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.
   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
*/

#define Py_USE_NEW_NAMES 1

#include "config.h"

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include "myproto.h"
#include "mymalloc.h"
#include "intrcheck.h"


#ifdef WITH_READLINE

extern char *readline();
extern int rl_initialize();
extern int rl_insert();
extern int rl_bind_key();
extern void add_history();
extern char *rl_readline_name;

#include <setjmp.h>
#include <signal.h>

static jmp_buf jbuf;

/* ARGSUSED */
static RETSIGTYPE
onintr(sig)
	int sig;
{
	longjmp(jbuf, 1);
}

void
PyOS_ReadlineInit()
{
	static int been_here;
	if (!been_here) {
		/* Force rebind of TAB to insert-tab */
		rl_readline_name = "python";
		rl_initialize();
		rl_bind_key('\t', rl_insert);
		been_here++;
	}
}

char *
PyOS_GnuReadline(prompt)
	char *prompt;
{
	int n;
	char *p;
	RETSIGTYPE (*old_inthandler)();
	PyOS_ReadlineInit();
	old_inthandler = signal(SIGINT, onintr);
	if (setjmp(jbuf)) {
#ifdef HAVE_SIGRELSE
		/* This seems necessary on SunOS 4.1 (Rasmus Hahn) */
		sigrelse(SIGINT);
#endif
		signal(SIGINT, old_inthandler);
		return NULL;
	}
	p = readline(prompt);
	signal(SIGINT, old_inthandler);
	if (p == NULL) {
		p = malloc(1);
		if (p != NULL)
			*p = '\0';
		return p;
	}
	n = strlen(p);
	if (n > 0)
		add_history(p);
	if ((p = realloc(p, n+2)) != NULL) {
		p[n] = '\n';
		p[n+1] = '\0';
	}
	return p;
}

#endif /* !WITH_READLINE */


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

static int
my_fgets(buf, len, fp)
	char *buf;
	int len;
	FILE *fp;
{
	char *p;
	for (;;) {
		errno = 0;
		p = fgets(buf, len, fp);
		if (p != NULL)
			return 0; /* No error */
		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(prompt)
	char *prompt;
{
	int n;
	char *p;
	n = 100;
	if ((p = malloc(n)) == NULL)
		return NULL;
	fflush(stdout);
	if (prompt)
		fprintf(stderr, "%s", prompt);
	fflush(stderr);
	switch (my_fgets(p, n, stdin)) {
	case 0: /* Normal case */
		break;
	case 1: /* Interrupt */
		free(p);
		return NULL;
	case -1: /* EOF */
	case -2: /* Error */
	default: /* Shouldn't happen */
		*p = '\0';
		break;
	}
#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
	n = strlen(p);
	while (n > 0 && p[n-1] != '\n') {
		int incr = n+2;
		p = realloc(p, n + incr);
		if (p == NULL)
			return NULL;
		if (my_fgets(p+n, incr, stdin) != 0)
			break;
		n += strlen(p+n);
	}
	return realloc(p, n+1);
}


/* By initializing this function pointer, systems embedding Python can
   override the readline function. */

char *(*PyOS_ReadlineFunctionPointer) Py_PROTO((char *));


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

char *
PyOS_Readline(prompt)
	char *prompt;
{
	if (PyOS_ReadlineFunctionPointer == NULL) {
#ifdef WITH_READLINE
		if (isatty(fileno(stdin)))
			PyOS_ReadlineFunctionPointer = PyOS_GnuReadline;
		else
#endif
			PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
	}
	return (*PyOS_ReadlineFunctionPointer)(prompt);
}