Re: [PATCHES] 21.3.50 for Cygwin: patch 5

[Joe Buehler <jbuehler@hekimian.com>]

Eli Zaretskii wrote:

>>+#ifdef _P
>>+#undef _P
>>+#endif
>>  #ifndef _P
>>  # ifdef __STDC__
>>  #  define _P(a) a

> Why isn't the original #ifndef guard enough to solve the problem on 
> Cygwin?  Could you please show how does the original code fail, and 
> explain why?

The problem is that _P is defined in the cygwin header files in a manner
that is incompatible with its usage above.  It is one of a set of macros
used in code that classifies characters as white space, printable, etc.:

ctype.h:#define _P	020
ctype.h:#define ispunct(c)	((_ctype_+1)[(unsigned)(c)]&_P)
ctype.h:#define isprint(c)	((_ctype_+1)[(unsigned)(c)]&(_P|_U|_L|_N|_B))
ctype.h:#define	isgraph(c)	((_ctype_+1)[(unsigned)(c)]&(_P|_U|_L|_N))

The above usage in pop.c does not seem correct to me -- aren't symbols
beginning with _ supposed to be reserved for the compilation system, to avoid
conflicts such as this one?

>>--- src/mem-limits.h	19 Aug 2002 17:45:50 -0000	1.31
>>+++ src/mem-limits.h	6 Dec 2002 16:35:33 -0000
>>@@ -46,6 +46,10 @@
>>  #define BSD4_2
>>  #endif
>>
>>+#ifdef CYGWIN
>>+#define BSD4_2
>>+#endif
> 
> 
> Can't this be done in src/s/cygwin.h?

Setgid on a directory does not cause group inheritance under cygwin,
so the code in dired.c for BSD4_2 is incorrect in that case.  The ifdef
could be moved to dired.c.  I don't like the idea of defining it in
cygwin.h, however, since BSD4_2 has nothing to do with cygwin...
-- 
Joe Buehler