1 /* Read block from given position in file without changing file pointer.
3 Copyright (C) 1997-2023 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
23 /* Note: This implementation of pread is not multithread-safe. */
26 __libc_pread (int fd
, void *buf
, size_t nbyte
, off_t offset
)
28 /* Since we must not change the file pointer preserve the value so that
29 we can restore it later. */
32 off_t old_offset
= __libc_lseek (fd
, 0, SEEK_CUR
);
33 if (old_offset
== (off_t
) -1)
36 /* Set to wanted position. */
37 if (__libc_lseek (fd
, offset
, SEEK_SET
) == (off_t
) -1)
40 /* Write out the data. */
41 result
= __libc_read (fd
, buf
, nbyte
);
43 /* Now we have to restore the position. If this fails we have to
44 return this as an error. But if the writing also failed we
47 if (__libc_lseek (fd
, old_offset
, SEEK_SET
) == (off_t
) -1)
50 __set_errno (save_errno
);
53 __set_errno (save_errno
);
59 strong_alias (__libc_pread
, __pread
)
60 weak_alias (__libc_pread
, pread
)