fcntl.go

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build dragonfly || freebsd || linux || netbsd || openbsd
     6  // +build dragonfly freebsd linux netbsd openbsd
     7  
     8  package unix
     9  
    10  import "unsafe"
    11  
    12  // fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
    13  // systems by fcntl_linux_32bit.go to be SYS_FCNTL64.
    14  var fcntl64Syscall uintptr = SYS_FCNTL
    15  
    16  func fcntl(fd int, cmd, arg int) (int, error) {
    17  	valptr, _, errno := Syscall(fcntl64Syscall, uintptr(fd), uintptr(cmd), uintptr(arg))
    18  	var err error
    19  	if errno != 0 {
    20  		err = errno
    21  	}
    22  	return int(valptr), err
    23  }
    24  
    25  // FcntlInt performs a fcntl syscall on fd with the provided command and argument.
    26  func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
    27  	return fcntl(int(fd), cmd, arg)
    28  }
    29  
    30  // FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
    31  func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
    32  	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
    33  	if errno == 0 {
    34  		return nil
    35  	}
    36  	return errno
    37  }
    38
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