeout value is too large"); + return NULL; + } + timeout_us = (PY_TIMEOUT_T)(timeout * 1e6); + if (timeout_us <= 0) { + PyErr_SetString(PyExc_ValueError, "timeout must be greater than 0"); + return NULL; + } + + tstate = get_thread_state(); + if (tstate == NULL) + return NULL; + + file = faulthandler_get_fileno(file, &fd); + if (file == NULL) + return NULL; + + /* format the timeout */ + header = format_timeout(timeout); + if (header == NULL) + return PyErr_NoMemory(); + header_len = strlen(header); + + /* Cancel previous thread, if running */ + cancel_dump_tracebacks_later(); + + Py_XDECREF(thread.file); + Py_INCREF(file); + thread.file = file; + thread.fd = fd; + thread.timeout_us = timeout_us; + thread.repeat = repeat; + thread.interp = tstate->interp; + thread.exit = exit; + thread.header = header; + thread.header_len = header_len; + + /* Arm these locks to serve as events when released */ + PyThread_acquire_lock(thread.running, 1); + + if (PyThread_start_new_thread(faulthandler_thread, NULL) == -1) { + PyThread_release_lock(thread.running); + Py_CLEAR(thread.file); + free(header); + thread.header = NULL; + PyErr_SetString(PyExc_RuntimeError, + "unable to start watchdog thread"); + return NULL; + } + + Py_RETURN_NONE; +} + +static PyObject* +faulthandler_cancel_dump_tracebacks_later_py(PyObject *self) +{ + cancel_dump_tracebacks_later(); + Py_RETURN_NONE; +} +#endif /* FAULTHANDLER_LATER */ + +#ifdef FAULTHANDLER_WATCHDOG + +static void +file_watchdog(void *unused) +{ + PyLockStatus st; + PY_TIMEOUT_T timeout; + +#define MAXDATA 1024 + char buf1[MAXDATA], buf2[MAXDATA]; + char *data = buf1, *old_data = buf2; + Py_ssize_t data_len, old_data_len = -1; + +#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) + sigset_t set; + + /* we don't want to receive any signal */ + sigfillset(&set); + pthread_sigmask(SIG_SETMASK, &set, NULL); +#endif + + /* On first pass, feed file contents immediately */ + timeout = 0; + do { + st = PyThread_acquire_lock_timed(watchdog.cancel_event, + timeout, 0); + timeout = watchdog.period_us; + if (st == PY_LOCK_ACQUIRED) { + PyThread_release_lock(watchdog.cancel_event); + break; + } + /* Timeout => read and write data */ + assert(st == PY_LOCK_FAILURE); + + if (lseek(watchdog.rfd, 0, SEEK_SET) < 0) { + break; + } + data_len = read(watchdog.rfd, data, MAXDATA); + if (data_len < 0) { + break; + } + if (data_len != old_data_len || memcmp(data, old_data, data_len)) { + char *tdata; + Py_ssize_t tlen; + /* Contents changed, feed them to wfd */ + long x = (long) data_len; + /* We can't do anything if the consumer is too slow, just bail out */ + if (write(watchdog.wfd, (void *) &x, sizeof(x)) < sizeof(x)) + break; + if (write(watchdog.wfd, data, data_len) < data_len) + break; + tdata = data; + data = old_data; + old_data = tdata; + tlen = data_len; + data_len = old_data_len; + old_data_len = tlen; + } + } while (1); + + close(watchdog.rfd); + close(watchdog.wfd); + + /* The only way out */ + PyThread_release_lock(watchdog.running); +#undef MAXDATA +} + +static void +cancel_file_watchdog(void) +{ + /* Notify cancellation */ + PyThread_release_lock(watchdog.cancel_event); + + /* Wait for thread to join */ + PyThread_acquire_lock(watchdog.running, 1); + PyThread_release_lock(watchdog.running); + + /* The main thread should always hold the cancel_event lock */ + PyThread_acquire_lock(watchdog.cancel_event, 1); +} + +static PyObject* +faulthandler_file_watchdog(PyObject *self, + PyObject *args, PyObject *kwargs) +{ + static char *kwlist[] = {"rfd", "wfd", "period", NULL}; + double period; + PY_TIMEOUT_T period_us; + int rfd, wfd; + + if (!PyArg_ParseTupleAndKeywords(args, kwargs, + "iid:_file_watchdog", kwlist, + &rfd, &wfd, &period)) + return NULL; + if ((period * 1e6) >= (double) PY_TIMEOUT_MAX) { + PyErr_SetString(PyExc_OverflowError, "period value is too large"); + return NULL; + } + period_us = (PY_TIMEOUT_T)(period * 1e6); + if (period_us <= 0) { + PyErr_SetString(PyExc_ValueError, "period must be greater than 0"); + return NULL; + } + + /* Cancel previous thread, if running */ + cancel_file_watchdog(); + + watchdog.rfd = rfd; + watchdog.wfd = wfd; + watchdog.period_us = period_us; + + /* Arm these locks to serve as events when released */ + PyThread_acquire_lock(watchdog.running, 1); + + if (PyThread_start_new_thread(file_watchdog, NULL) == -1) { + PyThread_release_lock(watchdog.running); + PyErr_SetString(PyExc_RuntimeError, + "unable to start file watchdog thread"); + return NULL; + } + + Py_RETURN_NONE; +} + +static PyObject* +faulthandler_cancel_file_watchdog(PyObject *self) +{ + cancel_file_watchdog(); + Py_RETURN_NONE; +} +#endif /* FAULTHANDLER_WATCHDOG */ + +#ifdef FAULTHANDLER_USER +static int +faulthandler_register(int signum, int chain, _Py_sighandler_t *p_previous) +{ +#ifdef HAVE_SIGACTION + struct sigaction action; + action.sa_handler = faulthandler_user; + sigemptyset(&action.sa_mask); + /* if the signal is received while the kernel is executing a system + call, try to restart the system call instead of interrupting it and + return EINTR. */ + action.sa_flags = SA_RESTART; + if (chain) { + /* do not prevent the signal from being received from within its + own signal handler */ + action.sa_flags = SA_NODEFER; + } +#ifdef HAVE_SIGALTSTACK + if (stack.ss_sp != NULL) { + /* Call the signal handler on an alternate signal stack + provided by sigaltstack() */ + action.sa_flags |= SA_ONSTACK; + } +#endif + return sigaction(signum, &action, p_previous); +#else + _Py_sighandler_t previous; + previous = signal(signum, faulthandler_user); + if (p_previous != NULL) + *p_previous = previous; + return (previous == SIG_ERR); +#endif +} + +/* Handler of user signals (e.g. SIGUSR1). + + Dump the traceback of the current thread, or of all threads if + thread.all_threads is true. + + This function is signal safe and should only call signal safe functions. */ + +static void +faulthandler_user(int signum) +{ + user_signal_t *user; + PyThreadState *tstate; + int save_errno = errno; + + user = &user_signals[signum]; + if (!user->enabled) + return; + +#ifdef WITH_THREAD + /* PyThreadState_Get() doesn't give the state of the current thread if + the thread doesn't hold the GIL. Read the thread local storage (TLS) + instead: call PyGILState_GetThisThreadState(). */ + tstate = PyGILState_GetThisThreadState(); +#else + tstate = PyThreadState_Get(); +#endif + + if (user->all_threads) + _Py_DumpTracebackThreads(user->fd, user->interp, tstate); + else { + if (tstate == NULL) + return; + _Py_DumpTraceback(user->fd, tstate); + } +#ifdef HAVE_SIGACTION + if (user->chain) { + (void)sigaction(signum, &user->previous, NULL); + /* call the previous signal handler */ + raise(signum); + (void)faulthandler_register(signum, user->chain, NULL); + } +#else + if (user->chain) { + /* call the previous signal handler */ + user->previous(signum); + } +#endif + errno = save_errno; +} + +static int +check_signum(int signum) +{ + unsigned int i; + + for (i=0; i < faulthandler_nsignals; i++) { + if (faulthandler_handlers[i].signum == signum) { + PyErr_Format(PyExc_RuntimeError, + "signal %i cannot be registered, " + "use enable() instead", + signum); + return 0; + } + } + if (signum < 1 || NSIG <= signum) { + PyErr_SetString(PyExc_ValueError, "signal number out of range"); + return 0; + } + return 1; +} + +static PyObject* +faulthandler_register_py(PyObject *self, + PyObject *args, PyObject *kwargs) +{ + static char *kwlist[] = {"signum", "file", "all_threads", "chain", NULL}; + int signum; + PyObject *file = NULL; + int all_threads = 1; + int chain = 0; + int fd; + user_signal_t *user; + _Py_sighandler_t previous; + PyThreadState *tstate; + int err; + + if (!PyArg_ParseTupleAndKeywords(args, kwargs, + "i|Oii:register", kwlist, + &signum, &file, &all_threads, &chain)) + return NULL; + + if (!check_signum(signum)) + return NULL; + + tstate = get_thread_state(); + if (tstate == NULL) + return NULL; + + file = faulthandler_get_fileno(file, &fd); + if (file == NULL) + return NULL; + + if (user_signals == NULL) { + user_signals = calloc(NSIG, sizeof(user_signal_t)); + if (user_signals == NULL) + return PyErr_NoMemory(); + } + user = &user_signals[signum]; + + if (!user->enabled) { + err = faulthandler_register(signum, chain, &previous); + if (err) { + PyErr_SetFromErrno(PyExc_OSError); + return NULL; + } + } + + Py_XDECREF(user->file); + Py_INCREF(file); + user->file = file; + user->fd = fd; + user->all_threads = all_threads; + user->chain = chain; + user->previous = previous; + user->interp = tstate->interp; + user->enabled = 1; + + Py_RETURN_NONE; +} + +static int +faulthandler_unregister(user_signal_t *user, int signum) +{ + if (!user->enabled) + return 0; + user->enabled = 0; +#ifdef HAVE_SIGACTION + (void)sigaction(signum, &user->previous, NULL); +#else + (void)signal(signum, user->previous); +#endif + Py_CLEAR(user->file); + user->fd = -1; + return 1; +} + +static PyObject* +faulthandler_unregister_py(PyObject *self, PyObject *args) +{ + int signum; + user_signal_t *user; + int change; + + if (!PyArg_ParseTuple(args, "i:unregister", &signum)) + return NULL; + + if (!check_signum(signum)) + return NULL; + + if (user_signals == NULL) + Py_RETURN_FALSE; + + user = &user_signals[signum]; + change = faulthandler_unregister(user, signum); + return PyBool_FromLong(change); +} +#endif /* FAULTHANDLER_USER */ + + +static PyObject * +faulthandler_read_null(PyObject *self, PyObject *args) +{ + int *x = NULL, y; + int release_gil = 0; + if (!PyArg_ParseTuple(args, "|i:_read_null", &release_gil)) + return NULL; + if (release_gil) { + Py_BEGIN_ALLOW_THREADS + y = *x; + Py_END_ALLOW_THREADS + } else + y = *x; + return PyLong_FromLong(y); + +} + +static PyObject * +faulthandler_sigsegv(PyObject *self, PyObject *args) +{ +#if defined(MS_WINDOWS) + /* For SIGSEGV, faulthandler_fatal_error() restores the previous signal + handler and then gives back the execution flow to the program (without + explicitly calling the previous error handler). In a normal case, the + SIGSEGV was raised by the kernel because of a fault, and so if the + program retries to execute the same instruction, the fault will be + raised again. + + Here the fault is simulated by a fake SIGSEGV signal raised by the + application. We have to raise SIGSEGV at lease twice: once for + faulthandler_fatal_error(), and one more time for the previous signal + handler. */ + while(1) + raise(SIGSEGV); +#else + raise(SIGSEGV); +#endif + Py_RETURN_NONE; +} + +static PyObject * +faulthandler_sigfpe(PyObject *self, PyObject *args) +{ + /* Do an integer division by zero: raise a SIGFPE on Intel CPU, but not on + PowerPC. Use volatile to disable compile-time optimizations. */ + volatile int x = 1, y = 0, z; + z = x / y; + /* If the division by zero didn't raise a SIGFPE (e.g. on PowerPC), + raise it manually. */ + raise(SIGFPE); + /* This line is never reached, but we pretend to make something with z + to silence a compiler warning. */ + return PyLong_FromLong(z); +} + +static PyObject * +faulthandler_sigabrt(PyObject *self, PyObject *args) +{ +#ifdef _MSC_VER + /* Visual Studio: configure abort() to not display an error message nor + open a popup asking to report the fault. */ + _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT); +#endif + abort(); + Py_RETURN_NONE; +} + +#ifdef SIGBUS +static PyObject * +faulthandler_sigbus(PyObject *self, PyObject *args) +{ + raise(SIGBUS); + Py_RETURN_NONE; +} +#endif + +#ifdef SIGILL +static PyObject * +faulthandler_sigill(PyObject *self, PyObject *args) +{ + raise(SIGILL); + Py_RETURN_NONE; +} +#endif + +static PyObject * +faulthandler_fatal_error_py(PyObject *self, PyObject *args) +{ + char *message; + if (!PyArg_ParseTuple(args, "y:fatal_error", &message)) + return NULL; + Py_FatalError(message); + Py_RETURN_NONE; +} + +#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION) +static void* +stack_overflow(void *min_sp, void *max_sp, size_t *depth) +{ + /* allocate 4096 bytes on the stack at each call */ + unsigned char buffer[4096]; + void *sp = &buffer; + *depth += 1; + if (sp < min_sp || max_sp < sp) + return sp; + buffer[0] = 1; + buffer[4095] = 0; + return stack_overflow(min_sp, max_sp, depth); +} + +static PyObject * +faulthandler_stack_overflow(PyObject *self) +{ + size_t depth, size; + char *sp = (char *)&depth, *stop; + + depth = 0; + stop = stack_overflow(sp - STACK_OVERFLOW_MAX_SIZE, + sp + STACK_OVERFLOW_MAX_SIZE, + &depth); + if (sp < stop) + size = stop - sp; + else + size = sp - stop; + PyErr_Format(PyExc_RuntimeError, + "unable to raise a stack overflow (allocated %zu bytes " + "on the stack, %zu recursive calls)", + size, depth); + return NULL; +} +#endif + + +static int +faulthandler_traverse(PyObject *module, visitproc visit, void *arg) +{ +#ifdef FAULTHANDLER_USER + unsigned int signum; +#endif + +#ifdef FAULTHANDLER_LATER + Py_VISIT(thread.file); +#endif +#ifdef FAULTHANDLER_USER + if (user_signals != NULL) { + for (signum=0; signum < NSIG; signum++) + Py_VISIT(user_signals[signum].file); + } +#endif + Py_VISIT(fatal_error.file); + return 0; +} + +PyDoc_STRVAR(module_doc, +"faulthandler module."); + +static PyMethodDef module_methods[] = { + {"enable", + (PyCFunction)faulthandler_enable, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("enable(file=sys.stderr, all_threads=True): " + "enable the fault handler")}, + {"disable", (PyCFunction)faulthandler_disable_py, METH_NOARGS, + PyDoc_STR("disable(): disable the fault handler")}, + {"is_enabled", (PyCFunction)faulthandler_is_enabled, METH_NOARGS, + PyDoc_STR("is_enabled()->bool: check if the handler is enabled")}, + {"dump_traceback", + (PyCFunction)faulthandler_dump_traceback_py, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("dump_traceback(file=sys.stderr, all_threads=True): " + "dump the traceback of the current thread, or of all threads " + "if all_threads is True, into file")}, +#ifdef FAULTHANDLER_LATER + {"dump_tracebacks_later", + (PyCFunction)faulthandler_dump_tracebacks_later, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("dump_tracebacks_later(timeout, repeat=False, file=sys.stderrn, exit=False):\n" + "dump the traceback of all threads in timeout seconds,\n" + "or each timeout seconds if repeat is True. If exit is True, " + "call _exit(1) which is not safe.")}, + {"cancel_dump_tracebacks_later", + (PyCFunction)faulthandler_cancel_dump_tracebacks_later_py, METH_NOARGS, + PyDoc_STR("cancel_dump_tracebacks_later():\ncancel the previous call " + "to dump_tracebacks_later().")}, +#endif + +#ifdef FAULTHANDLER_WATCHDOG + {"_file_watchdog", + (PyCFunction)faulthandler_file_watchdog, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("_file_watchdog(rfd, wfd, period):\n" + "feed the contents of 'rfd' to 'wfd', if changed,\n" + "every 'period seconds'.")}, + {"_cancel_file_watchdog", + (PyCFunction)faulthandler_cancel_file_watchdog, METH_NOARGS, + PyDoc_STR("_cancel_file_watchdog():\ncancel the previous call " + "to _file_watchdog().")}, +#endif + +#ifdef FAULTHANDLER_USER + {"register", + (PyCFunction)faulthandler_register_py, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("register(signum, file=sys.stderr, all_threads=True, chain=False): " + "register an handler for the signal 'signum': dump the " + "traceback of the current thread, or of all threads if " + "all_threads is True, into file")}, + {"unregister", + faulthandler_unregister_py, METH_VARARGS|METH_KEYWORDS, + PyDoc_STR("unregister(signum): unregister the handler of the signal " + "'signum' registered by register()")}, +#endif + + {"_read_null", faulthandler_read_null, METH_VARARGS, + PyDoc_STR("_read_null(release_gil=False): read from NULL, raise " + "a SIGSEGV or SIGBUS signal depending on the platform")}, + {"_sigsegv", faulthandler_sigsegv, METH_VARARGS, + PyDoc_STR("_sigsegv(): raise a SIGSEGV signal")}, + {"_sigabrt", faulthandler_sigabrt, METH_VARARGS, + PyDoc_STR("_sigabrt(): raise a SIGABRT signal")}, + {"_sigfpe", (PyCFunction)faulthandler_sigfpe, METH_NOARGS, + PyDoc_STR("_sigfpe(): raise a SIGFPE signal")}, +#ifdef SIGBUS + {"_sigbus", (PyCFunction)faulthandler_sigbus, METH_NOARGS, + PyDoc_STR("_sigbus(): raise a SIGBUS signal")}, +#endif +#ifdef SIGILL + {"_sigill", (PyCFunction)faulthandler_sigill, METH_NOARGS, + PyDoc_STR("_sigill(): raise a SIGILL signal")}, +#endif + {"_fatal_error", faulthandler_fatal_error_py, METH_VARARGS, + PyDoc_STR("_fatal_error(message): call Py_FatalError(message)")}, +#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION) + {"_stack_overflow", (PyCFunction)faulthandler_stack_overflow, METH_NOARGS, + PyDoc_STR("_stack_overflow(): recursive call to raise a stack overflow")}, +#endif + {NULL, NULL} /* sentinel */ +}; + +static struct PyModuleDef module_def = { + PyModuleDef_HEAD_INIT, + "faulthandler", + module_doc, + 0, /* non-negative size to be able to unload the module */ + module_methods, + NULL, + faulthandler_traverse, + NULL, + NULL +}; + +PyMODINIT_FUNC +PyInit_faulthandler(void) +{ + return PyModule_Create(&module_def); +} + +/* Call faulthandler.enable() if the PYTHONFAULTHANDLER environment variable + is defined, or if sys._xoptions has a 'faulthandler' key. */ + +static int +faulthandler_env_options(void) +{ + PyObject *xoptions, *key, *module, *res; + _Py_IDENTIFIER(enable); + + if (!Py_GETENV("PYTHONFAULTHANDLER")) { + int has_key; + + xoptions = PySys_GetXOptions(); + if (xoptions == NULL) + return -1; + + key = PyUnicode_FromString("faulthandler"); + if (key == NULL) + return -1; + + has_key = PyDict_Contains(xoptions, key); + Py_DECREF(key); + if (!has_key) + return 0; + } + + module = PyImport_ImportModule("faulthandler"); + if (module == NULL) { + return -1; + } + res = _PyObject_CallMethodId(module, &PyId_enable, ""); + Py_DECREF(module); + if (res == NULL) + return -1; + Py_DECREF(res); + return 0; +} + +int _PyFaulthandler_Init(void) +{ +#ifdef HAVE_SIGALTSTACK + int err; + + /* Try to allocate an alternate stack for faulthandler() signal handler to + * be able to allocate memory on the stack, even on a stack overflow. If it + * fails, ignore the error. */ + stack.ss_flags = 0; + stack.ss_size = SIGSTKSZ; + stack.ss_sp = PyMem_Malloc(stack.ss_size); + if (stack.ss_sp != NULL) { + err = sigaltstack(&stack, NULL); + if (err) { + PyMem_Free(stack.ss_sp); + stack.ss_sp = NULL; + } + } +#endif +#ifdef FAULTHANDLER_LATER + thread.file = NULL; + thread.cancel_event = PyThread_allocate_lock(); + thread.running = PyThread_allocate_lock(); + if (!thread.cancel_event || !thread.running) { + PyErr_SetString(PyExc_RuntimeError, + "could not allocate locks for faulthandler"); + return -1; + } + PyThread_acquire_lock(thread.cancel_event, 1); +#endif +#ifdef FAULTHANDLER_WATCHDOG + watchdog.cancel_event = PyThread_allocate_lock(); + watchdog.running = PyThread_allocate_lock(); + if (!watchdog.cancel_event || !watchdog.running) { + PyErr_SetString(PyExc_RuntimeError, + "could not allocate locks for faulthandler"); + return -1; + } + PyThread_acquire_lock(watchdog.cancel_event, 1); +#endif + + return faulthandler_env_options(); +} + +void _PyFaulthandler_Fini(void) +{ +#ifdef FAULTHANDLER_USER + unsigned int signum; +#endif + +#ifdef FAULTHANDLER_LATER + /* later */ + cancel_dump_tracebacks_later(); + if (thread.cancel_event) { + PyThread_release_lock(thread.cancel_event); + PyThread_free_lock(thread.cancel_event); + thread.cancel_event = NULL; + } + if (thread.running) { + PyThread_free_lock(thread.running); + thread.running = NULL; + } +#endif + +#ifdef FAULTHANDLER_WATCHDOG + /* file watchdog */ + cancel_file_watchdog(); + if (watchdog.cancel_event) { + PyThread_release_lock(watchdog.cancel_event); + PyThread_free_lock(watchdog.cancel_event); + watchdog.cancel_event = NULL; + } + if (watchdog.running) { + PyThread_free_lock(watchdog.running); + watchdog.running = NULL; + } +#endif + +#ifdef FAULTHANDLER_USER + /* user */ + if (user_signals != NULL) { + for (signum=0; signum < NSIG; signum++) + faulthandler_unregister(&user_signals[signum], signum); + free(user_signals); + user_signals = NULL; + } +#endif + + /* fatal */ + faulthandler_disable(); +#ifdef HAVE_SIGALTSTACK + if (stack.ss_sp != NULL) { + PyMem_Free(stack.ss_sp); + stack.ss_sp = NULL; + } +#endif +} |