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Fix overflow in list value parsing.

On 64 bit systems an integer overflow between strtol and int casting
could occur, resulting in out of boundary writes. Using strtonum fixes
this issue and leads to better error messages.

ok schwarze

/*	$OpenBSD: cut.c,v 1.24 2018/03/30 09:25:06 tobias Exp $	*/
/*	$NetBSD: cut.c,v 1.9 1995/09/02 05:59:23 jtc Exp $	*/

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam S. Moskowitz of Menlo Consulting and Marciano Pitargue.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char	dchar[5];
int	dlen;

int	bflag;
int	cflag;
int	dflag;
int	fflag;
int	nflag;
int	sflag;

void	b_cut(FILE *, char *);
void	c_cut(FILE *, char *);
void	f_cut(FILE *, char *);
void	get_list(char *);
void	usage(void);

int
main(int argc, char *argv[])
{
	FILE *fp;
	void (*fcn)(FILE *, char *);
	int ch, rval;

	setlocale(LC_CTYPE, "");

	if (pledge("stdio rpath", NULL) == -1)
		err(1, "pledge");

	dchar[0] = '\t';		/* default delimiter */
	dchar[1] = '\0';
	dlen = 1;

	while ((ch = getopt(argc, argv, "b:c:d:f:sn")) != -1)
		switch(ch) {
		case 'b':
			get_list(optarg);
			bflag = 1;
			break;
		case 'c':
			get_list(optarg);
			cflag = 1;
			break;
		case 'd':
			if ((dlen = mblen(optarg, MB_CUR_MAX)) == -1)
				usage();
			assert(dlen < sizeof(dchar));
			(void)memcpy(dchar, optarg, dlen);
			dchar[dlen] = '\0';
			dflag = 1;
			break;
		case 'f':
			get_list(optarg);
			fflag = 1;
			break;
		case 'n':
			nflag = 1;
			break;
		case 's':
			sflag = 1;
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (bflag + cflag + fflag != 1 ||
	    (nflag && !bflag) ||
	    ((dflag || sflag) && !fflag))
		usage();

	if (MB_CUR_MAX == 1) {
		nflag = 0;
		if (cflag) {
			bflag = 1;
			cflag = 0;
		}
	}

	fcn = fflag ? f_cut : (cflag || nflag) ? c_cut : b_cut;

	rval = 0;
	if (*argv)
		for (; *argv; ++argv) {
			if (strcmp(*argv, "-") == 0)
				fcn(stdin, "stdin");
			else {
				if ((fp = fopen(*argv, "r"))) {
					fcn(fp, *argv);
					(void)fclose(fp);
				} else {
					rval = 1;
					warn("%s", *argv);
				}
			}
		}
	else {
		if (pledge("stdio rpath", NULL) == -1)
			err(1, "pledge");

		fcn(stdin, "stdin");
	}
	exit(rval);
}

int autostart, autostop, maxval;

char positions[_POSIX2_LINE_MAX + 1];

int
read_number(char **p)
{
	size_t pos;
	int dash, n;
	const char *errstr;
	char *q;

	q = *p + strcspn(*p, "-");
	dash = *q == '-';
	*q = '\0';
	n = strtonum(*p, 1, _POSIX2_LINE_MAX, &errstr);
	if (errstr != NULL)
		errx(1, "[-bcf] list: %s %s (allowed 1-%d)", *p, errstr,
		    _POSIX2_LINE_MAX);
	if (dash)
		*q = '-';
	*p = q;

	return n;
}

void
get_list(char *list)
{
	int setautostart, start, stop;
	char *p;

	/*
	 * set a byte in the positions array to indicate if a field or
	 * column is to be selected; use +1, it's 1-based, not 0-based.
	 * This parser is less restrictive than the Draft 9 POSIX spec.
	 * POSIX doesn't allow lists that aren't in increasing order or
	 * overlapping lists.  We also handle "-3-5" although there's no
	 * real reason too.
	 */
	while ((p = strsep(&list, ", \t"))) {
		setautostart = start = stop = 0;
		if (*p == '-') {
			++p;
			setautostart = 1;
		}
		if (isdigit((unsigned char)*p)) {
			start = stop = read_number(&p);
			if (setautostart && start > autostart)
				autostart = start;
		}
		if (*p == '-') {
			if (isdigit((unsigned char)p[1])) {
				++p;
				stop = read_number(&p);
			}
			if (*p == '-') {
				++p;
				if (!autostop || autostop > stop)
					autostop = stop;
			}
		}
		if (*p != '\0' || !stop || !start)
			errx(1, "[-bcf] list: illegal list value");
		if (maxval < stop)
			maxval = stop;
		if (start <= stop)
			memset(positions + start, 1, stop - start + 1);
	}

	/* overlapping ranges */
	if (autostop && maxval > autostop)
		maxval = autostop;

	/* set autostart */
	if (autostart)
		memset(positions + 1, '1', autostart);
}

/* ARGSUSED */
void
b_cut(FILE *fp, char *fname)
{
	int ch, col;
	char *pos;

	for (;;) {
		pos = positions + 1;
		for (col = maxval; col; --col) {
			if ((ch = getc(fp)) == EOF)
				return;
			if (ch == '\n')
				break;
			if (*pos++)
				(void)putchar(ch);
		}
		if (ch != '\n') {
			if (autostop)
				while ((ch = getc(fp)) != EOF && ch != '\n')
					(void)putchar(ch);
			else
				while ((ch = getc(fp)) != EOF && ch != '\n')
					;
		}
		(void)putchar('\n');
	}
}

void
c_cut(FILE *fp, char *fname)
{
	static char	*line = NULL;
	static size_t	 linesz = 0;
	ssize_t		 linelen;
	char		*cp, *pos, *maxpos;
	int		 len;

	while ((linelen = getline(&line, &linesz, fp)) != -1) {
		if (line[linelen - 1] == '\n')
			line[linelen - 1] = '\0';

		cp = line;
		pos = positions + 1;
		maxpos = pos + maxval;
		while(pos < maxpos && *cp != '\0') {
			len = mblen(cp, MB_CUR_MAX);
			if (len == -1)
				len = 1;
			pos += nflag ? len : 1;
			if (pos[-1] == '\0')
				cp += len;
			else
				while (len--)
					putchar(*cp++);
		}
		if (autostop)
			puts(cp);
		else
			putchar('\n');
	}
}

void
f_cut(FILE *fp, char *fname)
{
	static char	*line = NULL;
	static size_t	 linesz = 0;
	ssize_t		 linelen;
	char		*sp, *ep, *pos, *maxpos;
	int		 output;

	while ((linelen = getline(&line, &linesz, fp)) != -1) {
		if (line[linelen - 1] == '\n')
			line[linelen - 1] = '\0';

		if ((ep = strstr(line, dchar)) == NULL) {
			if (!sflag)
				puts(line);
			continue;
		}

		pos = positions + 1;
		maxpos = pos + maxval;
		output = 0;
		sp = line;
		for (;;) {
			if (*pos++) {
				if (output)
					fputs(dchar, stdout);
				while (sp < ep)
					putchar(*sp++);
				output = 1;
			} else
				sp = ep;
			if (*sp == '\0' || pos == maxpos)
				break;
			sp += dlen;
			if ((ep = strstr(sp, dchar)) == NULL)
				ep = strchr(sp, '\0');
		}
		if (autostop)
			puts(sp);
		else
			putchar('\n');
	}
}

void
usage(void)
{
	(void)fprintf(stderr,
	    "usage: cut -b list [-n] [file ...]\n"
	    "       cut -c list [file ...]\n"
	    "       cut -f list [-s] [-d delim] [file ...]\n");
	exit(1);
}