lib/getline.c

   1 /* getline.c -- Replacement for GNU C library function getline
   2
   3 Copyright (C) 1993, 1996, 1997 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 #if defined __GNU_LIBRARY__ && HAVE_GETDELIM
  35
  36 int
  37 getline (lineptr, n, stream)
  38      char **lineptr;
  39      size_t *n;
  40      FILE *stream;
  41 {
  42   return getdelim (lineptr, n, '\n', stream);
  43 }
  44
  45
  46 #else /* ! have getdelim */
  47
  48 # define NDEBUG
  49 # include <assert.h>
  50
  51 # if STDC_HEADERS
  52 #  include <stdlib.h>
  53 # else
  54 char *malloc (), *realloc ();
  55 # endif
  56
  57 /* Always add at least this many bytes when extending the buffer.  */
  58 # define MIN_CHUNK 64
  59
  60 /* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
  61    + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
  62    malloc (or NULL), pointing to *N characters of space.  It is realloc'd
  63    as necessary.  Return the number of characters read (not including the
  64    null terminator), or -1 on error or EOF.  */
  65
  66 int
  67 getstr (lineptr, n, stream, terminator, offset)
  68      char **lineptr;
  69      size_t *n;
  70      FILE *stream;
  71      char terminator;
  72      size_t offset;
  73 {
  74   int nchars_avail;             /* Allocated but unused chars in *LINEPTR.  */
  75   char *read_pos;               /* Where we're reading into *LINEPTR. */
  76   int ret;
  77
  78   if (!lineptr || !n || !stream)
  79     return -1;
  80
  81   if (!*lineptr)
  82     {
  83       *n = MIN_CHUNK;
  84       *lineptr = malloc (*n);
  85       if (!*lineptr)
  86         return -1;
  87     }
  88
  89   nchars_avail = *n - offset;
  90   read_pos = *lineptr + offset;
  91
  92   for (;;)
  93     {
  94       register int c = getc (stream);
  95
  96       /* We always want at least one char left in the buffer, since we
  97          always (unless we get an error while reading the first char)
  98          NUL-terminate the line buffer.  */
  99
 100       assert(*n - nchars_avail == read_pos - *lineptr);
 101       if (nchars_avail < 2)
 102         {
 103           if (*n > MIN_CHUNK)
 104             *n *= 2;
 105           else
 106             *n += MIN_CHUNK;
 107
 108           nchars_avail = *n + *lineptr - read_pos;
 109           *lineptr = realloc (*lineptr, *n);
 110           if (!*lineptr)
 111             return -1;
 112           read_pos = *n - nchars_avail + *lineptr;
 113           assert(*n - nchars_avail == read_pos - *lineptr);
 114         }
 115
 116       if (c == EOF || ferror (stream))
 117         {
 118           /* Return partial line, if any.  */
 119           if (read_pos == *lineptr)
 120             return -1;
 121           else
 122             break;
 123         }
 124
 125       *read_pos++ = c;
 126       nchars_avail--;
 127
 128       if (c == terminator)
 129         /* Return the line.  */
 130         break;
 131     }
 132
 133   /* Done - NUL terminate and return the number of chars read.  */
 134   *read_pos = '\0';
 135
 136   ret = read_pos - (*lineptr + offset);
 137   return ret;
 138 }
 139
 140 int
 141 getline (lineptr, n, stream)
 142      char **lineptr;
 143      size_t *n;
 144      FILE *stream;
 145 {
 146   return getstr (lineptr, n, stream, '\n', 0);
 147 }
 148
 149 int
 150 getdelim (lineptr, n, delimiter, stream)
 151      char **lineptr;
 152      size_t *n;
 153      int delimiter;
 154      FILE *stream;
 155 {
 156   return getstr (lineptr, n, stream, delimiter, 0);
 157 }
 158 #endif