editor: fix edge case with in memory file-store size limit There are a few cases where we will set a single file into to the editor's FileStore object more than once. Notably, for copied and then modified files, we will set it at least twice. Three times if editing fails (which it can for symlinks). If we pass the in-memory storage limit in between the first (or second if editing fails) time we set the file and the last time we set the file, we will write the data to the in memory store the first time and the file store the last time. We didn't remove it form the in-memory store though, and we always prefer reading from the in-memory store. This means we can sometimes end up with the wrong version of a file. This is fairly unlikely to happen in normal use since you need to hit the memory limit between two writes to the store for the same file. We only write a file multiple times if a) the file (and not one of it's parent directories) is copied and then modified or b) editing fails. From what I can tell, it's only common for editing to fail for symlinks, and they ten to be relatively small data that is unlikely to push over the limit. Finally, the default limit is 100MB which I would expect to be most often either well over (source code) or well under (binaries or automated changes) the size of the changes files in a single commit. The easiest way to reproduce this is to set the in-memory cache size to 0 and then commit a copied and modified symlink. The empty-string version from the failed editing will be the one that persists. I happened to stumble upon this while trying (and failing) to test a bug-fix for a related bug with identical symptoms (empty simlink). I have seen this in the wild, once, but couldn't reproduce it at the time. The repo in question is quite large and quite active, so I am quite confident in my estimation that this is a real, but very rare, problem. The test changes attached to this was mneant to test a related bug, but turned out not to actually cover the bug in question. They did trigger this bug though, and are worthwhile to test, so I kept them.

#!/bin/sh
mkdir temp
cd temp
svnadmin create repo
svn co file://`pwd`/repo wc
cd wc
mkdir branches trunk tags
mkdir tags/versions
mkdir tags/blah
svn add *
svn ci -m 'btt'
cd trunk
for a in alpha beta gamma delta ; do
    echo $a > $a
    svn add $a
done
svn ci -m 'Add files.'
cd ..
svn up
svn cp trunk branches/dev_branch
svn ci -m 'branch'
cd branches/dev_branch
svn rm delta
echo narf > alpha
echo iota > iota
svn add iota
svn ci -m 'branch changes'
cd ../..
svn up
svn cp branches/dev_branch tags/versions/branch_version
svn ci -m 'Make a tag in tags/versions from branches/dev_branch'
svn up
svn cp trunk tags/blah/trunktag
svn ci -m 'Make a tag in tags/blah from trunk'
svn up
cd ../..
svnadmin dump temp/repo > unusual_tags.svndump
echo
echo 'Complete.'
echo 'You probably want to clean up temp now.'
echo 'Dump in unusual_tags.svndump'
exit 0