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Add fix for overflow error in MXParser buffer sizing #72

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Add fix for overflow error in MXParser buffer sizing #72

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341a72f
Add fix for overflow error in MXParser buffer sizing
mealingr Nov 25, 2019
6c55f73
simplify the fix
mealingr Nov 27, 2019
a3f9276
call public api for test
mealingr Nov 28, 2019
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7 changes: 5 additions & 2 deletions src/main/java/org/codehaus/plexus/util/xml/pull/MXParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -401,9 +401,11 @@ protected void ensureEntityCapacity()
protected int bufLoadFactor = 95; // 99%
// protected int bufHardLimit; // only matters when expanding

protected float bufferLoadFactor = bufLoadFactor / 100f;

protected char buf[] = new char[Runtime.getRuntime().freeMemory() > 1000000L ? READ_CHUNK_SIZE : 256];

protected int bufSoftLimit = ( bufLoadFactor * buf.length ) / 100; // desirable size of buffer
protected int bufSoftLimit = (int) (bufferLoadFactor * buf.length); // desirable size of buffer

protected boolean preventBufferCompaction;

Expand Down Expand Up @@ -3656,7 +3658,8 @@ else if ( expand )
buf = newBuf;
if ( bufLoadFactor > 0 )
{
bufSoftLimit = ( bufLoadFactor * buf.length ) / 100;
// Include fix for https://web.archive.org/web/20070831191548/http://www.extreme.indiana.edu/bugzilla/show_bug.cgi?id=228
bufSoftLimit = (int) (bufferLoadFactor * buf.length);
}

}
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17 changes: 17 additions & 0 deletions src/test/java/org/codehaus/plexus/util/xml/pull/MXParserTest.java
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Expand Up @@ -391,6 +391,23 @@ public void testSubsequentProcessingInstructionMoreThan8k()
assertEquals( XmlPullParser.END_TAG, parser.nextToken() );
}

@Test
public void testFillBuf_NoOverflow()
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Could you write the test in terms of the public API? Accessing directly the fields and calling directy fillBuf() is not the normal use the parser. I'm thinking generating a big enough XML file, parsing it, showing that fails without the patch and pass the test with the patch in place.

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@mealingr mealingr Nov 28, 2019 •
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Could you write the test in terms of the public API? Accessing directly the fields and calling directy fillBuf() is not the normal use the parser. I'm thinking generating a big enough XML file, parsing it, showing that fails without the patch and pass the test with the patch in place.

Sure a3f9276 (without the patch that test fails with java.io.IOException: error reading input, returned 0)

throws Exception
{
MXParser parser = new MXParser();
parser.reader = new StringReader("testFillBuf_NoOverflow");
parser.bufEnd = 15941364;
parser.buf = new char[16777216];

parser.fillBuf();

// Without this fix
// https://web.archive.org/web/20070831191548/http://www.extreme.indiana.edu/bugzilla/show_bug.cgi?id=228
// the integer value overflows to -11072962
assertTrue(parser.bufSoftLimit >= 0);
}

public void testMalformedProcessingInstructionAfterTag()
throws Exception
{
Expand Down