1 /* $NetBSD: head.c,v 1.23 2010/03/31 21:55:23 joerg Exp $ */
2
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/cdefs.h>
33 #ifndef lint
34 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1992, 1993\
35 The Regents of the University of California. All rights reserved.");
36 #endif /* not lint */
37
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
41 #else
42 __RCSID("$NetBSD: head.c,v 1.23 2010/03/31 21:55:23 joerg Exp $");
43 #endif
44 #endif /* not lint */
45
46 #include <sys/types.h>
47
48 #include <ctype.h>
49 #include <err.h>
50 #include <errno.h>
51 #include <inttypes.h>
52 #include <limits.h>
53 #include <locale.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <unistd.h>
58
59 /*
60 * head - give the first few lines of a stream or of each of a set of files
61 *
62 * Bill Joy UCB August 24, 1977
63 */
64
65 static void head(FILE *, intmax_t, intmax_t);
66 static void obsolete(char *[]);
67 __dead static void usage(void);
68
69
70 int
main(int argc,char * argv[])71 main(int argc, char *argv[])
72 {
73 int ch;
74 FILE *fp;
75 int first;
76 uintmax_t linecnt;
77 uintmax_t bytecnt;
78 char *ep;
79 int eval = 0;
80 int qflag = 0;
81 int vflag = 0;
82
83 (void)setlocale(LC_ALL, "");
84 obsolete(argv);
85 linecnt = 10;
86 bytecnt = 0;
87 while ((ch = getopt(argc, argv, "c:n:qv")) != -1)
88 switch(ch) {
89 case 'c':
90 errno = 0;
91 bytecnt = strtoimax(optarg, &ep, 10);
92 if ((bytecnt == INTMAX_MAX && errno == ERANGE) ||
93 *ep || bytecnt <= 0)
94 errx(1, "illegal byte count -- %s", optarg);
95 break;
96
97 case 'n':
98 errno = 0;
99 linecnt = strtoimax(optarg, &ep, 10);
100 if ((linecnt == INTMAX_MAX && errno == ERANGE) ||
101 *ep || linecnt <= 0)
102 errx(1, "illegal line count -- %s", optarg);
103 break;
104
105 case 'q':
106 qflag = 1;
107 vflag = 0;
108 break;
109
110 case 'v':
111 qflag = 0;
112 vflag = 1;
113 break;
114
115 case '?':
116 default:
117 usage();
118 }
119 argc -= optind;
120 argv += optind;
121
122 if (*argv)
123 for (first = 1; *argv; ++argv) {
124 if ((fp = fopen(*argv, "r")) == NULL) {
125 warn("%s", *argv);
126 eval = 1;
127 continue;
128 }
129 if (vflag || (qflag == 0 && argc > 1)) {
130 (void)printf("%s==> %s <==\n",
131 first ? "" : "\n", *argv);
132 first = 0;
133 }
134 head(fp, linecnt, bytecnt);
135 (void)fclose(fp);
136 }
137 else
138 head(stdin, linecnt, bytecnt);
139 exit(eval);
140 }
141
142 static void
head(FILE * fp,intmax_t cnt,intmax_t bytecnt)143 head(FILE *fp, intmax_t cnt, intmax_t bytecnt)
144 {
145 char buf[65536];
146 size_t len, rv, rv2;
147 int ch;
148
149 if (bytecnt) {
150 while (bytecnt) {
151 len = sizeof(buf);
152 if (bytecnt > (intmax_t)sizeof(buf))
153 len = sizeof(buf);
154 else
155 len = bytecnt;
156 rv = fread(buf, 1, len, fp);
157 if (rv == 0)
158 break; /* Distinguish EOF and error? */
159 rv2 = fwrite(buf, 1, rv, stdout);
160 if (rv2 != rv) {
161 if (feof(stdout))
162 errx(1, "EOF on stdout");
163 else
164 err(1, "failure writing to stdout");
165 }
166 bytecnt -= rv;
167 }
168 } else {
169 while ((ch = getc(fp)) != EOF) {
170 if (putchar(ch) == EOF)
171 err(1, "stdout");
172 if (ch == '\n' && --cnt == 0)
173 break;
174 }
175 }
176 }
177
178 static void
obsolete(char * argv[])179 obsolete(char *argv[])
180 {
181 char *ap;
182
183 while ((ap = *++argv)) {
184 /* Return if "--" or not "-[0-9]*". */
185 if (ap[0] != '-' || ap[1] == '-' ||
186 !isdigit((unsigned char)ap[1]))
187 return;
188 if ((ap = malloc(strlen(*argv) + 2)) == NULL)
189 err(1, NULL);
190 ap[0] = '-';
191 ap[1] = 'n';
192 (void)strcpy(ap + 2, *argv + 1);
193 *argv = ap;
194 }
195 }
196
197 static void
usage(void)198 usage(void)
199 {
200
201 (void)fprintf(stderr, "usage: %s [-n lines] [file ...]\n",
202 getprogname());
203 exit(1);
204 }
205