libc: Add localeconv()

Always returns the default C locale values.

libs/libc/include/locale.h

@@ -5,13 +5,42 @@
 #define LC_CTYPE 1
 #define LC_COLLATE 2
 #define LC_NUMERIC 3
+#define LC_MONETARY 4
+#define LC_TIME 5
+
+/* Structure representing numeric formatting information for the current locale. */
+struct lconv
+{
+    char* decimal_point;
+    char* thousands_sep;
+    char* grouping;
+    char* int_curr_symbol;
+    char* currency_symbol;
+    char* mon_decimal_point;
+    char* mon_thousands_sep;
+    char* mon_grouping;
+    char* positive_sign;
+    char* negative_sign;
+    char int_frac_digits;
+    char frac_digits;
+    char p_cs_precedes;
+    char p_sep_by_space;
+    char n_cs_precedes;
+    char n_sep_by_space;
+    char p_sign_posn;
+    char n_sign_posn;
+};
 
 #ifdef __cplusplus
 extern "C"
 {
 #endif
 
-    char* setlocale(int category, const char* locale); // Not implemented.
+    /* Set or query the current locale. */
+    char* setlocale(int category, const char* locale);
+
+    /* Retrieve numeric formatting information for the current locale. */
+    struct lconv* localeconv(void);
 
 #ifdef __cplusplus
 }

libs/libc/src/locale.cpp

@@ -1,12 +1,25 @@
+#include <limits.h>
 #include <locale.h>
 #include <luna.h>
 
 static char default_locale[] = "C";
 
+static char dot[] = ".";
+static char empty[] = "";
+
+static struct lconv default_lconv = {dot,      empty,    empty,    empty,    empty,    empty,
+                                     empty,    empty,    empty,    empty,    CHAR_MAX, CHAR_MAX,
+                                     CHAR_MAX, CHAR_MAX, CHAR_MAX, CHAR_MAX, CHAR_MAX, CHAR_MAX};
+
 extern "C"
 {
     char* setlocale(int, const char*)
     {
         return default_locale;
     }
+
+    struct lconv* localeconv(void)
+    {
+        return &default_lconv;
+    }
 }