Annotation of src/usr.bin/head/head.c, Revision 1.23
1.23 ! cheloha 1: /* $OpenBSD: head.c,v 1.22 2021/10/10 15:57:25 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: {
! 99: FILE *fp;
! 100: int ch;
! 101: static int first = 1;
! 102:
! 103: if (path != NULL) {
! 104: fp = fopen(path, "r");
! 105: if (fp == NULL) {
! 106: warn("%s", path);
! 107: return 1;
1.1 deraadt 108: }
1.23 ! cheloha 109: if (need_header) {
! 110: printf("%s==> %s <==\n", first ? "" : "\n", path);
! 111: first = 0;
! 112: }
! 113: } else
! 114: fp = stdin;
! 115:
! 116: for (; count > 0 && !feof(fp); --count)
! 117: while ((ch = getc(fp)) != EOF)
! 118: if (putchar(ch) == '\n')
! 119: break;
! 120: fclose(fp);
! 121:
! 122: return 0;
1.1 deraadt 123: }
124:
125:
126: static void
1.11 deraadt 127: usage(void)
1.1 deraadt 128: {
1.14 jmc 129: fputs("usage: head [-count | -n count] [file ...]\n", stderr);
1.1 deraadt 130: exit(1);
131: }