1/* See LICENSE file for copyright and license details. */
 2
 3
 4
 5#include <fcntl.h>
 6#include <string.h>
 7#include <unistd.h>
 8
 9#include "util.h"
10
11static void
12usage(void)
13{
14	eprintf("usage: %s [-u] [file ...]\n", argv0);
15}
16
17// ?man cat: concatenate files and print to standard output
18// ?man arguments: file ...
19// ?man cat reads each file in sequence and writes it to standard output
20// ?man if no file is given, or a file is -, standard input is read
21int
22main(int argc, char *argv[])
23{
24	int fd, ret = 0;
25
26	ARGBEGIN {
27	// ?man -u: specify u option
28	case 'u':
29		// ?man -u: ignored; accepted for posix compatibility; output is always unbuffered
30		break;
31	default:
32		usage();
33	} ARGEND
34
35	if (!argc) {
36		if (concat(0, "<stdin>", 1, "<stdout>") < 0)
37			ret = 1;
38	} else {
39		for (; *argv; argc--, argv++) {
40			if (!strcmp(*argv, "-")) {
41				*argv = "<stdin>";
42				fd = 0;
43			} else if ((fd = open(*argv, O_RDONLY)) < 0) {
44				weprintf("open %s:", *argv);
45				ret = 1;
46				continue;
47			}
48			switch (concat(fd, *argv, 1, "<stdout>")) {
49			case -1:
50				ret = 1;
51				break;
52			case -2:
53				return 1;  /* exit on write error */
54			}
55			if (fd != 0)
56				close(fd);
57		}
58	}
59
60	// ?man
61	// ?man ## Exit status
62	// ?man
63	// ?man cat exits 0 on success, and >0 if an error occurs reading any file
64	// ?man or writing to standard output
65	// ?man
66	// ?man ## See also
67	// ?man
68	// ?man cp(1), dd(1)
69	// ?man
70
71	return ret;
72}