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Is it possible to use a modified installer that hashes and then re-uses files that are not modified?

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Last seen: 3 months 4 weeks ago
Joined: 2007-08-09 09:58
Is it possible to use a modified installer that hashes and then re-uses files that are not modified?

For example, if a Firefox update changes two files, firefox.exe and a .dll, why are all PortableApps users re-downloading the entire Firefox installer? you could just have the installer use an index of the updated installer files, CRC32 or some other hash to verify the already installed unchanged versions, then supply the updated files.

Also, if the altered portions of the updated file contents are very small, you could use something like ParPar to patch those, yielding even more bandwidth.

At the end of the operation, hash check prevents failure to update, with ability to download full installer to fix problematic issues.

Yeah, probably way too much work, but the bandwidth savings....

John T. Haller
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Last seen: 6 hours 12 min ago
Joined: 2005-11-28 22:21

First, the PA.c Installer is based on NSIS which doesn't have delta functionality built in. It would need to be custom written or adapted from another product and I do not have the time or desire to do this. Second, I would not have the time to maintain the patch builds for each release. Firefox is a huge time effort to build, upload, and post as it consists of 39 different language packages. This takes a while on my desktop. Third, Firefox deltas (.mar files) are a lot bigger than you think they are. A point release (x.y.0 to x.y.1) seems to be about 8-12MB and major releases (1.0.0 to 2.0.0) seem to be 10-16MB over the last couple releases. Double those numbers as Firefox Portable is both 32-bit and 64-bit in each package. And then make it larger since we'd be doing full files for all changed files not just deltas unless someone comes along and writes an installer that does us.

In short, the complexity and build time makes it highly unlikely.

Sometimes, the impossible can become possible, if you're awesome!

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