xref: /src/sys/ddb/db_input.c

/*	$NetBSD: db_input.c,v 1.28 2020/10/30 06:57:08 skrll Exp $	*/

/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 *
 *	Author: David B. Golub, Carnegie Mellon University
 *	Date:	7/90
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: db_input.c,v 1.28 2020/10/30 06:57:08 skrll Exp $");

#ifdef _KERNEL_OPT
#include "opt_ddbparam.h"
#endif

#include <sys/param.h>
#include <sys/proc.h>

#include <ddb/ddb.h>

#include <dev/cons.h>

#ifndef DDB_HISTORY_SIZE
#define DDB_HISTORY_SIZE 0
#endif /* DDB_HISTORY_SIZE */

/*
 * Character input and editing.
 */

/*
 * We don't track output position while editing input,
 * since input always ends with a new-line.  We just
 * reset the line position at the end.
 */
static char    *db_lbuf_start;	/* start of input line buffer */
static char    *db_lbuf_end;	/* end of input line buffer */
static char    *db_lc;		/* current character */
static char    *db_le;		/* one past last character */
#if DDB_HISTORY_SIZE != 0
static char	db_history[DDB_HISTORY_SIZE];	/* start of history buffer */
static char    *db_history_curr = db_history;	/* start of current line */
static char    *db_history_last = db_history;	/* start of last line */
static char    *db_history_prev = (char *) 0;	/* start of previous line */
#endif


#define	CTRL(c)		((c) & 0x1f)
#define	isspace(c)	((c) == ' ' || (c) == '\t')
#define	BLANK		' '
#define	BACKUP		'\b'

static int	cnmaygetc(void);
static void	db_putstring(const char *, int);
static void	db_putnchars(int, int);
static void	db_delete(int, int);
static void	db_delete_line(void);
static int	db_inputchar(int);

static void
db_putstring(const char *s, int count)
{

	while (--count >= 0)
		cnputc(*s++);
}

static void
db_putnchars(int c, int count)
{

	while (--count >= 0)
		cnputc(c);
}

/*
 * Delete N characters, forward or backward
 */
#define	DEL_FWD		0
#define	DEL_BWD		1
static void
db_delete(int n, int bwd)
{
	char *p;

	if (bwd) {
		db_lc -= n;
		db_putnchars(BACKUP, n);
	}
	for (p = db_lc; p < db_le-n; p++) {
		*p = *(p+n);
		cnputc(*p);
	}
	db_putnchars(BLANK, n);
	db_putnchars(BACKUP, db_le - db_lc);
	db_le -= n;
}

static void
db_delete_line(void)
{

	db_delete(db_le - db_lc, DEL_FWD);
	db_delete(db_lc - db_lbuf_start, DEL_BWD);
	db_le = db_lc = db_lbuf_start;
}

#if DDB_HISTORY_SIZE != 0

#define INC_DB_CURR() do {						\
	++db_history_curr;						\
	if (db_history_curr > db_history + DDB_HISTORY_SIZE - 1)	\
		db_history_curr = db_history;				\
    } while (0)
#define DEC_DB_CURR() do {						\
	--db_history_curr;						\
	if (db_history_curr < db_history)				\
		db_history_curr = db_history + DDB_HISTORY_SIZE - 1;	\
    } while (0)

static inline void
db_hist_put(int c)
{
	KASSERT(&db_history[0]  <= db_history_last);
	KASSERT(db_history_last <= &db_history[DDB_HISTORY_SIZE-1]);

	*db_history_last++ = c;

	if (db_history_last > &db_history[DDB_HISTORY_SIZE-1])
	    db_history_last = db_history;
}
#endif


/* returns true at end-of-line */
static int
db_inputchar(int c)
{
	switch (c) {
	case CTRL('b'):
		/* back up one character */
		if (db_lc > db_lbuf_start) {
			cnputc(BACKUP);
			db_lc--;
		}
		break;
	case CTRL('f'):
		/* forward one character */
		if (db_lc < db_le) {
			cnputc(*db_lc);
			db_lc++;
		}
		break;
	case CTRL('a'):
		/* beginning of line */
		while (db_lc > db_lbuf_start) {
			cnputc(BACKUP);
			db_lc--;
		}
		break;
	case CTRL('e'):
		/* end of line */
		while (db_lc < db_le) {
			cnputc(*db_lc);
			db_lc++;
		}
		break;
	case CTRL('h'):
	case 0177:
		/* erase previous character */
		if (db_lc > db_lbuf_start)
			db_delete(1, DEL_BWD);
		break;
	case CTRL('d'):
		/* erase next character */
		if (db_lc < db_le)
			db_delete(1, DEL_FWD);
		break;
	case CTRL('k'):
		/* delete to end of line */
		if (db_lc < db_le)
			db_delete(db_le - db_lc, DEL_FWD);
		break;
	case CTRL('u'):
		/* delete line */
		db_delete_line();
		break;
	case CTRL('t'):
		/* twiddle last 2 characters */
		if (db_lc >= db_lbuf_start + 1) {
			if (db_lc < db_le) {
				c = db_lc[-1];
				db_lc[-1] = db_lc[0];
				db_lc[0] = c;
				cnputc(BACKUP);
				cnputc(db_lc[-1]);
				cnputc(db_lc[0]);
				db_lc++;
			} else if (db_lc >= db_lbuf_start + 2) {
				c = db_lc[-2];
				db_lc[-2] = db_lc[-1];
				db_lc[-1] = c;
				cnputc(BACKUP);
				cnputc(BACKUP);
				cnputc(db_lc[-2]);
				cnputc(db_lc[-1]);
			}
		}
		break;
#if DDB_HISTORY_SIZE != 0
	case CTRL('p'):
		DEC_DB_CURR();
		while (db_history_curr != db_history_last) {
			DEC_DB_CURR();
			if (*db_history_curr == '\0')
				break;
		}
		db_delete_line();
		if (db_history_curr == db_history_last) {
			INC_DB_CURR();
			db_le = db_lc = db_lbuf_start;
		} else {
			char *p;
			INC_DB_CURR();
			for (p = db_history_curr, db_le = db_lbuf_start;
			     *p; ) {
				*db_le++ = *p++;
				if (p >= db_history + DDB_HISTORY_SIZE) {
					p = db_history;
				}
			}
			db_lc = db_le;
		}
		db_putstring(db_lbuf_start, db_le - db_lbuf_start);
		break;
	case CTRL('n'):
		while (db_history_curr != db_history_last) {
			if (*db_history_curr == '\0')
				break;
			INC_DB_CURR();
		}
		if (db_history_curr != db_history_last) {
			INC_DB_CURR();
			db_delete_line();
			if (db_history_curr != db_history_last) {
				char *p;
				for (p = db_history_curr,
				     db_le = db_lbuf_start; *p;) {
					*db_le++ = *p++;
					if (p >= db_history + DDB_HISTORY_SIZE) {
						p = db_history;
					}
				}
				db_lc = db_le;
			}
			db_putstring(db_lbuf_start, db_le - db_lbuf_start);
		}
		break;
#endif
	case CTRL('r'):
		db_putstring("^R\n", 3);
		if (db_le > db_lbuf_start) {
			db_putstring(db_lbuf_start, db_le - db_lbuf_start);
			db_putnchars(BACKUP, db_le - db_lc);
		}
		break;
	case '\n':
	case '\r':
#if DDB_HISTORY_SIZE != 0
		/* Check if it same than previous line */
		if (db_history_curr == db_history_prev) {
			char *pp, *pc;

			/* Is it unmodified */
			for (pp = db_history_prev, pc = db_lbuf_start;
			     pc != db_le && *pp; pp++, pc++) {
				if (*pp != *pc)
					break;
				if (++pp >= db_history + DDB_HISTORY_SIZE) {
					pp = db_history;
				}
				if (++pc >= db_history + DDB_HISTORY_SIZE) {
					pc = db_history;
				}
			}
			if (!*pp && pc == db_le) {
				/* Repeted previous line, not saved */
				db_history_curr = db_history_last;
				*db_le++ = c;
				return (true);
			}
		}
		if (db_le != db_lbuf_start) {
			char *p;

			db_history_prev = db_history_last;

			for (p = db_lbuf_start; p != db_le; ) {
				db_hist_put(*p++);
			}
			db_hist_put(0);
		}
		db_history_curr = db_history_last;
#endif
		*db_le++ = c;
		return (1);
	default:
		if (db_le == db_lbuf_end) {
			cnputc('\007');
		}
		else if (c >= ' ' && c <= '~') {
			char *p;

			for (p = db_le; p > db_lc; p--)
				*p = *(p-1);
			*db_lc++ = c;
			db_le++;
			cnputc(c);
			db_putstring(db_lc, db_le - db_lc);
			db_putnchars(BACKUP, db_le - db_lc);
		}
		break;
	}
	return (0);
}

int
db_readline(char *lstart, int lsize)
{

	db_force_whitespace();	/* synch output position */

	db_lbuf_start = lstart;
	db_lbuf_end   = lstart + lsize;
	db_lc = lstart;
	db_le = lstart;

	while (!db_inputchar(cngetc()))
		continue;

	db_putchar('\n');	/* synch output position */

	*db_le = 0;
	return (db_le - db_lbuf_start);
}

void
db_check_interrupt(void)
{
	int	c;

	c = cnmaygetc();
	switch (c) {
	case -1:		/* no character */
		return;

	case CTRL('c'):
		db_error((char *)0);
		/*NOTREACHED*/

	case CTRL('s'):
		do {
			c = cnmaygetc();
			if (c == CTRL('c')) {
				db_error((char *)0);
				/*NOTREACHED*/
			}
		} while (c != CTRL('q'));
		break;

	default:
		/* drop on floor */
		break;
	}
}

static int
cnmaygetc(void)
{

	return (-1);
}