lib/getline.c

   1 /* getline.c -- Replacement for GNU C library function getline
   2
   3 Copyright (C) 1993, 1996 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 #define _GNU_SOURCE     1
  28 #include <stdio.h>
  29 #include <sys/types.h>
  30
  31 #if defined __GNU_LIBRARY__ && HAVE_GETDELIM
  32
  33 int
  34 getline (lineptr, n, stream)
  35      char **lineptr;
  36      size_t *n;
  37      FILE *stream;
  38 {
  39   return getdelim (lineptr, n, '\n', stream);
  40 }
  41
  42
  43 #else /* ! have getdelim */
  44
  45 # define NDEBUG
  46 # include <assert.h>
  47
  48 # if STDC_HEADERS
  49 #  include <stdlib.h>
  50 # else
  51 char *malloc (), *realloc ();
  52 # endif
  53
  54 /* Always add at least this many bytes when extending the buffer.  */
  55 # define MIN_CHUNK 64
  56
  57 /* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
  58    + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
  59    malloc (or NULL), pointing to *N characters of space.  It is realloc'd
  60    as necessary.  Return the number of characters read (not including the
  61    null terminator), or -1 on error or EOF.  */
  62
  63 int
  64 getstr (lineptr, n, stream, terminator, offset)
  65      char **lineptr;
  66      size_t *n;
  67      FILE *stream;
  68      char terminator;
  69      size_t offset;
  70 {
  71   int nchars_avail;             /* Allocated but unused chars in *LINEPTR.  */
  72   char *read_pos;               /* Where we're reading into *LINEPTR. */
  73   int ret;
  74
  75   if (!lineptr || !n || !stream)
  76     return -1;
  77
  78   if (!*lineptr)
  79     {
  80       *n = MIN_CHUNK;
  81       *lineptr = malloc (*n);
  82       if (!*lineptr)
  83         return -1;
  84     }
  85
  86   nchars_avail = *n - offset;
  87   read_pos = *lineptr + offset;
  88
  89   for (;;)
  90     {
  91       register int c = getc (stream);
  92
  93       /* We always want at least one char left in the buffer, since we
  94          always (unless we get an error while reading the first char)
  95          NUL-terminate the line buffer.  */
  96
  97       assert(*n - nchars_avail == read_pos - *lineptr);
  98       if (nchars_avail < 2)
  99         {
 100           if (*n > MIN_CHUNK)
 101             *n *= 2;
 102           else
 103             *n += MIN_CHUNK;
 104
 105           nchars_avail = *n + *lineptr - read_pos;
 106           *lineptr = realloc (*lineptr, *n);
 107           if (!*lineptr)
 108             return -1;
 109           read_pos = *n - nchars_avail + *lineptr;
 110           assert(*n - nchars_avail == read_pos - *lineptr);
 111         }
 112
 113       if (c == EOF || ferror (stream))
 114         {
 115           /* Return partial line, if any.  */
 116           if (read_pos == *lineptr)
 117             return -1;
 118           else
 119             break;
 120         }
 121
 122       *read_pos++ = c;
 123       nchars_avail--;
 124
 125       if (c == terminator)
 126         /* Return the line.  */
 127         break;
 128     }
 129
 130   /* Done - NUL terminate and return the number of chars read.  */
 131   *read_pos = '\0';
 132
 133   ret = read_pos - (*lineptr + offset);
 134   return ret;
 135 }
 136
 137 int
 138 getline (lineptr, n, stream)
 139      char **lineptr;
 140      size_t *n;
 141      FILE *stream;
 142 {
 143   return getstr (lineptr, n, stream, '\n', 0);
 144 }
 145
 146 int
 147 getdelim (lineptr, n, delimiter, stream)
 148      char **lineptr;
 149      size_t *n;
 150      int delimiter;
 151      FILE *stream;
 152 {
 153   return getstr (lineptr, n, stream, delimiter, 0);
 154 }
 155 #endif