/* 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 __VMSextern 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; #ifdef RISCOSint Py_RISCOSWimpFlag;#endif /* This function restarts a fgets() after an EINTR error occurred   except if PyOS_InterruptOccurred() returns true. */ static intmy_fgets(char *buf, int len, FILE *fp){	char *p;	for (;;) {		if (PyOS_InputHook != NULL)			(void)(PyOS_InputHook)();		errno = 0;		p = fgets(buf, len, fp);		if (p != NULL)			return 0; /* No error */#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())		*/		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()) {				return 1; /* Interrupt */			}			/* 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)) {			return -1; /* EOF */		}#ifdef EINTR		if (errno == 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;			}		}#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);#ifndef RISCOS	if (prompt)		fprintf(stderr, "%s", prompt);#else	if (prompt) {		if(Py_RISCOSWimpFlag)			fprintf(stderr, "\x0cr%s\x0c", prompt);		else			fprintf(stderr, "%s", prompt);	}#endif	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;}