[mikeash]

Did you adjust the offset like I said you would probably need to?

[mfukar]

I can't see any changes in `safercopy` or in the calling code you provided - only the invocations from the shell showing the prog terminating.

[mikeash]

My point is that the offset value needed to produce the described behavior depends on various implementation-specific things, so that constant may need to be altered when trying the code on other compilers, OSes, or CPU architectures.