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59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/* Linux implementation of preadv2.
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Copyright (C) 2017-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <sys/uio.h>
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#include <sysdep-cancel.h>
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#ifndef __OFF_T_MATCHES_OFF64_T
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# if !defined (__NR_preadv2) && defined (__NR_pread64v2)
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# define __NR_preadv2 __NR_pread64v2
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# endif
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ssize_t
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preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
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int flags)
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{
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# ifdef __NR_preadv2
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ssize_t result = SYSCALL_CANCEL (preadv2, fd, vector, count,
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LO_HI_LONG (offset), flags);
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if (result >= 0 || errno != ENOSYS)
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return result;
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# endif
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/* Trying to emulate the preadv2 syscall flags is troublesome:
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* We can not temporary change the file state of the O_DSYNC and O_SYNC
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flags to emulate RWF_{D}SYNC (attempts to change the state of using
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fcntl are silently ignored).
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* IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
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semantic not provided by any other flag (O_NONBLOCK for instance). */
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if (flags != 0)
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{
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__set_errno (ENOTSUP);
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return -1;
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}
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if (offset == -1)
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return __readv (fd, vector, count);
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else
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return preadv (fd, vector, count, offset);
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}
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#endif
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