codeset problems in wprintf and wcsftime
Wed Mar 31 22:05:00 GMT 2010
On 2 March 2010 20:47, Corinna Vinschen:
>> - Add another flag __HAVE_WCHAR_LOCALE_INFO__ or something. Used in
>> vfwprintf and wcsftime it would use different code for targets
>> which only have the multibyte locale info and targets which have
>> also the wide char representation.
> Attached is a patch which does that and more. I do not intend to apply
> this patch before the next Cygwin release 1.7.2 is out (which will be
> RSN), but I wanted to show what I have, so you guys can make a sanity
> check on the new code if you're interested in this stuff.
> Here's what the patch does, in random order:
> - Add a new macro called __HAVE_LOCALE_INFO_EXTENDED__ which guards
> (almost) all of the new locale definitions.
> - Add two files locale/lctype.[ch], which define a basic LC_CTYPE
> datastructure and functions as in the other categories.
> This adds two features. One of them is for all targets.
> - The global variables lc_ctype_charset, __mb_cur_max, and
> lc_message_charset are no longer used on targets defining
> __HAVE_LOCALE_INFO__. The reason is that global variables disallow
> to define thread-local locales. These are a GNU extension which
> have been added to the latest POSIX-1.2008 standard, see
> The replacement are codeset and mb_cur_max members in the LC_CTYPE
> structure, and codeset in the LC_MESSAGES structure.
> This affects especially the MB_CUR_MAX definition in stdlib.h. It's
> not any longer just __mb_cur_max, rather it calls the new
> __locale_mb_cur_max() function.
I'm concerned about the level of indirection that this entails.
Leaving out the ifdef's, we've got:
return __get_current_ctype_locale ()->mb_cur_max;
Actually, I think there's a bug here: __get_current_ctype_locale()
returns a pointer to lc_ctype_T struct, and the mb_cur_max field in
that is of type 'const char *'. Looking at the code in
__ctype_load_locale(), this is intentional, because apparently it's
meant to point into a char array pointed to by _ctype_locale_buf. So I
think there's a '*' missing in the function above.
But I'm puzzled about why that indirection into _ctype_locale_buf is
there in the first place. Why not just store mb_cur_max directly in
the lc_ctype_T struct?
The __ctype_locale_buf also holds the name of the selected charset,
and I don't like the charset and mb_cur_max being mixed up in that
way, and I think this is really ugly:
/* Max encoding_len + NUL byte + 1 byte mb_cur_max plus trailing NUL byte */
#define _CTYPE_BUF_SIZE 34
static char _ctype_locale_buf[_CTYPE_BUF_SIZE];
What's the idea behind that? And indeed, why not store the codeset
string directly in an array in lc_ctype_T?
Also, in __get_current_ctype, there's this:
struct lc_ctype_T *
: (struct lc_ctype_T *)&_C_ctype_locale);
Checking whether we're in the "C" locale every single time seems
rather inefficient. Wouldn't it be better to initialise _ctype_locale
with the contents _C_ctype_locale and later copy it in again when the
C locale is selected?
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