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
     6  
     7  package unix
     8  
     9  import "unsafe"
    10  
    11  // fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
    12  // systems by fcntl_linux_32bit.go to be SYS_FCNTL64.
    13  var fcntl64Syscall uintptr = SYS_FCNTL
    14  
    15  func fcntl(fd int, cmd, arg int) (int, error) {
    16  	valptr, _, errno := Syscall(fcntl64Syscall, uintptr(fd), uintptr(cmd), uintptr(arg))
    17  	var err error
    18  	if errno != 0 {
    19  		err = errno
    20  	}
    21  	return int(valptr), err
    22  }
    23  
    24  // FcntlInt performs a fcntl syscall on fd with the provided command and argument.
    25  func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
    26  	return fcntl(int(fd), cmd, arg)
    27  }
    28  
    29  // FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
    30  func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
    31  	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
    32  	if errno == 0 {
    33  		return nil
    34  	}
    35  	return errno
    36  }
    37
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