lib/getline.c

   1 /* getline.c -- Replacement for GNU C library function getline
   2
   3 Copyright (C) 1993, 1996, 1997, 1998 Free Software Foundation, Inc.
   4
   5 This program is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful, but
  11 WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
  18
  19 /* Written by Jan Brittenson, bson@gnu.ai.mit.edu.  */
  20
  21 #if HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 /* The `getdelim' function is only declared if the following symbol
  26    is defined.  */
  27 #ifndef _GNU_SOURCE
  28 # define _GNU_SOURCE 1
  29 #endif
  30
  31 #include <stdio.h>
  32 #include <sys/types.h>
  33
  34 /* define getstr even if the other functions are unneeded */
  35 # define NDEBUG
  36 # include <assert.h>
  37
  38 # if STDC_HEADERS
  39 #  include <stdlib.h>
  40 # else
  41 char *malloc (), *realloc ();
  42 # endif
  43
  44 /* Always add at least this many bytes when extending the buffer.  */
  45 # define MIN_CHUNK 64
  46
  47 /* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
  48    + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
  49    malloc (or NULL), pointing to *N characters of space.  It is realloc'd
  50    as necessary.  Return the number of characters read (not including the
  51    null terminator), or -1 on error or EOF.  */
  52
  53 ssize_t
  54 getstr (char **lineptr, size_t *n, FILE *stream, char terminator, size_t offset)
  55 {
  56   int nchars_avail;             /* Allocated but unused chars in *LINEPTR.  */
  57   char *read_pos;               /* Where we're reading into *LINEPTR. */
  58   ssize_t ret;
  59
  60   if (!lineptr || !n || !stream)
  61     return -1;
  62
  63   if (!*lineptr)
  64     {
  65       *n = MIN_CHUNK;
  66       *lineptr = malloc (*n);
  67       if (!*lineptr)
  68         return -1;
  69     }
  70
  71   nchars_avail = *n - offset;
  72   read_pos = *lineptr + offset;
  73
  74   for (;;)
  75     {
  76       register int c = getc (stream);
  77
  78       /* We always want at least one char left in the buffer, since we
  79          always (unless we get an error while reading the first char)
  80          NUL-terminate the line buffer.  */
  81
  82       assert(*n - nchars_avail == read_pos - *lineptr);
  83       if (nchars_avail < 2)
  84         {
  85           if (*n > MIN_CHUNK)
  86             *n *= 2;
  87           else
  88             *n += MIN_CHUNK;
  89
  90           nchars_avail = *n + *lineptr - read_pos;
  91           *lineptr = realloc (*lineptr, *n);
  92           if (!*lineptr)
  93             return -1;
  94           read_pos = *n - nchars_avail + *lineptr;
  95           assert(*n - nchars_avail == read_pos - *lineptr);
  96         }
  97
  98       if (c == EOF || ferror (stream))
  99         {
 100           /* Return partial line, if any.  */
 101           if (read_pos == *lineptr)
 102             return -1;
 103           else
 104             break;
 105         }
 106
 107       *read_pos++ = c;
 108       nchars_avail--;
 109
 110       if (c == terminator)
 111         /* Return the line.  */
 112         break;
 113     }
 114
 115   /* Done - NUL terminate and return the number of chars read.  */
 116   *read_pos = '\0';
 117
 118   ret = read_pos - (*lineptr + offset);
 119   return ret;
 120 }
 121
 122 #ifndef HAVE_GETLINE
 123 #if defined __GNU_LIBRARY__ && HAVE_GETDELIM
 124 ssize_t
 125 getline (char **lineptr, size_t *n, FILE *stream)
 126 {
 127   return getdelim (lineptr, n, '\n', stream);
 128 }
 129
 130 #else /* ! have getdelim */
 131
 132 ssize_t
 133 getline (char **lineptr, size_t *n, FILE *stream)
 134 {
 135   return getstr (lineptr, n, stream, '\n', 0);
 136 }
 137
 138 #endif
 139 #endif
 140
 141
 142 #if ! (defined __GNU_LIBRARY__ && HAVE_GETDELIM)
 143 ssize_t
 144 getdelim (char **lineptr, size_t *n, int delimiter, FILE *stream)
 145 {
 146   return getstr (lineptr, n, stream, delimiter, 0);
 147 }
 148 #endif