Annotation of src/usr.bin/head/head.c, Revision 1.24
1.24 ! cheloha 1: /* $OpenBSD: head.c,v 1.23 2022/01/29 00:19:04 cheloha Exp $ */
1.2 deraadt 2:
1.1 deraadt 3: /*
4: * Copyright (c) 1980, 1987 Regents of the University of California.
5: * 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.
1.10 millert 15: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 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 <stdio.h>
33: #include <stdlib.h>
34: #include <ctype.h>
1.4 aaron 35: #include <limits.h>
1.7 deraadt 36: #include <err.h>
1.4 aaron 37: #include <errno.h>
1.1 deraadt 38: #include <unistd.h>
39:
1.23 cheloha 40: int head_file(const char *, long, int);
1.8 millert 41: static void usage(void);
1.1 deraadt 42:
43: /*
44: * head - give the first few lines of a stream or of each of a set of files
45: *
46: * Bill Joy UCB August 24, 1977
47: */
48:
49: int
1.11 deraadt 50: main(int argc, char *argv[])
1.1 deraadt 51: {
1.22 cheloha 52: const char *errstr;
1.23 cheloha 53: int ch;
1.4 aaron 54: long linecnt = 10;
1.17 tedu 55: int status = 0;
1.1 deraadt 56:
1.20 deraadt 57: if (pledge("stdio rpath", NULL) == -1)
58: err(1, "pledge");
1.19 deraadt 59:
1.1 deraadt 60: /* handle obsolete -number syntax */
1.16 deraadt 61: if (argc > 1 && argv[1][0] == '-' &&
62: isdigit((unsigned char)argv[1][1])) {
1.22 cheloha 63: linecnt = strtonum(argv[1] + 1, 1, LONG_MAX, &errstr);
64: if (errstr != NULL)
65: errx(1, "count is %s: %s", errstr, argv[1] + 1);
1.13 tedu 66: argc--;
67: argv++;
1.1 deraadt 68: }
69:
1.13 tedu 70: while ((ch = getopt(argc, argv, "n:")) != -1) {
1.1 deraadt 71: switch (ch) {
72: case 'n':
1.22 cheloha 73: linecnt = strtonum(optarg, 1, LONG_MAX, &errstr);
74: if (errstr != NULL)
75: errx(1, "count is %s: %s", errstr, optarg);
1.1 deraadt 76: break;
77: default:
1.21 tb 78: usage();
1.1 deraadt 79: }
1.13 tedu 80: }
1.1 deraadt 81: argc -= optind, argv += optind;
1.4 aaron 82:
1.23 cheloha 83: if (argc == 0) {
84: if (pledge("stdio", NULL) == -1)
85: err(1, "pledge");
86:
87: status = head_file(NULL, linecnt, 0);
88: } else {
89: for (; *argv != NULL; argv++)
90: status |= head_file(*argv, linecnt, argc > 1);
91: }
92:
93: return status;
94: }
95:
96: int
97: head_file(const char *path, long count, int need_header)
98: {
1.24 ! cheloha 99: const char *name;
1.23 cheloha 100: FILE *fp;
1.24 ! cheloha 101: int ch, status = 0;
1.23 cheloha 102: static int first = 1;
103:
104: if (path != NULL) {
1.24 ! cheloha 105: name = path;
! 106: fp = fopen(name, "r");
1.23 cheloha 107: if (fp == NULL) {
1.24 ! cheloha 108: warn("%s", name);
1.23 cheloha 109: return 1;
1.1 deraadt 110: }
1.23 cheloha 111: if (need_header) {
1.24 ! cheloha 112: printf("%s==> %s <==\n", first ? "" : "\n", name);
! 113: if (ferror(stdout))
! 114: err(1, "stdout");
1.23 cheloha 115: first = 0;
116: }
1.24 ! cheloha 117: } else {
! 118: name = "stdin";
1.23 cheloha 119: fp = stdin;
1.24 ! cheloha 120: }
! 121:
! 122: while ((ch = getc(fp)) != EOF) {
! 123: if (putchar(ch) == EOF)
! 124: err(1, "stdout");
! 125: if (ch == '\n' && --count == 0)
! 126: break;
! 127: }
! 128: if (ferror(fp)) {
! 129: warn("%s", name);
! 130: status = 1;
! 131: }
1.23 cheloha 132:
133: fclose(fp);
134:
1.24 ! cheloha 135: return status;
1.1 deraadt 136: }
137:
138:
139: static void
1.11 deraadt 140: usage(void)
1.1 deraadt 141: {
1.14 jmc 142: fputs("usage: head [-count | -n count] [file ...]\n", stderr);
1.1 deraadt 143: exit(1);
144: }
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