smalloc: possible array out-of-bound access when out of memory in init_library about selfie HOT 5 CLOSED

@maroneze Thanks a lot for pointing this out. The issue indeed has educational value. @ChristianMoesl did smalloc and will look into a fix. @ChristianMoesl I think, it is best to exit if initialization does not go through.

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For completeness, the same thing might happen with character_buffer (print <- print_format1 <- printf1 called if the first smalloc() fails); exiting early should avoid both issues.

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write() could also be used for this error message. However, selfie_name could not be printed in this case and the length of the printed error message would have to be a multiple of 8. (double-word alignment)

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@maroneze If you are interested in doing that please feel free to submit a PR. Keep in mind though that we need simple, educational code to be able to pull any PR. Many thanks!

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I proposed a PR, but not sure it is good enough, so feel free to dismiss it if you wish.

On the same kind of warnings, I have a few other issues with my analysis, mostly due to mismatches between the strict C semantics and the hardware model; for instance, when comparing strings such as "-c" (during argument parsing), the code in load_character, namely *((uint64_t*) s + a), implicitly assumes that the string s has at least 8 bytes, otherwise the memory access is invalid. This is more of a portability issue, and I don't have any suggestions other than padding the string with \0s (possibly with some macro).

And finally, function touch dereferences uninitialized memory (just after calling smalloc) using a type other than char, which in theory could trigger some trap representation and cause undefined behavior. Once again, this is more on the theoretical side, and probably not a real issue.

I'll try to identify some more "concerning" issues in the future and report them if I find anything. Just reported these here in case some zealous C language lawyer might wonder about them.

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