Add strtok_r.c

common/strtok_r.c

+/*
+ * public domain strtok_r()
+ */
+
+#include <string.h>
+
+char* strtok_r( char* str, const char* delim, char** nextp )
+{
+    char* ret;
+
+    if( str == NULL )
+    {
+        str = *nextp;
+    }
+
+    str += strspn( str, delim );
+
+    if( *str == '\0' )
+    {
+        return NULL;
+    }
+
+    ret = str;
+
+    str += strcspn( str, delim );
+
+    if( *str )
+    {
+        *str++ = '\0';
+    }
+
+    *nextp = str;
+
+    return ret;
+}