cpython/Parser/myreadline.c at pythoncapi · pythoncapi/cpython · GitHub

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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"

#include "internal/pystate.h"

#ifdef MS_WINDOWS

#define WIN32_LEAN_AND_MEAN

#include "windows.h"

#endif /* MS_WINDOWS */

PyThreadState* _PyOS_ReadlineTState = NULL;

#include "pythread.h"

static PyThread_type_lock _PyOS_ReadlineLock = NULL;

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);

p = fgets(buf, len, fp);

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;

PyEval_RestoreThread(_PyOS_ReadlineTState);

s = PyErr_CheckSignals();

PyEval_SaveThread();

if (s < 0)

return 1;

/* try again */

continue;

}

#endif

if (PyOS_InterruptOccurred()) {

return 1; /* Interrupt */

}

return -2; /* Error */

}

/* NOTREACHED */

}

#ifdef MS_WINDOWS

/* Readline implementation using ReadConsoleW */

extern char _get_console_type(HANDLE handle);

char *

_PyOS_WindowsConsoleReadline(HANDLE hStdIn)

{

static wchar_t wbuf_local[1024 * 16];

const DWORD chunk_size = 1024;

DWORD n_read, total_read, wbuflen, u8len;

wchar_t *wbuf;

char *buf = NULL;

int err = 0;

n_read = (DWORD)-1;

total_read = 0;

wbuf = wbuf_local;

wbuflen = sizeof(wbuf_local) / sizeof(wbuf_local[0]) - 1;

while (1) {

if (PyOS_InputHook != NULL) {

(void)(PyOS_InputHook)();

}

if (!ReadConsoleW(hStdIn, &wbuf[total_read], wbuflen - total_read, &n_read, NULL)) {

err = GetLastError();

goto exit;

}

if (n_read == (DWORD)-1 && (err = GetLastError()) == ERROR_OPERATION_ABORTED) {

break;

}

if (n_read == 0) {

int s;

err = GetLastError();

if (err != ERROR_OPERATION_ABORTED)

goto exit;

err = 0;

HANDLE hInterruptEvent = _PyOS_SigintEvent();

if (WaitForSingleObjectEx(hInterruptEvent, 100, FALSE)

== WAIT_OBJECT_0) {

ResetEvent(hInterruptEvent);

PyEval_RestoreThread(_PyOS_ReadlineTState);

s = PyErr_CheckSignals();

PyEval_SaveThread();

if (s < 0)

goto exit;

}

break;

}

total_read += n_read;

if (total_read == 0 || wbuf[total_read - 1] == L'\n') {

break;

}

wbuflen += chunk_size;

if (wbuf == wbuf_local) {

wbuf[total_read] = '\0';

wbuf = (wchar_t*)PyMem_RawMalloc(wbuflen * sizeof(wchar_t));

if (wbuf)

wcscpy_s(wbuf, wbuflen, wbuf_local);

}

else

wbuf = (wchar_t*)PyMem_RawRealloc(wbuf, wbuflen * sizeof(wchar_t));

}

if (wbuf[0] == '\x1a') {

buf = PyMem_RawMalloc(1);

if (buf)

buf[0] = '\0';

goto exit;

}

u8len = WideCharToMultiByte(CP_UTF8, 0, wbuf, total_read, NULL, 0, NULL, NULL);

buf = PyMem_RawMalloc(u8len + 1);

u8len = WideCharToMultiByte(CP_UTF8, 0, wbuf, total_read, buf, u8len, NULL, NULL);

buf[u8len] = '\0';

exit:

if (wbuf != wbuf_local)

PyMem_RawFree(wbuf);

if (err) {

PyEval_RestoreThread(_PyOS_ReadlineTState);

PyErr_SetFromWindowsErr(err);

PyEval_SaveThread();

}

return buf;

}

#endif

/* Readline implementation using fgets() */

char *

PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)

{

size_t n;

char *p, *pr;

#ifdef MS_WINDOWS

if (!Py_LegacyWindowsStdioFlag && sys_stdin == stdin) {

HANDLE hStdIn, hStdErr;

_Py_BEGIN_SUPPRESS_IPH

hStdIn = (HANDLE)_get_osfhandle(fileno(sys_stdin));

hStdErr = (HANDLE)_get_osfhandle(fileno(stderr));

_Py_END_SUPPRESS_IPH

if (_get_console_type(hStdIn) == 'r') {

fflush(sys_stdout);

if (prompt) {

if (_get_console_type(hStdErr) == 'w') {

wchar_t *wbuf;

int wlen;

wlen = MultiByteToWideChar(CP_UTF8, 0, prompt, -1,

NULL, 0);

if (wlen &&

(wbuf = PyMem_RawMalloc(wlen * sizeof(wchar_t)))) {

wlen = MultiByteToWideChar(CP_UTF8, 0, prompt, -1,

wbuf, wlen);

if (wlen) {

DWORD n;

fflush(stderr);

/* wlen includes null terminator, so subtract 1 */

WriteConsoleW(hStdErr, wbuf, wlen - 1, &n, NULL);

}

PyMem_RawFree(wbuf);

}

} else {

fprintf(stderr, "%s", prompt);

fflush(stderr);

}

clearerr(sys_stdin);

return _PyOS_WindowsConsoleReadline(hStdIn);

}

#endif

n = 100;

p = (char *)PyMem_RawMalloc(n);

if (p == 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_RawFree(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;

if (incr > INT_MAX) {

PyMem_RawFree(p);

PyErr_SetString(PyExc_OverflowError, "input line too long");

return NULL;

}

pr = (char *)PyMem_RawRealloc(p, n + incr);

if (pr == NULL) {

PyMem_RawFree(p);

PyErr_NoMemory();

return NULL;

}

p = pr;

if (my_fgets(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);

PyErr_NoMemory();

return NULL;

}

return pr;

}

/* 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 *, const char *) = NULL;

/* Interface used by tokenizer.c and bltinmodule.c */

char *

PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)

{

char *rv, *res;

size_t len;

if (_PyOS_ReadlineTState == PyThreadState_GET()) {

PyErr_SetString(PyExc_RuntimeError,

"can't re-enter readline");

return NULL;

}

if (PyOS_ReadlineFunctionPointer == NULL) {

PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;

}

if (_PyOS_ReadlineLock == NULL) {

_PyOS_ReadlineLock = PyThread_allocate_lock();

}

_PyOS_ReadlineTState = PyThreadState_GET();

Py_BEGIN_ALLOW_THREADS

PyThread_acquire_lock(_PyOS_ReadlineLock, 1);

/* 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

PyThread_release_lock(_PyOS_ReadlineLock);

_PyOS_ReadlineTState = NULL;

if (rv == NULL)

return NULL;

len = strlen(rv) + 1;

res = PyMem_Malloc(len);

if (res != NULL)

memcpy(res, rv, len);

PyMem_RawFree(rv);

return res;

}

cpython/Parser/myreadline.c at pythoncapi · pythoncapi/cpython · GitHub

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