issue28797.go

     1  // run
     2  
     3  // Copyright 2018 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  
     7  package main
     8  
     9  import (
    10  	"fmt"
    11  )
    12  
    13  // test expects f to panic, but not to run out of memory,
    14  // which is a non-panic fatal error.  OOM results from failure
    15  // to properly check negative limit.
    16  func test(f func()) {
    17  	defer func() {
    18  		r := recover()
    19  		if r == nil {
    20  			panic("panic wasn't recoverable")
    21  		}
    22  	}()
    23  	f()
    24  }
    25  
    26  //go:noinline
    27  func id(x int) int {
    28  	return x
    29  }
    30  
    31  func main() {
    32  	test(foo)
    33  	test(bar)
    34  }
    35  
    36  func foo() {
    37  	b := make([]byte, 0)
    38  	b = append(b, 1)
    39  	id(len(b))
    40  	id(len(b) - 2)
    41  	s := string(b[1 : len(b)-2])
    42  	fmt.Println(s)
    43  }
    44  
    45  func bar() {
    46  	b := make([]byte, 1)
    47  	b = append(b, 1)
    48  	i := id(-1)
    49  	if i < len(b) { // establish value is not too large.
    50  		s := string(b[1:i]) // should check for negative also.
    51  		fmt.Println(s)
    52  	}
    53  }
    54
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