lib/linebuffer.c

   1 /* linebuffer.c -- read arbitrarily long lines
   2    Copyright (C) 1986, 1991, 1998, 1999, 2001 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 Richard Stallman. */
  19 \f
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <sys/types.h>
  26 #include "linebuffer.h"
  27 #include "unlocked-io.h"
  28 #include "xalloc.h"
  29
  30 void free ();
  31
  32 /* Initialize linebuffer LINEBUFFER for use. */
  33
  34 void
  35 initbuffer (struct linebuffer *linebuffer)
  36 {
  37   linebuffer->length = 0;
  38   linebuffer->size = 200;
  39   linebuffer->buffer = xmalloc (linebuffer->size);
  40 }
  41
  42 /* Read an arbitrarily long line of text from STREAM into LINEBUFFER.
  43    Keep the newline; append a newline if it's the last line of a file
  44    that ends in a non-newline character.  Do not null terminate.
  45    Therefore the stream can contain NUL bytes, and the length
  46    (including the newline) is returned in linebuffer->length.
  47    Return NULL upon error, or when STREAM is empty.
  48    Otherwise, return LINEBUFFER.  */
  49 struct linebuffer *
  50 readline (struct linebuffer *linebuffer, FILE *stream)
  51 {
  52   int c;
  53   char *buffer = linebuffer->buffer;
  54   char *p = linebuffer->buffer;
  55   char *end = buffer + linebuffer->size; /* Sentinel. */
  56
  57   if (feof (stream) || ferror (stream))
  58     return NULL;
  59
  60   do
  61     {
  62       c = getc (stream);
  63       if (c == EOF)
  64         {
  65           if (p == buffer)
  66             return NULL;
  67           if (p[-1] == '\n')
  68             break;
  69           c = '\n';
  70         }
  71       if (p == end)
  72         {
  73           linebuffer->size *= 2;
  74           buffer = xrealloc (buffer, linebuffer->size);
  75           p = p - linebuffer->buffer + buffer;
  76           linebuffer->buffer = buffer;
  77           end = buffer + linebuffer->size;
  78         }
  79       *p++ = c;
  80     }
  81   while (c != '\n');
  82
  83   linebuffer->length = p - buffer;
  84   return linebuffer;
  85 }
  86
  87 /* Free linebuffer LINEBUFFER and its data, all allocated with malloc. */
  88
  89 void
  90 freebuffer (struct linebuffer *linebuffer)
  91 {
  92   free (linebuffer->buffer);
  93   free (linebuffer);
  94 }