add _NL_LOCALE_NAME extension to nl_langinfo

since setlocale(cat, NULL) is required to return the setting for the
global locale, there is no standard mechanism to obtain the name of
the currently active thread-local locale set by uselocale. this makes
it impossible for application/library software to load appropriate
translations, etc. unless using the gettext implementation provided by
libc, which has privileged access to libc internals.

to fill this gap, glibc introduced the _NL_LOCALE_NAME macro which can
be used with nl_langinfo to obtain the name. GNU gettext/gnulib code
already use this functionality on glibc, and can easily be adapted to
make use of it on non-glibc systems if it's available; for other
systems they poke at locale implementation internals, which we want to
avoid. this patch provides a compatible interface to the one glibc
introduced.

1 files changed, 6 insertions, 0 deletions

diff --git a/include/langinfo.h b/include/langinfo.h
index 2153c42e..519c0612 100644
--- a/include/langinfo.h
+++ b/include/langinfo.h
@@ -77,6 +77,12 @@ extern "C" {
 #define YESEXPR 0x50000
 #define NOEXPR 0x50001
 
+#define _NL_LOCALE_NAME(cat) (((cat)<<16) | 0xffff)
+
+#if defined(_GNU_SOURCE)
+#define NL_LOCALE_NAME(cat) _NL_LOCALE_NAME(cat)
+#endif
+
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 #define YESSTR 0x50002
 #define NOSTR 0x50003