mirror of https://github.com/python/cpython.git
207 lines
5.2 KiB
C
207 lines
5.2 KiB
C
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/* Readline interface for tokenizer.c and [raw_]input() in bltinmodule.c.
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By default, or when stdin is not a tty device, we have a super
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simple my_readline function using fgets.
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Optionally, we can use the GNU readline library.
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my_readline() has a different return value from GNU readline():
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- NULL if an interrupt occurred or if an error occurred
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- a malloc'ed empty string if EOF was read
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- a malloc'ed string ending in \n normally
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*/
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#include "Python.h"
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#ifdef MS_WINDOWS
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#define WIN32_LEAN_AND_MEAN
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#include "windows.h"
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#endif /* MS_WINDOWS */
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#ifdef __VMS
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extern char* vms__StdioReadline(FILE *sys_stdin, FILE *sys_stdout, char *prompt);
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#endif
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PyThreadState* _PyOS_ReadlineTState;
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#ifdef WITH_THREAD
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#include "pythread.h"
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static PyThread_type_lock _PyOS_ReadlineLock = NULL;
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#endif
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int (*PyOS_InputHook)(void) = NULL;
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/* This function restarts a fgets() after an EINTR error occurred
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except if PyOS_InterruptOccurred() returns true. */
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static int
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my_fgets(char *buf, int len, FILE *fp)
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{
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char *p;
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for (;;) {
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if (PyOS_InputHook != NULL)
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(void)(PyOS_InputHook)();
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errno = 0;
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p = fgets(buf, len, fp);
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if (p != NULL)
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return 0; /* No error */
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#ifdef MS_WINDOWS
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/* In the case of a Ctrl+C or some other external event
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interrupting the operation:
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Win2k/NT: ERROR_OPERATION_ABORTED is the most recent Win32
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error code (and feof() returns TRUE).
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Win9x: Ctrl+C seems to have no effect on fgets() returning
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early - the signal handler is called, but the fgets()
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only returns "normally" (ie, when Enter hit or feof())
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*/
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if (GetLastError()==ERROR_OPERATION_ABORTED) {
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/* Signals come asynchronously, so we sleep a brief
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moment before checking if the handler has been
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triggered (we cant just return 1 before the
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signal handler has been called, as the later
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signal may be treated as a separate interrupt).
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*/
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Sleep(1);
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if (PyOS_InterruptOccurred()) {
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return 1; /* Interrupt */
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}
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/* Either the sleep wasn't long enough (need a
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short loop retrying?) or not interrupted at all
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(in which case we should revisit the whole thing!)
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Logging some warning would be nice. assert is not
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viable as under the debugger, the various dialogs
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mean the condition is not true.
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*/
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}
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#endif /* MS_WINDOWS */
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if (feof(fp)) {
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return -1; /* EOF */
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}
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#ifdef EINTR
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if (errno == EINTR) {
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int s;
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#ifdef WITH_THREAD
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PyEval_RestoreThread(_PyOS_ReadlineTState);
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#endif
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s = PyErr_CheckSignals();
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#ifdef WITH_THREAD
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PyEval_SaveThread();
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#endif
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if (s < 0) {
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return 1;
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}
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}
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#endif
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if (PyOS_InterruptOccurred()) {
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return 1; /* Interrupt */
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}
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return -2; /* Error */
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}
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/* NOTREACHED */
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}
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/* Readline implementation using fgets() */
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char *
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PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
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{
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size_t n;
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char *p;
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n = 100;
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if ((p = (char *)PyMem_MALLOC(n)) == NULL)
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return NULL;
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fflush(sys_stdout);
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if (prompt)
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fprintf(stderr, "%s", prompt);
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fflush(stderr);
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switch (my_fgets(p, (int)n, sys_stdin)) {
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case 0: /* Normal case */
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break;
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case 1: /* Interrupt */
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PyMem_FREE(p);
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return NULL;
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case -1: /* EOF */
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case -2: /* Error */
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default: /* Shouldn't happen */
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*p = '\0';
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break;
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}
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n = strlen(p);
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while (n > 0 && p[n-1] != '\n') {
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size_t incr = n+2;
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p = (char *)PyMem_REALLOC(p, n + incr);
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if (p == NULL)
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return NULL;
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if (incr > INT_MAX) {
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PyErr_SetString(PyExc_OverflowError, "input line too long");
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}
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if (my_fgets(p+n, (int)incr, sys_stdin) != 0)
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break;
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n += strlen(p+n);
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}
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return (char *)PyMem_REALLOC(p, n+1);
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}
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/* By initializing this function pointer, systems embedding Python can
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override the readline function.
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Note: Python expects in return a buffer allocated with PyMem_Malloc. */
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char *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, char *);
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/* Interface used by tokenizer.c and bltinmodule.c */
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char *
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PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
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{
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char *rv;
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if (_PyOS_ReadlineTState == PyThreadState_GET()) {
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PyErr_SetString(PyExc_RuntimeError,
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"can't re-enter readline");
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return NULL;
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}
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if (PyOS_ReadlineFunctionPointer == NULL) {
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#ifdef __VMS
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PyOS_ReadlineFunctionPointer = vms__StdioReadline;
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#else
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PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
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#endif
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}
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#ifdef WITH_THREAD
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if (_PyOS_ReadlineLock == NULL) {
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_PyOS_ReadlineLock = PyThread_allocate_lock();
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}
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#endif
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_PyOS_ReadlineTState = PyThreadState_GET();
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Py_BEGIN_ALLOW_THREADS
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#ifdef WITH_THREAD
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PyThread_acquire_lock(_PyOS_ReadlineLock, 1);
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#endif
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/* This is needed to handle the unlikely case that the
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* interpreter is in interactive mode *and* stdin/out are not
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* a tty. This can happen, for example if python is run like
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* this: python -i < test1.py
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*/
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if (!isatty (fileno (sys_stdin)) || !isatty (fileno (sys_stdout)))
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rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt);
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else
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rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout,
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prompt);
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Py_END_ALLOW_THREADS
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#ifdef WITH_THREAD
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PyThread_release_lock(_PyOS_ReadlineLock);
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#endif
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_PyOS_ReadlineTState = NULL;
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return rv;
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}
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