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bpo-42923: Py_FatalError() avoids fprintf() #24242

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Merged
merged 1 commit into from
Jan 18, 2021
Merged

bpo-42923: Py_FatalError() avoids fprintf() #24242

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10 changes: 3 additions & 7 deletions Include/internal/pycore_traceback.h
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Original file line number Diff line number Diff line change
Expand Up @@ -76,15 +76,11 @@ PyAPI_FUNC(void) _Py_DumpDecimal(
int fd,
unsigned long value);

/* Format an integer as hexadecimal into the file descriptor fd with at least
width digits.

The maximum width is sizeof(unsigned long)*2 digits.

This function is signal safe. */
/* Format an integer as hexadecimal with width digits into fd file descriptor.
The function is signal safe. */
PyAPI_FUNC(void) _Py_DumpHexadecimal(
int fd,
unsigned long value,
uintptr_t value,
Py_ssize_t width);

PyAPI_FUNC(PyObject*) _PyTraceBack_FromFrame(
Expand Down
76 changes: 40 additions & 36 deletions Python/pylifecycle.c
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,9 @@
#endif


#define PUTS(fd, str) _Py_write_noraise(fd, str, (int)strlen(str))


_Py_IDENTIFIER(flush);
_Py_IDENTIFIER(name);
_Py_IDENTIFIER(stdin);
Expand Down Expand Up @@ -2348,8 +2351,7 @@ static void
_Py_FatalError_DumpTracebacks(int fd, PyInterpreterState *interp,
PyThreadState *tstate)
{
fputc('\n', stderr);
fflush(stderr);
PUTS(fd, "\n");

/* display the current Python stack */
_Py_DumpTracebackThreads(fd, interp, tstate);
Expand Down Expand Up @@ -2451,30 +2453,31 @@ fatal_output_debug(const char *msg)


static void
fatal_error_dump_runtime(FILE *stream, _PyRuntimeState *runtime)
fatal_error_dump_runtime(int fd, _PyRuntimeState *runtime)
{
fprintf(stream, "Python runtime state: ");
PUTS(fd, "Python runtime state: ");
PyThreadState *finalizing = _PyRuntimeState_GetFinalizing(runtime);
if (finalizing) {
fprintf(stream, "finalizing (tstate=%p)", finalizing);
PUTS(fd, "finalizing (tstate=0x");
_Py_DumpHexadecimal(fd, (uintptr_t)finalizing, sizeof(finalizing) * 2);
PUTS(fd, ")");
}
else if (runtime->initialized) {
fprintf(stream, "initialized");
PUTS(fd, "initialized");
}
else if (runtime->core_initialized) {
fprintf(stream, "core initialized");
PUTS(fd, "core initialized");
}
else if (runtime->preinitialized) {
fprintf(stream, "preinitialized");
PUTS(fd, "preinitialized");
}
else if (runtime->preinitializing) {
fprintf(stream, "preinitializing");
PUTS(fd, "preinitializing");
}
else {
fprintf(stream, "unknown");
PUTS(fd, "unknown");
}
fprintf(stream, "\n");
fflush(stream);
PUTS(fd, "\n");
}


Expand All @@ -2494,10 +2497,9 @@ fatal_error_exit(int status)


static void _Py_NO_RETURN
fatal_error(FILE *stream, int header, const char *prefix, const char *msg,
fatal_error(int fd, int header, const char *prefix, const char *msg,
int status)
{
const int fd = fileno(stream);
static int reentrant = 0;

if (reentrant) {
Expand All @@ -2508,29 +2510,22 @@ fatal_error(FILE *stream, int header, const char *prefix, const char *msg,
reentrant = 1;

if (header) {
fprintf(stream, "Fatal Python error: ");
PUTS(fd, "Fatal Python error: ");
if (prefix) {
fputs(prefix, stream);
fputs(": ", stream);
PUTS(fd, prefix);
PUTS(fd, ": ");
}
if (msg) {
fputs(msg, stream);
PUTS(fd, msg);
}
else {
fprintf(stream, "<message not set>");
PUTS(fd, "<message not set>");
}
fputs("\n", stream);
fflush(stream);
PUTS(fd, "\n");
}

_PyRuntimeState *runtime = &_PyRuntime;
fatal_error_dump_runtime(stream, runtime);

PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
PyInterpreterState *interp = NULL;
if (tstate != NULL) {
interp = tstate->interp;
}
fatal_error_dump_runtime(fd, runtime);

/* Check if the current thread has a Python thread state
and holds the GIL.
Expand All @@ -2540,8 +2535,17 @@ fatal_error(FILE *stream, int header, const char *prefix, const char *msg,

tss_tstate != tstate if the current Python thread does not hold the GIL.
*/
PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
PyInterpreterState *interp = NULL;
PyThreadState *tss_tstate = PyGILState_GetThisThreadState();
if (tstate != NULL) {
interp = tstate->interp;
}
else if (tss_tstate != NULL) {
interp = tss_tstate->interp;
}
int has_tstate_and_gil = (tss_tstate != NULL && tss_tstate == tstate);

if (has_tstate_and_gil) {
/* If an exception is set, print the exception with its traceback */
if (!_Py_FatalError_PrintExc(tss_tstate)) {
Expand Down Expand Up @@ -2578,14 +2582,14 @@ fatal_error(FILE *stream, int header, const char *prefix, const char *msg,
void _Py_NO_RETURN
Py_FatalError(const char *msg)
{
fatal_error(stderr, 1, NULL, msg, -1);
fatal_error(fileno(stderr), 1, NULL, msg, -1);
}


void _Py_NO_RETURN
_Py_FatalErrorFunc(const char *func, const char *msg)
{
fatal_error(stderr, 1, func, msg, -1);
fatal_error(fileno(stderr), 1, func, msg, -1);
}


Expand All @@ -2600,12 +2604,12 @@ _Py_FatalErrorFormat(const char *func, const char *format, ...)
reentrant = 1;

FILE *stream = stderr;
fprintf(stream, "Fatal Python error: ");
const int fd = fileno(stream);
PUTS(fd, "Fatal Python error: ");
if (func) {
fputs(func, stream);
fputs(": ", stream);
PUTS(fd, func);
PUTS(fd, ": ");
}
fflush(stream);

va_list vargs;
#ifdef HAVE_STDARG_PROTOTYPES
Expand All @@ -2619,7 +2623,7 @@ _Py_FatalErrorFormat(const char *func, const char *format, ...)
fputs("\n", stream);
fflush(stream);

fatal_error(stream, 0, NULL, NULL, -1);
fatal_error(fd, 0, NULL, NULL, -1);
}


Expand All @@ -2630,7 +2634,7 @@ Py_ExitStatusException(PyStatus status)
exit(status.exitcode);
}
else if (_PyStatus_IS_ERROR(status)) {
fatal_error(stderr, 1, status.func, status.err_msg, 1);
fatal_error(fileno(stderr), 1, status.func, status.err_msg, 1);
}
else {
Py_FatalError("Py_ExitStatusException() must not be called on success");
Expand Down
11 changes: 4 additions & 7 deletions Python/traceback.c
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Original file line number Diff line number Diff line change
Expand Up @@ -649,15 +649,12 @@ _Py_DumpDecimal(int fd, unsigned long value)
_Py_write_noraise(fd, ptr, end - ptr);
}

/* Format an integer in range [0; 0xffffffff] to hexadecimal of 'width' digits,
and write it into the file fd.

This function is signal safe. */

/* Format an integer as hexadecimal with width digits into fd file descriptor.
The function is signal safe. */
void
_Py_DumpHexadecimal(int fd, unsigned long value, Py_ssize_t width)
_Py_DumpHexadecimal(int fd, uintptr_t value, Py_ssize_t width)
{
char buffer[sizeof(unsigned long) * 2 + 1], *ptr, *end;
char buffer[sizeof(uintptr_t) * 2 + 1], *ptr, *end;
const Py_ssize_t size = Py_ARRAY_LENGTH(buffer) - 1;

if (width > size)
Expand Down