Add strupr and strlwr

libc/include/string.h

@@ -51,6 +51,9 @@ char *strsep(char **, const char *);
 size_t strcspn(const char *, const char *);
 size_t strspn(const char *, const char *);
 
+char *strlwr(char *str);
+char *strupr(char *str);
+
 /* Linux silly hour */
 char *strfry(char *);
 

libc/string/Makefile

@@ -31,6 +31,8 @@ OBJS = \
 	strspn.o \
 	strstr.o \
 	strtok.o \
+	strlwr.o \
+	strupr.o \
 	# end of list
 
 .PHONY: all

libc/string/strlwr.c

@@ -0,0 +1,12 @@
+#include <string.h>
+#include <ctype.h>
+
+char *
+strlwr(char *str)
+{
+    unsigned char *p;
+
+    for (p = (unsigned char *)str; *p != '\0'; p++)
+        *p = tolower(*p);
+    return str;
+}

libc/string/strupr.c

@@ -0,0 +1,12 @@
+#include <string.h>
+#include <ctype.h>
+
+char *
+strupr(char *str)
+{
+    unsigned char *p;
+
+    for (p = (unsigned char *)str; *p != '\0'; p++)
+        *p = toupper(*p);
+    return str;
+}