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[3.9] bpo-40826: Fix GIL usage in PyOS_Readline() (GH-20613) (GH-20616) 

* bpo-40826: Fix GIL usage in PyOS_Readline() (GH-20579)

Fix GIL usage in PyOS_Readline(): lock the GIL to set an exception.

Pass tstate to my_fgets() and _PyOS_WindowsConsoleReadline(). Cleanup
these functions.

(cherry picked from commit c353764fd5)

* bpo-40826: Add _PyOS_InterruptOccurred(tstate) function (GH-20599)

my_fgets() now calls _PyOS_InterruptOccurred(tstate) to check for
pending signals, rather calling PyOS_InterruptOccurred().

my_fgets() is called with the GIL released, whereas
PyOS_InterruptOccurred() must be called with the GIL held.

test_repl: use text=True and avoid SuppressCrashReport in
test_multiline_string_parsing().

Fix my_fgets() on Windows: fgets(fp) does crash if fileno(fp) is closed.

(cherry picked from commit fa7ab6aa0f)
This commit is contained in:
Victor Stinner 2020-06-03 18:28:18 +02:00 committed by GitHub
parent 5b8787ef19
commit 6f7346bb39
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 128 additions and 43 deletions
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3
Include/internal/pycore_pystate.h
View File

@ -317,6 +317,9 @@ PyAPI_FUNC(void) _PyInterpreterState_DeleteExceptMain(_PyRuntimeState *runtime);
PyAPI_FUNC(void) _PyGILState_Reinit(_PyRuntimeState *runtime);
PyAPI_FUNC(int) _PyOS_InterruptOccurred(PyThreadState *tstate);
#ifdef __cplusplus
}
#endif

22
Lib/test/test_repl.py
View File

@ -29,7 +29,9 @@ def spawn_repl(*args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kw):
# test.support.script_helper.
env = kw.setdefault('env', dict(os.environ))
env['TERM'] = 'vt100'
return subprocess.Popen(cmd_line, executable=sys.executable,
return subprocess.Popen(cmd_line,
executable=sys.executable,
text=True,
stdin=subprocess.PIPE,
stdout=stdout, stderr=stderr,
**kw)
@ -49,12 +51,11 @@ class TestInteractiveInterpreter(unittest.TestCase):
sys.exit(0)
"""
user_input = dedent(user_input)
user_input = user_input.encode()
p = spawn_repl()
with SuppressCrashReport():
p.stdin.write(user_input)
output = kill_python(p)
self.assertIn(b'After the exception.', output)
self.assertIn('After the exception.', output)
# Exit code 120: Py_FinalizeEx() failed to flush stdout and stderr.
self.assertIn(p.returncode, (1, 120))
@ -86,13 +87,22 @@ class TestInteractiveInterpreter(unittest.TestCase):
</test>"""
'''
user_input = dedent(user_input)
user_input = user_input.encode()
p = spawn_repl()
with SuppressCrashReport():
p.stdin.write(user_input)
p.stdin.write(user_input)
output = kill_python(p)
self.assertEqual(p.returncode, 0)
def test_close_stdin(self):
user_input = dedent('''
import os
print("before close")
os.close(0)
''')
process = spawn_repl()
output = process.communicate(user_input)[0]
self.assertEqual(process.returncode, 0)
self.assertIn('before close', output)
if __name__ == "__main__":
unittest.main()

2
Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst Normal file
View File

@ -0,0 +1,2 @@
Fix GIL usage in :c:func:`PyOS_Readline`: lock the GIL to set an exception
and pass the Python thread state when checking if there is a pending signal.

26
Modules/signalmodule.c
View File

@ -187,14 +187,20 @@ itimer_retval(struct itimerval *iv)
#endif
static int
is_main(_PyRuntimeState *runtime)
is_main_interp(_PyRuntimeState *runtime, PyInterpreterState *interp)
{
unsigned long thread = PyThread_get_thread_ident();
PyInterpreterState *interp = _PyRuntimeState_GetThreadState(runtime)->interp;
return (thread == runtime->main_thread
&& interp == runtime->interpreters.main);
}
static int
is_main(_PyRuntimeState *runtime)
{
PyInterpreterState *interp = _PyRuntimeState_GetThreadState(runtime)->interp;
return is_main_interp(runtime, interp);
}
static PyObject *
signal_default_int_handler(PyObject *self, PyObject *args)
{
@ -1726,12 +1732,14 @@ PyOS_FiniInterrupts(void)
finisignal();
}
// The caller doesn't have to hold the GIL
int
PyOS_InterruptOccurred(void)
_PyOS_InterruptOccurred(PyThreadState *tstate)
{
if (_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
_PyRuntimeState *runtime = &_PyRuntime;
if (!is_main(runtime)) {
if (!is_main_interp(runtime, tstate->interp)) {
return 0;
}
_Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
@ -1740,6 +1748,16 @@ PyOS_InterruptOccurred(void)
return 0;
}
// The caller must to hold the GIL
int
PyOS_InterruptOccurred(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyOS_InterruptOccurred(tstate);
}
static void
_clear_pending_signals(void)
{

118
Parser/myreadline.c
View File

@ -25,25 +25,36 @@ static PyThread_type_lock _PyOS_ReadlineLock = NULL;
int (*PyOS_InputHook)(void) = NULL;
/* This function restarts a fgets() after an EINTR error occurred
except if PyOS_InterruptOccurred() returns true. */
except if _PyOS_InterruptOccurred() returns true. */
static int
my_fgets(char *buf, int len, FILE *fp)
my_fgets(PyThreadState* tstate, char *buf, int len, FILE *fp)
{
#ifdef MS_WINDOWS
HANDLE hInterruptEvent;
HANDLE handle;
_Py_BEGIN_SUPPRESS_IPH
handle = (HANDLE)_get_osfhandle(fileno(fp));
_Py_END_SUPPRESS_IPH
/* bpo-40826: fgets(fp) does crash if fileno(fp) is closed */
if (handle == INVALID_HANDLE_VALUE) {
return -1; /* EOF */
}
#endif
char *p;
int err;
while (1) {
if (PyOS_InputHook != NULL)
if (PyOS_InputHook != NULL) {
(void)(PyOS_InputHook)();
}
errno = 0;
clearerr(fp);
p = fgets(buf, len, fp);
if (p != NULL)
char *p = fgets(buf, len, fp);
if (p != NULL) {
return 0; /* No error */
err = errno;
}
int err = errno;
#ifdef MS_WINDOWS
/* Ctrl-C anywhere on the line or Ctrl-Z if the only character
on a line will set ERROR_OPERATION_ABORTED. Under normal
@ -59,7 +70,7 @@ my_fgets(char *buf, int len, FILE *fp)
through to check for EOF.
*/
if (GetLastError()==ERROR_OPERATION_ABORTED) {
hInterruptEvent = _PyOS_SigintEvent();
HANDLE hInterruptEvent = _PyOS_SigintEvent();
switch (WaitForSingleObjectEx(hInterruptEvent, 10, FALSE)) {
case WAIT_OBJECT_0:
ResetEvent(hInterruptEvent);
@ -69,23 +80,27 @@ my_fgets(char *buf, int len, FILE *fp)
}
}
#endif /* MS_WINDOWS */
if (feof(fp)) {
clearerr(fp);
return -1; /* EOF */
}
#ifdef EINTR
if (err == EINTR) {
int s;
PyEval_RestoreThread(_PyOS_ReadlineTState);
s = PyErr_CheckSignals();
PyEval_RestoreThread(tstate);
int s = PyErr_CheckSignals();
PyEval_SaveThread();
if (s < 0)
return 1;
/* try again */
if (s < 0) {
return 1;
}
/* try again */
continue;
}
#endif
if (PyOS_InterruptOccurred()) {
if (_PyOS_InterruptOccurred(tstate)) {
return 1; /* Interrupt */
}
return -2; /* Error */
@ -99,7 +114,7 @@ my_fgets(char *buf, int len, FILE *fp)
extern char _get_console_type(HANDLE handle);
char *
_PyOS_WindowsConsoleReadline(HANDLE hStdIn)
_PyOS_WindowsConsoleReadline(PyThreadState *tstate, HANDLE hStdIn)
{
static wchar_t wbuf_local[1024 * 16];
const DWORD chunk_size = 1024;
@ -134,11 +149,12 @@ _PyOS_WindowsConsoleReadline(HANDLE hStdIn)
if (WaitForSingleObjectEx(hInterruptEvent, 100, FALSE)
== WAIT_OBJECT_0) {
ResetEvent(hInterruptEvent);
PyEval_RestoreThread(_PyOS_ReadlineTState);
PyEval_RestoreThread(tstate);
s = PyErr_CheckSignals();
PyEval_SaveThread();
if (s < 0)
if (s < 0) {
goto exit;
}
}
break;
}
@ -151,17 +167,22 @@ _PyOS_WindowsConsoleReadline(HANDLE hStdIn)
if (wbuf == wbuf_local) {
wbuf[total_read] = '\0';
wbuf = (wchar_t*)PyMem_RawMalloc(wbuflen * sizeof(wchar_t));
if (wbuf)
if (wbuf) {
wcscpy_s(wbuf, wbuflen, wbuf_local);
}
else {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
goto exit;
}
}
else {
wchar_t *tmp = PyMem_RawRealloc(wbuf, wbuflen * sizeof(wchar_t));
if (tmp == NULL) {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
goto exit;
}
wbuf = tmp;
@ -170,33 +191,45 @@ _PyOS_WindowsConsoleReadline(HANDLE hStdIn)
if (wbuf[0] == '\x1a') {
buf = PyMem_RawMalloc(1);
if (buf)
if (buf) {
buf[0] = '\0';
}
else {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
}
goto exit;
}
u8len = WideCharToMultiByte(CP_UTF8, 0, wbuf, total_read, NULL, 0, NULL, NULL);
u8len = WideCharToMultiByte(CP_UTF8, 0,
wbuf, total_read,
NULL, 0,
NULL, NULL);
buf = PyMem_RawMalloc(u8len + 1);
if (buf == NULL) {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
goto exit;
}
u8len = WideCharToMultiByte(CP_UTF8, 0, wbuf, total_read, buf, u8len, NULL, NULL);
u8len = WideCharToMultiByte(CP_UTF8, 0,
wbuf, total_read,
buf, u8len,
NULL, NULL);
buf[u8len] = '\0';
exit:
if (wbuf != wbuf_local)
if (wbuf != wbuf_local) {
PyMem_RawFree(wbuf);
}
if (err) {
PyEval_RestoreThread(_PyOS_ReadlineTState);
PyEval_RestoreThread(tstate);
PyErr_SetFromWindowsErr(err);
PyEval_SaveThread();
}
return buf;
}
@ -210,6 +243,8 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
{
size_t n;
char *p, *pr;
PyThreadState *tstate = _PyOS_ReadlineTState;
assert(tstate != NULL);
#ifdef MS_WINDOWS
if (!Py_LegacyWindowsStdioFlag && sys_stdin == stdin) {
@ -231,7 +266,9 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
if (wlen) {
wbuf = PyMem_RawMalloc(wlen * sizeof(wchar_t));
if (wbuf == NULL) {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
return NULL;
}
wlen = MultiByteToWideChar(CP_UTF8, 0, prompt, -1,
@ -250,7 +287,7 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
}
}
clearerr(sys_stdin);
return _PyOS_WindowsConsoleReadline(hStdIn);
return _PyOS_WindowsConsoleReadline(tstate, hStdIn);
}
}
#endif
@ -258,16 +295,19 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
n = 100;
p = (char *)PyMem_RawMalloc(n);
if (p == NULL) {
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
return NULL;
}
fflush(sys_stdout);
if (prompt)
if (prompt) {
fprintf(stderr, "%s", prompt);
}
fflush(stderr);
switch (my_fgets(p, (int)n, sys_stdin)) {
switch (my_fgets(tstate, p, (int)n, sys_stdin)) {
case 0: /* Normal case */
break;
case 1: /* Interrupt */
@ -279,29 +319,40 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
*p = '\0';
break;
}
n = strlen(p);
while (n > 0 && p[n-1] != '\n') {
size_t incr = n+2;
if (incr > INT_MAX) {
PyMem_RawFree(p);
PyEval_RestoreThread(tstate);
PyErr_SetString(PyExc_OverflowError, "input line too long");
PyEval_SaveThread();
return NULL;
}
pr = (char *)PyMem_RawRealloc(p, n + incr);
if (pr == NULL) {
PyMem_RawFree(p);
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
return NULL;
}
p = pr;
if (my_fgets(p+n, (int)incr, sys_stdin) != 0)
if (my_fgets(tstate, p+n, (int)incr, sys_stdin) != 0) {
break;
}
n += strlen(p+n);
}
pr = (char *)PyMem_RawRealloc(p, n+1);
if (pr == NULL) {
PyMem_RawFree(p);
PyEval_RestoreThread(tstate);
PyErr_NoMemory();
PyEval_SaveThread();
return NULL;
}
return pr;
@ -324,7 +375,8 @@ PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
char *rv, *res;
size_t len;
if (_PyOS_ReadlineTState == _PyThreadState_GET()) {
PyThreadState *tstate = _PyThreadState_GET();
if (_PyOS_ReadlineTState == tstate) {
PyErr_SetString(PyExc_RuntimeError,
"can't re-enter readline");
return NULL;
@ -343,7 +395,7 @@ PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
}
}
_PyOS_ReadlineTState = _PyThreadState_GET();
_PyOS_ReadlineTState = tstate;
Py_BEGIN_ALLOW_THREADS
PyThread_acquire_lock(_PyOS_ReadlineLock, 1);