executable_sysctl.go

     1  // Copyright 2016 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 freebsd || dragonfly
     6  
     7  package os
     8  
     9  import (
    10  	"syscall"
    11  	"unsafe"
    12  )
    13  
    14  func executable() (string, error) {
    15  	mib := [4]int32{_CTL_KERN, _KERN_PROC, _KERN_PROC_PATHNAME, -1}
    16  
    17  	n := uintptr(0)
    18  	// get length
    19  	_, _, err := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
    20  	if err != 0 {
    21  		return "", err
    22  	}
    23  	if n == 0 { // shouldn't happen
    24  		return "", nil
    25  	}
    26  	buf := make([]byte, n)
    27  	_, _, err = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
    28  	if err != 0 {
    29  		return "", err
    30  	}
    31  	if n == 0 { // shouldn't happen
    32  		return "", nil
    33  	}
    34  	return string(buf[:n-1]), nil
    35  }
    36
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