src/unsafe/unsafe.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
	Package unsafe contains operations that step around the type safety of Go programs.

	Packages that import unsafe may be non-portable and are not protected by the
	Go 1 compatibility guidelines.
*/
package unsafe

// ArbitraryType is here for the purposes of documentation only and is not actually
// part of the unsafe package.  It represents the type of an arbitrary Go expression.
type ArbitraryType int

// Pointer represents a pointer to an arbitrary type.  There are four special operations
// available for type Pointer that are not available for other types.
//	1) A pointer value of any type can be converted to a Pointer.
//	2) A Pointer can be converted to a pointer value of any type.
//	3) A uintptr can be converted to a Pointer.
//	4) A Pointer can be converted to a uintptr.
// Pointer therefore allows a program to defeat the type system and read and write
// arbitrary memory. It should be used with extreme care.
type Pointer *ArbitraryType

// Sizeof takes an expression x of any type and returns the size in bytes
// of a hypothetical variable v as if v was declared via var v = x.
// The size does not include any memory possibly referenced by x.
// For instance, if x is a slice,  Sizeof returns the size of the slice
// descriptor, not the size of the memory referenced by the slice.
func Sizeof(x ArbitraryType) uintptr

// Offsetof returns the offset within the struct of the field represented by x,
// which must be of the form structValue.field.  In other words, it returns the
// number of bytes between the start of the struct and the start of the field.
func Offsetof(x ArbitraryType) uintptr

// Alignof takes an expression x of any type and returns the alignment
// of a hypothetical variable v as if v was declared via var v = x.
// It is the largest value m such that the address of v is zero mod m.
func Alignof(x ArbitraryType) uintptr