From 19b03021545ec0a86e8bdc0df8c8c20e2cea90e6 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 3 Apr 2024 23:58:13 +0200
Subject: [PATCH] Add non-locale aware CPLTolower() and CPLToupper()

---
 port/cpl_string.cpp | 30 ++++++++++++++++++++++++++++++
 port/cpl_string.h   |  3 +++
 2 files changed, 33 insertions(+)

diff --git a/port/cpl_string.cpp b/port/cpl_string.cpp
index bbdddb651063..f7372c29f7cd 100644
--- a/port/cpl_string.cpp
+++ b/port/cpl_string.cpp
@@ -3021,3 +3021,33 @@ char **CSLParseCommandLine(const char *pszCommandLine)
 {
     return CSLTokenizeString(pszCommandLine);
 }
+
+/************************************************************************/
+/*                              CPLToupper()                            */
+/************************************************************************/
+
+/** Converts a (ASCII) lowercase character to uppercase.
+ *
+ * Same as standard toupper(), except that it is not locale sensitive.
+ *
+ * @since GDAL 3.9
+ */
+int CPLToupper(int c)
+{
+    return (c >= 'a' && c <= 'z') ? (c - 'a' + 'A') : c;
+}
+
+/************************************************************************/
+/*                              CPLTolower()                            */
+/************************************************************************/
+
+/** Converts a (ASCII) uppercase character to lowercase.
+ *
+ * Same as standard tolower(), except that it is not locale sensitive.
+ *
+ * @since GDAL 3.9
+ */
+int CPLTolower(int c)
+{
+    return (c >= 'A' && c <= 'Z') ? (c - 'A' + 'a') : c;
+}
diff --git a/port/cpl_string.h b/port/cpl_string.h
index cf577d46901b..f666bab9ab2c 100644
--- a/port/cpl_string.h
+++ b/port/cpl_string.h
@@ -190,6 +190,9 @@ typedef enum
 
 CPLValueType CPL_DLL CPLGetValueType(const char *pszValue);
 
+int CPL_DLL CPLToupper(int c);
+int CPL_DLL CPLTolower(int c);
+
 size_t CPL_DLL CPLStrlcpy(char *pszDest, const char *pszSrc, size_t nDestSize);
 size_t CPL_DLL CPLStrlcat(char *pszDest, const char *pszSrc, size_t nDestSize);
 size_t CPL_DLL CPLStrnlen(const char *pszStr, size_t nMaxLen);