From e47c3bbbfb9d65c251037ccd81932932764f17dc Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 5 Nov 2016 03:06:18 +0900
Subject: [PATCH] graphics: Limit image size strictly

---
 image_test.go              | 77 ++++++++++++++++++++++++++++++++++++++
 imageimpl.go               | 30 ++++++++++++++-
 internal/graphics/image.go |  2 +
 3 files changed, 108 insertions(+), 1 deletion(-)

diff --git a/image_test.go b/image_test.go
index e2ad53bcd..eb9a7f9bd 100644
--- a/image_test.go
+++ b/image_test.go
@@ -419,3 +419,80 @@ func TestImageFill(t *testing.T) {
 		}
 	}
 }
+
+func TestImageSize(t *testing.T) {
+	sizes := []struct {
+		width  int
+		height int
+		error  bool
+	}{
+		{
+			width:  -1,
+			height: -1,
+			error:  true,
+		},
+		{
+			width:  -1,
+			height: 1,
+			error:  true,
+		},
+		{
+			width:  1,
+			height: -1,
+			error:  true,
+		},
+		{
+			width:  0,
+			height: 0,
+			error:  true,
+		},
+		{
+			width:  0,
+			height: 1,
+			error:  true,
+		},
+		{
+			width:  1,
+			height: 0,
+			error:  true,
+		},
+		{
+			width:  1,
+			height: 1,
+			error:  false,
+		},
+		{
+			width:  4096,
+			height: 4096,
+			error:  false,
+		},
+		{
+			width:  4096,
+			height: 4097,
+			error:  true,
+		},
+		{
+			width:  4097,
+			height: 4096,
+			error:  true,
+		},
+		{
+			width:  4097,
+			height: 4097,
+			error:  true,
+		},
+	}
+	for _, size := range sizes {
+		_, err := NewImage(size.width, size.height, FilterNearest)
+		if err == nil {
+			if size.error {
+				t.Errorf("NewImage(%d, %d, ...) must cause error but not", size.width, size.height)
+			}
+			return
+		} else {
+			if !size.error {
+				t.Errorf("NewImage(%d, %d, ...) must not cause error but did: %s", size.width, size.height, err)
+			}
+		}
+	}
+}
diff --git a/imageimpl.go b/imageimpl.go
index c6afef451..9c4fa804f 100644
--- a/imageimpl.go
+++ b/imageimpl.go
@@ -23,6 +23,7 @@ import (
 	"runtime"
 	"sync"
 
+	"github.com/hajimehoshi/ebiten/internal/graphics"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 	"github.com/hajimehoshi/ebiten/internal/restorable"
 )
@@ -32,7 +33,27 @@ type imageImpl struct {
 	m          sync.Mutex
 }
 
+func checkSize(width, height int) error {
+	if width <= 0 {
+		return fmt.Errorf("ebiten: width must be more than 0")
+	}
+	if height <= 0 {
+		return fmt.Errorf("ebiten: height must be more than 0")
+	}
+	if width > graphics.ImageMaxSize {
+		return fmt.Errorf("ebiten: width must be less than or equal to %d", graphics.ImageMaxSize)
+	}
+	if height > graphics.ImageMaxSize {
+		return fmt.Errorf("ebiten: height must be less than or equal to %d", graphics.ImageMaxSize)
+	}
+	return nil
+}
+
 func newImageImpl(width, height int, filter Filter, volatile bool) (*imageImpl, error) {
+	if err := checkSize(width, height); err != nil {
+		return nil, err
+	}
+
 	img, err := restorable.NewImage(width, height, glFilter(filter), volatile)
 	if err != nil {
 		return nil, err
@@ -47,7 +68,10 @@ func newImageImpl(width, height int, filter Filter, volatile bool) (*imageImpl,
 func newImageImplFromImage(source image.Image, filter Filter) (*imageImpl, error) {
 	size := source.Bounds().Size()
 	w, h := size.X, size.Y
-	// TODO: Return error when the image is too big!
+	if err := checkSize(w, h); err != nil {
+		return nil, err
+	}
+
 	// Don't lock while manipulating an image.Image interface.
 
 	// It is necessary to copy the source image since the actual construction of
@@ -74,6 +98,10 @@ func newImageImplFromImage(source image.Image, filter Filter) (*imageImpl, error
 }
 
 func newScreenImageImpl(width, height int) (*imageImpl, error) {
+	if err := checkSize(width, height); err != nil {
+		return nil, err
+	}
+
 	img, err := restorable.NewScreenFramebufferImage(width, height)
 	if err != nil {
 		return nil, err
diff --git a/internal/graphics/image.go b/internal/graphics/image.go
index 024eb464f..9379d8a17 100644
--- a/internal/graphics/image.go
+++ b/internal/graphics/image.go
@@ -29,6 +29,8 @@ type Image struct {
 	height      int
 }
 
+const ImageMaxSize = viewportSize
+
 func NewImage(width, height int, filter opengl.Filter) (*Image, error) {
 	i := &Image{
 		width:  width,