* Copyright (c) 1980, 1987, 1992, 1993

/* $NetBSD: head.c,v 1.24 2016/05/12 01:56:44 nonaka Exp $ */

/*
* 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
* 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 <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1992, 1993\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: head.c,v 1.24 2016/05/12 01:56:44 nonaka Exp $");
#endif
#endif /* not lint */

#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <locale.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 *, intmax_t, intmax_t);
static void obsolete(char *[]);
__dead static void usage(void);

int
main(int argc, char *argv[])
{
int ch;
FILE *fp;
int first;
intmax_t linecnt;
intmax_t bytecnt;
char *ep;
int eval = 0;
int qflag = 0;
int vflag = 0;

(void)setlocale(LC_ALL, "");
obsolete(argv);
linecnt = 10;
bytecnt = 0;
while ((ch = getopt(argc, argv, "c:n:qv")) != -1)
switch(ch) {
case 'c':
errno = 0;
bytecnt = strtoimax(optarg, &ep, 10);
if ((bytecnt == INTMAX_MAX && errno == ERANGE) ||
*ep || bytecnt <= 0)
errx(1, "illegal byte count -- %s", optarg);
break;

case 'n':
errno = 0;
linecnt = strtoimax(optarg, &ep, 10);
if ((linecnt == INTMAX_MAX && errno == ERANGE) ||
*ep || linecnt <= 0)
errx(1, "illegal line count -- %s", optarg);
break;

case 'q':
qflag = 1;
vflag = 0;
break;

case 'v':
qflag = 0;
vflag = 1;
break;

case '?':
default:
usage();
}
argc -= optind;
argv += optind;

if (*argv)
for (first = 1; *argv; ++argv) {
if ((fp = fopen(*argv, "r")) == NULL) {
warn("%s", *argv);
eval = 1;
continue;
}
if (vflag || (qflag == 0 && argc > 1)) {
(void)printf("%s==> %s <==\n",
first ? "" : "\n", *argv);
first = 0;
}
head(fp, linecnt, bytecnt);
(void)fclose(fp);
}
else
head(stdin, linecnt, bytecnt);
exit(eval);
}

static void
head(FILE *fp, intmax_t cnt, intmax_t bytecnt)
{
char buf[65536];
size_t len, rv, rv2;
int ch;

if (bytecnt) {
while (bytecnt) {
len = sizeof(buf);
if (bytecnt > (intmax_t)sizeof(buf))
len = sizeof(buf);
else
len = bytecnt;
rv = fread(buf, 1, len, fp);
if (rv == 0)
break; /* Distinguish EOF and error? */
rv2 = fwrite(buf, 1, rv, stdout);
if (rv2 != rv) {
if (feof(stdout))
errx(1, "EOF on stdout");
else
err(1, "failure writing to stdout");
}
bytecnt -= rv;
}
} else {
while ((ch = getc(fp)) != EOF) {
if (putchar(ch) == EOF)
err(1, "stdout");
if (ch == '\n' && --cnt == 0)
break;
}
}
}

static void
obsolete(char *argv[])
{
char *ap;

while ((ap = *++argv)) {
/* Return if "--" or not "-[0-9]*". */
if (ap[0] != '-' || ap[1] == '-' ||
!isdigit((unsigned char)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: %s [-n lines] [file ...]\n",
getprogname());
exit(1);
}