examples/loadables/cat.c

   1 /*
   2  * cat replacement
   3  *
   4  * no options - the way cat was intended
   5  */
   6
   7 #include <fcntl.h>
   8 #include <errno.h>
   9
  10 #include "builtins.h"
  11 #include "shell.h"
  12
  13 #ifndef errno
  14 extern int errno;
  15 #endif
  16
  17 extern char *strerror ();
  18 extern char **make_builtin_argv ();
  19
  20 static int
  21 fcopy(fd)
  22 int     fd;
  23 {
  24         char    buf[1024], *s;
  25         int     n, w, e;
  26
  27         while (n = read(fd, buf, sizeof (buf))) {
  28                 w = write(1, buf, n);
  29                 if (w != n) {
  30                         e = errno;
  31                         write(2, "cat: write error: ", 18);
  32                         s = strerror(e);
  33                         write(2, s, strlen(s));
  34                         write(2, "\n", 1);
  35                         return 1;
  36                 }
  37         }
  38         return 0;
  39 }
  40
  41 cat_main (argc, argv)
  42 int     argc;
  43 char    **argv;
  44 {
  45         int     i, fd, r;
  46         char    *s;
  47
  48         if (argc == 1)
  49                 return (fcopy(0));
  50
  51         for (i = r = 1; i < argc; i++) {
  52                 if (argv[i][0] == '-' && argv[i][1] == '\0')
  53                         fd = 0;
  54                 else {
  55                         fd = open(argv[i], O_RDONLY, 0666);
  56                         if (fd < 0) {
  57                                 s = strerror(errno);
  58                                 write(2, "cat: cannot open ", 17);
  59                                 write(2, argv[i], strlen(argv[i]));
  60                                 write(2, ": ", 2);
  61                                 write(2, s, strlen(s));
  62                                 write(2, "\n", 1);
  63                                 continue;
  64                         }
  65                 }
  66                 r = fcopy(fd);
  67                 if (fd != 0)
  68                         close(fd);
  69         }
  70         return (r);
  71 }
  72
  73 cat_builtin(list)
  74 WORD_LIST *list;
  75 {
  76         char    **v;
  77         int     c, r;
  78
  79         v = make_builtin_argv(list, &c);
  80         r = cat_main(c, v);
  81         free(v);
  82
  83         return r;
  84 }
  85
  86 char *cat_doc[] = {
  87         "Read each FILE and display it on the standard output.   If any",
  88         "FILE is `-' or if no FILE argument is given, the standard input",
  89         "is read.",
  90         (char *)0
  91 };
  92
  93 struct builtin cat_struct = {
  94         "cat",
  95         cat_builtin,
  96         BUILTIN_ENABLED,
  97         cat_doc,
  98         "cat [-] [file ...]",
  99         0
 100 };