include/linux/ctype.h

include/linux/ctype.h defines the following macros:

• isalnum(c)
• isalpha(c)
• iscntrl(c)
• isgraph(c)
• islower(c)
• isprint(c)
• ispunct(c)
• isspace(c)
• isupper(c)
• isxdigit(c)
• isascii(c)
• toascii(c)
• isdigit(c) (if not available as GCC built-in, isdigit is an inline function)
• tolower(c)
• toupper(c)

A comment in the source file states that EOF is not handled as required by the standard C library.