1 /* Linux implementation of preadv2.
2 Copyright (C) 2017-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <sys/uio.h>
20 #include <sysdep-cancel.h>
21
22 #ifndef __OFF_T_MATCHES_OFF64_T
23
24 ssize_t
preadv2(int fd,const struct iovec * vector,int count,off_t offset,int flags)25 preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
26 int flags)
27 {
28 ssize_t result = SYSCALL_CANCEL (preadv2, fd, vector, count,
29 LO_HI_LONG (offset), flags);
30 if (result >= 0 || errno != ENOSYS)
31 return result;
32
33 /* Trying to emulate the preadv2 syscall flags is troublesome:
34
35 * We can not temporary change the file state of the O_DSYNC and O_SYNC
36 flags to emulate RWF_{D}SYNC (attempts to change the state of using
37 fcntl are silently ignored).
38
39 * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
40 semantic not provided by any other flag (O_NONBLOCK for instance). */
41
42 if (flags != 0)
43 {
44 __set_errno (ENOTSUP);
45 return -1;
46 }
47 if (offset == -1)
48 return __readv (fd, vector, count);
49 else
50 return preadv (fd, vector, count, offset);
51 }
52
53 #endif
54