[Python-checkins] bpo-40826: Fix GIL usage in PyOS_Readline() (GH-20579)

Mon Jun 1 14:59:44 EDT 2020

https://github.com/python/cpython/commit/c353764fd564e401cf47a5d9efab18c72c60014e
commit: c353764fd564e401cf47a5d9efab18c72c60014e
branch: master
author: Victor Stinner <vstinner at python.org>
committer: GitHub <noreply at github.com>
date: 2020年06月01日T20:59:35+02:00
summary:
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.
files:
A Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst
M Parser/myreadline.c

diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst
new file mode 100644
index 0000000000000..f79f20d21d49c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-01-20-31-07.bpo-40826.XCI4M2.rst	
@@ -0,0 +1 @@
+Fix GIL usage in :c:func:`PyOS_Readline`: lock the GIL to set an exception.
diff --git a/Parser/myreadline.c b/Parser/myreadline.c
index 04c2793225cb3..d2787f0d345cf 100644
--- a/Parser/myreadline.c
+++ b/Parser/myreadline.c
@@ -27,22 +27,24 @@ int (*PyOS_InputHook)(void) = NULL;
 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;
 #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
@@ -68,22 +70,26 @@ 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()) {
 return 1; /* Interrupt */
 }
@@ -98,7 +104,7 @@ 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;
@@ -133,11 +139,12 @@ _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;
 }
@@ -150,17 +157,22 @@ _PyOS_WindowsConsoleReadline(HANDLE hStdIn)
 if (wbuf == wbuf_local) {
 wbuf[total_read] = '0円';
 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;
@@ -169,33 +181,45 @@ _PyOS_WindowsConsoleReadline(HANDLE hStdIn)
 
 if (wbuf[0] == '\x1a') {
 buf = PyMem_RawMalloc(1);
- if (buf)
+ if (buf) {
 buf[0] = '0円';
+ }
 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円';
 
 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;
 }
 
@@ -209,6 +233,8 @@ 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) {
@@ -230,7 +256,9 @@ 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,
@@ -249,7 +277,7 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
 }
 }
 clearerr(sys_stdin);
- return _PyOS_WindowsConsoleReadline(hStdIn);
+ return _PyOS_WindowsConsoleReadline(tstate, hStdIn);
 }
 }
 #endif
@@ -257,16 +285,19 @@ 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 */
@@ -278,29 +309,40 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
 *p = '0円';
 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;
@@ -323,7 +365,8 @@ 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;
@@ -342,7 +385,7 @@ 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);
 
