1 /* An lseek() function that detects pipes.
2 Copyright (C) 2007, 2009-2018 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3, or (at your option)
7 any later version.
8
9 This program 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
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with this program; if not, see <https://www.gnu.org/licenses/>. */
16
17 #include <config.h>
18
19 /* Specification. */
20 #include <unistd.h>
21
22 #if defined _WIN32 && ! defined __CYGWIN__
23 /* Windows platforms. */
24 /* Get GetFileType. */
25 # include <windows.h>
26 /* Get _get_osfhandle. */
27 # if GNULIB_MSVC_NOTHROW
28 # include "msvc-nothrow.h"
29 # else
30 # include <io.h>
31 # endif
32 #else
33 # include <sys/stat.h>
34 #endif
35 #include <errno.h>
36
37 #undef lseek
38
39 off_t
rpl_lseek(int fd,off_t offset,int whence)40 rpl_lseek (int fd, off_t offset, int whence)
41 {
42 #if defined _WIN32 && ! defined __CYGWIN__
43 /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals. */
44 HANDLE h = (HANDLE) _get_osfhandle (fd);
45 if (h == INVALID_HANDLE_VALUE)
46 {
47 errno = EBADF;
48 return -1;
49 }
50 if (GetFileType (h) != FILE_TYPE_DISK)
51 {
52 errno = ESPIPE;
53 return -1;
54 }
55 #else
56 /* BeOS lseek mistakenly succeeds on pipes... */
57 struct stat statbuf;
58 if (fstat (fd, &statbuf) < 0)
59 return -1;
60 if (!S_ISREG (statbuf.st_mode))
61 {
62 errno = ESPIPE;
63 return -1;
64 }
65 #endif
66 #if _GL_WINDOWS_64_BIT_OFF_T
67 return _lseeki64 (fd, offset, whence);
68 #else
69 return lseek (fd, offset, whence);
70 #endif
71 }
72