This is the mail archive of the mailing list for the Cygwin project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Repeated gcc yields differing .exe files wrote:

The fact that hello.exe alters seems a bit non-optimal to me, given that
md5sums are a pretty standard way for people like you and me to check that
we're running the same stuff, intended to do the same thing. Incidentally,
it's always the same two bytes that alter:
As egor said: it's the timestamp. Almost every object file format in use today has compilation timestamps to identify when the executable was created; many even have other tagging information identifying the compilation environment.

It's a completely invalid assumption that the same source compiled twice will give identical binary files. This is a GOOD thing, because it identifies a *binary* precisely, you know if it has been replaced, even with something "identical". This is especially important when you're installing a full installation of some product with many files - you can take an overall checksum of everything, and verify that nothing has been touched or tampered with.

Unsubscribe info:
Bug reporting:

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]