| // 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. |
| */ |
| 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 three 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 returns the size in bytes occupied by the value v. The size is that of the |
| // "top level" of the value only. For instance, if v is a slice, it returns the size of |
| // the slice descriptor, not the size of the memory referenced by the slice. |
| func Sizeof(v ArbitraryType) int |
| |
| // Offsetof returns the offset within the struct of the field represented by v, |
| // which must be of the form struct_value.field. In other words, it returns the |
| // number of bytes between the start of the struct and the start of the field. |
| func Offsetof(v ArbitraryType) int |
| |
| // Alignof returns the alignment of the value v. It is the maximum value m such |
| // that the address of a variable with the type of v will always always be zero mod m. |
| // If v is of the form obj.f, it returns the alignment of field f within struct object obj. |
| func Alignof(v ArbitraryType) int |
| |
| // Typeof returns the type of an interface value, a runtime.Type. |
| func Typeof(i interface{}) (typ interface{}) |
| |
| // Reflect unpacks an interface value into its type and the address of a copy of the |
| // internal value. |
| func Reflect(i interface{}) (typ interface{}, addr Pointer) |
| |
| // Unreflect inverts Reflect: Given a type and a pointer to a value, it returns an |
| // empty interface value with contents the type and the value (not the pointer to |
| // the value). The typ is assumed to contain a pointer to a runtime type; the type |
| // information in the interface{} is ignored, so that, for example, both |
| // *reflect.structType and *runtime.StructType can be passed for typ. |
| func Unreflect(typ interface{}, addr Pointer) (ret interface{}) |
| |
| // New allocates and returns a pointer to memory for a new value of the given type. |
| // The typ is assumed to hold a pointer to a runtime type. |
| // Callers should use reflect.MakeZero instead of invoking unsafe.New directly. |
| func New(typ interface{}) Pointer |
| |
| // NewArray allocates and returns a pointer to an array of n elements of the given type. |
| // The typ is assumed to hold a pointer to a runtime type. |
| // Callers should use reflect.MakeSlice instead of invoking unsafe.NewArray directly. |
| func NewArray(typ interface{}, n int) Pointer |