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/* Readline interface for tokenizer.c and [raw_]input() in bltinmodule.c.
By default, or when stdin is not a tty device, we have a super
simple my_readline function using fgets.
Optionally, we can use the GNU readline library.
my_readline() has a different return value from GNU readline():
- NULL if an interrupt occurred or if an error occurred
- a malloc'ed empty string if EOF was read
- a malloc'ed string ending in \n normally
*/
#include "Python.h"
#ifdef MS_WINDOWS
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
#endif /* MS_WINDOWS */
#ifdef __VMS
extern char* vms__StdioReadline(FILE *sys_stdin, FILE *sys_stdout, char *prompt);
#endif
PyThreadState* _PyOS_ReadlineTState;
#ifdef WITH_THREAD
#include "pythread.h"
static PyThread_type_lock _PyOS_ReadlineLock = NULL;
#endif
int (*PyOS_InputHook)(void) = NULL;
/* This function restarts a fgets() after an EINTR error occurred
except if PyOS_InterruptOccurred() returns true. */
static int
my_fgets(char *buf, int len, FILE *fp)
{
#ifdef MS_WINDOWS
HANDLE hInterruptEvent;
#endif
char *p;
int err;
while (1) {
if (PyOS_InputHook != NULL)
(void)(PyOS_InputHook)();
errno = 0;
clearerr(fp);
if (_PyVerify_fd(fileno(fp)))
p = fgets(buf, len, fp);
else
p = NULL;
if (p != NULL)
return 0; /* No error */
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
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) {
hInterruptEvent = _PyOS_SigintEvent();
switch (WaitForSingleObjectEx(hInterruptEvent, 10, FALSE)) {
case WAIT_OBJECT_0:
ResetEvent(hInterruptEvent);
return 1; /* Interrupt */
case WAIT_FAILED:
return -2; /* Error */
}
}
#endif /* MS_WINDOWS */
if (feof(fp)) {
clearerr(fp);
return -1; /* EOF */
}
#ifdef EINTR
if (err == EINTR) {
int s;
#ifdef WITH_THREAD
PyEval_RestoreThread(_PyOS_ReadlineTState);
#endif
s = PyErr_CheckSignals();
#ifdef WITH_THREAD
PyEval_SaveThread();
#endif
if (s < 0)
return 1;
/* try again */
continue;
}
#endif
if (PyOS_InterruptOccurred()) {
return 1; /* Interrupt */
}
return -2; /* Error */
}
/* NOTREACHED */
}
/* Readline implementation using fgets() */
char *
PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
{
size_t n;
char *p;
n = 100;
if ((p = (char *)PyMem_MALLOC(n)) == NULL)
return NULL;
fflush(sys_stdout);
if (prompt)
fprintf(stderr, "%s", prompt);
fflush(stderr);
switch (my_fgets(p, (int)n, sys_stdin)) {
case 0: /* Normal case */
break;
case 1: /* Interrupt */
PyMem_FREE(p);
return NULL;
case -1: /* EOF */
case -2: /* Error */
default: /* Shouldn't happen */
*p = '\0';
break;
}
n = strlen(p);
while (n > 0 && p[n-1] != '\n') {
size_t incr = n+2;
p = (char *)PyMem_REALLOC(p, n + incr);
if (p == NULL)
return NULL;
if (incr > INT_MAX) {
PyErr_SetString(PyExc_OverflowError, "input line too long");
}
if (my_fgets(p+n, (int)incr, sys_stdin) != 0)
break;
n += strlen(p+n);
}
return (char *)PyMem_REALLOC(p, n+1);
}
/* By initializing this function pointer, systems embedding Python can
override the readline function.
Note: Python expects in return a buffer allocated with PyMem_Malloc. */
char *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, char *);
/* Interface used by tokenizer.c and bltinmodule.c */
char *
PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
{
char *rv;
if (_PyOS_ReadlineTState == PyThreadState_GET()) {
PyErr_SetString(PyExc_RuntimeError,
"can't re-enter readline");
return NULL;
}
if (PyOS_ReadlineFunctionPointer == NULL) {
#ifdef __VMS
PyOS_ReadlineFunctionPointer = vms__StdioReadline;
#else
PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
#endif
}
#ifdef WITH_THREAD
if (_PyOS_ReadlineLock == NULL) {
_PyOS_ReadlineLock = PyThread_allocate_lock();
}
#endif
_PyOS_ReadlineTState = PyThreadState_GET();
Py_BEGIN_ALLOW_THREADS
#ifdef WITH_THREAD
PyThread_acquire_lock(_PyOS_ReadlineLock, 1);
#endif
/* This is needed to handle the unlikely case that the
* interpreter is in interactive mode *and* stdin/out are not
* a tty. This can happen, for example if python is run like
* this: python -i < test1.py
*/
if (!isatty (fileno (sys_stdin)) || !isatty (fileno (sys_stdout)))
rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt);
else
rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout,
prompt);
Py_END_ALLOW_THREADS
#ifdef WITH_THREAD
PyThread_release_lock(_PyOS_ReadlineLock);
#endif
_PyOS_ReadlineTState = NULL;
return rv;
}
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