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#1 --test ?
Hi, if I may, I would just like start by saying that
squashfs is next best thing to having a compressed-rw
filesystem. Most of us never modify a good portion of our
harddrives, and using this fs is perfect for that. I have
one tiny suggestion though. It's probably a dumb and
usless idea ;), but how about an option to "test-write" a
squashfs. That way if don't have the room to actually
write the fs, we could at least see a printout of how big
the fs would be and a few other statistics.
Btw, I think squashfs is awsome! Keep up the good
work guys!
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Closing because it has been here for over four years (almost the entire lifetime of Squashfs!)
Adding a test option would be useful, but it is essentially an impossible option to add because of duplicate checking. When Mksquashfs adds a file to the filesystem it first checks to see if it is a duplicate of a file already in the filesystem. To do this it needs access to the filesystem being created - if the -test option is being used then there isn't a filesystem there to check. There are only two ways around this, one is to check for duplicates against the original file (rather than the file stored in the filesystem), but this is extremely dangerous because the original file could have changed after the file was stored in the filesystem, and the consequence of this is a 'corrupt' filesystem, you would have a file marked as a duplicate of another file when it isn't, this is why duplicate checking has always been against the filesystem. The other alternative is not to do duplicate checking when the -test option is used, but this obviously defeats the whole purpose of -test, if there are a lot of duplicates in the filesystem the size estimate produced by -test would be misleading.