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https://issues.apache.org/jira/browse/IMAGING-164?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bruno P. Kinoshita updated IMAGING-164:
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Summary: Simplify code in IcoImageParser::writeImage (was: Possible
dereferencing of null pointer in IcoImageParser::writeImage)
> Simplify code in IcoImageParser::writeImage
> --------------------------------------------
>
> Key: IMAGING-164
> URL: https://issues.apache.org/jira/browse/IMAGING-164
> Project: Commons Imaging
> Issue Type: Improvement
> Components: Format: ICO
> Reporter: Michael Groß
> Priority: Major
> Labels: github
> Fix For: Review Patch
>
>
> org.apache.commons.imaging.formats.ico.IcoImageParser::writeImage(final
> BufferedImage src, final OutputStream os, final ImagingParameters params)
> may throw an unexpected NullPointerException because it of the following code:
> {noformat}
> final SimplePalette palette = paletteFactory.makeExactRgbPaletteSimple(src,
> 256);
> {noformat}
> Then asking if the created palette is null. I will discuss where it comes
> from below. For now it is interesting that we set the variable bitCount
> despite the SimplePalette is null. Currently this makes no sense because the
> code will throw a NullPointerException later if SimplePalette is null.
> {noformat}
> if (palette == null) {
> if (hasTransparency) {
> bitCount = 32;
> } else {
> bitCount = 24;
> }
> {noformat}
> In the later for-loop we try to call *getPaletteIndex(rgb)* on the
> SimplePalette instance. If it contains null, we'll get a NullPointerException
> here.
> {noformat}
> for (int y = src.getHeight() - 1; y >= 0; y--) {
> for (int x = 0; x < src.getWidth(); x++) {
> final int argb = src.getRGB(x, y);
> if (bitCount < 8) {
> final int rgb = 0xffffff & argb;
> final int index = palette.getPaletteIndex(rgb); //
> possible NullPointerException
> ...
> } else if (bitCount == 8) {
> final int rgb = 0xffffff & argb;
> final int index = palette.getPaletteIndex(rgb); //
> possible NullPointerException
> {noformat}
> Why can SimplePalette be null? It comes from
> PaletteFactory::makeExactRgbPaletteSimple(final BufferedImage src, final int
> max). As it's javadoc says it will "fails by returning null if there are more
> than max colors necessary":
> {noformat}
> if (rgbs.add(rgb) && rgbs.size() > max) {
> return null;
> }
> {noformat}
> My first idea goes to throw a RunTimeException rather than returning null.
> But one has to check if there are cases where the return of null triggers
> some error handling i.e. increasing the number of colors or creating a
> different type of object.
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