Line data    Source code

       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, 2004, 2006 Free
       5             :    Software 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 3 of the License, or
      10             :    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
      19             : 
      20             : /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu.  */
      21             : 
      22             : #include <config.h>
      23             : 
      24             : #include "getndelim2.h"
      25             : 
      26             : #include <stdlib.h>
      27             : #include <stddef.h>
      28             : 
      29             : #if USE_UNLOCKED_IO
      30             : # include "unlocked-io.h"
      31             : #endif
      32             : 
      33             : #include <limits.h>
      34             : #include <stdint.h>
      35             : 
      36             : #ifndef SSIZE_MAX
      37             : # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
      38             : #endif
      39             : 
      40             : /* The maximum value that getndelim2 can return without suffering from
      41             :    overflow problems, either internally (because of pointer
      42             :    subtraction overflow) or due to the API (because of ssize_t).  */
      43             : #define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX)
      44             : 
      45             : /* Try to add at least this many bytes when extending the buffer.
      46             :    MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM.  */
      47             : #define MIN_CHUNK 64
      48             : 
      49             : ssize_t
      50          15 : getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
      51             :             int delim1, int delim2, FILE *stream)
      52             : {
      53             :   size_t nbytes_avail;          /* Allocated but unused bytes in *LINEPTR.  */
      54             :   char *read_pos;               /* Where we're reading into *LINEPTR. */
      55          15 :   ssize_t bytes_stored = -1;
      56          15 :   char *ptr = *lineptr;
      57          15 :   size_t size = *linesize;
      58             : 
      59          15 :   if (!ptr)
      60             :     {
      61           7 :       size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
      62           7 :       ptr = malloc (size);
      63           7 :       if (!ptr)
      64           0 :         return -1;
      65             :     }
      66             : 
      67          15 :   if (size < offset)
      68           0 :     goto done;
      69             : 
      70          15 :   nbytes_avail = size - offset;
      71          15 :   read_pos = ptr + offset;
      72             : 
      73          15 :   if (nbytes_avail == 0 && nmax <= size)
      74           0 :     goto done;
      75             : 
      76             :   for (;;)
      77           3 :     {
      78             :       /* Here always ptr + size == read_pos + nbytes_avail.  */
      79             : 
      80             :       int c;
      81             : 
      82             :       /* We always want at least one byte left in the buffer, since we
      83             :          always (unless we get an error while reading the first byte)
      84             :          NUL-terminate the line buffer.  */
      85             : 
      86          18 :       if (nbytes_avail < 2 && size < nmax)
      87             :         {
      88           0 :           size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
      89             :           char *newptr;
      90             : 
      91           0 :           if (! (size < newsize && newsize <= nmax))
      92           0 :             newsize = nmax;
      93             : 
      94           0 :           if (GETNDELIM2_MAXIMUM < newsize - offset)
      95             :             {
      96           0 :               size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
      97           0 :               if (size == newsizemax)
      98           0 :                 goto done;
      99           0 :               newsize = newsizemax;
     100             :             }
     101             : 
     102           0 :           nbytes_avail = newsize - (read_pos - ptr);
     103           0 :           newptr = realloc (ptr, newsize);
     104           0 :           if (!newptr)
     105           0 :             goto done;
     106           0 :           ptr = newptr;
     107           0 :           size = newsize;
     108           0 :           read_pos = size - nbytes_avail + ptr;
     109             :         }
     110             : 
     111          18 :       c = getc (stream);
     112          18 :       if (c == EOF)
     113             :         {
     114             :           /* Return partial line, if any.  */
     115           3 :           if (read_pos == ptr)
     116           2 :             goto done;
     117             :           else
     118           1 :             break;
     119             :         }
     120             : 
     121          15 :       if (nbytes_avail >= 2)
     122             :         {
     123          15 :           *read_pos++ = c;
     124          15 :           nbytes_avail--;
     125             :         }
     126             : 
     127          15 :       if (c == delim1 || c == delim2)
     128             :         /* Return the line.  */
     129             :         break;
     130             :     }
     131             : 
     132             :   /* Done - NUL terminate and return the number of bytes read.
     133             :      At this point we know that nbytes_avail >= 1.  */
     134          13 :   *read_pos = '\0';
     135             : 
     136          13 :   bytes_stored = read_pos - (ptr + offset);
     137             : 
     138          15 :  done:
     139          15 :   *lineptr = ptr;
     140          15 :   *linesize = size;
     141          15 :   return bytes_stored;
     142             : }