java: new helper library for the Android port

src/util/StringUtil.hxx

@@ -22,6 +22,8 @@
 
 #include "Compiler.h"
 
+#include <stddef.h>
+
 /**
  * Returns a pointer to the first non-whitespace character in the
  * string, or to the end of the string.
@@ -55,6 +57,18 @@ gcc_pure
 bool
 StringEndsWith(const char *haystack, const char *needle);
 
+/**
+ * Copy a string.  If the buffer is too small, then the string is
+ * truncated.  This is a safer version of strncpy().
+ *
+ * @param size the size of the destination buffer (including the null
+ * terminator)
+ * @return a pointer to the null terminator
+ */
+gcc_nonnull_all
+char *
+CopyString(char *dest, const char *src, size_t size);
+
 /**
  * Checks whether a string array contains the specified string.
  *