lib/readtokens0.c

   1 /* readtokens0.c -- Read NUL-separated tokens from an input stream.
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18    Written by Jim Meyering. */
  19
  20 #include <config.h>
  21 #include <stdlib.h>
  22
  23 #include "readtokens0.h"
  24
  25 #define obstack_chunk_alloc malloc
  26 #define obstack_chunk_free free
  27
  28 void
  29 readtokens0_init (struct Tokens *t)
  30 {
  31   t->n_tok = 0;
  32   t->tok = NULL;
  33   t->tok_len = NULL;
  34   obstack_init (&t->o_data);
  35   obstack_init (&t->o_tok);
  36   obstack_init (&t->o_tok_len);
  37 }
  38
  39 void
  40 readtokens0_free (struct Tokens *t)
  41 {
  42   obstack_free (&t->o_data, NULL);
  43   obstack_free (&t->o_tok, NULL);
  44   obstack_free (&t->o_tok_len, NULL);
  45 }
  46
  47 /* Finalize (in the obstack_finish sense) the current token
  48    and record its pointer and length.  */
  49 static void
  50 save_token (struct Tokens *t)
  51 {
  52   /* Don't count the trailing NUL byte in the length.  */
  53   size_t len = obstack_object_size (&t->o_data) - 1;
  54   char const *s = obstack_finish (&t->o_data);
  55   obstack_ptr_grow (&t->o_tok, s);
  56   obstack_grow (&t->o_tok_len, &len, sizeof len);
  57   t->n_tok++;
  58 }
  59
  60 /* Read NUL-separated tokens from stream IN into T until EOF or error.
  61    The final NUL is optional.  Always append a NULL pointer to the
  62    resulting list of token pointers, but that pointer isn't counted
  63    via t->n_tok.  Return true if successful.  */
  64 bool
  65 readtokens0 (FILE *in, struct Tokens *t)
  66 {
  67
  68   while (1)
  69     {
  70       int c = fgetc (in);
  71       if (c == EOF)
  72         {
  73           size_t len = obstack_object_size (&t->o_data);
  74           /* If the current object has nonzero length, then there
  75              was no NUL byte at EOF -- or maybe there was an error,
  76              in which case, we need to append a NUL byte to our buffer.  */
  77           if (len)
  78             {
  79               obstack_1grow (&t->o_data, '\0');
  80               save_token (t);
  81             }
  82
  83           break;
  84         }
  85
  86       obstack_1grow (&t->o_data, c);
  87       if (c == '\0')
  88         save_token (t);
  89     }
  90
  91   /* Add a NULL pointer at the end, in case the caller (like du)
  92      requires an argv-style array of strings.  */
  93   obstack_ptr_grow (&t->o_tok, NULL);
  94
  95   t->tok = obstack_finish (&t->o_tok);
  96   t->tok_len = obstack_finish (&t->o_tok_len);
  97   return ! ferror (in);
  98 }