summaryrefslogtreecommitdiff
path: root/lib/gl/lseek.c
blob: feec8310bd6ae6a7992c8af73b17e748659822b5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
/* An lseek() function that detects pipes.
   Copyright (C) 2007 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License along
   with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

/* Specification.  */
#include <unistd.h>

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Windows platforms.  */
/* Get GetFileType.  */
# include <windows.h>
#else
# include <sys/stat.h>
#endif
#include <errno.h>

#undef lseek

off_t
rpl_lseek (int fd, off_t offset, int whence)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */
  HANDLE h = (HANDLE) _get_osfhandle (fd);
  if (h == INVALID_HANDLE_VALUE)
    {
      errno = EBADF;
      return -1;
    }
  if (GetFileType (h) != FILE_TYPE_DISK)
    {
      errno = ESPIPE;
      return -1;
    }
#else
  /* BeOS lseek mistakenly succeeds on pipes...  */
  struct stat statbuf;
  if (fstat (fd, &statbuf) < 0)
    return -1;
  if (!S_ISREG (statbuf.st_mode))
    {
      errno = ESPIPE;
      return -1;
    }
#endif
  return lseek (fd, offset, whence);
}