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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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
#ifndef lint
static const char copyright[] =
"@(#) 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
static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*
* 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 *, size_t);
static void obsolete(char *[]);
static void usage(void);
int
main(int argc, char *argv[])
{
int ch;
FILE *fp;
int first, linecnt = -1, bytecnt = -1, eval = 0;
char *ep;
obsolete(argv);
while ((ch = getopt(argc, argv, "n:c:")) != -1)
switch(ch) {
case 'c':
bytecnt = strtol(optarg, &ep, 10);
if (*ep || bytecnt <= 0)
errx(1, "illegal byte count -- %s", optarg);
break;
case 'n':
linecnt = strtol(optarg, &ep, 10);
if (*ep || linecnt <= 0)
errx(1, "illegal line count -- %s", optarg);
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
if (linecnt != -1 && bytecnt != -1)
errx(1, "can't combine line and byte counts");
if (linecnt == -1 )
linecnt = 10;
if (*argv) {
for (first = 1; *argv; ++argv) {
if ((fp = fopen(*argv, "r")) == NULL) {
warn("%s", *argv);
eval = 1;
continue;
}
if (argc > 1) {
(void)printf("%s==> %s <==\n",
first ? "" : "\n", *argv);
first = 0;
}
if (bytecnt == -1)
head(fp, linecnt);
else
head_bytes(fp, bytecnt);
(void)fclose(fp);
}
} else if (bytecnt == -1)
head(stdin, linecnt);
else
head_bytes(stdin, bytecnt);
exit(eval);
}
static void
head(FILE *fp, int cnt)
{
char *cp;
size_t error, readlen;
while (cnt && (cp = fgetln(fp, &readlen)) != NULL) {
error = fwrite(cp, sizeof(char), readlen, stdout);
if (error != readlen)
err(1, "stdout");
cnt--;
}
}
static void
head_bytes(FILE *fp, size_t cnt)
{
char buf[4096];
size_t readlen;
while (cnt) {
if (cnt < sizeof(buf))
readlen = cnt;
else
readlen = sizeof(buf);
readlen = fread(buf, sizeof(char), readlen, fp);
if (readlen == 0)
break;
if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
err(1, "stdout");
cnt -= readlen;
}
}
static void
obsolete(char *argv[])
{
char *ap;
while ((ap = *++argv)) {
/* 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);
ap[0] = '-';
ap[1] = 'n';
(void)strcpy(ap + 2, *argv + 1);
*argv = ap;
}
}
static void
usage(void)
{
(void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
exit(1);
}
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