libio/iogetdelim.c

   1 /* Copyright (C) 1994-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 #include <stdlib.h>
  28 #include "libioP.h"
  29 #include <string.h>
  30 #include <errno.h>
  31 #include <limits.h>
  32
  33 /* Read up to (and including) a TERMINATOR from FP into *LINEPTR
  34    (and null-terminate it).  *LINEPTR is a pointer returned from malloc (or
  35    NULL), pointing to *N characters of space.  It is realloc'ed as
  36    necessary.  Returns the number of characters read (not including the
  37    null terminator), or -1 on error or EOF.  */
  38
  39 ssize_t
  40 __getdelim (char **lineptr, size_t *n, int delimiter, FILE *fp)
  41 {
  42   ssize_t result;
  43   ssize_t cur_len = 0;
  44   ssize_t len;
  45
  46   CHECK_FILE (fp, -1);
  47   _IO_acquire_lock (fp);
  48   if (_IO_ferror_unlocked (fp))
  49     {
  50       result = -1;
  51       goto unlock_return;
  52     }
  53
  54   if (lineptr == NULL || n == NULL)
  55     {
  56       __set_errno (EINVAL);
  57       fseterr_unlocked (fp);
  58       result = -1;
  59       goto unlock_return;
  60     }
  61
  62   if (*lineptr == NULL || *n == 0)
  63     {
  64       *n = 120;
  65       *lineptr = (char *) malloc (*n);
  66       if (*lineptr == NULL)
  67         {
  68           fseterr_unlocked (fp);
  69           result = -1;
  70           goto unlock_return;
  71         }
  72     }
  73
  74   len = fp->_IO_read_end - fp->_IO_read_ptr;
  75   if (len <= 0)
  76     {
  77       if (__underflow (fp) == EOF)
  78         {
  79           result = -1;
  80           goto unlock_return;
  81         }
  82       len = fp->_IO_read_end - fp->_IO_read_ptr;
  83     }
  84
  85   for (;;)
  86     {
  87       size_t needed;
  88       char *t;
  89       t = (char *) memchr ((void *) fp->_IO_read_ptr, delimiter, len);
  90       if (t != NULL)
  91         len = (t - fp->_IO_read_ptr) + 1;
  92       if (__glibc_unlikely (len >= SSIZE_MAX - cur_len))
  93         {
  94           __set_errno (EOVERFLOW);
  95           fseterr_unlocked (fp);
  96           result = -1;
  97           goto unlock_return;
  98         }
  99       /* Make enough space for len+1 (for final NUL) bytes.  */
 100       needed = cur_len + len + 1;
 101       if (needed > *n)
 102         {
 103           char *new_lineptr;
 104
 105           if (needed < 2 * *n)
 106             needed = 2 * *n;  /* Be generous. */
 107           new_lineptr = (char *) realloc (*lineptr, needed);
 108           if (new_lineptr == NULL)
 109             {
 110               fseterr_unlocked (fp);
 111               result = -1;
 112               goto unlock_return;
 113             }
 114           *lineptr = new_lineptr;
 115           *n = needed;
 116         }
 117       memcpy (*lineptr + cur_len, (void *) fp->_IO_read_ptr, len);
 118       fp->_IO_read_ptr += len;
 119       cur_len += len;
 120       if (t != NULL || __underflow (fp) == EOF)
 121         break;
 122       len = fp->_IO_read_end - fp->_IO_read_ptr;
 123     }
 124   (*lineptr)[cur_len] = '\0';
 125   result = cur_len;
 126
 127 unlock_return:
 128   _IO_release_lock (fp);
 129   return result;
 130 }
 131 libc_hidden_def (__getdelim)
 132 weak_alias (__getdelim, getdelim)