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