From 407eed212ac09cd69aa95e2584673fc3ee9295ec Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Sat, 19 Apr 2025 20:02:01 +0300
Subject: [PATCH] LibC: Implement nl_langinfo

All values are from POSIX locale except CODESET which can be "UTF-8"
depending on the current locale
---
 userspace/libraries/LibC/CMakeLists.txt |  1 +
 userspace/libraries/LibC/langinfo.cpp   | 90 +++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 userspace/libraries/LibC/langinfo.cpp

diff --git a/userspace/libraries/LibC/CMakeLists.txt b/userspace/libraries/LibC/CMakeLists.txt
index d0f38f67..ba65d7eb 100644
--- a/userspace/libraries/LibC/CMakeLists.txt
+++ b/userspace/libraries/LibC/CMakeLists.txt
@@ -11,6 +11,7 @@ set(LIBC_SOURCES
 	ftw.cpp
 	grp.cpp
 	inttypes.cpp
+	langinfo.cpp
 	libgen.cpp
 	locale.cpp
 	malloc.cpp
diff --git a/userspace/libraries/LibC/langinfo.cpp b/userspace/libraries/LibC/langinfo.cpp
new file mode 100644
index 00000000..ce6dbbdd
--- /dev/null
+++ b/userspace/libraries/LibC/langinfo.cpp
@@ -0,0 +1,90 @@
+#include <langinfo.h>
+#include <locale.h>
+
+#include <BAN/Assert.h>
+
+static const char* nl_langinfo_impl(nl_item item)
+{
+	// only codeset is affected by current locales
+	if (item == CODESET)
+	{
+		switch (__getlocale(LC_CTYPE))
+		{
+			case LOCALE_INVALID: ASSERT_NOT_REACHED();
+			case LOCALE_UTF8:    return "UTF-8";
+			case LOCALE_POSIX:   return "ANSI_X3.4-1968";
+		}
+		ASSERT_NOT_REACHED();
+	}
+
+	// other values from POSIX locale
+	switch (item)
+	{
+		// LC_TIME
+		case D_T_FMT:    return "%a %b %e %H:%M:%S %Y";
+		case D_FMT:      return "%m/%d/%y";
+		case T_FMT:      return "%H:%M:%S";
+		case AM_STR:     return "AM";
+		case PM_STR:     return "PM";
+		case T_FMT_AMPM: return "%I:%M:%S %p";
+		case ERA:         return "";
+		case ERA_D_T_FMT: return "";
+		case ERA_D_FMT:   return "";
+		case ERA_T_FMT:   return "";
+		case DAY_1: return "Sunday";
+		case DAY_2: return "Monday";
+		case DAY_3: return "Tuesday";
+		case DAY_4: return "Wednesday";
+		case DAY_5: return "Thursday";
+		case DAY_6: return "Friday";
+		case DAY_7: return "Saturday";
+		case ABDAY_1: return "Sun";
+		case ABDAY_2: return "Mon";
+		case ABDAY_3: return "Tue";
+		case ABDAY_4: return "Wed";
+		case ABDAY_5: return "Thu";
+		case ABDAY_6: return "Fri";
+		case ABDAY_7: return "Sat";
+		case MON_1:  return "January";
+		case MON_2:  return "February";
+		case MON_3:  return "March";
+		case MON_4:  return "April";
+		case MON_5:  return "May";
+		case MON_6:  return "June";
+		case MON_7:  return "July";
+		case MON_8:  return "August";
+		case MON_9:  return "September";
+		case MON_10: return "October";
+		case MON_11: return "November";
+		case MON_12: return "December";
+		case ABMON_1:  return "Jan";
+		case ABMON_2:  return "Feb";
+		case ABMON_3:  return "Mar";
+		case ABMON_4:  return "Apr";
+		case ABMON_5:  return "May";
+		case ABMON_6:  return "Jun";
+		case ABMON_7:  return "Jul";
+		case ABMON_8:  return "Aug";
+		case ABMON_9:  return "Sep";
+		case ABMON_10: return "Oct";
+		case ABMON_11: return "Nov";
+		case ABMON_12: return "Dec";
+		// LC_NUMERIC
+		case RADIXCHAR: return ".";
+		case THOUSEP:   return "";
+		// LC_MESSAGES
+		case YESEXPR: return "^[yY]";
+		case NOEXPR:  return "^[nN]";
+		// LC_MONETARY
+		case CRNCYSTR: return "";
+	}
+
+	return "";
+}
+
+char* nl_langinfo(nl_item item)
+{
+	// NOTE: POSIX says "The application shall not modify the string returned"
+	//       so const_cast from string literal *should* be fine
+	return const_cast<char*>(nl_langinfo_impl(item));
+}