__attribute__((nonnull)) will help catching "calling with NULL" mistake on
compile time.
I also convert xStrdup into a macro, that will do assert() inline when the
code is *not* built with -DNDEBUG . For release builds (with -DNDEBUG),
preprocessor trick will ensure that generated code remains the same.
This effectively reverts "Stricter strdup." 4674b4a732
If str is NULL upon the calling of strdup(), it should crash with SIGSEGV.
Just let it crash. Adding the "if (!str) fail();" code serves nothing but
bloat.
calloc() allows 'nmemb' or 'size' to be zero, in which case NULL may be
returned. Letting htop die because of either argument being zero doesn't
make sense.
As a side note: As size_t is unsigned, compiler should be able to optimize
conditional (nmemb > 0 && size > 0) to (nmemb && size). This theorically
shouldn't increase code size too much.
