cpython/Parser/myreadline.c

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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.
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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 */
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int (*PyOS_InputHook)(void) = NULL;
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#ifdef RISCOS
int Py_RISCOSWimpFlag;
#endif
/* 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)
{
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) {
if (PyOS_InterruptOccurred()) {
return 1; /* Interrupt */
}
continue;
}
#endif
if (PyOS_InterruptOccurred()) {
return 1; /* Interrupt */
}
return -2; /* Error */
}
/* NOTREACHED */
}
/* Readline implementation using fgets() */
char *
PyOS_StdioReadline(char *prompt)
{
size_t n;
char *p;
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n = 100;
if ((p = PyMem_MALLOC(n)) == NULL)
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return NULL;
fflush(stdout);
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#ifndef RISCOS
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if (prompt)
fprintf(stderr, "%s", prompt);
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#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, stdin)) {
case 0: /* Normal case */
break;
case 1: /* Interrupt */
PyMem_FREE(p);
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return NULL;
case -1: /* EOF */
case -2: /* Error */
default: /* Shouldn't happen */
*p = '\0';
break;
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}
#ifdef MPW
/* Hack for MPW C where the prompt comes right back in the input */
/* XXX (Actually this would be rather nice on most systems...) */
n = strlen(prompt);
if (strncmp(p, prompt, n) == 0)
memmove(p, p + n, strlen(p) - n + 1);
#endif
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n = strlen(p);
while (n > 0 && p[n-1] != '\n') {
size_t incr = n+2;
p = PyMem_REALLOC(p, n + incr);
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if (p == NULL)
return NULL;
if (incr > INT_MAX) {
PyErr_SetString(PyExc_OverflowError, "input line too long");
}
if (my_fgets(p+n, (int)incr, stdin) != 0)
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break;
n += strlen(p+n);
}
return 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)(char *);
/* Interface used by tokenizer.c and bltinmodule.c */
char *
PyOS_Readline(char *prompt)
{
char *rv;
if (PyOS_ReadlineFunctionPointer == NULL) {
PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
}
Py_BEGIN_ALLOW_THREADS
rv = (*PyOS_ReadlineFunctionPointer)(prompt);
Py_END_ALLOW_THREADS
return rv;
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}