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improve POSIX compliance by continuing to process the remaining file
operands after not finding an input file.

from the IEEE Std 1003.1-2008 (``POSIX.1'') rationale:

    "Unlike other utilities, some historical implementations of cut
     exit after not finding an input file, rather than continuing to
     process the remaining file operands.  This behavior is prohibited
     by this volume of POSIX.1-2008, where only the exit status is
     affected by this problem."

joint work with jmc@, who identified the compliance issue, and millert@

ok millert@, jmc@

/*	$OpenBSD: cut.c,v 1.17 2014/02/01 23:34:49 sobrado 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 <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>

int	cflag;
char	dchar;
int	dflag;
int	fflag;
int	sflag;

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, eval = 0;

	setlocale (LC_ALL, "");

	dchar = '\t';			/* default delimiter is \t */

	/* Since we don't support multi-byte characters, the -c and -b 
	   options are equivalent, and the -n option is meaningless. */
	while ((ch = getopt(argc, argv, "b:c:d:f:sn")) != -1)
		switch(ch) {
		case 'b':
		case 'c':
			fcn = c_cut;
			get_list(optarg);
			cflag = 1;
			break;
		case 'd':
			dchar = *optarg;
			dflag = 1;
			break;
		case 'f':
			get_list(optarg);
			fcn = f_cut;
			fflag = 1;
			break;
		case 's':
			sflag = 1;
			break;
		case 'n':
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (fflag) {
		if (cflag)
			usage();
	} else if (!cflag || dflag || sflag)
		usage();

	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 {
					eval = 1;
					warn("%s", *argv);
				}
			}
		}
	else
		fcn(stdin, "stdin");
	exit(eval);
}

int autostart, autostop, maxval;

char positions[_POSIX2_LINE_MAX + 1];

void
get_list(char *list)
{
	int setautostart, start, stop;
	char *pos;
	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 = strtol(p, &p, 10);
			if (setautostart && start > autostart)
				autostart = start;
		}
		if (*p == '-') {
			if (isdigit((unsigned char)p[1]))
				stop = strtol(p + 1, &p, 10);
			if (*p == '-') {
				++p;
				if (!autostop || autostop > stop)
					autostop = stop;
			}
		}
		if (*p)
			errx(1, "[-bcf] list: illegal list value");
		if (!stop || !start)
			errx(1, "[-bcf] list: values may not include zero");
		if (stop > _POSIX2_LINE_MAX)
			errx(1, "[-bcf] list: %d too large (max %d)",
			    stop, _POSIX2_LINE_MAX);
		if (maxval < stop)
			maxval = stop;
		for (pos = positions + start; start++ <= stop; *pos++ = 1)
			;
	}

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

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

/* ARGSUSED */
void
c_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
f_cut(FILE *fp, char *fname)
{
	int ch, field, isdelim;
	char *pos, *p, sep;
	int output;
	size_t len;
	char *lbuf, *tbuf;

	for (sep = dchar, tbuf = NULL; (lbuf = fgetln(fp, &len));) {
		output = 0;
		if (lbuf[len - 1] != '\n') {
			/* no newline at the end of the last line so add one */
			if ((tbuf = (char *)malloc(len + 1)) == NULL)
				err(1, NULL);
			memcpy(tbuf, lbuf, len);
			tbuf[len] = '\n';
			lbuf = tbuf;
		}
		for (isdelim = 0, p = lbuf;; ++p) {
			ch = *p;
			/* this should work if newline is delimiter */
			if (ch == sep)
				isdelim = 1;
			if (ch == '\n') {
				if (!isdelim && !sflag)
					(void)fwrite(lbuf, len, 1, stdout);
				break;
			}
		}
		if (!isdelim)
			continue;

		pos = positions + 1;
		for (field = maxval, p = lbuf; field; --field, ++pos) {
			if (*pos) {
				if (output++)
					(void)putchar(sep);
				while ((ch = *p++) != '\n' && ch != sep)
					(void)putchar(ch);
			} else
				while ((ch = *p++) != '\n' && ch != sep)
					;
			if (ch == '\n')
				break;
		}
		if (ch != '\n') {
			if (autostop) {
				if (output)
					(void)putchar(sep);
				for (; (ch = *p) != '\n'; ++p)
					(void)putchar(ch);
			} else
				for (; (ch = *p) != '\n'; ++p)
					;
		}
		(void)putchar('\n');
	}
	if (tbuf)
		free(tbuf);
}

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);
}