lib/linebuffer.c

   1 /* linebuffer.c -- read arbitrarily long lines
   2
   3    Copyright (C) 1986, 1991, 1998, 1999, 2001, 2003 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* Written by Richard Stallman. */
  21 \f
  22 #ifdef HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sys/types.h>
  30 #include "linebuffer.h"
  31 #include "unlocked-io.h"
  32 #include "xalloc.h"
  33
  34 /* Initialize linebuffer LINEBUFFER for use. */
  35
  36 void
  37 initbuffer (struct linebuffer *linebuffer)
  38 {
  39   memset (linebuffer, 0, sizeof *linebuffer);
  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 when stream is empty.  Return NULL and set errno upon
  48    error; callers can distinguish this case from the empty case by
  49    invoking ferror (stream).
  50    Otherwise, return LINEBUFFER.  */
  51 struct linebuffer *
  52 readlinebuffer (struct linebuffer *linebuffer, FILE *stream)
  53 {
  54   int c;
  55   char *buffer = linebuffer->buffer;
  56   char *p = linebuffer->buffer;
  57   char *end = buffer + linebuffer->size; /* Sentinel. */
  58
  59   if (feof (stream))
  60     return NULL;
  61
  62   do
  63     {
  64       c = getc (stream);
  65       if (c == EOF)
  66         {
  67           if (p == buffer || ferror (stream))
  68             return NULL;
  69           if (p[-1] == '\n')
  70             break;
  71           c = '\n';
  72         }
  73       if (p == end)
  74         {
  75           size_t oldsize = linebuffer->size;
  76           buffer = x2realloc (buffer, &linebuffer->size);
  77           p = buffer + oldsize;
  78           linebuffer->buffer = buffer;
  79           end = buffer + linebuffer->size;
  80         }
  81       *p++ = c;
  82     }
  83   while (c != '\n');
  84
  85   linebuffer->length = p - buffer;
  86   return linebuffer;
  87 }
  88
  89 /* Free the buffer that was allocated for linebuffer LINEBUFFER.  */
  90
  91 void
  92 freebuffer (struct linebuffer *linebuffer)
  93 {
  94   free (linebuffer->buffer);
  95 }