-# define obstack_fgrow4(Obs, Format, Arg1, Arg2, Arg3, Arg4) \
- do { \
- char buf[4096]; \
- sprintf (buf, Format, Arg1, Arg2, Arg3, Arg4); \
- obstack_grow (Obs, buf, strlen (buf)); \
+
+/* Output Str both quoted for M4 (i.e., embed in [[...]]), and escaped
+ for our postprocessing (i.e., escape M4 special characters). If
+ Str is empty (or NULL), output "[]" instead of "[[]]" as it make M4
+ programming easier (m4_ifval can be used).
+
+ For instance "[foo]" -> "[[@{foo@}]]", "$$" -> "[[$][$][]]". */
+
+# define obstack_quote(Obs, Str) \
+ do { \
+ char const* obstack_quote_p = Str; \
+ if (obstack_quote_p && obstack_quote_p[0]) \
+ { \
+ obstack_sgrow (Obs, "[["); \
+ obstack_escape (Obs, obstack_quote_p); \
+ obstack_sgrow (Obs, "]]"); \
+ } \
+ else \
+ obstack_sgrow (Obs, "[]"); \