examples/loadables/strftime.c

   1 /* strftime - loadable builtin interface to strftime(3) */
   2
   3 /* See Makefile for compilation details. */
   4
   5 /*
   6    Copyright (C) 1999-2009 Free Software Foundation, Inc.
   7
   8    This file is part of GNU Bash.
   9    Bash is free software: you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation, either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    Bash is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include <config.h>
  24
  25 #if defined (HAVE_UNISTD_H)
  26 #  include <unistd.h>
  27 #endif
  28
  29 #include "bashtypes.h"
  30 #include "posixtime.h"
  31
  32 #include <stdio.h>
  33
  34 #include "builtins.h"
  35 #include "shell.h"
  36 #include "common.h"
  37
  38 int
  39 strftime_builtin (list)
  40      WORD_LIST *list;
  41 {
  42   char *format, *tbuf;
  43   size_t tbsize, tsize;
  44   time_t secs;
  45   struct tm *t;
  46   int n;
  47   intmax_t i;
  48
  49   if (list == 0)
  50     {
  51       builtin_usage ();
  52       return (EX_USAGE);
  53     }
  54
  55   if (no_options (list))
  56     return (EX_USAGE);
  57
  58   format = list->word->word;
  59   if (format == 0 || *format == 0)
  60     {
  61       printf ("\n");
  62       return (EXECUTION_SUCCESS);
  63     }
  64
  65   list = list->next;
  66
  67   if (list && list->word->word)
  68     {
  69       n = legal_number (list->word->word, &i);
  70       if (n == 0 || i < 0 || i != (time_t)i)
  71         {
  72           sh_invalidnum (list->word->word);
  73           return (EXECUTION_FAILURE);
  74         }
  75       else
  76         secs = i;
  77     }
  78   else
  79     secs = NOW;
  80
  81   t = localtime (&secs);
  82
  83   tbsize = strlen (format) * 4;
  84   tbuf = 0;
  85
  86   /* Now try to figure out how big the buffer should really be.  strftime(3)
  87      will return the number of bytes placed in the buffer unless it's greater
  88      than MAXSIZE, in which case it returns 0. */
  89   for (n = 1; n < 4; n++)
  90     {
  91       tbuf = xrealloc (tbuf, tbsize * n);
  92       tsize = strftime (tbuf, tbsize * n, format, t);
  93       if (tsize)
  94         break;
  95     }
  96
  97   printf ("%s\n", tbuf);
  98   free (tbuf);
  99
 100   return (EXECUTION_SUCCESS);
 101 }
 102
 103 /* An array of strings forming the `long' documentation for a builtin xxx,
 104    which is printed by `help xxx'.  It must end with a NULL. */
 105 char *strftime_doc[] = {
 106         "Display formatted time.",
 107         "",
 108         "Converts date and time format to a string and displays it on the",
 109         "standard output.  If the optional second argument is supplied, it",
 110         "is used as the number of seconds since the epoch to use in the",
 111         "conversion, otherwise the current time is used.",
 112         (char *)NULL
 113 };
 114
 115 /* The standard structure describing a builtin command.  bash keeps an array
 116    of these structures.  The flags must include BUILTIN_ENABLED so the
 117    builtin can be used. */
 118 struct builtin strftime_struct = {
 119         "strftime",             /* builtin name */
 120         strftime_builtin,       /* function implementing the builtin */
 121         BUILTIN_ENABLED,        /* initial flags for builtin */
 122         strftime_doc,           /* array of long documentation strings. */
 123         "strftime format [seconds]",    /* usage synopsis; becomes short_doc */
 124         0                       /* reserved for internal use */
 125 };