Matt Whitlock 41d31dcd19 avoid UB when calling ctype functions ...

The character classification functions in <ctype.h> are designed to
classify characters returned by <stdio.h> getchar() and friends, which
return characters as signed integers in the range 0 to 255 or EOF. The
behavior of the ctype functions is undefined if they are passed a value
outside of that range, which may happen if they are passed a char-typed
value and the system's char type is signed.

<ccan/str/str.h> defines some inline utility functions that perform the
necessary cast to coerce a char-typed argument into the allowed value
range. Call these wrappers instead of the bare ctype functions when
classifying char-typed characters.

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2025-08-18 14:03:20 +09:30

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