1/* vi: set sw=4 ts=4: */
2/*
3 * Mini head implementation for busybox
4 *
5 *
6 * Copyright (C) 1999,2000,2001 by Lineo, inc.
7 * Written by John Beppu <beppu@lineo.com>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 *
23 */
24
25#include <errno.h>
26#include <stdio.h>
27#include <getopt.h>
28#include <stdlib.h>
29#include <string.h>
30#include "busybox.h"
31
32static int head(int len, FILE *fp)
33{
34	int i;
35	char *input;
36
37	for (i = 0; i < len; i++) {
38		if ((input = get_line_from_file(fp)) == NULL)
39			break;
40		fputs(input, stdout);
41		free(input);
42	}
43	return 0;
44}
45
46/* BusyBoxed head(1) */
47int head_main(int argc, char **argv)
48{
49	FILE *fp;
50	int need_headers, opt, len = 10, status = EXIT_SUCCESS;
51
52	/* parse argv[] */
53	while ((opt = getopt(argc, argv, "n:")) > 0) {
54		switch (opt) {
55		case 'n':
56			len = atoi(optarg);
57			if (len >= 1)
58				break;
59			/* fallthrough */
60		default:
61			show_usage();
62		}
63	}
64
65	/* get rest of argv[] or stdin if nothing's left */
66	if (argv[optind] == NULL) {
67		head(len, stdin);
68		return status;
69	}
70
71	need_headers = optind != (argc - 1);
72	while (argv[optind]) {
73		if (strcmp(argv[optind], "-") == 0) {
74			fp = stdin;
75			argv[optind] = "standard input";
76		} else {
77			if ((fp = wfopen(argv[optind], "r")) == NULL)
78				status = EXIT_FAILURE;
79		}
80		if (fp) {
81			if (need_headers) {
82				printf("==> %s <==\n", argv[optind]);
83			}
84			head(len, fp);
85			if (errno) {
86				perror_msg("%s", argv[optind]);
87				status = EXIT_FAILURE;
88				errno = 0;
89			}
90			if (optind < argc - 1)
91				putchar('\n');
92			if (fp != stdin)
93				fclose(fp);
94		}
95		optind++;
96	}
97
98	return status;
99}
100