examples/loadables/dirname.c

   1 /* dirname - return directory portion of pathname */
   2
   3 /* See Makefile for compilation details. */
   4
   5 #include "config.h"
   6
   7 #if defined (HAVE_UNISTD_H)
   8 #  include <unistd.h>
   9 #endif
  10
  11 #include <stdio.h>
  12 #include "builtins.h"
  13 #include "shell.h"
  14
  15 dirname_builtin (list)
  16      WORD_LIST *list;
  17 {
  18   int slen;
  19   char *string;
  20
  21   if (list == 0 || list->next)
  22     {
  23       builtin_usage ();
  24       return (EX_USAGE);
  25     }
  26
  27   if (no_options (list))
  28     return (EX_USAGE);
  29
  30   string = list->word->word;
  31   slen = strlen (string);
  32
  33   /* Strip trailing slashes */
  34   while (slen > 0 && string[slen - 1] == '/')
  35     slen--;
  36
  37   /* (2) If string consists entirely of slash characters, string shall be
  38          set to a single slash character.  In this case, skip steps (3)
  39          through (8). */
  40   if (slen == 0)
  41     {
  42       fputs ("/\n", stdout);
  43       return (EXECUTION_SUCCESS);
  44     }
  45
  46   /* (3) If there are any trailing slash characters in string, they
  47          shall be removed. */
  48   string[slen] = '\0';
  49
  50   /* (4) If there are no slash characters remaining in string, string
  51          shall be set to a single period character.  In this case, skip
  52          steps (5) through (8).
  53
  54      (5) If there are any trailing nonslash characters in string,
  55          they shall be removed. */
  56
  57   while (--slen >= 0)
  58     if (string[slen] == '/')
  59       break;
  60
  61   if (slen < 0)
  62     {
  63       fputs (".\n", stdout);
  64       return (EXECUTION_SUCCESS);
  65     }
  66
  67   /* (7) If there are any trailing slash characters in string, they
  68          shall be removed. */
  69   while (--slen >= 0)
  70     if (string[slen] != '/')
  71       break;
  72   string[++slen] = '\0';
  73
  74   /* (8) If the remaining string is empty, string shall be set to a single
  75          slash character. */
  76   printf ("%s\n", (slen == 0) ? "/" : string);
  77   return (EXECUTION_SUCCESS);
  78 }
  79
  80 char *dirname_doc[] = {
  81         "The STRING is converted to the name of the directory containing",
  82         "the filename corresponding to the last pathname component in STRING.",
  83         (char *)NULL
  84 };
  85
  86 /* The standard structure describing a builtin command.  bash keeps an array
  87    of these structures. */
  88 struct builtin dirname_struct = {
  89         "dirname",              /* builtin name */
  90         dirname_builtin,        /* function implementing the builtin */
  91         BUILTIN_ENABLED,        /* initial flags for builtin */
  92         dirname_doc,            /* array of long documentation strings. */
  93         "dirname string",       /* usage synopsis */
  94         0                       /* reserved for internal use */
  95 };