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
57 static void head(FILE *, intmax_t);
58 static void head_bytes(FILE *, off_t);
59 static void obsolete(char *[]);
60 static void usage(void) __dead2;
61
62 static 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
72 int
main(int argc,char * argv[])73 main(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
156 static void
head(FILE * fp,intmax_t cnt)157 head(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
171 static void
head_bytes(FILE * fp,off_t cnt)172 head_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
191 static void
obsolete(char * argv[])192 obsolete(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
209 static void
usage(void)210 usage(void)
211 {
212
213 (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
214 exit(1);
215 }
216