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uniq(1): freopen(3) stdin, stdout

uniq(1) defaults to stdin and stdout, has exactly one input and one
output, and permits the user to replace the default input and/or the
default output with a given file.

freopen(3) is the right idiom in this context.  Get rid of file() and
the extra FILE pointers.  Switch from fprintf(3) to printf(3).

While here, const the "str" argument to show().

Thread: https://marc.info/?l=openbsd-tech&m=164078603312936&w=2

ok millert@

/*	$OpenBSD: uniq.c,v 1.31 2022/01/01 02:20:38 cheloha Exp $	*/
/*	$NetBSD: uniq.c,v 1.7 1995/08/31 22:03:48 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
 * Case Larsen.
 *
 * 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>
#include <wchar.h>
#include <wctype.h>

int cflag, dflag, iflag, uflag;
int numchars, numfields, repeats;

void	 show(const char *);
char	*skip(char *);
void	 obsolete(char *[]);
__dead void	usage(void);

int
main(int argc, char *argv[])
{
	char *p, *prevline, *t, *thisline, *tmp;
	size_t prevsize, thissize, tmpsize;
	ssize_t len;
	int ch;

	setlocale(LC_CTYPE, "");

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

	obsolete(argv);
	while ((ch = getopt(argc, argv, "cdf:is:u")) != -1) {
		const char *errstr;

		switch (ch) {
		case 'c':
			cflag = 1;
			break;
		case 'd':
			dflag = 1;
			break;
		case 'f':
			numfields = (int)strtonum(optarg, 0, INT_MAX,
			    &errstr);
			if (errstr)
				errx(1, "field skip value is %s: %s",
				    errstr, optarg);
			break;
		case 'i':
			iflag = 1;
			break;
		case 's':
			numchars = (int)strtonum(optarg, 0, INT_MAX,
			    &errstr);
			if (errstr)
				errx(1,
				    "character skip value is %s: %s",
				    errstr, optarg);
			break;
		case 'u':
			uflag = 1;
			break;
		default:
			usage();
		}
	}

	argc -= optind;
	argv += optind;

	/* If neither -d nor -u are set, default is -d -u. */
	if (!dflag && !uflag)
		dflag = uflag = 1;

	if (argc > 2)
		usage();
	if (argc >= 1 && strcmp(argv[0], "-") != 0) {
		if (freopen(argv[0], "r", stdin) == NULL)
			err(1, "%s", argv[0]);
	}
	if (argc == 2 && strcmp(argv[1], "-") != 0) {
		if (freopen(argv[1], "w", stdout) == NULL)
			err(1, "%s", argv[1]);
	}

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

	prevsize = 0;
	prevline = NULL;
	if ((len = getline(&prevline, &prevsize, stdin)) == -1) {
		free(prevline);
		if (ferror(stdin))
			err(1, "getline");
		exit(0);
	}
	if (prevline[len - 1] == '\n')
		prevline[len - 1] = '\0';
	if (numfields || numchars)
		p = skip(prevline);
	else
		p = prevline;
	
	thissize = 0;
	thisline = NULL;
	while ((len = getline(&thisline, &thissize, stdin)) != -1) {
		if (thisline[len - 1] == '\n')
			thisline[len - 1] = '\0';

		/* If requested get the chosen fields + character offsets. */
		if (numfields || numchars)
			t = skip(thisline);
		else
			t = thisline;

		/* If different, print; set previous to new value. */
		if ((iflag ? strcasecmp : strcmp)(p, t)) {
			show(prevline);
			tmp = prevline;
			prevline = thisline;
			thisline = tmp;
			tmp = p;
			p = t;
			t = tmp;
			tmpsize = prevsize;
			prevsize = thissize;
			thissize = tmpsize;
			repeats = 0;
		} else
			++repeats;
	}
	free(thisline);
	if (ferror(stdin))
		err(1, "getline");

	show(prevline);
	free(prevline);

	exit(0);
}

/*
 * show --
 *	Output a line depending on the flags and number of repetitions
 *	of the line.
 */
void
show(const char *str)
{
	if ((dflag && repeats) || (uflag && !repeats)) {
		if (cflag)
			printf("%4d %s\n", repeats + 1, str);
		else
			printf("%s\n", str);
	}
}

char *
skip(char *str)
{
	wchar_t wc;
	int nchars, nfields;
	int len;
	int field_started;

	for (nfields = numfields; nfields && *str; nfields--) {
		/* Skip one field, including preceding blanks. */
		for (field_started = 0; *str != '\0'; str += len) {
			if ((len = mbtowc(&wc, str, MB_CUR_MAX)) == -1) {
				(void)mbtowc(NULL, NULL, MB_CUR_MAX);
				wc = L'?';
				len = 1;
			}
			if (iswblank(wc)) {
				if (field_started)
					break;
			} else
				field_started = 1;
		}
	}

	/* Skip some additional characters. */
	for (nchars = numchars; nchars-- && *str != '\0'; str += len)
		if ((len = mblen(str, MB_CUR_MAX)) == -1)
			len = 1;

	return (str);
}

void
obsolete(char *argv[])
{
	size_t len;
	char *ap, *p, *start;

	while ((ap = *++argv)) {
		/* Return if "--" or not an option of any form. */
		if (ap[0] != '-') {
			if (ap[0] != '+')
				return;
		} else if (ap[1] == '-')
			return;
		if (!isdigit((unsigned char)ap[1]))
			continue;
		/*
		 * Digit signifies an old-style option.  Malloc space for dash,
		 * new option and argument.
		 */
		len = strlen(ap) + 3;
		if ((start = p = malloc(len)) == NULL)
			err(1, "malloc");
		*p++ = '-';
		*p++ = ap[0] == '+' ? 's' : 'f';
		(void)strlcpy(p, ap + 1, len - 2);
		*argv = start;
	}
}

__dead void
usage(void)
{
	extern char *__progname;

	(void)fprintf(stderr,
	    "usage: %s [-ci] [-d | -u] [-f fields] [-s chars] [input_file [output_file]]\n",
	    __progname);
	exit(1);
}