Re: [PATCH] IBM z/OS + EBCDIC support

[Paul Eggert]

Thanks for explaining.  I still see a problem with the proposed patch, 
though, in that (if I'm understanding it correctly) it would cause 
c_isalpha (120) to succeed, even though EBCDIC 120 corresponds to U+00CC 
LATIN CAPITAL LETTER I WITH GRAVE, and that is not supposed to be an 
alphabetic character in the stripped-down C locale.  Code that uses 
c-ctype wants only ASCII letters, and departing from this would likely 
break things.

Worse, the C expression "c_ispunct ('[')" might return false, as the 
library may be in a locale that's incompatible with the mode the 
compiler was in when it compiled the '['.

Looking at the web page you mentioned, it appears that one approach is 
to assume EBCDIC 1047 (this seems to be the default and typical setting 
for C programs) at both compile-time and run-time.  We can check the 
compile-time assumption without any code overhead.  The proposed patch 
does that.  If someone ally wants to use a different code page, either 
at compile-time or at run-time, more code will need to be written (most 
likely by the poor soul who actually needs that feature).

> Yes, all control characters appear to be in [\x00-\x3F], but not 
> everything in that range is a control character. (I remember 0x04 was 
> not.) I tried making c_iscntrl() a simple range check at first, but 
> that did not agree with the system iscntrl().

Thanks, this should be fixed in the attached patch, which I've installed.

0001-c-ctype-assume-EBCDIC-1047-for-c_iscntrl.patch
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