1// run
2
3// Copyright 2021 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7package main
8
9import (
10	"math"
11	"unsafe"
12)
13
14const maxUintptr = 1 << (8 * unsafe.Sizeof(uintptr(0)))
15
16func main() {
17	var p [10]byte
18
19	// unsafe.Add
20	{
21		p1 := unsafe.Pointer(&p[1])
22		assert(unsafe.Add(p1, 1) == unsafe.Pointer(&p[2]))
23		assert(unsafe.Add(p1, -1) == unsafe.Pointer(&p[0]))
24	}
25
26	// unsafe.Slice
27	{
28		s := unsafe.Slice(&p[0], len(p))
29		assert(&s[0] == &p[0])
30		assert(len(s) == len(p))
31		assert(cap(s) == len(p))
32
33		// nil pointer with zero length returns nil
34		assert(unsafe.Slice((*int)(nil), 0) == nil)
35
36		// nil pointer with positive length panics
37		mustPanic(func() { _ = unsafe.Slice((*int)(nil), 1) })
38
39		// negative length
40		var neg int = -1
41		mustPanic(func() { _ = unsafe.Slice(new(byte), neg) })
42
43		// length too large
44		var tooBig uint64 = math.MaxUint64
45		mustPanic(func() { _ = unsafe.Slice(new(byte), tooBig) })
46
47		// size overflows address space
48		mustPanic(func() { _ = unsafe.Slice(new(uint64), maxUintptr/8) })
49		mustPanic(func() { _ = unsafe.Slice(new(uint64), maxUintptr/8+1) })
50
51		// sliced memory overflows address space
52		last := (*byte)(unsafe.Pointer(^uintptr(0)))
53		_ = unsafe.Slice(last, 1)
54		mustPanic(func() { _ = unsafe.Slice(last, 2) })
55	}
56
57	// unsafe.String
58	{
59		s := unsafe.String(&p[0], len(p))
60		assert(s == string(p[:]))
61		assert(len(s) == len(p))
62
63		// the empty string
64		assert(unsafe.String(nil, 0) == "")
65
66		// nil pointer with positive length panics
67		mustPanic(func() { _ = unsafe.String(nil, 1) })
68
69		// negative length
70		var neg int = -1
71		mustPanic(func() { _ = unsafe.String(new(byte), neg) })
72
73		// length too large
74		var tooBig uint64 = math.MaxUint64
75		mustPanic(func() { _ = unsafe.String(new(byte), tooBig) })
76
77		// string memory overflows address space
78		last := (*byte)(unsafe.Pointer(^uintptr(0)))
79		_ = unsafe.String(last, 1)
80		mustPanic(func() { _ = unsafe.String(last, 2) })
81	}
82
83	// unsafe.StringData
84	{
85		var s = "string"
86		assert(string(unsafe.Slice(unsafe.StringData(s), len(s))) == s)
87	}
88
89	//unsafe.SliceData
90	{
91		var s = []byte("slice")
92		assert(unsafe.String(unsafe.SliceData(s), len(s)) == string(s))
93	}
94}
95
96func assert(ok bool) {
97	if !ok {
98		panic("FAIL")
99	}
100}
101
102func mustPanic(f func()) {
103	defer func() {
104		assert(recover() != nil)
105	}()
106	f()
107}
108