Add output and two-way processors to API. Update Mac config stuff.

28 files changed, 1149 insertions, 94 deletions

diff --git a/ChangeLog b/ChangeLog
index 7063a365..489ffa8b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,28 @@
+2012-08-22         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Add output wrapper and two-way processor to extension API.
+
+	* awk.h (struct redirect): Replace output FILE * with awk_output_buf_t.
+	(register_output_wrapper, register_two_way_processor): Declare.
+	* builtin.c (efwrite): Adjust logic to use rp->output data and
+	functions if rp is not NULL. Remove redundant declaration of function.
+	(do_fflush, do_printf, do_print, do_print_rec): Same adjustment.
+	* ext.c (make_builtin): Adjust error messages.
+	* gawkapi.c (api_register_output_wrapper,
+	api_register_two_way_processor): New functions.
+	(sym_update_real): Adjust code formatting.
+	* gawkapi.h (awk_input_parser_t): Make next pointer awk_const.
+	(awk_output_buf_t, awk_two_way_processor_t): New structs.
+	(api_register_output_wrapper, api_register_two_way_processor): New APIs.
+	(dl_load_func): Allow for empty function table (NULL elements).
+	* io.c (find_output_wrapper, init_output_wrapper, find_two_processor,
+	gawk_fwrite, gawk_ferror, gawk_fflush, gawk_fclose): New functions.
+	(redirect): Call init_output_wrapper, find_output_wrapper as needed.
+	Adjust use of rp->fp to rp->output.fp and also function calls.
+	(close_rp, close_redir, flush_io): Same adjustment.
+	(two_way_open): Same adjustment. Call find_two_way_processor, and
+	find_output_wrapper, as needed.
+
 2012-08-17         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* Update infrastructure: Automake 1.12.3 and bison 2.6.2.
diff --git a/awk.h b/awk.h
index e7998626..9b595072 100644
--- a/awk.h
+++ b/awk.h
@@ -933,7 +933,6 @@ struct redirect {
 #		define	RED_SOCKET	1024
 #		define	RED_TCP		2048
 	char *value;
-	FILE *fp;
 	FILE *ifp;	/* input fp, needed for PIPES_SIMULATED */
 	IOBUF *iop;
 	int pid;
@@ -941,6 +940,7 @@ struct redirect {
 	struct redirect *prev;
 	struct redirect *next;
 	const char *mode;
+	awk_output_buf_t output;
 };
 
 /*
@@ -1543,6 +1543,8 @@ extern int isdirpunct(int c);
 /* io.c */
 extern void init_io(void);
 extern void register_input_parser(awk_input_parser_t *input_parser);
+extern void register_output_wrapper(awk_output_wrapper_t *wrapper);
+extern void register_two_way_processor(awk_two_way_processor_t *processor);
 extern void set_FNR(void);
 extern void set_NR(void);
 
diff --git a/builtin.c b/builtin.c
index 3576372c..6a2d9d6b 100644
--- a/builtin.c
+++ b/builtin.c
@@ -92,9 +92,6 @@ fatal(_("attempt to use array `%s' in a scalar context"), array_vname(s1)); \
  */
 #define GAWK_RANDOM_MAX 0x7fffffffL
 
-static void efwrite(const void *ptr, size_t size, size_t count, FILE *fp,
-		       const char *from, struct redirect *rp, bool flush);
-
 /* efwrite --- like fwrite, but with error checking */
 
 static void
@@ -107,14 +104,23 @@ efwrite(const void *ptr,
 	bool flush)
 {
 	errno = 0;
-	if (fwrite(ptr, size, count, fp) != count)
+	if (rp != NULL) {
+		if (rp->output.gawk_fwrite(ptr, size, count, fp, rp->output.opaque) != count)
+			goto wrerror;
+	} else if (fwrite(ptr, size, count, fp) != count)
 		goto wrerror;
 	if (flush
 	  && ((fp == stdout && output_is_tty)
 	      || (rp != NULL && (rp->flag & RED_NOBUF)))) {
-		fflush(fp);
-		if (ferror(fp))
-			goto wrerror;
+		if (rp != NULL) {
+			rp->output.gawk_fflush(fp, rp->output.opaque);
+			if (rp->output.gawk_ferror(fp, rp->output.opaque))
+				goto wrerror;
+		} else {
+			fflush(fp);
+			if (ferror(fp))
+				goto wrerror;
+		}
 	}
 	return;
 
@@ -207,9 +213,9 @@ do_fflush(int nargs)
 			DEREF(tmp);
 			return make_number((AWKNUM) status);
 		}
-		fp = rp->fp;
+		fp = rp->output.fp;
 		if (fp != NULL)
-			status = fflush(fp);
+			status = rp->output.gawk_fflush(fp, rp->output.opaque);
 	} else if ((fp = stdfile(tmp->stptr, tmp->stlen)) != NULL) {
 		status = fflush(fp);
 	} else {
@@ -1615,7 +1621,7 @@ do_printf(int nargs, int redirtype)
 			fatal(_("attempt to use array `%s' in a scalar context"), array_vname(redir_exp));
 		rp = redirect(redir_exp, redirtype, & errflg);
 		if (rp != NULL)
-			fp = rp->fp;
+			fp = rp->output.fp;
 	} else
 		fp = output_fp;
 
@@ -1631,7 +1637,7 @@ do_printf(int nargs, int redirtype)
 		}
 		efwrite(tmp->stptr, sizeof(char), tmp->stlen, fp, "printf", rp, true);
 		if (rp != NULL && (rp->flag & RED_TWOWAY) != 0)
-			fflush(rp->fp);
+			rp->output.gawk_fflush(rp->output.fp, rp->output.opaque);
 		DEREF(tmp);
 	} else
 		gawk_exit(EXIT_FATAL);
@@ -2041,7 +2047,7 @@ do_print(int nargs, int redirtype)
 			fatal(_("attempt to use array `%s' in a scalar context"), array_vname(redir_exp));
 		rp = redirect(redir_exp, redirtype, & errflg);
 		if (rp != NULL)
-			fp = rp->fp;
+			fp = rp->output.fp;
 	} else
 		fp = output_fp;
 
@@ -2084,7 +2090,7 @@ do_print(int nargs, int redirtype)
 		efwrite(ORS, sizeof(char), (size_t) ORSlen, fp, "print", rp, true);
 
 	if (rp != NULL && (rp->flag & RED_TWOWAY) != 0)
-		fflush(rp->fp);
+		rp->output.gawk_fflush(rp->output.fp, rp->output.opaque);
 }
 
 /* do_print_rec --- special case printing of $0, for speed */
@@ -2103,7 +2109,7 @@ do_print_rec(int nargs, int redirtype)
 		redir_exp = TOP();
 		rp = redirect(redir_exp, redirtype, & errflg);
 		if (rp != NULL)
-			fp = rp->fp;
+			fp = rp->output.fp;
 		DEREF(redir_exp);
 		decr_sp();
 	} else
@@ -2126,7 +2132,7 @@ do_print_rec(int nargs, int redirtype)
 		efwrite(ORS, sizeof(char), (size_t) ORSlen, fp, "print", rp, true);
 
 	if (rp != NULL && (rp->flag & RED_TWOWAY) != 0)
-		fflush(rp->fp);
+		rp->output.gawk_fflush(rp->output.fp, rp->output.opaque);
 }
 
 #if MBS_SUPPORT
diff --git a/ext.c b/ext.c
index 17ade95a..3f4b95f8 100644
--- a/ext.c
+++ b/ext.c
@@ -90,12 +90,12 @@ make_builtin(const awk_ext_func_t *funcinfo)
 
 	sp = name;
 	if (sp == NULL || *sp == '\0')
-		fatal(_("extension: missing function name"));
+		fatal(_("make_builtin: missing function name"));
 
 	while ((c = *sp++) != '\0') {
 		if ((sp == &name[1] && c != '_' && ! isalpha((unsigned char) c))
 				|| (sp > &name[1] && ! is_identchar((unsigned char) c)))
-			fatal(_("extension: illegal character `%c' in function name `%s'"), c, name);
+			fatal(_("make_builtin: illegal character `%c' in function name `%s'"), c, name);
 	}
 
 	f = lookup(name);
@@ -103,17 +103,17 @@ make_builtin(const awk_ext_func_t *funcinfo)
 	if (f != NULL) {
 		if (f->type == Node_func) {
 			/* user-defined function */
-			fatal(_("extension: can't redefine function `%s'"), name);
+			fatal(_("make_builtin: can't redefine function `%s'"), name);
 		} else if (f->type == Node_ext_func) {
 			/* multiple extension() calls etc. */ 
 			if (do_lint)
-				lintwarn(_("extension: function `%s' already defined"), name);
+				lintwarn(_("make_builtin: function `%s' already defined"), name);
 			return false;
 		} else
 			/* variable name etc. */ 
-			fatal(_("extension: function name `%s' previously defined"), name);
+			fatal(_("make_builtin: function name `%s' previously defined"), name);
 	} else if (check_special(name) >= 0)
-		fatal(_("extension: can't use gawk built-in `%s' as function name"), name); 
+		fatal(_("make_builtin: can't use gawk built-in `%s' as function name"), name); 
 
 	if (count < 0)
 		fatal(_("make_builtin: negative argument count for function `%s'"),
diff --git a/extension/ChangeLog b/extension/ChangeLog
index bc4b060b..0a15220a 100644
--- a/extension/ChangeLog
+++ b/extension/ChangeLog
@@ -1,3 +1,8 @@
+2012-08-22         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* revoutput.c: New testing extension for output wrapper.
+	* Makefile.am: Build revoutput extension.
+
 2012-08-08         Arnold D. Robbins     <arnold@skeeve.com>
 
 	Add fts() to filefuncs.
diff --git a/extension/Makefile.am b/extension/Makefile.am
index bf9a715f..f7d939a4 100644
--- a/extension/Makefile.am
+++ b/extension/Makefile.am
@@ -38,6 +38,8 @@ pkgextension_LTLIBRARIES =	\
 	ordchr.la	\
 	readdir.la	\
 	readfile.la	\
+	revoutput.la	\
+	revtwoway.la	\
 	rwarray.la	\
 	testext.la	\
 	time.la
@@ -49,27 +51,43 @@ MY_LIBS = $(LIBINTL)
 filefuncs_la_SOURCES  = filefuncs.c stack.h stack.c
 filefuncs_la_LDFLAGS  = $(MY_MODULE_FLAGS)
 filefuncs_la_LIBADD   = $(MY_LIBS)
+
 fnmatch_la_SOURCES    = fnmatch.c
 fnmatch_la_LDFLAGS    = $(MY_MODULE_FLAGS)
 fnmatch_la_LIBADD     = $(MY_LIBS)
+
 fork_la_SOURCES       = fork.c
 fork_la_LDFLAGS       = $(MY_MODULE_FLAGS)
 fork_la_LIBADD        = $(MY_LIBS)
+
 ordchr_la_SOURCES     = ordchr.c
 ordchr_la_LDFLAGS     = $(MY_MODULE_FLAGS)
 ordchr_la_LIBADD      = $(MY_LIBS)
+
 readdir_la_SOURCES    = readdir.c
 readdir_la_LDFLAGS    = $(MY_MODULE_FLAGS)
 readdir_la_LIBADD     = $(MY_LIBS)
+
 readfile_la_SOURCES   = readfile.c
 readfile_la_LDFLAGS   = $(MY_MODULE_FLAGS)
 readfile_la_LIBADD    = $(MY_LIBS)
+
+revoutput_la_SOURCES  = revoutput.c
+revoutput_la_LDFLAGS  = $(MY_MODULE_FLAGS)
+revoutput_la_LIBADD   = $(MY_LIBS)
+
+revtwoway_la_SOURCES  = revtwoway.c
+revtwoway_la_LDFLAGS  = $(MY_MODULE_FLAGS)
+revtwoway_la_LIBADD   = $(MY_LIBS)
+
 rwarray_la_SOURCES    = rwarray.c
 rwarray_la_LDFLAGS    = $(MY_MODULE_FLAGS)
 rwarray_la_LIBADD     = $(MY_LIBS)
+
 time_la_SOURCES       = time.c
 time_la_LDFLAGS       = $(MY_MODULE_FLAGS)
 time_la_LIBADD        = $(MY_LIBS)
+
 testext_la_SOURCES    = testext.c
 testext_la_LDFLAGS    = $(MY_MODULE_FLAGS)
 testext_la_LIBADD     = $(MY_LIBS)
diff --git a/extension/Makefile.in b/extension/Makefile.in
index 59ead43b..bebc006b 100644
--- a/extension/Makefile.in
+++ b/extension/Makefile.in
@@ -90,13 +90,13 @@ DIST_COMMON = README $(am__configure_deps) $(srcdir)/Makefile.am \
 	build-aux/install-sh build-aux/ltmain.sh build-aux/missing
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/gettext.m4 \
-	$(top_srcdir)/m4/iconv.m4 $(top_srcdir)/m4/lib-ld.m4 \
-	$(top_srcdir)/m4/lib-link.m4 $(top_srcdir)/m4/lib-prefix.m4 \
-	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltoptions.m4 \
-	$(top_srcdir)/m4/ltsugar.m4 $(top_srcdir)/m4/ltversion.m4 \
-	$(top_srcdir)/m4/lt~obsolete.m4 $(top_srcdir)/m4/nls.m4 \
-	$(top_srcdir)/m4/po.m4 $(top_srcdir)/m4/progtest.m4 \
-	$(top_srcdir)/configure.ac
+	$(top_srcdir)/m4/iconv.m4 $(top_srcdir)/m4/intlmacosx.m4 \
+	$(top_srcdir)/m4/lib-ld.m4 $(top_srcdir)/m4/lib-link.m4 \
+	$(top_srcdir)/m4/lib-prefix.m4 $(top_srcdir)/m4/libtool.m4 \
+	$(top_srcdir)/m4/ltoptions.m4 $(top_srcdir)/m4/ltsugar.m4 \
+	$(top_srcdir)/m4/ltversion.m4 $(top_srcdir)/m4/lt~obsolete.m4 \
+	$(top_srcdir)/m4/nls.m4 $(top_srcdir)/m4/po.m4 \
+	$(top_srcdir)/m4/progtest.m4 $(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
 am__CONFIG_DISTCLEAN_FILES = config.status config.cache config.log \
@@ -173,6 +173,18 @@ readfile_la_OBJECTS = $(am_readfile_la_OBJECTS)
 readfile_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) \
 	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
 	$(readfile_la_LDFLAGS) $(LDFLAGS) -o $@
+revoutput_la_DEPENDENCIES = $(am__DEPENDENCIES_2)
+am_revoutput_la_OBJECTS = revoutput.lo
+revoutput_la_OBJECTS = $(am_revoutput_la_OBJECTS)
+revoutput_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) \
+	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
+	$(revoutput_la_LDFLAGS) $(LDFLAGS) -o $@
+revtwoway_la_DEPENDENCIES = $(am__DEPENDENCIES_2)
+am_revtwoway_la_OBJECTS = revtwoway.lo
+revtwoway_la_OBJECTS = $(am_revtwoway_la_OBJECTS)
+revtwoway_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) \
+	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
+	$(revtwoway_la_LDFLAGS) $(LDFLAGS) -o $@
 rwarray_la_DEPENDENCIES = $(am__DEPENDENCIES_2)
 am_rwarray_la_OBJECTS = rwarray.lo
 rwarray_la_OBJECTS = $(am_rwarray_la_OBJECTS)
@@ -206,11 +218,13 @@ LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
 	$(LDFLAGS) -o $@
 SOURCES = $(filefuncs_la_SOURCES) $(fnmatch_la_SOURCES) \
 	$(fork_la_SOURCES) $(ordchr_la_SOURCES) $(readdir_la_SOURCES) \
-	$(readfile_la_SOURCES) $(rwarray_la_SOURCES) \
+	$(readfile_la_SOURCES) $(revoutput_la_SOURCES) \
+	$(revtwoway_la_SOURCES) $(rwarray_la_SOURCES) \
 	$(testext_la_SOURCES) $(time_la_SOURCES)
 DIST_SOURCES = $(filefuncs_la_SOURCES) $(fnmatch_la_SOURCES) \
 	$(fork_la_SOURCES) $(ordchr_la_SOURCES) $(readdir_la_SOURCES) \
-	$(readfile_la_SOURCES) $(rwarray_la_SOURCES) \
+	$(readfile_la_SOURCES) $(revoutput_la_SOURCES) \
+	$(revtwoway_la_SOURCES) $(rwarray_la_SOURCES) \
 	$(testext_la_SOURCES) $(time_la_SOURCES)
 RECURSIVE_TARGETS = all-recursive check-recursive dvi-recursive \
 	html-recursive info-recursive install-data-recursive \
@@ -312,6 +326,7 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@
 INSTALL_SCRIPT = @INSTALL_SCRIPT@
 INSTALL_STRIP_PROGRAM = @INSTALL_STRIP_PROGRAM@
 INTLLIBS = @INTLLIBS@
+INTL_MACOSX_LIBS = @INTL_MACOSX_LIBS@
 LD = @LD@
 LDFLAGS = @LDFLAGS@
 LIBICONV = @LIBICONV@
@@ -422,6 +437,8 @@ pkgextension_LTLIBRARIES = \
 	ordchr.la	\
 	readdir.la	\
 	readfile.la	\
+	revoutput.la	\
+	revtwoway.la	\
 	rwarray.la	\
 	testext.la	\
 	time.la
@@ -447,6 +464,12 @@ readdir_la_LIBADD = $(MY_LIBS)
 readfile_la_SOURCES = readfile.c
 readfile_la_LDFLAGS = $(MY_MODULE_FLAGS)
 readfile_la_LIBADD = $(MY_LIBS)
+revoutput_la_SOURCES = revoutput.c
+revoutput_la_LDFLAGS = $(MY_MODULE_FLAGS)
+revoutput_la_LIBADD = $(MY_LIBS)
+revtwoway_la_SOURCES = revtwoway.c
+revtwoway_la_LDFLAGS = $(MY_MODULE_FLAGS)
+revtwoway_la_LIBADD = $(MY_LIBS)
 rwarray_la_SOURCES = rwarray.c
 rwarray_la_LDFLAGS = $(MY_MODULE_FLAGS)
 rwarray_la_LIBADD = $(MY_LIBS)
@@ -567,6 +590,10 @@ readdir.la: $(readdir_la_OBJECTS) $(readdir_la_DEPENDENCIES) $(EXTRA_readdir_la_
 	$(readdir_la_LINK) -rpath $(pkgextensiondir) $(readdir_la_OBJECTS) $(readdir_la_LIBADD) $(LIBS)
 readfile.la: $(readfile_la_OBJECTS) $(readfile_la_DEPENDENCIES) $(EXTRA_readfile_la_DEPENDENCIES) 
 	$(readfile_la_LINK) -rpath $(pkgextensiondir) $(readfile_la_OBJECTS) $(readfile_la_LIBADD) $(LIBS)
+revoutput.la: $(revoutput_la_OBJECTS) $(revoutput_la_DEPENDENCIES) $(EXTRA_revoutput_la_DEPENDENCIES) 
+	$(revoutput_la_LINK) -rpath $(pkgextensiondir) $(revoutput_la_OBJECTS) $(revoutput_la_LIBADD) $(LIBS)
+revtwoway.la: $(revtwoway_la_OBJECTS) $(revtwoway_la_DEPENDENCIES) $(EXTRA_revtwoway_la_DEPENDENCIES) 
+	$(revtwoway_la_LINK) -rpath $(pkgextensiondir) $(revtwoway_la_OBJECTS) $(revtwoway_la_LIBADD) $(LIBS)
 rwarray.la: $(rwarray_la_OBJECTS) $(rwarray_la_DEPENDENCIES) $(EXTRA_rwarray_la_DEPENDENCIES) 
 	$(rwarray_la_LINK) -rpath $(pkgextensiondir) $(rwarray_la_OBJECTS) $(rwarray_la_LIBADD) $(LIBS)
 testext.la: $(testext_la_OBJECTS) $(testext_la_DEPENDENCIES) $(EXTRA_testext_la_DEPENDENCIES) 
@@ -586,6 +613,8 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ordchr.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/readdir.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/readfile.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/revoutput.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/revtwoway.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rwarray.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/stack.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/testext.Plo@am__quote@
diff --git a/extension/aclocal.m4 b/extension/aclocal.m4
index db5d9f86..18cab755 100644
--- a/extension/aclocal.m4
+++ b/extension/aclocal.m4
@@ -1003,6 +1003,7 @@ AC_SUBST([am__untar])
 
 m4_include([m4/gettext.m4])
 m4_include([m4/iconv.m4])
+m4_include([m4/intlmacosx.m4])
 m4_include([m4/lib-ld.m4])
 m4_include([m4/lib-link.m4])
 m4_include([m4/lib-prefix.m4])
diff --git a/extension/configh.in b/extension/configh.in
index 73ce026c..571b7a7e 100644
--- a/extension/configh.in
+++ b/extension/configh.in
@@ -4,6 +4,14 @@
    language is requested. */
 #undef ENABLE_NLS
 
+/* Define to 1 if you have the MacOS X function CFLocaleCopyCurrent in the
+   CoreFoundation framework. */
+#undef HAVE_CFLOCALECOPYCURRENT
+
+/* Define to 1 if you have the MacOS X function CFPreferencesCopyAppValue in
+   the CoreFoundation framework. */
+#undef HAVE_CFPREFERENCESCOPYAPPVALUE
+
 /* Define if the GNU dcgettext() function is already present or preinstalled.
    */
 #undef HAVE_DCGETTEXT
@@ -32,6 +40,9 @@
 /* Define to 1 if you have the `fts_read' function. */
 #undef HAVE_FTS_READ
 
+/* Define to 1 if you have the `getdtablesize' function. */
+#undef HAVE_GETDTABLESIZE
+
 /* Define to 1 if you have the `GetSystemTimeAsFileTime' function. */
 #undef HAVE_GETSYSTEMTIMEASFILETIME
 
diff --git a/extension/configure b/extension/configure
index 732bfc93..7030c8b1 100755
--- a/extension/configure
+++ b/extension/configure
@@ -662,6 +662,7 @@ LIBINTL
 INTLLIBS
 LTLIBICONV
 LIBICONV
+INTL_MACOSX_LIBS
 EGREP
 GREP
 CPP
@@ -5090,7 +5091,81 @@ fi
 
 
 
-    gt_INTL_MACOSX
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for CFPreferencesCopyAppValue" >&5
+$as_echo_n "checking for CFPreferencesCopyAppValue... " >&6; }
+if ${gt_cv_func_CFPreferencesCopyAppValue+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gt_save_LIBS="$LIBS"
+     LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
+     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <CoreFoundation/CFPreferences.h>
+int
+main ()
+{
+CFPreferencesCopyAppValue(NULL, NULL)
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  gt_cv_func_CFPreferencesCopyAppValue=yes
+else
+  gt_cv_func_CFPreferencesCopyAppValue=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+     LIBS="$gt_save_LIBS"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gt_cv_func_CFPreferencesCopyAppValue" >&5
+$as_echo "$gt_cv_func_CFPreferencesCopyAppValue" >&6; }
+  if test $gt_cv_func_CFPreferencesCopyAppValue = yes; then
+
+$as_echo "#define HAVE_CFPREFERENCESCOPYAPPVALUE 1" >>confdefs.h
+
+  fi
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for CFLocaleCopyCurrent" >&5
+$as_echo_n "checking for CFLocaleCopyCurrent... " >&6; }
+if ${gt_cv_func_CFLocaleCopyCurrent+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gt_save_LIBS="$LIBS"
+     LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
+     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <CoreFoundation/CFLocale.h>
+int
+main ()
+{
+CFLocaleCopyCurrent();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  gt_cv_func_CFLocaleCopyCurrent=yes
+else
+  gt_cv_func_CFLocaleCopyCurrent=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+     LIBS="$gt_save_LIBS"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gt_cv_func_CFLocaleCopyCurrent" >&5
+$as_echo "$gt_cv_func_CFLocaleCopyCurrent" >&6; }
+  if test $gt_cv_func_CFLocaleCopyCurrent = yes; then
+
+$as_echo "#define HAVE_CFLOCALECOPYCURRENT 1" >>confdefs.h
+
+  fi
+  INTL_MACOSX_LIBS=
+  if test $gt_cv_func_CFPreferencesCopyAppValue = yes || test $gt_cv_func_CFLocaleCopyCurrent = yes; then
+    INTL_MACOSX_LIBS="-Wl,-framework -Wl,CoreFoundation"
+  fi
+
+
 
 
 
@@ -13453,7 +13528,7 @@ done
 
 
 for ac_func in fdopendir fnmatch fts_open fts_read gettimeofday \
-		nanosleep select GetSystemTimeAsFileTime
+		getdtablesize nanosleep select GetSystemTimeAsFileTime
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/extension/configure.ac b/extension/configure.ac
index 33009611..4869584b 100644
--- a/extension/configure.ac
+++ b/extension/configure.ac
@@ -51,7 +51,7 @@ fi
 AC_CHECK_HEADERS(dirent.h fnmatch.h fts.h time.h sys/time.h sys/select.h)
 
 AC_CHECK_FUNCS(fdopendir fnmatch fts_open fts_read gettimeofday \
-		nanosleep select GetSystemTimeAsFileTime)
+		getdtablesize nanosleep select GetSystemTimeAsFileTime)
 
 dnl checks for compiler characteristics
 AC_C_INLINE
diff --git a/extension/m4/ChangeLog b/extension/m4/ChangeLog
index 9ce57384..c1223391 100644
--- a/extension/m4/ChangeLog
+++ b/extension/m4/ChangeLog
@@ -1,3 +1,7 @@
+2012-08-24         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* intlmacosx.m4: New file.
+
 2012-07-30         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* gettext.m4, iconv.m4, lib-ld.m4, lib-link.m4, lib-prefix.m4,
diff --git a/extension/m4/intlmacosx.m4 b/extension/m4/intlmacosx.m4
new file mode 100644
index 00000000..dd910259
--- /dev/null
+++ b/extension/m4/intlmacosx.m4
@@ -0,0 +1,51 @@
+# intlmacosx.m4 serial 3 (gettext-0.18)
+dnl Copyright (C) 2004-2010 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl
+dnl This file can can be used in projects which are not available under
+dnl the GNU General Public License or the GNU Library General Public
+dnl License but which still want to provide support for the GNU gettext
+dnl functionality.
+dnl Please note that the actual code of the GNU gettext library is covered
+dnl by the GNU Library General Public License, and the rest of the GNU
+dnl gettext package package is covered by the GNU General Public License.
+dnl They are *not* in the public domain.
+
+dnl Checks for special options needed on MacOS X.
+dnl Defines INTL_MACOSX_LIBS.
+AC_DEFUN([gt_INTL_MACOSX],
+[
+  dnl Check for API introduced in MacOS X 10.2.
+  AC_CACHE_CHECK([for CFPreferencesCopyAppValue],
+    [gt_cv_func_CFPreferencesCopyAppValue],
+    [gt_save_LIBS="$LIBS"
+     LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
+     AC_TRY_LINK([#include <CoreFoundation/CFPreferences.h>],
+       [CFPreferencesCopyAppValue(NULL, NULL)],
+       [gt_cv_func_CFPreferencesCopyAppValue=yes],
+       [gt_cv_func_CFPreferencesCopyAppValue=no])
+     LIBS="$gt_save_LIBS"])
+  if test $gt_cv_func_CFPreferencesCopyAppValue = yes; then
+    AC_DEFINE([HAVE_CFPREFERENCESCOPYAPPVALUE], [1],
+      [Define to 1 if you have the MacOS X function CFPreferencesCopyAppValue in the CoreFoundation framework.])
+  fi
+  dnl Check for API introduced in MacOS X 10.3.
+  AC_CACHE_CHECK([for CFLocaleCopyCurrent], [gt_cv_func_CFLocaleCopyCurrent],
+    [gt_save_LIBS="$LIBS"
+     LIBS="$LIBS -Wl,-framework -Wl,CoreFoundation"
+     AC_TRY_LINK([#include <CoreFoundation/CFLocale.h>], [CFLocaleCopyCurrent();],
+       [gt_cv_func_CFLocaleCopyCurrent=yes],
+       [gt_cv_func_CFLocaleCopyCurrent=no])
+     LIBS="$gt_save_LIBS"])
+  if test $gt_cv_func_CFLocaleCopyCurrent = yes; then
+    AC_DEFINE([HAVE_CFLOCALECOPYCURRENT], [1],
+      [Define to 1 if you have the MacOS X function CFLocaleCopyCurrent in the CoreFoundation framework.])
+  fi
+  INTL_MACOSX_LIBS=
+  if test $gt_cv_func_CFPreferencesCopyAppValue = yes || test $gt_cv_func_CFLocaleCopyCurrent = yes; then
+    INTL_MACOSX_LIBS="-Wl,-framework -Wl,CoreFoundation"
+  fi
+  AC_SUBST([INTL_MACOSX_LIBS])
+])
diff --git a/extension/readdir.3am b/extension/readdir.3am
index 5f6ae06f..9cb4862e 100644
--- a/extension/readdir.3am
+++ b/extension/readdir.3am
@@ -1,4 +1,4 @@
-.TH READDIR 3am "Aug 08 2012" "Free Software Foundation" "GNU Awk Extension Modules"
+.TH READDIR 3am "Aug 23 2012" "Free Software Foundation" "GNU Awk Extension Modules"
 .SH NAME
 readdir \- directory input parser for gawk
 .SH SYNOPSIS
@@ -49,7 +49,20 @@ causes the extension to use
 to retrieve the appropriate information. This is not the default, since
 .IR stat (2)
 is a potentially expensive operation.
-... .SH NOTES
+.SH NOTES
+On GNU/Linux systems, there are filesystems that don't support the
+.B d_type
+entry (see
+.IR readdir (3)),
+and so the file type is always
+.BR u .
+Therefore, using
+.B readdir_do_ftype(1)
+is advisable even on GNU/Linux systems. In this case, the
+.I readdir
+extension will fall back to using
+.IR stat (2)
+when it encounters an unknown file type.
 ... .SH BUGS
 .SH EXAMPLE
 .ft CW
diff --git a/extension/readdir.c b/extension/readdir.c
index c28764e8..3eae4079 100644
--- a/extension/readdir.c
+++ b/extension/readdir.c
@@ -60,17 +60,15 @@ static awk_bool_t (*init_func)(void) = init_readdir;
 
 int plugin_is_GPL_compatible;
 
-#ifdef DT_BLK
-static const int do_ftype = 1;
-#else
 static int do_ftype;
-#endif
 
 /* ftype --- return type of file as a single character string */
 
 static const char *
 ftype(struct dirent *entry)
 {
+	struct stat sbuf;
+
 #ifdef DT_BLK
 	switch (entry->d_type) {
 	case DT_BLK:	return "b";
@@ -81,12 +79,17 @@ ftype(struct dirent *entry)
 	case DT_REG:	return "f";
 	case DT_SOCK:	return "s";
 	default:
-	case DT_UNKNOWN:	return "u";
+	case DT_UNKNOWN:
+			/*
+			 * Could be that filesystem doesn't support d_type,
+			 * even if the OS does. (E.g., XFS on GNU/Linux).
+			 * So let lstat() do it.
+			 */
+			break;
 	}
-#else
-	struct stat sbuf;
+#endif
 
-	if (lstat(entry->d_name, & sbuf) < 0)
+	if (! do_ftype || lstat(entry->d_name, & sbuf) < 0)
 		return "u";
 
 	switch (sbuf.st_mode & S_IFMT) {
@@ -108,9 +111,9 @@ ftype(struct dirent *entry)
 #endif /* S_IFDOOR */
 	}
 	return "u";
-#endif
 }
 
+/* data type for the opaque pointer: */
 
 typedef struct open_directory {
 	DIR *dp;
@@ -138,6 +141,7 @@ dir_get_record(char **out, struct iobuf_public *iobuf, int *errcode,
 
 	the_dir = (open_directory_t *) iobuf->opaque;
 	dp = the_dir->dp;
+
 	/*
 	 * Initialize errno, since readdir does not set it to zero on EOF.
 	 */
@@ -280,9 +284,7 @@ do_readdir_do_ftype(int nargs, awk_value_t *result)
 		goto out;
 	}
 
-#ifndef DT_BLK
 	do_ftype = (flag.num_value != 0.0);
-#endif
 
 out:
 	return result;
diff --git a/extension/revoutput.c b/extension/revoutput.c
new file mode 100644
index 00000000..c1ea1ddc
--- /dev/null
+++ b/extension/revoutput.c
@@ -0,0 +1,136 @@
+/*
+ * revoutput.c --- Provide an output wrapper that reverses lines.
+ *
+ * Arnold Robbins
+ * arnold@skeeve.com
+ * Written 8/2012
+ */
+
+/*
+ * Copyright (C) 2012 the Free Software Foundation, Inc.
+ * 
+ * This file is part of GAWK, the GNU implementation of the
+ * AWK Programming Language.
+ * 
+ * GAWK is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * GAWK is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "config.h"
+
+#include "gawkapi.h"
+
+#include "gettext.h"
+#define _(msgid)  gettext(msgid)
+#define N_(msgid) msgid
+
+static const gawk_api_t *api;	/* for convenience macros to work */
+static awk_ext_id_t *ext_id;
+
+static awk_bool_t init_revout(void);
+static awk_bool_t (*init_func)(void) = init_revout;
+
+int plugin_is_GPL_compatible;
+
+/* rev_fwrite --- write out characters in reverse order */
+
+static size_t
+rev_fwrite(const void *buf, size_t size, size_t count, FILE *fp, void *opaque)
+{
+	const char *cp = buf;
+	int nbytes = size * count;
+
+	(void) opaque;
+
+	for (; nbytes >= 1; nbytes--)
+		putc(cp[nbytes-1], fp);
+
+	return (size * count);
+}
+
+
+/* revout_can_take_file --- return true if we want the file */
+
+static int
+revout_can_take_file(const awk_output_buf_t *outbuf)
+{
+	awk_value_t value;
+
+	if (outbuf == NULL)
+		return 0;
+
+	if (! sym_lookup("REVOUT", AWK_NUMBER, & value))
+		return 0;
+
+	return (value.num_value != 0);
+}
+
+/*
+ * revout_take_control_of --- set up output wrapper.
+ * We can assume that revout_can_take_file just returned true,
+ * and no state has changed since then.
+ */
+
+static int
+revout_take_control_of(awk_output_buf_t *outbuf)
+{
+	if (outbuf == NULL)
+		return 0;
+
+	outbuf->gawk_fwrite = rev_fwrite;
+	outbuf->redirected = 1;
+	return 1;
+}
+
+static awk_output_wrapper_t output_wrapper = {
+	"revout",
+	revout_can_take_file,
+	revout_take_control_of,
+	NULL
+};
+
+/* init_revout --- set things ups */
+
+static awk_bool_t
+init_revout()
+{
+	awk_value_t value;
+
+	register_output_wrapper(& output_wrapper);
+
+	make_number(0.0, & value);	/* init to false */
+	if (! sym_update("REVOUT", & value)) {
+		warning(ext_id, _("revout: could not initialize REVOUT variable"));
+
+		return 0;
+	}
+
+	return 1;
+}
+
+static awk_ext_func_t func_table[] = {
+	{ NULL, NULL, 0 }
+};
+
+/* define the dl_load function using the boilerplate macro */
+
+dl_load_func(func_table, revout, "")
diff --git a/extension/revtwoway.c b/extension/revtwoway.c
new file mode 100644
index 00000000..7ab9366e
--- /dev/null
+++ b/extension/revtwoway.c
@@ -0,0 +1,335 @@
+/*
+ * revtwoway.c --- Provide a two-way processor that reverses lines.
+ *
+ * Arnold Robbins
+ * arnold@skeeve.com
+ * Written 8/2012
+ */
+
+/*
+ * Copyright (C) 2012 the Free Software Foundation, Inc.
+ * 
+ * This file is part of GAWK, the GNU implementation of the
+ * AWK Programming Language.
+ * 
+ * GAWK is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * GAWK is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "config.h"
+
+#include "gawkapi.h"
+
+#include "gettext.h"
+#define _(msgid)  gettext(msgid)
+#define N_(msgid) msgid
+
+static const gawk_api_t *api;	/* for convenience macros to work */
+static awk_ext_id_t *ext_id;
+
+static awk_bool_t init_revtwoway(void);
+static awk_bool_t (*init_func)(void) = init_revtwoway;
+
+int plugin_is_GPL_compatible;
+
+/*
+ * Use this variable to provide a value != INVALID_HANDLE in the IOBUF_PUBLIC
+ * and != NULL in the awk_output_buf_t.  The idea is to have a value that
+ * is greater than the largest allowable file descriptor.
+ */
+static size_t max_fds;
+
+#ifndef HAVE_GETDTABLESIZE
+/* getdtablesize --- replacement version that should be good enough */
+
+static inline int
+getdtablesize()
+{
+	/*
+	 * Algorithm for the GNULIB folks:
+	 *
+	 * Set up a bitmap of 2048 elements.
+	 * Initialize it to zero.
+	 * In a loop, do
+	 * 	fd = open("/dev/null", O_RDONLY)
+	 * 	set the bit corresponding to fd in the bit map
+	 * until it fails.
+	 * Get the highest value that succeeded and increment it by one
+	 * --> that is how many descriptors we have.
+	 * Loop over the bitmap to close all the file descriptors we opened.
+	 *
+	 * Do all this upon the first call and return static values upon
+	 * subsequent calls.
+	 */
+
+	/* In the meantime, this is good enough for us: */
+	return 1024;
+}
+#endif
+
+/*
+ * IMPORTANT NOTE: This is a NOT a true general purpose
+ * extension.  It is intended to demonstrate how to set up
+ * all the "plumbing" and to work one record at a time, ONLY.
+ *
+ * While it would be possible to set up buffering and manage it,
+ * that would duplicate a large chunk of the code in gawk's
+ * get_a_record() function, and there's no real point in doing that.
+ */
+
+/* the data in the opaque pointer */
+typedef struct two_way_proc_data {
+	size_t size;	/* size of allocated buffer */
+	size_t len;	/* how much is actually in use */
+	char *data;
+	size_t in_use;	/* use count, must hit zero to be freed */
+} two_way_proc_data_t;
+
+/* close_two_proc_data --- release the data */
+
+static void
+close_two_proc_data(two_way_proc_data_t *proc_data)
+{
+	if (proc_data->in_use > 1) {
+		proc_data->in_use--;
+		return;
+	}
+
+	free(proc_data->data);
+	free(proc_data);
+}
+
+/*
+ * Input side of the two-way processor (input TO gawk)
+ */
+
+/* rev2way_get_record --- get one record at a time out of a directory */
+
+static int
+rev2way_get_record(char **out, struct iobuf_public *iobuf, int *errcode,
+		char **rt_start, size_t *rt_len)
+{
+	int len = 0;	/* for now */
+	two_way_proc_data_t *proc_data;
+
+	/*
+	 * The caller sets *errcode to 0, so we should set it only if an
+	 * error occurs.
+	 */
+
+	if (out == NULL || iobuf == NULL || iobuf->opaque == NULL)
+		return EOF;
+
+	proc_data = (two_way_proc_data_t *) iobuf->opaque;
+	if (proc_data->len == 0)
+		return 0;
+
+	*out = proc_data->data;
+
+	len = proc_data->len;
+	proc_data->len = 0;
+
+	*rt_len = 0;	/* default: set RT to "" */
+	if (proc_data->data[len-1] == '\n') {
+		while (proc_data->data[len-1] == '\n') {
+			len--;
+			(*rt_len)++;
+		}
+		*rt_start = proc_data->data + len;
+	}
+
+	return len;
+}
+
+/* rev2way_close --- close up input side when done */
+
+static void
+rev2way_close(struct iobuf_public *iobuf)
+{
+	two_way_proc_data_t *proc_data;
+
+	if (iobuf == NULL || iobuf->opaque == NULL)
+		return;
+
+	proc_data = (two_way_proc_data_t *) iobuf->opaque;
+	close_two_proc_data(proc_data);
+
+	iobuf->fd = INVALID_HANDLE;
+}
+
+
+/*
+ * Output side of the two-way processor (output FROM gawk)
+ */
+
+/* rev2way_fwrite --- write out characters in reverse order */
+
+static size_t
+rev2way_fwrite(const void *buf, size_t size, size_t count, FILE *fp, void *opaque)
+{
+	two_way_proc_data_t *proc_data;
+	size_t amount, char_count;
+	char *src, *dest;
+
+	if (opaque == NULL)
+		return 0;	/* error */
+
+	proc_data = (two_way_proc_data_t *) opaque;
+	amount = size * count;
+
+	/* do the dance */
+	if (amount > proc_data->size || proc_data->len > 0) {
+		if (proc_data->data == NULL)
+			emalloc(proc_data->data, char *,  amount, "rev2way_fwrite");
+		else
+			erealloc(proc_data->data, char *, proc_data->size + amount, "rev2way_fwrite");
+		proc_data->size += amount;
+	}
+
+	src = (char *) buf + amount -1;
+	dest = proc_data->data + proc_data->len;
+	for (char_count = amount; char_count > 0; char_count--) {
+		/* copy in backwards */
+		*dest++ = *src--;
+	}
+	proc_data->len += amount;
+
+	return amount;
+}
+
+/* rev2way_fflush --- do nothing hook for fflush */
+
+static int
+rev2way_fflush(FILE *fp, void *opaque)
+{
+	(void) fp;
+	(void) opaque;
+
+	return 0;
+}
+
+/* rev2way_ferror --- do nothing hook for ferror */
+
+static int
+rev2way_ferror(FILE *fp, void *opaque)
+{
+	(void) fp;
+	(void) opaque;
+
+	return 0;
+}
+
+/* rev2way_fclose --- close output side of two-way processor */
+
+static int
+rev2way_fclose(FILE *fp, void *opaque)
+{
+	two_way_proc_data_t *proc_data;
+
+	if (opaque == NULL)
+		return EOF;	/* error */
+
+	(void) fp;
+
+	proc_data = (two_way_proc_data_t *) opaque;
+	close_two_proc_data(proc_data);
+
+	return 0;
+}
+
+
+/* revtwoway_can_two_way --- return true if we want the file */
+
+static int
+revtwoway_can_take_two_way(const char *name)
+{
+	return (name != NULL && strcmp(name, "/magic/mirror") == 0);
+}
+
+/*
+ * revtwoway_take_control_of --- set up two way processor
+ * We can assume that revtwoway_can_take_two_way just returned true,
+ * and no state has changed since then.
+ */
+
+static int
+revtwoway_take_control_of(const char *name, IOBUF_PUBLIC *inbuf, awk_output_buf_t *outbuf)
+{
+	two_way_proc_data_t *proc_data;
+
+	if (inbuf == NULL || outbuf == NULL)
+		return 0;
+
+	emalloc(proc_data, two_way_proc_data_t *, sizeof(two_way_proc_data_t), "revtwoway_take_control_of");
+	proc_data->in_use = 2;
+	proc_data->size = 0;
+	proc_data->len = 0;
+	proc_data->data = NULL;
+
+	if (max_fds + 1 == 0)	/* wrapped. ha! */
+		max_fds = getdtablesize();
+
+	/* input side: */
+	inbuf->get_record = rev2way_get_record;
+	inbuf->close_func = rev2way_close;
+	inbuf->fd = max_fds;
+	inbuf->opaque = proc_data;
+
+	/* output side: */
+	outbuf->fp = (FILE *) max_fds++;
+	outbuf->opaque = proc_data;
+	outbuf->gawk_fwrite = rev2way_fwrite;
+	outbuf->gawk_fflush = rev2way_fflush;
+	outbuf->gawk_ferror = rev2way_ferror;
+	outbuf->gawk_fclose = rev2way_fclose;
+	outbuf->redirected = 1;
+	return 1;
+}
+
+static awk_two_way_processor_t two_way_processor = {
+	"revtwoway",
+	revtwoway_can_take_two_way,
+	revtwoway_take_control_of,
+	NULL
+};
+
+/* init_revtwoway --- set things ups */
+
+static awk_bool_t
+init_revtwoway()
+{
+	register_two_way_processor(& two_way_processor);
+
+	max_fds = getdtablesize();
+
+	return 1;
+}
+
+static awk_ext_func_t func_table[] = {
+	{ NULL, NULL, 0 }
+};
+
+/* define the dl_load function using the boilerplate macro */
+
+dl_load_func(func_table, revtwoway, "")
diff --git a/gawkapi.c b/gawkapi.c
index c34b52bb..8fd20472 100644
--- a/gawkapi.c
+++ b/gawkapi.c
@@ -228,6 +228,33 @@ api_register_input_parser(awk_ext_id_t id, awk_input_parser_t *input_parser)
 	register_input_parser(input_parser);
 }
 
+/* api_register_output_wrapper --- egister an output wrapper, for writing files / two-way pipes */
+
+static void api_register_output_wrapper(awk_ext_id_t id,
+		awk_output_wrapper_t *output_wrapper)
+{
+	(void) id;
+
+	if (output_wrapper == NULL)
+		return;
+
+	register_output_wrapper(output_wrapper);
+}
+
+/* api_register_two_way_processor --- register a processor for two way I/O */
+
+static void
+api_register_two_way_processor(awk_ext_id_t id,
+		awk_two_way_processor_t *two_way_processor)
+{
+	(void) id;
+
+	if (two_way_processor == NULL)
+		return;
+
+	register_two_way_processor(two_way_processor);
+}
+
 /* Functions to update ERRNO */
 
 /* api_update_ERRNO_int --- update ERRNO with an integer value */
@@ -526,20 +553,25 @@ sym_update_real(awk_ext_id_t id,
 			if (is_const)
 				node->var_assign = set_constant;
 		}
+
 		return true;
 	}
 
-	/* If we get here, then it exists already.  Any valid type is
-	 * OK except for AWK_ARRAY. */
-	if ((value->val_type != AWK_ARRAY) &&
-		(node->type == Node_var || node->type == Node_var_new)) {
+	/*
+	 * If we get here, then it exists already.  Any valid type is
+	 * OK except for AWK_ARRAY.
+	 */
+	if (    value->val_type != AWK_ARRAY
+	    && (node->type == Node_var || node->type == Node_var_new)) {
 		unref(node->var_value);
 		node->var_value = awk_value_to_node(value);
 		/* let the extension change its own variable */
 		if (is_const)
 			node->var_assign = set_constant;
+
 		return true;
 	}
+
 	return false;
 }
 
@@ -961,6 +993,8 @@ gawk_api_t api_impl = {
 	api_lintwarn,
 
 	api_register_input_parser,
+	api_register_output_wrapper,
+	api_register_two_way_processor,
 
 	api_update_ERRNO_int,
 	api_update_ERRNO_string,
diff --git a/gawkapi.h b/gawkapi.h
index 9b89e425..3c369a8f 100644
--- a/gawkapi.h
+++ b/gawkapi.h
@@ -150,9 +150,68 @@ typedef struct input_parser {
 	 * It should return non-zero if successful.
 	 */
 	int (*take_control_of)(IOBUF_PUBLIC *iobuf);
-	struct input_parser *awk_const next;	/* for use by gawk */
+	awk_const struct input_parser *awk_const next;	/* for use by gawk */
 } awk_input_parser_t;
 
+/*
+ * Similar for output wrapper.
+ */
+
+typedef struct {
+	const char *name;
+	const char *mode;	/* mode argument to fopen */
+	FILE *fp;
+	int redirected;		/* true if a wrapper is active */
+	void *opaque;		/* for use by output wrapper */
+
+	/*
+	 * Replacement functions for I/O.  Just like the regular
+	 * versions but also take the opaque pointer argument.
+	 */
+	size_t (*gawk_fwrite)(const void *buf, size_t size, size_t count, FILE *fp, void *opaque);
+	int (*gawk_fflush)(FILE *fp, void *opaque);
+	int (*gawk_ferror)(FILE *fp, void *opaque);
+	int (*gawk_fclose)(FILE *fp, void *opaque);
+} awk_output_buf_t;
+
+typedef struct output_wrapper {
+	const char *name;
+	/*
+	 * The can_take_file function should return non-zero if the wrapper
+	 * would like to process this file.  It should not change any gawk
+	 * state!
+	 */
+	int (*can_take_file)(const awk_output_buf_t *outbuf);
+	/*
+	 * If this wrapper is selected, then take_control_of will be called.
+	 * It can assume that a previous call to can_take_file was successful,
+	 * and no gawk state has changed since that call.  It should populate
+	 * the awk_output_buf_t function pointers and opaque pointer as needed.
+	 * It should return non-zero if successful.
+	 */
+	int (*take_control_of)(awk_output_buf_t *outbuf);
+	awk_const struct output_wrapper *awk_const next;  /* for use by gawk */
+} awk_output_wrapper_t;
+
+typedef struct two_way_processor {
+	const char *name;
+	/*
+	 * The can_take_file function should return non-zero if the two-way processor
+	 * would like to parse this file.  It should not change any gawk
+	 * state!
+	 */
+	int (*can_take_two_way)(const char *name);
+	/*
+	 * If this processor is selected, then take_control_of will be called.
+	 * It can assume that a previous call to can_take_file was successful,
+	 * and no gawk state has changed since that call.  It should populate
+	 * the IOBUF_PUBLIC and awk_otuput_buf_t structures as needed.
+	 * It should return non-zero if successful.
+	 */
+	int (*take_control_of)(const char *name, IOBUF_PUBLIC *inbuf, awk_output_buf_t *outbuf);
+	awk_const struct two_way_processor *awk_const next;  /* for use by gawk */
+} awk_two_way_processor_t;
+
 
 enum {
 	GAWK_API_MAJOR_VERSION = 0,
@@ -355,6 +414,12 @@ typedef struct gawk_api {
 	/* Register an input parser; for opening files read-only */
 	void (*api_register_input_parser)(awk_ext_id_t id, awk_input_parser_t *input_parser);
 
+	/* Register an output wrapper, for writing files / two-way pipes */
+	void (*api_register_output_wrapper)(awk_ext_id_t id, awk_output_wrapper_t *output_wrapper);
+
+	/* Register a processor for two way I/O */
+	void (*api_register_two_way_processor)(awk_ext_id_t id, awk_two_way_processor_t *two_way_processor);
+
 	/* Functions to update ERRNO */
 	void (*api_update_ERRNO_int)(awk_ext_id_t id, int errno_val);
 	void (*api_update_ERRNO_string)(awk_ext_id_t id, const char *string);
@@ -535,6 +600,9 @@ typedef struct gawk_api {
 #define lintwarn	api->api_lintwarn
 
 #define register_input_parser(parser)	(api->api_register_input_parser(ext_id, parser))
+#define register_output_wrapper(wrapper) (api->api_register_output_wrapper(ext_id, wrapper))
+#define register_two_way_processor(processor) \
+	(api->api_register_two_way_processor(ext_id, processor))
 
 #define update_ERRNO_int(e)	(api->api_update_ERRNO_int(ext_id, e))
 #define update_ERRNO_string(str) \
@@ -717,6 +785,8 @@ int dl_load(const gawk_api_t *const api_p, awk_ext_id_t id)  \
 \
 	/* load functions */ \
 	for (i = 0, j = sizeof(func_table) / sizeof(func_table[0]); i < j; i++) { \
+		if (func_table[i].name == NULL) \
+			break; \
 		if (! add_ext_func(& func_table[i], name_space)) { \
 			warning(ext_id, #module ": could not add %s\n", \
 					func_table[i].name); \
diff --git a/io.c b/io.c
index 589abbf4..d4f7535f 100644
--- a/io.c
+++ b/io.c
@@ -210,6 +210,9 @@ static int str2mode(const char *mode);
 static int two_way_open(const char *str, struct redirect *rp);
 static int pty_vs_pipe(const char *command);
 static void find_input_parser(IOBUF *iop);
+static bool find_output_wrapper(awk_output_buf_t *outbuf);
+static void init_output_wrapper(awk_output_buf_t *outbuf);
+static bool find_two_way_processor(const char *name, struct redirect *rp);
 
 static RECVALUE rs1scan(IOBUF *iop, struct recmatch *recm, SCANSTATE *state);
 static RECVALUE rsnullscan(IOBUF *iop, struct recmatch *recm, SCANSTATE *state);
@@ -688,7 +691,7 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 	if (do_lint && (redir_exp->flags & STRCUR) == 0)
 		lintwarn(_("expression in `%s' redirection only has numeric value"),
 			what);
-	redir_exp= force_string(redir_exp);
+	redir_exp = force_string(redir_exp);
 	str = redir_exp->stptr;
 
 	if (str == NULL || *str == '\0')
@@ -759,7 +762,7 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 		str[redir_exp->stlen] = '\0';
 		rp->value = str;
 		rp->flag = tflag;
-		rp->fp = NULL;
+		init_output_wrapper(& rp->output);
 		rp->iop = NULL;
 		rp->pid = -1;
 		rp->status = 0;
@@ -767,7 +770,7 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 		str = rp->value;	/* get \0 terminated string */
 	save_rp = rp;
 
-	while (rp->fp == NULL && rp->iop == NULL) {
+	while (rp->output.fp == NULL && rp->iop == NULL) {
 		if (! new_rp && rp->flag & RED_EOF) {
 			/*
 			 * Encountered EOF on file or pipe -- must be cleared
@@ -792,12 +795,12 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 			(void) flush_io();
 
 			os_restore_mode(fileno(stdin));
-			if ((rp->fp = popen(str, binmode("w"))) == NULL)
+			if ((rp->output.fp = popen(str, binmode("w"))) == NULL)
 				fatal(_("can't open pipe `%s' for output (%s)"),
 						str, strerror(errno));
 
 			/* set close-on-exec */
-			os_close_on_exec(fileno(rp->fp), str, "pipe", "to");
+			os_close_on_exec(fileno(rp->output.fp), str, "pipe", "to");
 			rp->flag |= RED_NOBUF;
 			break;
 		case redirect_pipein:
@@ -844,15 +847,16 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 
 		if (mode != NULL) {
 			errno = 0;
+			rp->output.mode = mode;
 			fd = devopen(str, mode);
 
 			if (fd > INVALID_HANDLE) {
 				if (fd == fileno(stdin))
-					rp->fp = stdin;
+					rp->output.fp = stdin;
 				else if (fd == fileno(stdout))
-					rp->fp = stdout;
+					rp->output.fp = stdout;
 				else if (fd == fileno(stderr))
-					rp->fp = stderr;
+					rp->output.fp = stderr;
 				else {
 					const char *omode = mode;
 #if defined(F_GETFL) && defined(O_APPEND)
@@ -863,13 +867,13 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 						omode = binmode("a");
 #endif
 					os_close_on_exec(fd, str, "file", "");
-					rp->fp = fdopen(fd, (const char *) omode);
+					rp->output.fp = fdopen(fd, (const char *) omode);
 					rp->mode = (const char *) mode;
 					/* don't leak file descriptors */
-					if (rp->fp == NULL)
+					if (rp->output.fp == NULL)
 						close(fd);
 				}
-				if (rp->fp != NULL && os_isatty(fd))
+				if (rp->output.fp != NULL && os_isatty(fd))
 					rp->flag |= RED_NOBUF;
 
 				/* Move rp to the head of the list. */
@@ -882,9 +886,10 @@ redirect(NODE *redir_exp, int redirtype, int *errflg)
 					red_head = rp;
 				}
 			}
+			find_output_wrapper(& rp->output);
 		}
 
-		if (rp->fp == NULL && rp->iop == NULL) {
+		if (rp->output.fp == NULL && rp->iop == NULL) {
 			/* too many files open -- close one and try again */
 			if (errno == EMFILE || errno == ENFILE)
 				close_one();
@@ -978,16 +983,16 @@ close_one()
 	/* now work back up through the list */
 	for (rp = rplast; rp != NULL; rp = rp->prev) {
 		/* don't close standard files! */
-		if (rp->fp == NULL || rp->fp == stderr || rp->fp == stdout)
+		if (rp->output.fp == NULL || rp->output.fp == stderr || rp->output.fp == stdout)
 			continue;
 
 		if ((rp->flag & (RED_FILE|RED_WRITE)) == (RED_FILE|RED_WRITE)) {
 			rp->flag |= RED_USED;
 			errno = 0;
-			if (fclose(rp->fp) != 0)
+			if (rp->output.gawk_fclose(rp->output.fp, rp->output.opaque) != 0)
 				warning(_("close of `%s' failed (%s)."),
 					rp->value, strerror(errno));
-			rp->fp = NULL;
+			rp->output.fp = NULL;
 			break;
 		}
 	}
@@ -1071,18 +1076,18 @@ close_rp(struct redirect *rp, two_way_close_type how)
 	errno = 0;
 	if ((rp->flag & RED_TWOWAY) != 0) {	/* two-way pipe */
 		/* write end: */
-		if ((how == CLOSE_ALL || how == CLOSE_TO) && rp->fp != NULL) {
+		if ((how == CLOSE_ALL || how == CLOSE_TO) && rp->output.fp != NULL) {
 #ifdef HAVE_SOCKETS
 			if ((rp->flag & RED_TCP) != 0)
-				(void) shutdown(fileno(rp->fp), SHUT_WR);
+				(void) shutdown(fileno(rp->output.fp), SHUT_WR);
 #endif /* HAVE_SOCKETS */
 
 			if ((rp->flag & RED_PTY) != 0) {
-				fwrite("\004\n", sizeof("\004\n") - 1, 1, rp->fp);
-				fflush(rp->fp);
+				rp->output.gawk_fwrite("\004\n", sizeof("\004\n") - 1, 1, rp->output.fp, rp->output.opaque);
+				rp->output.gawk_fflush(rp->output.fp, rp->output.opaque);
 			}
-			status = fclose(rp->fp);
-			rp->fp = NULL;
+			status = rp->output.gawk_fclose(rp->output.fp, rp->output.opaque);
+			rp->output.fp = NULL;
 		}
 
 		/* read end: */
@@ -1100,14 +1105,14 @@ close_rp(struct redirect *rp, two_way_close_type how)
 		}
 	} else if ((rp->flag & (RED_PIPE|RED_WRITE)) == (RED_PIPE|RED_WRITE)) {
 		/* write to pipe */
-		status = pclose(rp->fp);
+		status = pclose(rp->output.fp);
 		if ((BINMODE & 1) != 0)
 			os_setbinmode(fileno(stdin), O_BINARY);
 
-		rp->fp = NULL;
-	} else if (rp->fp != NULL) {	/* write to file */
-		status = fclose(rp->fp);
-		rp->fp = NULL;
+		rp->output.fp = NULL;
+	} else if (rp->output.fp != NULL) {	/* write to file */
+		status = rp->output.gawk_fclose(rp->output.fp, rp->output.opaque);
+		rp->output.fp = NULL;
 	} else if (rp->iop != NULL) {	/* read from pipe/file */
 		if ((rp->flag & RED_PIPE) != 0)		/* read from pipe */
 			status = gawk_pclose(rp);
@@ -1130,7 +1135,7 @@ close_redir(struct redirect *rp, bool exitwarn, two_way_close_type how)
 
 	if (rp == NULL)
 		return 0;
-	if (rp->fp == stdout || rp->fp == stderr)
+	if (rp->output.fp == stdout || rp->output.fp == stderr)
 		goto checkwarn;		/* bypass closing, remove from list */
 
 	if (do_lint && (rp->flag & RED_TWOWAY) == 0 && how != CLOSE_ALL)
@@ -1188,7 +1193,7 @@ checkwarn:
 	}
 
 	/* remove it from the list if closing both or both ends have been closed */
-	if (how == CLOSE_ALL || (rp->iop == NULL && rp->fp == NULL)) {
+	if (how == CLOSE_ALL || (rp->iop == NULL && rp->output.fp == NULL)) {
 		if (rp->next != NULL)
 			rp->next->prev = rp->prev;
 		if (rp->prev != NULL)
@@ -1220,8 +1225,8 @@ flush_io()
 	}
 	for (rp = red_head; rp != NULL; rp = rp->next)
 		/* flush both files and pipes, what the heck */
-		if ((rp->flag & RED_WRITE) && rp->fp != NULL) {
-			if (fflush(rp->fp)) {
+		if ((rp->flag & RED_WRITE) && rp->output.fp != NULL) {
+			if (rp->output.gawk_fflush(rp->output.fp, rp->output.opaque)) {
 				if (rp->flag  & RED_PIPE)
 					warning(_("pipe flush of `%s' failed (%s)."),
 						rp->value, strerror(errno));
@@ -1647,14 +1652,14 @@ two_way_open(const char *str, struct redirect *rp)
 		fd = devopen(str, "rw");
 		if (fd == INVALID_HANDLE)
 			return false;
-		rp->fp = fdopen(fd, "w");
-		if (rp->fp == NULL) {
+		rp->output.fp = fdopen(fd, "w");
+		if (rp->output.fp == NULL) {
 			close(fd);
 			return false;
 		}
 		newfd = dup(fd);
 		if (newfd < 0) {
-			fclose(rp->fp);
+			rp->output.gawk_fclose(rp->output.fp, rp->output.opaque);
 			return false;
 		}
 		os_close_on_exec(fd, str, "socket", "to/from");
@@ -1667,7 +1672,7 @@ two_way_open(const char *str, struct redirect *rp)
 				update_ERRNO_int(rp->iop->errcode);
 			iop_close(rp->iop);
 			rp->iop = NULL;
-			fclose(rp->fp);
+			rp->output.gawk_fclose(rp->output.fp, rp->output.opaque);
 			return false;
 		}
 		rp->flag |= RED_SOCKET;
@@ -1675,8 +1680,12 @@ two_way_open(const char *str, struct redirect *rp)
 	}
 #endif /* HAVE_SOCKETS */
 
+	/* case 2: see if an extension wants it */
+	if (find_two_way_processor(str, rp))
+		return true;
+
 #if defined(HAVE_TERMIOS_H) && ! defined(ZOS_USS)
-	/* case 2: use ptys for two-way communications to child */
+	/* case 3: use ptys for two-way communications to child */
 	if (! no_ptys && pty_vs_pipe(str)) {
 		static bool initialized = false;
 		static char first_pty_letter;
@@ -1876,8 +1885,9 @@ two_way_open(const char *str, struct redirect *rp)
 		 * Force read and write ends of two-way connection to
 		 * be different fd's so they can be closed independently.
 		 */
+		rp->output.mode = "w";
 		if ((dup_master = dup(master)) < 0
-		    || (rp->fp = fdopen(dup_master, "w")) == NULL) {
+		    || (rp->output.fp = fdopen(dup_master, "w")) == NULL) {
 			iop_close(rp->iop);
 			rp->iop = NULL;
 			(void) close(master);
@@ -1885,7 +1895,8 @@ two_way_open(const char *str, struct redirect *rp)
 			if (dup_master > 0)
 				(void) close(dup_master);
 			return false;
-		}
+		} else
+			find_output_wrapper(& rp->output);
 		rp->flag |= RED_PTY;
 		os_close_on_exec(master, str, "pipe", "from");
 		os_close_on_exec(dup_master, str, "pipe", "to");
@@ -1896,7 +1907,7 @@ two_way_open(const char *str, struct redirect *rp)
 
 use_pipes:
 #ifndef PIPES_SIMULATED		/* real pipes */
-	/* case 3: two way pipe to a child process */
+	/* case 4: two way pipe to a child process */
     {
 	int ptoc[2], ctop[2];
 	int pid;
@@ -2033,8 +2044,9 @@ use_pipes:
 
 		return false;
 	}
-	rp->fp = fdopen(ptoc[1], "w");
-	if (rp->fp == NULL) {
+	rp->output.fp = fdopen(ptoc[1], "w");
+	rp->output.mode = "w";
+	if (rp->output.fp == NULL) {
 		iop_close(rp->iop);
 		rp->iop = NULL;
 		(void) close(ctop[0]);
@@ -2045,6 +2057,8 @@ use_pipes:
 
 		return false;
 	}
+	else
+		find_output_wrapper(& rp->output);
 
 #ifndef __EMX__
 	os_close_on_exec(ctop[0], str, "pipe", "from");
@@ -2677,6 +2691,124 @@ find_input_parser(IOBUF *iop)
 	}
 }
 
+/* output wrappers --- for use by extensions */
+
+static awk_output_wrapper_t *op_head, *op_tail;
+
+/*
+ * register_output_wrapper --- add an output wrapper to the list.
+ * 	Same stuff here as for input parsers.
+ */
+
+void
+register_output_wrapper(awk_output_wrapper_t *wrapper)
+{
+	if (wrapper == NULL)
+		fatal(_("register_output_wrapper: received NULL pointer"));
+
+	wrapper->next = NULL;	/* force it */
+	if (op_head == NULL) {
+		op_head = op_tail = wrapper;
+	} else {
+		op_tail->next = wrapper;
+		op_tail = op_tail->next;
+	}
+}
+
+/* find_output_wrapper --- search the list of output wrappers */
+
+static bool
+find_output_wrapper(awk_output_buf_t *outbuf)
+{
+	awk_output_wrapper_t *op, *op2;
+
+	/* if already associated with an output wrapper, bail out early */
+	if (outbuf->redirected)
+		return false;
+
+	op = op2 = NULL;
+	for (op2 = op_head; op2 != NULL; op2 = op2->next) {
+		if (op2->can_take_file(outbuf)) {
+			if (op == NULL)
+				op = op2;	/* found first one */
+			else
+				fatal(_("output wrapper `%s' conflicts with previously installed output wrapper `%s'"),
+						op2->name, op->name);
+		}
+	}
+
+	if (op != NULL) {
+		if (! op->take_control_of(outbuf)) {
+			warning(_("output wrapper `%s' failed to open `%s'"),
+					op->name, outbuf->name);
+			return false;
+		}
+		return true;
+	}
+
+	return false;
+}
+
+
+/* two way processors --- for use by extensions */
+
+static awk_two_way_processor_t *tw_head, *tw_tail;
+
+/* register_two_way_processor --- register a two-way I/O processor, for extensions */
+
+void
+register_two_way_processor(awk_two_way_processor_t *processor)
+{
+	if (processor == NULL)
+		fatal(_("register_output_processor: received NULL pointer"));
+
+	processor->next = NULL;	/* force it */
+	if (tw_head == NULL) {
+		tw_head = tw_tail = processor;
+	} else {
+		tw_tail->next = processor;
+		tw_tail = tw_tail->next;
+	}
+}
+
+/* find_two_way_processor --- search the list of two way processors */
+
+static bool
+find_two_way_processor(const char *name, struct redirect *rp)
+{
+	awk_two_way_processor_t *tw, *tw2;
+
+	/* if already associated with i/o, bail out early */
+	if (   (rp->iop != NULL && rp->iop->public.fd != INVALID_HANDLE)
+	    || rp->output.fp != NULL)
+		return false;
+
+	tw = tw2 = NULL;
+	for (tw2 = tw_head; tw2 != NULL; tw2 = tw2->next) {
+		if (tw2->can_take_two_way(name)) {
+			if (tw == NULL)
+				tw = tw2;	/* found first one */
+			else
+				fatal(_("two-way processor `%s' conflicts with previously installed two-way processor `%s'"),
+						tw2->name, tw->name);
+		}
+	}
+
+	if (tw != NULL) {
+		if (rp->iop == NULL)
+			rp->iop = iop_alloc(INVALID_HANDLE, name, 0);
+		if (! tw->take_control_of(name, & rp->iop->public, & rp->output)) {
+			warning(_("two way processor `%s' failed to open `%s'"),
+					tw->name, name);
+			return false;
+		}
+		iop_finish(rp->iop);
+		return true;
+	}
+
+	return false;
+}
+
 /*
  * IOBUF management is somewhat complicated.  In particular,
  * it is possible and OK for an IOBUF to be allocated with
@@ -3601,4 +3733,57 @@ read_with_timeout(int fd, char *buf, size_t size)
 #endif	/* __MINGW32__ */
 }
 
+/*
+ * Dummy pass through functions for default output.
+ */
+
+/* gawk_fwrite --- like fwrite */
+
+static size_t
+gawk_fwrite(const void *buf, size_t size, size_t count, FILE *fp, void *opaque)
+{
+	(void) opaque;
 
+	return fwrite(buf, size, count, fp);
+}
+
+static int
+gawk_fflush(FILE *fp, void *opaque)
+{
+	(void) opaque;
+
+	return fflush(fp);
+}
+
+static int
+gawk_ferror(FILE *fp, void *opaque)
+{
+	(void) opaque;
+
+	return ferror(fp);
+}
+
+static int
+gawk_fclose(FILE *fp, void *opaque)
+{
+	(void) opaque;
+
+	return fclose(fp);
+}
+
+
+/* init_output_wrapper --- initialize the output wrapper */
+
+static void
+init_output_wrapper(awk_output_buf_t *outbuf)
+{
+	outbuf->name = NULL;
+	outbuf->mode = NULL;
+	outbuf->fp = NULL;
+	outbuf->opaque = NULL;
+	outbuf->redirected = false;
+	outbuf->gawk_fwrite = gawk_fwrite;
+	outbuf->gawk_fflush = gawk_fflush;
+	outbuf->gawk_ferror = gawk_ferror;
+	outbuf->gawk_fclose = gawk_fclose;
+}
diff --git a/test/ChangeLog b/test/ChangeLog
index a0e3c0c4..5414bfce 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,8 @@
+2012-08-23         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* Makefile.am (revout, revtwoway): New tests.
+	* revout.awk, revout.ok, revtwoway.awk, revtwoway.ok: New files.
+
 2012-08-11         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* Makefile.am (EXTRA_DIST): Add inchello.awk and incdupe[4-7].ok.
diff --git a/test/Makefile.am b/test/Makefile.am
index 8b2f8577..ef833ef4 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -674,6 +674,10 @@ EXTRA_DIST = \
 	resplit.awk \
 	resplit.in \
 	resplit.ok \
+	revout.awk \
+	revout.ok \
+	revtwoway.awk \
+	revtwoway.ok \
 	rri1.awk \
 	rri1.in \
 	rri1.ok \
@@ -913,7 +917,7 @@ LOCALE_CHARSET_TESTS = \
 
 SHLIB_TESTS = \
 	assignconst fnmatch filefuncs fork fork2 fts ordchr ordchr2 \
-	readdir readfile rwarray testext time
+	readdir readfile revout revtwoway rwarray testext time
 
 # List of the tests which should be run with --lint option:
 NEED_LINT = \
diff --git a/test/Makefile.in b/test/Makefile.in
index f5ef08cc..c4b1bb60 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -886,6 +886,10 @@ EXTRA_DIST = \
 	resplit.awk \
 	resplit.in \
 	resplit.ok \
+	revout.awk \
+	revout.ok \
+	revtwoway.awk \
+	revtwoway.ok \
 	rri1.awk \
 	rri1.in \
 	rri1.ok \
@@ -1121,7 +1125,7 @@ LOCALE_CHARSET_TESTS = \
 
 SHLIB_TESTS = \
 	assignconst fnmatch filefuncs fork fork2 fts ordchr ordchr2 \
-	readdir readfile rwarray testext time
+	readdir readfile revout revtwoway rwarray testext time
 
 
 # List of the tests which should be run with --lint option:
@@ -3282,6 +3286,16 @@ ordchr:
 	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
 	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
 
+revout:
+	@echo $@
+	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
+	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
+
+revtwoway:
+	@echo $@
+	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
+	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
+
 rwarray:
 	@echo $@
 	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  < $(srcdir)/$@.in >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
diff --git a/test/Maketests b/test/Maketests
index 675551e3..3951c3ff 100644
--- a/test/Maketests
+++ b/test/Maketests
@@ -1239,6 +1239,16 @@ ordchr:
 	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
 	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
 
+revout:
+	@echo $@
+	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
+	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
+
+revtwoway:
+	@echo $@
+	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
+	@-$(CMP) $(srcdir)/$@.ok _$@ && rm -f _$@
+
 rwarray:
 	@echo $@
 	@AWKPATH=$(srcdir) $(AWK) -f $@.awk  < $(srcdir)/$@.in >_$@ 2>&1 || echo EXIT CODE: $$? >>_$@
diff --git a/test/revout.awk b/test/revout.awk
new file mode 100644
index 00000000..25f62fc7
--- /dev/null
+++ b/test/revout.awk
@@ -0,0 +1,6 @@
+@load "revoutput"
+
+BEGIN {
+	REVOUT = 1
+	print "hello, world" > "/dev/stdout"
+}
diff --git a/test/revout.ok b/test/revout.ok
new file mode 100644
index 00000000..8101cb93
--- /dev/null
+++ b/test/revout.ok
@@ -0,0 +1 @@
+dlrow ,olleh
diff --git a/test/revtwoway.awk b/test/revtwoway.awk
new file mode 100644
index 00000000..05bded5a
--- /dev/null
+++ b/test/revtwoway.awk
@@ -0,0 +1,11 @@
+@load "revtwoway"
+
+BEGIN {
+	cmd = "/magic/mirror"
+
+	print "hello, world" |& cmd
+	cmd |& getline line
+
+	printf("got back: <%s>, RT = <%s>\n", line, RT)
+	close(cmd)
+}
diff --git a/test/revtwoway.ok b/test/revtwoway.ok
new file mode 100644
index 00000000..b8a5ff31
--- /dev/null
+++ b/test/revtwoway.ok
@@ -0,0 +1,2 @@
+got back: <dlrow ,olleh>, RT = <
+>