Bug 382680

Description Damian 2012-06-14 17:37:52 EDT

Build Identifier: 

If you call the DiffFormatter's setContext() method with Integer.MAX_VALUE (which we're doing because we wanted full-context diffs) the format() method will get into an infinite loop.

This is because of the following...

 684   public void format(final EditList edits, final RawText a, final RawText b)
 685       throws IOException {
 686     for (int curIdx = 0; curIdx < edits.size();) {

     ...
 691       int aCur = Math.max(0, curEdit.getBeginA() - context);
 692       int bCur = Math.max(0, curEdit.getBeginB() - context);
 693       final int aEnd = Math.min(a.size(), endEdit.getEndA() + context);
 694       final int bEnd = Math.min(b.size(), endEdit.getEndB() + context);

The "endEdit.getEndA() + context" and "endEdit.getEndB() + context" experience an integer overflow, resulting in a massive negative value which causes the method to loop indefinitely.

Preferably there would either be a method to get the full context, or some check here to make sure that aEnd and bEnd don't end up with a negative value.

We're encountering this with stable-1.3 (commit id f70b24a), though at a quick glance this is still the case with the current master (commit id 55f42a8).

Cheers! -Damian


Reproducible: Always

Steps to Reproduce:
1. construct a DiffFormatter
2. call setContext(Integer.MAX_VALUE) on it
3. call its format() method on something