lib/linebuffer.c

   1 /* linebuffer.c -- read arbitrarily long lines
   2    Copyright (C) 1986, 1991 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
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Written by Richard Stallman. */
  19 \f
  20 #include <stdio.h>
  21 #include "linebuffer.h"
  22
  23 char *xmalloc ();
  24 char *xrealloc ();
  25 void free ();
  26
  27 /* Initialize linebuffer LINEBUFFER for use. */
  28
  29 void
  30 initbuffer (linebuffer)
  31      struct linebuffer *linebuffer;
  32 {
  33   linebuffer->length = 0;
  34   linebuffer->size = 200;
  35   linebuffer->buffer = (char *) xmalloc (linebuffer->size);
  36 }
  37
  38 /* Read an arbitrarily long line of text from STREAM into LINEBUFFER.
  39    Remove any newline.  Does not null terminate.
  40    Return LINEBUFFER, except at end of file return 0.  */
  41
  42 struct linebuffer *
  43 readline (linebuffer, stream)
  44      struct linebuffer *linebuffer;
  45      FILE *stream;
  46 {
  47   int c;
  48   char *buffer = linebuffer->buffer;
  49   char *p = linebuffer->buffer;
  50   char *end = buffer + linebuffer->size; /* Sentinel. */
  51
  52   if (feof (stream))
  53     {
  54       linebuffer->length = 0;
  55       return 0;
  56     }
  57
  58   while (1)
  59     {
  60       c = getc (stream);
  61       if (p == end)
  62         {
  63           linebuffer->size *= 2;
  64           buffer = (char *) xrealloc (buffer, linebuffer->size);
  65           p += buffer - linebuffer->buffer;
  66           linebuffer->buffer = buffer;
  67           end = buffer + linebuffer->size;
  68         }
  69       if (c == EOF || c == '\n')
  70         break;
  71       *p++ = c;
  72     }
  73
  74   if (feof (stream) && p == buffer)
  75     {
  76       linebuffer->length = 0;
  77       return 0;
  78     }
  79   linebuffer->length = p - linebuffer->buffer;
  80   return linebuffer;
  81 }
  82
  83 /* Free linebuffer LINEBUFFER and its data, all allocated with malloc. */
  84
  85 void
  86 freebuffer (linebuffer)
  87      struct linebuffer *linebuffer;
  88 {
  89   free (linebuffer->buffer);
  90   free (linebuffer);
  91 }