cpython/Parser/myreadline.c

/* Readline interface for the tokenizer 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 "pycore_fileutils.h"     // _Py_BEGIN_SUPPRESS_IPH
#include "pycore_pystate.h"   // _PyThreadState_GET()
#ifdef MS_WINDOWS
#  ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#  endif
#  include "windows.h"
#endif /* MS_WINDOWS */

#ifdef HAVE_UNISTD_H
#  include <unistd.h>             // isatty()
#endif


// Export the symbol since it's used by the readline shared extension
PyAPI_DATA(PyThreadState*) _PyOS_ReadlineTState;
PyThreadState *_PyOS_ReadlineTState = …;

static PyThread_type_lock _PyOS_ReadlineLock = …;

int (*PyOS_InputHook)(void) = …;

/* This function restarts a fgets() after an EINTR error occurred
   except if _PyOS_InterruptOccurred() returns true. */

static int
my_fgets(PyThreadState* tstate, char *buf, int len, FILE *fp)
{ … }

#ifdef HAVE_WINDOWS_CONSOLE_IO
/* Readline implementation using ReadConsoleW */

extern char _get_console_type(HANDLE handle);

char *
_PyOS_WindowsConsoleReadline(PyThreadState *tstate, 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 &&
            // GH-104668: See PyOS_ReadlineFunctionPointer's comment below...
            _Py_IsMainInterpreter(tstate->interp))
        {
            (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(tstate);
                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 {
                PyEval_RestoreThread(tstate);
                PyErr_NoMemory();
                PyEval_SaveThread();
                goto exit;
            }
        }
        else {
            wchar_t *tmp = PyMem_RawRealloc(wbuf, wbuflen * sizeof(wchar_t));
            if (tmp == NULL) {
                PyEval_RestoreThread(tstate);
                PyErr_NoMemory();
                PyEval_SaveThread();
                goto exit;
            }
            wbuf = tmp;
        }
    }

    if (wbuf[0] == '\x1a') {
        buf = PyMem_RawMalloc(1);
        if (buf) {
            buf[0] = '\0';
        }
        else {
            PyEval_RestoreThread(tstate);
            PyErr_NoMemory();
            PyEval_SaveThread();
        }
        goto exit;
    }

    u8len = WideCharToMultiByte(CP_UTF8, 0,
                                wbuf, total_read,
                                NULL, 0,
                                NULL, NULL);
    buf = PyMem_RawMalloc(u8len + 1);
    if (buf == NULL) {
        PyEval_RestoreThread(tstate);
        PyErr_NoMemory();
        PyEval_SaveThread();
        goto exit;
    }

    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(tstate);
        PyErr_SetFromWindowsErr(err);
        PyEval_SaveThread();
    }
    return buf;
}

#endif /* HAVE_WINDOWS_CONSOLE_IO */


/* Readline implementation using fgets() */

char *
PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
{ … }


/* 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 *) = …;


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

char *
PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
{ … }