Created attachment 326914 [details]
Tarball of three .gif images that eog (incorrectly) rejects

The Go program below generates two .gif files (attached as a tar.bz2). Both of these files are viewable with Firefox, Google Chrome and ImageMagick just fine, but not in Eye-of-Gnome, which AFAICT uses gdk-pixbuf.

The "GIF-image-loader-cannot-understand-this-image.gif" file triggers the code path at https://github.com/GNOME/gdk-pixbuf/blob/master/gdk-pixbuf/io-gif.c#L634 for which the comment immediately above says that: "FIXME - we should handle this case".

The "internal-error-in-the-GIF-loader.gif" file triggers the code path at https://github.com/GNOME/gdk-pixbuf/blob/master/gdk-pixbuf/io-gif.c#L500 and while I am not overly familiar with the gdk-pixbuf code, at the very least, untrusted image input should not trigger "internal errors", in my opinion.

A larger GIF image, lissajous.gif, is also in the tarball. It is the output of this Go program: https://github.com/adonovan/gopl.io/blob/master/ch1/lissajous/main.go

Once again, Firefox, Google Chrome and ImageMagick are all happy with this lissajous.gif file; Eye-of-Gnome is not, saying "Circular table entry in GIF file".

----
package main

import (
	"image"
	"image/color"
	"image/gif"
	"log"
	"os"
)

var palette = make([]color.Color, 256)

func main() {
	for i := range palette {
		palette[i] = color.Gray{byte(i)}
	}

	do(4, "GIF-image-loader-cannot-understand-this-image.gif")
	do(16, "internal-error-in-the-GIF-loader.gif")
}

func do(n int, filename string) {
	out, err := os.Create(filename)
	if err != nil {
		log.Fatal(err)
	}
	defer out.Close()

	// img is an n x n paletted image where every pixel is initialized to the
	// 0th entry in the palette.
	img := image.NewPaletted(image.Rect(0, 0, n, n), palette)

	// Change false to true in order to make each pixel have a distinct palette
	// index, so that the LZW compression step doesn't compress anything.
	//
	// Either way, this program should generate valid images, but when this is
	// false, it seems that eog cannot read the resultant GIF images, even
	// though Firefox, Google Chrome and ImageMagick can.
	if false {
		for i := range img.Pix {
			img.Pix[i] = byte(i)
		}
	}

	if err := gif.Encode(out, img, nil); err != nil {
		log.Fatal(err)
	}
}
----