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Issue #1677: Handle better a race condition between the interactive interpreter and

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the Ctrl-C signal handler on Windows
This commit is contained in:
Tim Golden 2012-06-29 18:39:26 +01:00
parent 25652884b4
commit 9175c3d804
1 changed files with 22 additions and 23 deletions
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45
Parser/myreadline.c
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@ -35,6 +35,9 @@ int (*PyOS_InputHook)(void) = NULL;
static int
my_fgets(char *buf, int len, FILE *fp)
{
#ifdef MS_WINDOWS
HANDLE hInterruptEvent;
#endif
char *p;
int err;
while (1) {
@ -50,32 +53,28 @@ my_fgets(char *buf, int len, FILE *fp)
return 0; /* No error */
err = errno;
#ifdef MS_WINDOWS
/* In the case of a Ctrl+C or some other external event
interrupting the operation:
Win2k/NT: ERROR_OPERATION_ABORTED is the most recent Win32
error code (and feof() returns TRUE).
Win9x: Ctrl+C seems to have no effect on fgets() returning
early - the signal handler is called, but the fgets()
only returns "normally" (ie, when Enter hit or feof())
/* Ctrl-C anywhere on the line or Ctrl-Z if the only character
on a line will set ERROR_OPERATION_ABORTED. Under normal
circumstances Ctrl-C will also have caused the SIGINT handler
to fire which will have set the event object returned by
_PyOS_SigintEvent. This signal fires in another thread and
is not guaranteed to have occurred before this point in the
code.
Therefore: check whether the event is set with a small timeout.
If it is, assume this is a Ctrl-C and reset the event. If it
isn't set assume that this is a Ctrl-Z on its own and drop
through to check for EOF.
*/
if (GetLastError()==ERROR_OPERATION_ABORTED) {
/* Signals come asynchronously, so we sleep a brief
moment before checking if the handler has been
triggered (we cant just return 1 before the
signal handler has been called, as the later
signal may be treated as a separate interrupt).
*/
Sleep(1);
if (PyOS_InterruptOccurred()) {
hInterruptEvent = _PyOS_SigintEvent();
switch (WaitForSingleObject(hInterruptEvent, 10)) {
case WAIT_OBJECT_0:
ResetEvent(hInterruptEvent);
return 1; /* Interrupt */
case WAIT_FAILED:
return -2; /* Error */
}
/* Either the sleep wasn't long enough (need a
short loop retrying?) or not interrupted at all
(in which case we should revisit the whole thing!)
Logging some warning would be nice. assert is not
viable as under the debugger, the various dialogs
mean the condition is not true.
*/
}
#endif /* MS_WINDOWS */
if (feof(fp)) {
@ -94,7 +93,7 @@ my_fgets(char *buf, int len, FILE *fp)
#endif
if (s < 0)
return 1;
/* try again */
/* try again */
continue;
}
#endif