1/*
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1980, 1987, 1992, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/capsicum.h>
33#include <sys/types.h>
34
35#include <capsicum_helpers.h>
36#include <ctype.h>
37#include <err.h>
38#include <errno.h>
39#include <getopt.h>
40#include <inttypes.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <unistd.h>
45
46#include <libutil.h>
47
48#include <libcasper.h>
49#include <casper/cap_fileargs.h>
50
51/*
52 * head - give the first few lines of a stream or of each of a set of files
53 *
54 * Bill Joy UCB August 24, 1977
55 */
56
57static void head(FILE *, intmax_t);
58static void head_bytes(FILE *, off_t);
59static void obsolete(char *[]);
60static void usage(void) __dead2;
61
62static const struct option long_opts[] =
63{
64	{"bytes",	required_argument,	NULL, 'c'},
65	{"lines",	required_argument,	NULL, 'n'},
66	{"quiet",	no_argument,		NULL, 'q'},
67	{"silent",	no_argument,		NULL, 'q'},
68	{"verbose",	no_argument,		NULL, 'v'},
69	{NULL,		no_argument,		NULL, 0}
70};
71
72int
73main(int argc, char *argv[])
74{
75	FILE *fp;
76	off_t bytecnt;
77	intmax_t linecnt;
78	int ch, first, eval;
79	fileargs_t *fa;
80	cap_rights_t rights;
81	int qflag = 0;
82	int vflag = 0;
83
84	linecnt = -1;
85	eval = 0;
86	bytecnt = -1;
87
88	obsolete(argv);
89	while ((ch = getopt_long(argc, argv, "+n:c:qv", long_opts, NULL)) != -1) {
90		switch(ch) {
91		case 'c':
92			if (expand_number(optarg, &bytecnt) || bytecnt <= 0)
93				errx(1, "illegal byte count -- %s", optarg);
94			break;
95		case 'n':
96			if (expand_number(optarg, &linecnt) || linecnt <= 0)
97				errx(1, "illegal line count -- %s", optarg);
98			break;
99		case 'q':
100			qflag = 1;
101			vflag = 0;
102			break;
103		case 'v':
104			qflag = 0;
105			vflag = 1;
106			break;
107		case '?':
108		default:
109			usage();
110			/* NOTREACHED */
111		}
112	}
113	argc -= optind;
114	argv += optind;
115
116	fa = fileargs_init(argc, argv, O_RDONLY, 0,
117	    cap_rights_init(&rights, CAP_READ, CAP_FSTAT, CAP_FCNTL), FA_OPEN);
118	if (fa == NULL)
119		err(1, "unable to init casper");
120
121	caph_cache_catpages();
122	if (caph_limit_stdio() < 0 || caph_enter_casper() < 0)
123		err(1, "unable to enter capability mode");
124
125	if (linecnt != -1 && bytecnt != -1)
126		errx(1, "can't combine line and byte counts");
127	if (linecnt == -1)
128		linecnt = 10;
129	if (*argv != NULL) {
130		for (first = 1; *argv != NULL; ++argv) {
131			if ((fp = fileargs_fopen(fa, *argv, "r")) == NULL) {
132				warn("%s", *argv);
133				eval = 1;
134				continue;
135			}
136			if (vflag || (qflag == 0 && argc > 1)) {
137				(void)printf("%s==> %s <==\n",
138				    first ? "" : "\n", *argv);
139				first = 0;
140			}
141			if (bytecnt == -1)
142				head(fp, linecnt);
143			else
144				head_bytes(fp, bytecnt);
145			(void)fclose(fp);
146		}
147	} else if (bytecnt == -1)
148		head(stdin, linecnt);
149	else
150		head_bytes(stdin, bytecnt);
151
152	fileargs_free(fa);
153	exit(eval);
154}
155
156static void
157head(FILE *fp, intmax_t cnt)
158{
159	char *cp = NULL;
160	size_t error, bufsize = 0;
161	ssize_t readlen;
162
163	while (cnt != 0 && (readlen = getline(&cp, &bufsize, fp)) >= 0) {
164		error = fwrite(cp, sizeof(char), readlen, stdout);
165		if ((ssize_t)error != readlen)
166			err(1, "stdout");
167		cnt--;
168	}
169}
170
171static void
172head_bytes(FILE *fp, off_t cnt)
173{
174	char buf[4096];
175	size_t readlen;
176
177	while (cnt) {
178		if ((uintmax_t)cnt < sizeof(buf))
179			readlen = cnt;
180		else
181			readlen = sizeof(buf);
182		readlen = fread(buf, sizeof(char), readlen, fp);
183		if (readlen == 0)
184			break;
185		if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
186			err(1, "stdout");
187		cnt -= readlen;
188	}
189}
190
191static void
192obsolete(char *argv[])
193{
194	char *ap;
195
196	while ((ap = *++argv)) {
197		/* Return if "--" or not "-[0-9]*". */
198		if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
199			return;
200		if ((ap = malloc(strlen(*argv) + 2)) == NULL)
201			err(1, NULL);
202		ap[0] = '-';
203		ap[1] = 'n';
204		(void)strcpy(ap + 2, *argv + 1);
205		*argv = ap;
206	}
207}
208
209static void
210usage(void)
211{
212
213	(void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
214	exit(1);
215}
216