gnu/dist/gettext/gettext-tools/lib/getndelim2.c

   1 /* getndelim2 - Read a line from a stream, stopping at one of 2 delimiters,
   2    with bounded memory allocation.
   3
   4    Copyright (C) 1993, 1996, 1997, 1998, 2000, 2003 Free Software
   5    Foundation, Inc.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software Foundation,
  19    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu.  */
  22
  23 #if HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 /* Specification.  */
  28 #include "getndelim2.h"
  29
  30 #if STDC_HEADERS
  31 # include <stdlib.h>
  32 #else
  33 char *malloc (), *realloc ();
  34 #endif
  35
  36 #include "unlocked-io.h"
  37
  38 /* Always add at least this many bytes when extending the buffer.  */
  39 #define MIN_CHUNK 64
  40
  41 ssize_t
  42 getndelim2 (char **lineptr, size_t *linesize, size_t nmax,
  43             FILE *stream, int delim1, int delim2, size_t offset)
  44 {
  45   size_t nbytes_avail;          /* Allocated but unused chars in *LINEPTR.  */
  46   char *read_pos;               /* Where we're reading into *LINEPTR. */
  47
  48   if (!lineptr || !linesize || !nmax || !stream)
  49     return -1;
  50
  51   if (!*lineptr)
  52     {
  53       size_t newlinesize = MIN_CHUNK;
  54
  55       if (newlinesize > nmax)
  56         newlinesize = nmax;
  57
  58       *linesize = newlinesize;
  59       *lineptr = malloc (*linesize);
  60       if (!*lineptr)
  61         return -1;
  62     }
  63
  64   if (*linesize < offset)
  65     return -1;
  66
  67   nbytes_avail = *linesize - offset;
  68   read_pos = *lineptr + offset;
  69
  70   if (nbytes_avail == 0 && *linesize >= nmax)
  71     return -1;
  72
  73   for (;;)
  74     {
  75       /* Here always *lineptr + *linesize == read_pos + nbytes_avail.  */
  76
  77       register int c = getc (stream);
  78
  79       /* We always want at least one char left in the buffer, since we
  80          always (unless we get an error while reading the first char)
  81          NUL-terminate the line buffer.  */
  82
  83       if (nbytes_avail < 2 && *linesize < nmax)
  84         {
  85           size_t newlinesize =
  86             (*linesize > MIN_CHUNK ? 2 * *linesize : *linesize + MIN_CHUNK);
  87
  88           if (newlinesize > nmax)
  89             newlinesize = nmax;
  90
  91           if (newlinesize > *linesize)
  92             {
  93               *linesize = newlinesize;
  94               nbytes_avail = *linesize + *lineptr - read_pos;
  95               *lineptr = realloc (*lineptr, *linesize);
  96               if (!*lineptr)
  97                 return -1;
  98               read_pos = *linesize - nbytes_avail + *lineptr;
  99             }
 100         }
 101
 102       if (c == EOF || ferror (stream))
 103         {
 104           /* Return partial line, if any.  */
 105           if (read_pos == *lineptr)
 106             return -1;
 107           else
 108             break;
 109         }
 110
 111       if (nbytes_avail >= 2)
 112         {
 113           *read_pos++ = c;
 114           nbytes_avail--;
 115         }
 116
 117       if (c == delim1 || (delim2 && c == delim2))
 118         /* Return the line.  */
 119         break;
 120     }
 121
 122   /* Done - NUL terminate and return the number of chars read.
 123      At this point we know that nbytes_avail >= 1.  */
 124   *read_pos = '\0';
 125
 126   return read_pos - (*lineptr + offset);
 127 }