Jason Harrop created XGC-150:
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Summary: ImageLoaderRawPNG never closes its ImageInputStream, so
the image file stays open until garbage collection
Key: XGC-150
URL: https://issues.apache.org/jira/browse/XGC-150
Project: XMLGraphicsCommons
Issue Type: Bug
Components: image codecs
Affects Versions: 2.11
Reporter: Jason Harrop
Attachments: XGC-150.patch
{{ImageLoaderRawPNG.loadImage()}} takes the {{ImageInputStream}} out of the
session's {{Source}}, detaches it with {{XmlSourceUtil.removeStreams(src)}}
("Remove streams as we do things with them at some later time"), wraps it for
{{PNGFile}}, and never closes it. But {{PNGFile}}'s constructor reads every
chunk it keeps (IHDR, PLTE, IDAT, tRNS, iCCP, sRGB) into memory, and
{{getImageRawPNG()}} serves the image data from those byte arrays, so nothing
reads the stream once {{PNGFile}} has been constructed.
So after FOP renders a PNG (to PDF, say), the PNG's file stays open until the
stream is garbage collected, and so does ImageIO's cache file ({{imageio*.tmp}}
in {{java.io.tmpdir}}) where the source came from an {{InputStream}}. On
Windows an open file can't be deleted, so an application can't remove the image
files it has just rendered. Seen from docx4j
(https://github.com/plutext/docx4j/issues/609), which writes pictures to
temporary files for FOP and deletes them after the conversion: on Linux,
{{/proc/self/fd}} still shows the PNG (deleted) and its {{imageio*.tmp}} open
once FOP has finished, while a JPEG in the same document has been closed.
Fix: close the stream in a {{finally}} once {{PNGFile}} has read it:
{code:java}
XmlSourceUtil.removeStreams(src);
try {
SeekableStream seekStream = new
ImageInputStreamSeekableStreamAdapter(in);
// PNGFile reads the chunks it needs into memory, so the stream is
done with after this
PNGFile im = new PNGFile(seekStream, info.getOriginalURI());
return im.getImageRawPNG(info);
} finally {
IOUtils.closeQuietly(in);
}
{code}
with a test, {{ImageLoaderRawPNGTestCase.testLoadImageClosesStream}}, which
fails without the fix. The full test suite passes and checkstyle is clean.
Patch attached; a PR follows.
Related: XGC-107 ({{ImageLoaderInternalTIFF}} doesn't close its source either).
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