sockcmsg_unix_other.go

     1  // Copyright 2019 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 aix || darwin || freebsd || linux || netbsd || openbsd || solaris
     6  
     7  package syscall
     8  
     9  import (
    10  	"runtime"
    11  )
    12  
    13  // Round the length of a raw sockaddr up to align it properly.
    14  func cmsgAlignOf(salen int) int {
    15  	salign := sizeofPtr
    16  
    17  	// dragonfly needs to check ABI version at runtime, see cmsgAlignOf in
    18  	// sockcmsg_dragonfly.go
    19  	switch runtime.GOOS {
    20  	case "aix":
    21  		// There is no alignment on AIX.
    22  		salign = 1
    23  	case "darwin", "ios", "illumos", "solaris":
    24  		// NOTE: It seems like 64-bit Darwin, Illumos and Solaris
    25  		// kernels still require 32-bit aligned access to network
    26  		// subsystem.
    27  		if sizeofPtr == 8 {
    28  			salign = 4
    29  		}
    30  	case "netbsd", "openbsd":
    31  		// NetBSD and OpenBSD armv7 require 64-bit alignment.
    32  		if runtime.GOARCH == "arm" {
    33  			salign = 8
    34  		}
    35  		// NetBSD aarch64 requires 128-bit alignment.
    36  		if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm64" {
    37  			salign = 16
    38  		}
    39  	}
    40  
    41  	return (salen + salign - 1) & ^(salign - 1)
    42  }
    43
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