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draw: fix crash caused by Scale by Copy shortcut

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When DstMask is not nil, this shortcut causes stack overflow because
Copy function in turn will call Scale with same dr and sr.

Fixes golang/go#23107

Change-Id: I8ccadbd9b7f16363ac17b6114308527d6fa9456e
Reviewed-on: https://go-review.googlesource.com/83537
Reviewed-by: Nigel Tao <nigeltao@golang.org>
Run-TryBot: Nigel Tao <nigeltao@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Jiulong Wang 2017-12-12 11:22:48 -08:00 committed by Nigel Tao
parent e5db4c4663
commit 12117c17ca
3 changed files with 20 additions and 6 deletions
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5
draw/gen.go
View File

@ -877,8 +877,9 @@ func relName(s string) string {
const (
codeRoot = `
func (z $receiver) Scale(dst Image, dr image.Rectangle, src image.Image, sr image.Rectangle, op Op, opts *Options) {
// Try to simplify a Scale to a Copy.
if dr.Size() == sr.Size() {
// Try to simplify a Scale to a Copy when DstMask is not specified.
// If DstMask is not nil, Copy will call Scale back with same dr and sr, and cause stack overflow.
if dr.Size() == sr.Size() && (opts == nil || opts.DstMask == nil) {
Copy(dst, dr.Min, src, sr, op, opts)
return
}

10
draw/impl.go
View File

@ -11,8 +11,9 @@ import (
)
func (z nnInterpolator) Scale(dst Image, dr image.Rectangle, src image.Image, sr image.Rectangle, op Op, opts *Options) {
// Try to simplify a Scale to a Copy.
if dr.Size() == sr.Size() {
// Try to simplify a Scale to a Copy when DstMask is not specified.
// If DstMask is not nil, Copy will call Scale back with same dr and sr, and cause stack overflow.
if dr.Size() == sr.Size() && (opts == nil || opts.DstMask == nil) {
Copy(dst, dr.Min, src, sr, op, opts)
return
}
@ -1048,8 +1049,9 @@ func (nnInterpolator) transform_Image_Image_Src(dst Image, dr, adr image.Rectang
}
func (z ablInterpolator) Scale(dst Image, dr image.Rectangle, src image.Image, sr image.Rectangle, op Op, opts *Options) {
// Try to simplify a Scale to a Copy.
if dr.Size() == sr.Size() {
// Try to simplify a Scale to a Copy when DstMask is not specified.
// If DstMask is not nil, Copy will call Scale back with same dr and sr, and cause stack overflow.
if dr.Size() == sr.Size() && (opts == nil || opts.DstMask == nil) {
Copy(dst, dr.Min, src, sr, op, opts)
return
}

11
draw/scale_test.go
View File

@ -551,6 +551,17 @@ func TestRectDstMask(t *testing.T) {
}
}
func TestDstMaskSameSizeCopy(t *testing.T) {
bounds := image.Rect(0, 0, 42, 42)
src := image.Opaque
dst := image.NewRGBA(bounds)
mask := image.NewRGBA(bounds)
Copy(dst, image.ZP, src, bounds, Src, &Options{
DstMask: mask,
})
}
// TODO: delete this wrapper type once Go 1.5 is released, where an
// image.Rectangle implements image.Image.
type rectImage image.Rectangle