mirror of
https://github.com/golang/go
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42 lines
1.1 KiB
Go
42 lines
1.1 KiB
Go
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package syscall
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import "unsafe"
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// On AIX, there is no flock() system call, we emulate it.
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// Moreover, we can't call the default fcntl syscall because the arguments
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// must be integer and it's not possible to transform a pointer (lk)
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// to a int value.
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// It's easier to call syscall6 than to transform fcntl for every GOOS.
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func fcntlFlock(fd, cmd int, lk *Flock_t) (err error) {
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_, _, e1 := syscall6(uintptr(unsafe.Pointer(&libc_fcntl)), 3, uintptr(fd), uintptr(cmd), uintptr(unsafe.Pointer(lk)), 0, 0, 0)
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if e1 != 0 {
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err = errnoErr(e1)
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}
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return
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}
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func Flock(fd int, op int) (err error) {
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lk := &Flock_t{}
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if (op & LOCK_UN) != 0 {
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lk.Type = F_UNLCK
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} else if (op & LOCK_EX) != 0 {
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lk.Type = F_WRLCK
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} else if (op & LOCK_SH) != 0 {
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lk.Type = F_RDLCK
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} else {
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return nil
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}
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if (op & LOCK_NB) != 0 {
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err = fcntlFlock(fd, F_SETLK, lk)
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if err != nil && (err == EAGAIN || err == EACCES) {
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return EWOULDBLOCK
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}
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return err
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}
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return fcntlFlock(fd, F_SETLKW, lk)
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}
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