github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/runtime/testdata/testprog/checkptr.go (about)

     1  // Copyright 2020 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  package main
     6  
     7  import (
     8  	"runtime"
     9  	"time"
    10  	"unsafe"
    11  )
    12  
    13  func init() {
    14  	register("CheckPtrAlignmentNoPtr", CheckPtrAlignmentNoPtr)
    15  	register("CheckPtrAlignmentPtr", CheckPtrAlignmentPtr)
    16  	register("CheckPtrAlignmentNilPtr", CheckPtrAlignmentNilPtr)
    17  	register("CheckPtrArithmetic", CheckPtrArithmetic)
    18  	register("CheckPtrArithmetic2", CheckPtrArithmetic2)
    19  	register("CheckPtrSize", CheckPtrSize)
    20  	register("CheckPtrSmall", CheckPtrSmall)
    21  	register("CheckPtrSliceOK", CheckPtrSliceOK)
    22  	register("CheckPtrSliceFail", CheckPtrSliceFail)
    23  	register("CheckPtrStringOK", CheckPtrStringOK)
    24  	register("CheckPtrStringFail", CheckPtrStringFail)
    25  	register("CheckPtrAlignmentNested", CheckPtrAlignmentNested)
    26  }
    27  
    28  func CheckPtrAlignmentNoPtr() {
    29  	var x [2]int64
    30  	p := unsafe.Pointer(&x[0])
    31  	sink2 = (*int64)(unsafe.Pointer(uintptr(p) + 1))
    32  }
    33  
    34  func CheckPtrAlignmentPtr() {
    35  	var x [2]int64
    36  	p := unsafe.Pointer(&x[0])
    37  	sink2 = (**int64)(unsafe.Pointer(uintptr(p) + 1))
    38  }
    39  
    40  // CheckPtrAlignmentNilPtr tests that checkptrAlignment doesn't crash
    41  // on nil pointers (#47430).
    42  func CheckPtrAlignmentNilPtr() {
    43  	var do func(int)
    44  	do = func(n int) {
    45  		// Inflate the stack so runtime.shrinkstack gets called during GC
    46  		if n > 0 {
    47  			do(n - 1)
    48  		}
    49  
    50  		var p unsafe.Pointer
    51  		_ = (*int)(p)
    52  	}
    53  
    54  	go func() {
    55  		for {
    56  			runtime.GC()
    57  		}
    58  	}()
    59  
    60  	go func() {
    61  		for i := 0; ; i++ {
    62  			do(i % 1024)
    63  		}
    64  	}()
    65  
    66  	time.Sleep(time.Second)
    67  }
    68  
    69  func CheckPtrArithmetic() {
    70  	var x int
    71  	i := uintptr(unsafe.Pointer(&x))
    72  	sink2 = (*int)(unsafe.Pointer(i))
    73  }
    74  
    75  func CheckPtrArithmetic2() {
    76  	var x [2]int64
    77  	p := unsafe.Pointer(&x[1])
    78  	var one uintptr = 1
    79  	sink2 = unsafe.Pointer(uintptr(p) & ^one)
    80  }
    81  
    82  func CheckPtrSize() {
    83  	p := new(int64)
    84  	sink2 = p
    85  	sink2 = (*[100]int64)(unsafe.Pointer(p))
    86  }
    87  
    88  func CheckPtrSmall() {
    89  	sink2 = unsafe.Pointer(uintptr(1))
    90  }
    91  
    92  func CheckPtrSliceOK() {
    93  	p := new([4]int64)
    94  	sink2 = unsafe.Slice(&p[1], 3)
    95  }
    96  
    97  func CheckPtrSliceFail() {
    98  	p := new(int64)
    99  	sink2 = p
   100  	sink2 = unsafe.Slice(p, 100)
   101  }
   102  
   103  func CheckPtrStringOK() {
   104  	p := new([4]byte)
   105  	sink2 = unsafe.String(&p[1], 3)
   106  }
   107  
   108  func CheckPtrStringFail() {
   109  	p := new(byte)
   110  	sink2 = p
   111  	sink2 = unsafe.String(p, 100)
   112  }
   113  
   114  func CheckPtrAlignmentNested() {
   115  	s := make([]int8, 100)
   116  	p := unsafe.Pointer(&s[0])
   117  	n := 9
   118  	_ = ((*[10]int8)(unsafe.Pointer((*[10]int64)(unsafe.Pointer(&p)))))[:n:n]
   119  }