mirror of
https://github.com/golang/go
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46 lines
1.1 KiB
Go
46 lines
1.1 KiB
Go
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// run
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"runtime"
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)
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var nilp *int
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var forceHeap interface{}
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func main() {
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// x is a pointer on the stack to heap-allocated memory.
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x := new([32]*int)
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forceHeap = x
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forceHeap = nil
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// Push a defer to be run when we panic below.
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defer func() {
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// Ignore the panic.
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recover()
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// Force a stack walk. Go 1.11 will fail because x is now
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// considered live again.
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runtime.GC()
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}()
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// Make x live at the defer's PC.
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runtime.KeepAlive(x)
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// x is no longer live. Garbage collect the [32]*int on the
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// heap.
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runtime.GC()
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// At this point x's dead stack slot points to dead memory.
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// Trigger a sigpanic. Since this is an implicit panic, we
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// don't have an explicit liveness map here.
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// Traceback used to use the liveness map of the most recent defer,
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// but in that liveness map, x will be live again even though
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// it points to dead memory. The fix is to use the liveness
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// map of a deferreturn call instead.
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*nilp = 0
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}
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