freebsd-dev/usr.bin/head/head.c

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/*
* SPDX-License-Identifier: BSD-3-Clause
*
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* Copyright (c) 1980, 1987, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* 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
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* 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.
*/
#ifndef lint
static const char copyright[] =
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"@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
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static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
#endif
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#endif /* not lint */
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#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
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#include <sys/capsicum.h>
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#include <sys/types.h>
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#include <capsicum_helpers.h>
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#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <getopt.h>
#include <inttypes.h>
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#include <stdio.h>
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#include <stdlib.h>
#include <string.h>
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#include <unistd.h>
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#include <libcasper.h>
#include <casper/cap_fileargs.h>
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/*
* head - give the first few lines of a stream or of each of a set of files
*
* Bill Joy UCB August 24, 1977
*/
static void head(FILE *, int);
static void head_bytes(FILE *, off_t);
static void obsolete(char *[]);
static void usage(void);
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static const struct option long_opts[] =
{
{"bytes", required_argument, NULL, 'c'},
{"lines", required_argument, NULL, 'n'},
{NULL, no_argument, NULL, 0}
};
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int
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main(int argc, char *argv[])
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{
FILE *fp;
char *ep;
off_t bytecnt;
int ch, first, linecnt, eval;
fileargs_t *fa;
cap_rights_t rights;
linecnt = -1;
eval = 0;
bytecnt = -1;
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obsolete(argv);
while ((ch = getopt_long(argc, argv, "+n:c:", long_opts, NULL)) != -1) {
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switch(ch) {
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case 'c':
bytecnt = strtoimax(optarg, &ep, 10);
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if (*ep || bytecnt <= 0)
errx(1, "illegal byte count -- %s", optarg);
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break;
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case 'n':
linecnt = strtol(optarg, &ep, 10);
if (*ep || linecnt <= 0)
errx(1, "illegal line count -- %s", optarg);
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break;
case '?':
default:
usage();
/* NOTREACHED */
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}
}
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argc -= optind;
argv += optind;
fa = fileargs_init(argc, argv, O_RDONLY, 0,
cap_rights_init(&rights, CAP_READ, CAP_FSTAT, CAP_FCNTL), FA_OPEN);
if (fa == NULL)
errx(1, "unable to init casper");
caph_cache_catpages();
if (caph_limit_stdio() < 0 || caph_enter_casper() < 0)
err(1, "unable to enter capability mode");
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if (linecnt != -1 && bytecnt != -1)
errx(1, "can't combine line and byte counts");
if (linecnt == -1)
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linecnt = 10;
if (*argv != NULL) {
for (first = 1; *argv != NULL; ++argv) {
if ((fp = fileargs_fopen(fa, *argv, "r")) == NULL) {
warn("%s", *argv);
eval = 1;
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continue;
}
if (argc > 1) {
(void)printf("%s==> %s <==\n",
first ? "" : "\n", *argv);
first = 0;
}
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if (bytecnt == -1)
head(fp, linecnt);
else
head_bytes(fp, bytecnt);
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(void)fclose(fp);
}
} else if (bytecnt == -1)
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head(stdin, linecnt);
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else
head_bytes(stdin, bytecnt);
fileargs_free(fa);
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exit(eval);
}
static void
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head(FILE *fp, int cnt)
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{
char *cp;
size_t error, readlen;
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while (cnt != 0 && (cp = fgetln(fp, &readlen)) != NULL) {
error = fwrite(cp, sizeof(char), readlen, stdout);
if (error != readlen)
err(1, "stdout");
cnt--;
}
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}
static void
head_bytes(FILE *fp, off_t cnt)
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{
char buf[4096];
size_t readlen;
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while (cnt) {
if ((uintmax_t)cnt < sizeof(buf))
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readlen = cnt;
else
readlen = sizeof(buf);
readlen = fread(buf, sizeof(char), readlen, fp);
if (readlen == 0)
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break;
if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
err(1, "stdout");
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cnt -= readlen;
}
}
static void
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obsolete(char *argv[])
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{
char *ap;
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while ((ap = *++argv)) {
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/* Return if "--" or not "-[0-9]*". */
if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
return;
if ((ap = malloc(strlen(*argv) + 2)) == NULL)
err(1, NULL);
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ap[0] = '-';
ap[1] = 'n';
(void)strcpy(ap + 2, *argv + 1);
*argv = ap;
}
}
static void
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usage(void)
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{
(void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
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exit(1);
}