diff --git a/CHANGES b/CHANGES
index ba70d925d3..c7bae302eb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+2667.	[func]		Add support for logging stack backtrace on assertion
+			failure (not available for all platforms). [RT #19780]
+
 2666.	[func]		Added an 'options' argument to dns_name_fromstring()
 			(API change from 9.7.0a2). [RT #20196]
 
diff --git a/bin/check/Makefile.in b/bin/check/Makefile.in
index 488a143d83..39af25cbe8 100644
--- a/bin/check/Makefile.in
+++ b/bin/check/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.33 2009/09/01 00:22:24 jinmei Exp $
+# $Id: Makefile.in,v 1.34 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -32,6 +32,7 @@ CWARNINGS =
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 ISCCFGLIBS =	../../lib/isccfg/libisccfg.@A@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 BIND9LIBS =	../../lib/bind9/libbind9.@A@
 
 DNSDEPLIBS =	../../lib/dns/libdns.@A@
@@ -39,7 +40,8 @@ ISCCFGDEPLIBS =	../../lib/isccfg/libisccfg.@A@
 ISCDEPLIBS =	../../lib/isc/libisc.@A@
 BIND9DEPLIBS =	../../lib/bind9/libbind9.@A@
 
-LIBS =		@LIBS@
+LIBS =		${ISCLIBS} @LIBS@
+NOSYMLIBS =	${ISCNOSYMLIBS} @LIBS@
 
 SUBDIRS =
 
@@ -69,14 +71,14 @@ named-checkzone.@O@: named-checkzone.c
 
 named-checkconf@EXEEXT@: named-checkconf.@O@ check-tool.@O@ ${ISCDEPLIBS} \
 		${ISCCFGDEPLIBS} ${BIND9DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	named-checkconf.@O@ check-tool.@O@ ${BIND9LIBS} ${ISCCFGLIBS} \
-	${DNSLIBS} ${ISCLIBS} ${LIBS}
+	export BASEOBJS="named-checkconf.@O@ check-tool.@O@"; \
+	export LIBS0="${BIND9LIBS} ${ISCCFGLIBS} ${DNSLIBS}"; \
+	${FINALBUILDCMD}
 
 named-checkzone@EXEEXT@: named-checkzone.@O@ check-tool.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	named-checkzone.@O@ check-tool.@O@ ${ISCCFGLIBS} ${DNSLIBS} \
-	${ISCLIBS} ${LIBS}
+	export BASEOBJS="named-checkzone.@O@ check-tool.@O@"; \
+	export LIBS0="${ISCCFGLIBS} ${DNSLIBS}"; \
+	${FINALBUILDCMD}
 
 doc man:: ${MANOBJS}
 
diff --git a/bin/confgen/Makefile.in b/bin/confgen/Makefile.in
index be9fc385b8..5bfdc6adfe 100644
--- a/bin/confgen/Makefile.in
+++ b/bin/confgen/Makefile.in
@@ -12,7 +12,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.5 2009/09/01 00:22:24 jinmei Exp $
+# $Id: Makefile.in,v 1.6 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -43,7 +43,10 @@ BIND9DEPLIBS =	../../lib/bind9/libbind9.@A@
 RNDCLIBS =	${ISCCFGLIBS} ${ISCCCLIBS} ${BIND9LIBS} ${DNSLIBS} ${ISCLIBS} @LIBS@
 RNDCDEPLIBS =	${ISCCFGDEPLIBS} ${ISCCCDEPLIBS} ${BIND9DEPLIBS} ${DNSDEPLIBS} ${ISCDEPLIBS}
 
-CONFLIBS =	${DNSLIBS} ${ISCLIBS} @LIBS@
+LIBS =		${DNSLIBS} ${ISCLIBS} @LIBS@
+
+NOSYMLIBS =	${DNSLIBS} ${ISCNOSYMLIBS} @LIBS@
+
 CONFDEPLIBS =	${DNSDEPLIBS} ${ISCDEPLIBS}
 
 SRCS=		rndc-confgen.c ddns-confgen.c
@@ -71,12 +74,12 @@ ddns-confgen.@O@: ddns-confgen.c
 	${LIBTOOL_MODE_COMPILE} ${CC} ${ALL_CFLAGS} -c ${srcdir}/ddns-confgen.c
 
 rndc-confgen@EXEEXT@: rndc-confgen.@O@ util.@O@ keygen.@O@ ${UOBJS} ${CONFDEPLIBS} 
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ rndc-confgen.@O@ util.@O@ keygen.@O@ \
-		${UOBJS} ${CONFLIBS}
+	export BASEOBJS="rndc-confgen.@O@ util.@O@ keygen.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 ddns-confgen@EXEEXT@: ddns-confgen.@O@ util.@O@ keygen.@O@ ${UOBJS} ${CONFDEPLIBS} 
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ ddns-confgen.@O@ util.@O@ keygen.@O@ \
-		${UOBJS} ${CONFLIBS}
+	export BASEOBJS="ddns-confgen.@O@ util.@O@ keygen.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 doc man:: ${MANOBJS}
 
diff --git a/bin/dig/Makefile.in b/bin/dig/Makefile.in
index ad8f2e8d98..ee57ce2dcb 100644
--- a/bin/dig/Makefile.in
+++ b/bin/dig/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.42 2009/09/01 00:22:24 jinmei Exp $
+# $Id: Makefile.in,v 1.43 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -33,6 +33,7 @@ ISCCFGLIBS =	../../lib/isccfg/libisccfg.@A@
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 BIND9LIBS =	../../lib/bind9/libbind9.@A@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 LWRESLIBS =	../../lib/lwres/liblwres.@A@
 
 ISCCFGDEPLIBS =	../../lib/isccfg/libisccfg.@A@
@@ -47,6 +48,9 @@ DEPLIBS =	${DNSDEPLIBS} ${BIND9DEPLIBS} ${ISCDEPLIBS} ${ISCCFGDEPLIBS} \
 LIBS =		${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} ${ISCLIBS} \
 		${ISCCFGLIBS} @IDNLIBS@ @LIBS@
 
+NOSYMLIBS =	${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} ${ISCNOSYMLIBS} \
+		${ISCCFGLIBS} @IDNLIBS@ @LIBS@
+
 SUBDIRS =
 
 TARGETS =	dig@EXEEXT@ host@EXEEXT@ nslookup@EXEEXT@
@@ -66,16 +70,16 @@ MANOBJS =	${MANPAGES} ${HTMLPAGES}
 @BIND9_MAKE_RULES@
 
 dig@EXEEXT@: dig.@O@ dighost.@O@ ${UOBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	dig.@O@ dighost.@O@ ${UOBJS} ${LIBS}
+	export BASEOBJS="dig.@O@ dighost.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 host@EXEEXT@: host.@O@ dighost.@O@ ${UOBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	host.@O@ dighost.@O@ ${UOBJS} ${LIBS}
+	export BASEOBJS="host.@O@ dighost.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 nslookup@EXEEXT@: nslookup.@O@ dighost.@O@ ${UOBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	nslookup.@O@ dighost.@O@ ${UOBJS} ${LIBS}
+	export BASEOBJS="nslookup.@O@ dighost.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 doc man:: ${MANOBJS}
 
diff --git a/bin/dnssec/Makefile.in b/bin/dnssec/Makefile.in
index ef4bedbcf5..2af3838fa8 100644
--- a/bin/dnssec/Makefile.in
+++ b/bin/dnssec/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.39 2009/09/01 00:22:24 jinmei Exp $
+# $Id: Makefile.in,v 1.40 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -30,6 +30,7 @@ CWARNINGS =
 
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 
 DNSDEPLIBS =	../../lib/dns/libdns.@A@
 ISCDEPLIBS =	../../lib/isc/libisc.@A@
@@ -38,6 +39,8 @@ DEPLIBS =	${DNSDEPLIBS} ${ISCDEPLIBS}
 
 LIBS =		${DNSLIBS} ${ISCLIBS} @LIBS@
 
+NOSYMLIBS =	${DNSLIBS} ${ISCNOSYMLIBS} @LIBS@
+
 # Alphabetically
 TARGETS =	dnssec-keygen@EXEEXT@ dnssec-signzone@EXEEXT@ \
 		dnssec-keyfromlabel@EXEEXT@ dnssec-dsfromkey@EXEEXT@ \
@@ -60,24 +63,24 @@ MANOBJS =	${MANPAGES} ${HTMLPAGES}
 @BIND9_MAKE_RULES@
 
 dnssec-dsfromkey@EXEEXT@: dnssec-dsfromkey.@O@ ${OBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	dnssec-dsfromkey.@O@ ${OBJS} ${LIBS}
+	export BASEOBJS="dnssec-dsfromkey.@O@ ${OBJS}"; \
+	${FINALBUILDCMD}
 
 dnssec-keyfromlabel@EXEEXT@: dnssec-keyfromlabel.@O@ ${OBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	dnssec-keyfromlabel.@O@ ${OBJS} ${LIBS}
+	export BASEOBJS="dnssec-keyfromlabel.@O@ ${OBJS}"; \
+	${FINALBUILDCMD}
 
 dnssec-keygen@EXEEXT@: dnssec-keygen.@O@ ${OBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	dnssec-keygen.@O@ ${OBJS} ${LIBS}
+	export BASEOBJS="dnssec-keygen.@O@ ${OBJS}"; \
+	${FINALBUILDCMD}
 
 dnssec-signzone.@O@: dnssec-signzone.c
 	${LIBTOOL_MODE_COMPILE} ${CC} ${ALL_CFLAGS} -DVERSION=\"${VERSION}\" \
 		-c ${srcdir}/dnssec-signzone.c
 
 dnssec-signzone@EXEEXT@: dnssec-signzone.@O@ ${OBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	dnssec-signzone.@O@ ${OBJS} ${LIBS}
+	export BASEOBJS="dnssec-signzone.@O@ ${OBJS}"; \
+	${FINALBUILDCMD}
 
 dnssec-revoke@EXEEXT@: dnssec-revoke.@O@ ${OBJS} ${DEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
diff --git a/bin/named/Makefile.in b/bin/named/Makefile.in
index cd2a0247ae..a5cbc1e4d6 100644
--- a/bin/named/Makefile.in
+++ b/bin/named/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.105 2009/09/01 00:22:25 jinmei Exp $
+# $Id: Makefile.in,v 1.106 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -53,6 +53,7 @@ DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 ISCCFGLIBS =	../../lib/isccfg/libisccfg.@A@
 ISCCCLIBS =	../../lib/isccc/libisccc.@A@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 LWRESLIBS =	../../lib/lwres/liblwres.@A@
 BIND9LIBS =	../../lib/bind9/libbind9.@A@
 
@@ -70,6 +71,10 @@ LIBS =		${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} \
 		${ISCCFGLIBS} ${ISCCCLIBS} ${ISCLIBS} \
 		${DLZDRIVER_LIBS} ${DBDRIVER_LIBS} @LIBS@
 
+NOSYMLIBS =	${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} \
+		${ISCCFGLIBS} ${ISCCCLIBS} ${ISCNOSYMLIBS} \
+		${DLZDRIVER_LIBS} ${DBDRIVER_LIBS} @LIBS@
+
 SUBDIRS =	unix
 
 TARGETS =	named@EXEEXT@ lwresd@EXEEXT@
@@ -86,10 +91,12 @@ OBJS =		builtin.@O@ client.@O@ config.@O@ control.@O@ \
 
 UOBJS =		unix/os.@O@
 
+SYMOBJS =	symtbl.@O@
+
 SRCS =		builtin.c client.c config.c control.c \
 		controlconf.c interfacemgr.c \
 		listenlist.c log.c logconf.c main.c notify.c \
-		query.c server.c sortlist.c statschannel.c \
+		query.c server.c sortlist.c statschannel.c symtbl.c symtbl-empty.c \
 		tkeyconf.c tsigconf.c update.c xfrout.c \
 		zoneconf.c \
 		lwaddr.c lwresd.c lwdclient.c lwderror.c lwdgabn.c \
@@ -122,8 +129,9 @@ config.@O@: config.c bind.keys.h
 		-c ${srcdir}/config.c
 
 named@EXEEXT@: ${OBJS} ${UOBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
-	${OBJS} ${UOBJS} ${LIBS}
+	export MAKE_SYMTABLE="yes"; \
+	export BASEOBJS="${OBJS} ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 lwresd@EXEEXT@: named@EXEEXT@
 	rm -f lwresd@EXEEXT@
diff --git a/bin/named/main.c b/bin/named/main.c
index a05daf15df..b0f0514133 100644
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: main.c,v 1.172 2009/05/07 09:33:52 fdupont Exp $ */
+/* $Id: main.c,v 1.173 2009/09/01 18:40:25 jinmei Exp $ */
 
 /*! \file */
 
@@ -26,6 +26,7 @@
 #include <string.h>
 
 #include <isc/app.h>
+#include <isc/backtrace.h>
 #include <isc/commandline.h>
 #include <isc/dir.h>
 #include <isc/entropy.h>
@@ -81,6 +82,13 @@
 #include <dlz/dlz_drivers.h>
 #endif
 
+/*
+ * The maximum number of stack frames to dump on assertion failure.
+ */
+#ifndef BACKTRACE_MAXFRAME
+#define BACKTRACE_MAXFRAME 128
+#endif
+
 static isc_boolean_t	want_stats = ISC_FALSE;
 static char		program_name[ISC_DIR_NAMEMAX] = "named";
 static char		absolute_conffile[ISC_DIR_PATHMAX];
@@ -134,6 +142,12 @@ static void
 assertion_failed(const char *file, int line, isc_assertiontype_t type,
 		 const char *cond)
 {
+	void *tracebuf[BACKTRACE_MAXFRAME];
+	int i, nframes;
+	isc_result_t result;
+	const char *logsuffix = "";
+	const char *fname;
+
 	/*
 	 * Handle assertion failures.
 	 */
@@ -145,10 +159,40 @@ assertion_failed(const char *file, int line, isc_assertiontype_t type,
 		 */
 		isc_assertion_setcallback(NULL);
 
+		result = isc_backtrace_gettrace(tracebuf, BACKTRACE_MAXFRAME,
+						&nframes);
+		if (result == ISC_R_SUCCESS && nframes > 0)
+			logsuffix = ", back trace";
 		isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
 			      NS_LOGMODULE_MAIN, ISC_LOG_CRITICAL,
-			      "%s:%d: %s(%s) failed", file, line,
-			      isc_assertion_typetotext(type), cond);
+			      "%s:%d: %s(%s) failed%s", file, line,
+			      isc_assertion_typetotext(type), cond, logsuffix);
+		if (result == ISC_R_SUCCESS) {
+			for (i = 0; i < nframes; i++) {
+				unsigned long offset;
+
+				fname = NULL;
+				result = isc_backtrace_getsymbol(tracebuf[i],
+								 &fname,
+								 &offset);
+				if (result == ISC_R_SUCCESS) {
+					isc_log_write(ns_g_lctx,
+						      NS_LOGCATEGORY_GENERAL,
+						      NS_LOGMODULE_MAIN,
+						      ISC_LOG_CRITICAL,
+						      "#%d %p in %s()+0x%lx", i,
+						      tracebuf[i], fname,
+						      offset);
+				} else {
+					isc_log_write(ns_g_lctx,
+						      NS_LOGCATEGORY_GENERAL,
+						      NS_LOGMODULE_MAIN,
+						      ISC_LOG_CRITICAL,
+						      "#%d %p in ??", i,
+						      tracebuf[i]);
+				}
+			}
+		}
 		isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
 			      NS_LOGMODULE_MAIN, ISC_LOG_CRITICAL,
 			      "exiting (due to assertion failure)");
@@ -584,6 +628,34 @@ destroy_managers(void) {
 	isc_hash_destroy();
 }
 
+static void
+dump_symboltable() {
+	int i;
+	isc_result_t result;
+	const char *fname;
+	const void *addr;
+
+	if (isc__backtrace_nsymbols == 0)
+		return;
+
+	if (!isc_log_wouldlog(ns_g_lctx, ISC_LOG_DEBUG(99)))
+		return;
+
+	isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL, NS_LOGMODULE_MAIN,
+		      ISC_LOG_DEBUG(99), "Symbol table:");
+
+	for (i = 0, result = ISC_R_SUCCESS; result == ISC_R_SUCCESS; i++) {
+		addr = NULL;
+		fname = NULL;
+		result = isc_backtrace_getsymbolfromindex(i, &addr, &fname);
+		if (result == ISC_R_SUCCESS) {
+			isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
+				      NS_LOGMODULE_MAIN, ISC_LOG_DEBUG(99),
+				      "[%d] %p %s", i, addr, fname);
+		}
+	}
+}
+
 static void
 setup(void) {
 	isc_result_t result;
@@ -691,6 +763,8 @@ setup(void) {
 	isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL, NS_LOGMODULE_MAIN,
 		      ISC_LOG_NOTICE, "built with %s", ns_g_configargs);
 
+	dump_symboltable();
+
 	/*
 	 * Get the initial resource limits.
 	 */
@@ -902,6 +976,9 @@ main(int argc, char *argv[]) {
 	if (strcmp(program_name, "lwresd") == 0)
 		ns_g_lwresdonly = ISC_TRUE;
 
+	if (result != ISC_R_SUCCESS)
+		ns_main_earlyfatal("failed to build internal symbol table");
+
 	isc_assertion_setcallback(assertion_failed);
 	isc_error_setfatal(library_fatal_error);
 	isc_error_setunexpected(library_unexpected_error);
diff --git a/bin/nsupdate/Makefile.in b/bin/nsupdate/Makefile.in
index 00d0fbd23e..b2ce180684 100644
--- a/bin/nsupdate/Makefile.in
+++ b/bin/nsupdate/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.33 2009/09/01 00:22:25 jinmei Exp $
+# $Id: Makefile.in,v 1.34 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -33,6 +33,7 @@ LWRESLIBS =	../../lib/lwres/liblwres.@A@
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 BIND9LIBS =	../../lib/bind9/libbind9.@A@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 ISCCFGLIBS =	../../lib/isccfg/libisccfg.@A@
 
 LWRESDEPLIBS =	../../lib/lwres/liblwres.@A@
@@ -45,6 +46,8 @@ DEPLIBS =	${DNSDEPLIBS} ${BIND9DEPLIBS} ${ISCDEPLIBS} ${ISCCFGDEPLIBS}
 
 LIBS =		${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} ${ISCCFGLIBS} ${ISCLIBS} @LIBS@
 
+NOSYMLIBS =	${LWRESLIBS} ${DNSLIBS} ${BIND9LIBS} ${ISCNOSYMLIBS} ${ISCCFGLIBS} @LIBS@
+
 SUBDIRS =
 
 TARGETS =	nsupdate@EXEEXT@
@@ -69,7 +72,8 @@ nsupdate.@O@: nsupdate.c
 		-c ${srcdir}/nsupdate.c
 
 nsupdate@EXEEXT@: nsupdate.@O@ ${UOBJS} ${DEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ nsupdate.@O@ ${UOBJS} ${LIBS}
+	export BASEOBJS="nsupdate.@O@ ${UOBJS}"; \
+	${FINALBUILDCMD}
 
 doc man:: ${MANOBJS}
 
diff --git a/bin/rndc/Makefile.in b/bin/rndc/Makefile.in
index 6ec10ba7d3..3334e445b6 100644
--- a/bin/rndc/Makefile.in
+++ b/bin/rndc/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.47 2009/09/01 00:22:25 jinmei Exp $
+# $Id: Makefile.in,v 1.48 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -32,6 +32,7 @@ CWARNINGS =
 ISCCFGLIBS =	../../lib/isccfg/libisccfg.@A@
 ISCCCLIBS =	../../lib/isccc/libisccc.@A@
 ISCLIBS =	../../lib/isc/libisc.@A@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 BIND9LIBS =	../../lib/bind9/libbind9.@A@
 
@@ -41,10 +42,11 @@ ISCDEPLIBS =	../../lib/isc/libisc.@A@
 DNSDEPLIBS =	../../lib/dns/libdns.@A@
 BIND9DEPLIBS =	../../lib/bind9/libbind9.@A@
 
-RNDCLIBS =	${ISCCFGLIBS} ${ISCCCLIBS} ${BIND9LIBS} ${DNSLIBS} ${ISCLIBS} @LIBS@
+LIBS =		${ISCLIBS} @LIBS@
+NOSYMLIBS =	${ISCNOSYMLIBS} @LIBS@
+
 RNDCDEPLIBS =	${ISCCFGDEPLIBS} ${ISCCCDEPLIBS} ${BIND9DEPLIBS} ${DNSDEPLIBS} ${ISCDEPLIBS}
 
-CONFLIBS =	${DNSLIBS} ${ISCLIBS} @LIBS@
 CONFDEPLIBS =	${DNSDEPLIBS} ${ISCDEPLIBS}
 
 SRCS=		rndc.c
@@ -67,8 +69,9 @@ rndc.@O@: rndc.c
 		-c ${srcdir}/rndc.c
 
 rndc@EXEEXT@: rndc.@O@ util.@O@ ${RNDCDEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ rndc.@O@ util.@O@ \
-		${RNDCLIBS}
+	export BASEOBJS="rndc.@O@ util.@O@"; \
+	export LIBS0="${ISCCFGLIBS} ${ISCCCLIBS} ${BIND9LIBS} ${DNSLIBS}"; \
+	${FINALBUILDCMD}
 
 doc man:: ${MANOBJS}
 
diff --git a/bin/tests/Makefile.in b/bin/tests/Makefile.in
index 20f1206046..4dbdb78d6f 100644
--- a/bin/tests/Makefile.in
+++ b/bin/tests/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.135 2009/09/01 00:22:25 jinmei Exp $
+# $Id: Makefile.in,v 1.136 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -29,11 +29,13 @@ CWARNINGS =
 
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 ISCLIBS =	../../lib/isc/libisc.@A@ @DNS_CRYPTO_LIBS@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@ @DNS_CRYPTO_LIBS@
 ISCCFGLIBS = 	../../lib/isccfg/libisccfg.@A@
 LWRESLIBS =	../../lib/lwres/liblwres.@A@
 
 DNSDEPLIBS =	../../lib/dns/libdns.@A@
 ISCDEPLIBS =	../../lib/isc/libisc.@A@
+ISCDEPNOSYMLIBS = ../../lib/isc/libisc-nosymtbl.@A@
 ISCCFGDEPLIBS = ../../lib/isccfg/libisccfg.@A@
 LWRESDEPLIBS =	../../lib/lwres/liblwres.@A@
 
@@ -52,6 +54,8 @@ TARGETS =	cfg_test@EXEEXT@
 # Alphabetically
 XTARGETS =	adb_test@EXEEXT@ \
 		byaddr_test@EXEEXT@ \
+		backtrace_test@EXEEXT@ \
+		backtrace_test_nosymtbl@EXEEXT@ \
 		byname_test@EXEEXT@ \
 		compress_test@EXEEXT@ \
 		db_test@EXEEXT@ \
@@ -91,6 +95,7 @@ SRCS =		cfg_test.c ${XSRCS}
 
 XSRCS =		adb_test.c \
 		byaddr_test.c \
+		backtrace_test.c \
 		byname_test.c \
 		compress_test.c \
 		db_test.c \
@@ -128,12 +133,41 @@ XSRCS =		adb_test.c \
 
 @BIND9_MAKE_RULES@
 
+# disable optimization for backtrace test to get the expected result	
+BTTEST_CFLAGS =	${EXT_CFLAGS} ${ALL_CPPFLAGS} -g ${ALWAYS_WARNINGS} \
+	${STD_CWARNINGS} ${CWARNINGS}
+
 all_tests: ${XTARGETS}
 
 adb_test@EXEEXT@: adb_test.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ adb_test.@O@ \
 		${DNSLIBS} ${ISCLIBS} ${LIBS}
 
+backtrace_test_nosymtbl@EXEEXT@: backtrace_test.c ${ISCDEPLIBS}
+	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${BTTEST_CFLAGS} ${LDFLAGS} -o $@ \
+	backtrace_test.c ${ISCLIBS} ${LIBS}
+
+backtrace_test@EXEEXT@: backtrace_test_nosymtbl@EXEEXT@
+	#first step: create a first symbol table
+	rm -f symtbl.c
+	if test X${MKSYMTBL_PROGRAM} != X; then \
+	${MKSYMTBL_PROGRAM} ${top_srcdir}/util/mksymtbl.pl $<; else \
+	cp ${top_srcdir}/lib/isc/backtrace-emptytbl.c symtbl.c; fi
+	#second step: build a binary with the first symbol table
+	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${BTTEST_CFLAGS} ${LDFLAGS} \
+	-o $@0 backtrace_test.c symtbl.c \
+	${ISCNOSYMLIBS} ${LIBS}
+	rm -f symtbl.c
+	#third step: create a second symbol table
+	if test X${MKSYMTBL_PROGRAM} != X; then \
+	${MKSYMTBL_PROGRAM} ${top_srcdir}/util/mksymtbl.pl $@0; else \
+	cp ${top_srcdir}/lib/isc/backtrace-emptytbl.c symtbl.c; fi
+	#fourth step: build the final binary
+	rm -f $@0
+	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${BTTEST_CFLAGS} ${LDFLAGS} \
+	-o $@ backtrace_test.c symtbl.c ${ISCNOSYMLIBS} ${LIBS}
+	rm -f symtbl.c
+
 nsecify@EXEEXT@: nsecify.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ nsecify.@O@ \
 		${DNSLIBS} ${ISCLIBS} ${LIBS}
@@ -280,6 +314,7 @@ distclean::
 clean distclean::
 	rm -f ${TARGETS} ${XTARGETS}
 	rm -f t_journal
+	rm -f backtrace_test_symtbl.c
 
 check: test
 
diff --git a/bin/tests/backtrace_test.c b/bin/tests/backtrace_test.c
new file mode 100644
index 0000000000..f2f27eaa58
--- /dev/null
+++ b/bin/tests/backtrace_test.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: backtrace_test.c,v 1.2 2009/09/01 18:40:25 jinmei Exp $ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include <isc/backtrace.h>
+#include <isc/result.h>
+
+const char *expected_symbols[] = {
+	"func3",
+	"func2",
+	"func1",
+	"main"
+};
+
+static int
+func3() {
+	void *tracebuf[16];
+	int i, nframes;
+	int error = 0;
+	const char *fname;
+	isc_result_t result;
+	unsigned long offset;
+
+	result = isc_backtrace_gettrace(tracebuf, 16, &nframes);
+	if (result != ISC_R_SUCCESS) {
+		printf("isc_backtrace_gettrace failed: %s\n",
+		       isc_result_totext(result));
+		return (1);
+	}
+		
+	if (nframes < 4)
+		error++;
+	
+	for (i = 0; i < 4 && i < nframes; i++) {
+		fname = NULL;
+		result = isc_backtrace_getsymbol(tracebuf[i], &fname, &offset);
+		if (result != ISC_R_SUCCESS) {
+			error++;
+			continue;
+		}
+		if (strcmp(fname, expected_symbols[i]) != 0)
+			error++;
+	}
+
+	if (error) {
+		printf("Unexpected result:\n");
+		printf("  # of frames: %d (expected: at least 4)\n", nframes);
+		printf("  symbols:\n");
+		for (i = 0; i < nframes; i++) {
+			fname = NULL;
+			result = isc_backtrace_getsymbol(tracebuf[i], &fname,
+							 &offset);
+			if (result == ISC_R_SUCCESS)
+				printf("  [%d] %s\n", i, fname);
+			else {
+				printf("  [%d] getsymbol failed: %s\n", i,
+				       isc_result_totext(result));
+			}
+		}
+	}
+
+	return (error);
+}
+
+static int
+func2() {
+	return (func3());
+}
+
+static int
+func1() {
+	return (func2());
+}
+
+int
+main() {
+	return (func1());
+}
diff --git a/bin/tools/Makefile.in b/bin/tools/Makefile.in
index 90a7b9eac9..0ed7b66e45 100644
--- a/bin/tools/Makefile.in
+++ b/bin/tools/Makefile.in
@@ -12,7 +12,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.8 2009/09/01 00:22:26 jinmei Exp $
+# $Id: Makefile.in,v 1.9 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -28,6 +28,7 @@ CWARNINGS =
 
 DNSLIBS =	../../lib/dns/libdns.@A@ @DNS_CRYPTO_LIBS@
 ISCLIBS =	../../lib/isc/libisc.@A@ @DNS_CRYPTO_LIBS@
+ISCNOSYMLIBS =	../../lib/isc/libisc-nosymtbl.@A@
 ISCCFGLIBS = 	../../lib/isccfg/libisccfg.@A@
 LWRESLIBS =	../../lib/lwres/liblwres.@A@
 
@@ -36,7 +37,8 @@ ISCDEPLIBS =	../../lib/isc/libisc.@A@
 ISCCFGDEPLIBS = ../../lib/isccfg/libisccfg.@A@
 LWRESDEPLIBS =	../../lib/lwres/liblwres.@A@
 
-LIBS =		@LIBS@
+LIBS =		${ISCLIBS} @LIBS@
+NOSYMLIBS =	${ISCNOSYMLIBS} @LIBS@
 
 SUBDIRS = 
 
@@ -53,13 +55,16 @@ MANOBJS =	${MANPAGES} ${HTMLPAGES}
 arpaname@EXEEXT@: arpaname.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ arpaname.@O@ \
 		${DNSLIBS} ${ISCLIBS} ${LIBS}
+
 journalprint@EXEEXT@: journalprint.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
-	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ journalprint.@O@ \
-		${DNSLIBS} ${ISCLIBS} ${LIBS}
+	export BASEOBJS="journalprint.@O@"; \
+	export LIBS0="${DNSLIBS}"; \
+	${FINALBUILDCMD}
 
 nsec3hash@EXEEXT@: nsec3hash.@O@ ${ISCDEPLIBS} ${DNSDEPLIBS}
-	${LIBTOOL_MODE_LINK} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ nsec3hash.@O@ \
-	${DNSLIBS} ${ISCLIBS} ${LIBS}
+	export BASEOBJS="nsec3hash.@O@"; \
+	export LIBS0="${DNSLIBS}"; \
+	${FINALBUILDCMD}
 
 genrandom@EXEEXT@: genrandom.@O@
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ genrandom.@O@ @GENRANDOMLIB@ ${LIBS}
diff --git a/config.h.in b/config.h.in
index 009515ef7f..cc78c6d318 100644
--- a/config.h.in
+++ b/config.h.in
@@ -16,7 +16,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: config.h.in,v 1.119 2009/09/01 17:54:16 jinmei Exp $ */
+/* $Id: config.h.in,v 1.120 2009/09/01 18:40:25 jinmei Exp $ */
 
 /*! \file */
 
@@ -334,6 +334,9 @@ int sigwait(const unsigned int *set, int *sig);
    non-blocking. */
 #undef USE_FIONBIO_IOCTL
 
+/** define if the system have backtrace function. */
+#undef HAVE_LIBCTRACE
+
 /* define if idnkit support is to be included. */
 #undef WITH_IDN
 
diff --git a/configure.in b/configure.in
index 11e79a334d..f224951cc1 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(1)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl
 
-AC_REVISION($Revision: 1.475 $)
+AC_REVISION($Revision: 1.476 $)
 
 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.59)
@@ -111,6 +111,8 @@ AC_SUBST(ETAGS)
 
 #
 # Perl is optional; it is used only by some of the system test scripts.
+# Note: the backtrace feature (see below) uses perl to build the symbol table,
+# but it still compiles without perl, in which case an empty table will be used.
 #
 AC_PATH_PROGS(PERL, perl5 perl)
 AC_SUBST(PERL)
@@ -1306,6 +1308,53 @@ case $use_libtool in
 		;;
 esac
 
+#
+# enable/disable dumping stack backtrace.  Also check if the system supports
+# glibc-compatible backtrace() function.
+#
+AC_ARG_ENABLE(backtrace,
+[  --enable-backtrace      log stack backtrace on abort [[default=yes]]],
+	      want_backtrace="$enableval",  want_backtrace="yes")
+case $want_backtrace in
+yes)
+	ISC_PLATFORM_USEBACKTRACE="#define ISC_PLATFORM_USEBACKTRACE 1"
+	AC_TRY_LINK([#include <execinfo.h>],
+	[return (backtrace((void **)0, 0));],
+	[AC_DEFINE([HAVE_LIBCTRACE], [], [if system have backtrace function])],)
+	;;
+*)
+	ISC_PLATFORM_USEBACKTRACE="#undef ISC_PLATFORM_USEBACKTRACE"
+	;;
+esac
+AC_SUBST(ISC_PLATFORM_USEBACKTRACE)
+
+AC_ARG_ENABLE(symtable,
+[  --enable-symtable       use internal symbol table for backtrace
+                          [[all|minimal(default)|none]]],
+		want_symtable="$enableval",  want_symtable="minimal")
+case $want_symtable in
+yes|all|minimal)
+	
+	if test "$PERL" == ""
+	then
+		AC_MSG_ERROR([Internal symbol table requires perl but no perl is found.
+Install perl or explicitly disable the feature by --disable-symtable.])
+	fi
+	if test "$use_libtool" = "yes"; then
+		AC_MSG_WARN([Internal symbol table does not work with libtool.  Disabling symtbol table.])
+	else
+		MKSYMTBL_PROGRAM="$PERL"
+		if test $want_symtable = all; then
+			ALWAYS_MAKE_SYMTABLE="yes"
+		fi
+	fi
+	;;
+*)
+	;;
+esac
+AC_SUBST(MKSYMTBL_PROGRAM)
+AC_SUBST(ALWAYS_MAKE_SYMTABLE)
+
 #
 # File name extension for static archive files, for those few places
 # where they are treated differently from dynamic ones.
diff --git a/lib/isc/Makefile.in b/lib/isc/Makefile.in
index ced0e64729..bbe3cd01e8 100644
--- a/lib/isc/Makefile.in
+++ b/lib/isc/Makefile.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.101 2009/09/01 00:22:28 jinmei Exp $
+# $Id: Makefile.in,v 1.102 2009/09/01 18:40:25 jinmei Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -50,8 +50,9 @@ WIN32OBJS = 	win32/condition.@O@ win32/dir.@O@ win32/file.@O@ \
 
 # Alphabetically
 OBJS =		@ISC_EXTRA_OBJS@ \
-		assertions.@O@ base32.@O@ base64.@O@ bitstring.@O@ buffer.@O@ \
-		bufferlist.@O@ commandline.@O@ error.@O@ event.@O@ \
+		assertions.@O@ backtrace.@O@ base32.@O@ base64.@O@ \
+		bitstring.@O@ buffer.@O@ bufferlist.@O@ commandline.@O@ \
+		error.@O@ event.@O@ \
 		hash.@O@ heap.@O@ hex.@O@ hmacmd5.@O@ hmacsha.@O@ \
 		httpd.@O@ inet_aton.@O@ iterated_hash.@O@ \
 		lex.@O@ lfsr.@O@ lib.@O@ log.@O@ \
@@ -62,6 +63,7 @@ OBJS =		@ISC_EXTRA_OBJS@ \
 		serial.@O@ sha1.@O@ sha2.@O@ sockaddr.@O@ stats.@O@ \
 		string.@O@ strtoul.@O@ symtab.@O@ task.@O@ taskpool.@O@ \
 		timer.@O@ version.@O@ ${UNIXOBJS} ${NLSOBJS} ${THREADOBJS}
+SYMTBLOBJS =	backtrace-emptytbl.@O@
 
 # Alphabetically
 SRCS =		@ISC_EXTRA_SRCS@ \
@@ -75,7 +77,7 @@ SRCS =		@ISC_EXTRA_SRCS@ \
 		parseint.c portset.c quota.c radix.c random.c \
 		ratelimiter.c refcount.c region.c result.c rwlock.c \
 		serial.c sha1.c sha2.c sockaddr.c stats.c string.c strtoul.c \
-		symtab.c task.c taskpool.c timer.c version.c
+		symtab.c symtbl-empty.c task.c taskpool.c timer.c version.c
 
 LIBS =		@LIBS@
 
@@ -92,17 +94,27 @@ version.@O@: version.c
 		-DLIBAGE=${LIBAGE} \
 		-c ${srcdir}/version.c
 
-libisc.@SA@: ${OBJS}
+libisc.@SA@: ${OBJS} ${SYMTBLOBJS}
+	${AR} ${ARFLAGS} $@ ${OBJS} ${SYMTBLOBJS}
+	${RANLIB} $@
+
+libisc-nosymtbl.@SA@: ${OBJS}
 	${AR} ${ARFLAGS} $@ ${OBJS}
 	${RANLIB} $@
 
-libisc.la: ${OBJS}
+libisc.la: ${OBJS} ${SYMTBLOBJS}
 	${LIBTOOL_MODE_LINK} \
 		${CC} ${ALL_CFLAGS} ${LDFLAGS} -o libisc.la -rpath ${libdir} \
 		-version-info ${LIBINTERFACE}:${LIBREVISION}:${LIBAGE} \
+		${OBJS} ${SYMTBLOBJS} ${LIBS}
+
+libisc-nosymtbl.la: ${OBJS}
+	${LIBTOOL_MODE_LINK} \
+		${CC} ${ALL_CFLAGS} ${LDFLAGS} -o libisc-nosymtbl.la -rpath ${libdir} \
+		-version-info ${LIBINTERFACE}:${LIBREVISION}:${LIBAGE} \
 		${OBJS} ${LIBS}
 
-timestamp: libisc.@A@
+timestamp: libisc.@A@ libisc-nosymtbl.@A@
 	touch timestamp
 
 installdirs:
@@ -115,4 +127,5 @@ install:: @ISC_ARCH_DIR@/include/isc/atomic.h
 	${INSTALL_DATA} @ISC_ARCH_DIR@/include/isc/atomic.h ${DESTDIR}${includedir}/isc
 
 clean distclean::
-	rm -f libisc.@A@ libisc.la timestamp
+	rm -f libisc.@A@ libisc-nosymtbl.@A@ libisc.la \
+	libisc-nosymtbl.la timestamp
diff --git a/lib/isc/assertions.c b/lib/isc/assertions.c
index 4c9251bdcf..0d5cc5c211 100644
--- a/lib/isc/assertions.c
+++ b/lib/isc/assertions.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: assertions.c,v 1.23 2008/10/15 23:47:31 tbox Exp $ */
+/* $Id: assertions.c,v 1.24 2009/09/01 18:40:25 jinmei Exp $ */
 
 /*! \file */
 
@@ -25,7 +25,16 @@
 #include <stdlib.h>
 
 #include <isc/assertions.h>
+#include <isc/backtrace.h>
 #include <isc/msgs.h>
+#include <isc/result.h>
+
+/*
+ * The maximum number of stack frames to dump on assertion failure.
+ */
+#ifndef BACKTRACE_MAXFRAME
+#define BACKTRACE_MAXFRAME 128
+#endif
 
 /*%
  * Forward.
@@ -87,10 +96,36 @@ static void
 default_callback(const char *file, int line, isc_assertiontype_t type,
 		 const char *cond)
 {
-	fprintf(stderr, "%s:%d: %s(%s) %s.\n",
+	void *tracebuf[BACKTRACE_MAXFRAME];
+	int i, nframes;
+	const char *logsuffix = ".";
+	const char *fname;
+	isc_result_t result;
+
+	result = isc_backtrace_gettrace(tracebuf, BACKTRACE_MAXFRAME, &nframes);
+		if (result == ISC_R_SUCCESS && nframes > 0)
+			logsuffix = ", back trace";
+
+	fprintf(stderr, "%s:%d: %s(%s) %s%s\n",
 		file, line, isc_assertion_typetotext(type), cond,
 		isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
-			       ISC_MSG_FAILED, "failed"));
+			       ISC_MSG_FAILED, "failed"), logsuffix);
+	if (result == ISC_R_SUCCESS) {
+		for (i = 0; i < nframes; i++) {
+			unsigned long offset;
+
+			fname = NULL;
+			result = isc_backtrace_getsymbol(tracebuf[i], &fname,
+							 &offset);
+			if (result == ISC_R_SUCCESS) {
+				fprintf(stderr, "#%d %p in %s()+0x%lx\n", i,
+					tracebuf[i], fname, offset);
+			} else {
+				fprintf(stderr, "#%d %p in ??\n", i,
+					tracebuf[i]);
+			}
+		}
+	}
 	fflush(stderr);
 	abort();
 	/* NOTREACHED */
diff --git a/lib/isc/backtrace-emptytbl.c b/lib/isc/backtrace-emptytbl.c
new file mode 100644
index 0000000000..a5e3187c36
--- /dev/null
+++ b/lib/isc/backtrace-emptytbl.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: backtrace-emptytbl.c,v 1.2 2009/09/01 18:40:25 jinmei Exp $ */
+
+/*! \file */
+
+/*
+ * This file defines an empty (default) symbol table used in backtrace.c
+ * If the application wants to have a complete symbol table, it should redefine
+ * isc__backtrace_symtable with the complete table in some way, and link the
+ * version of the library not including this definition
+ * (e.g. libisc-nosymbol.a).
+ */
+
+#include <isc/backtrace.h>
+
+const int isc__backtrace_nsymbols = 0;
+const isc_backtrace_symmap_t isc__backtrace_symtable[] = { { NULL, "" } };
diff --git a/lib/isc/backtrace.c b/lib/isc/backtrace.c
new file mode 100644
index 0000000000..26355ad55b
--- /dev/null
+++ b/lib/isc/backtrace.c
@@ -0,0 +1,285 @@
+/*
+ * Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: backtrace.c,v 1.2 2009/09/01 18:40:25 jinmei Exp $ */
+
+/*! \file */
+
+#include "config.h"
+
+#include <string.h>
+#include <stdlib.h>
+#ifdef HAVE_LIBCTRACE
+#include <execinfo.h>
+#endif
+
+#include <isc/backtrace.h>
+#include <isc/result.h>
+#include <isc/util.h>
+
+#ifdef ISC_PLATFORM_USEBACKTRACE
+/*
+ * Getting a back trace of a running process is tricky and highly platform
+ * dependent.  Our current approach is as follows:
+ * 1. If the system library supports the "backtrace()" function, use it.
+ * 2. Otherwise, if the compiler is gcc and the architecture is x86_64 or IA64,
+ *    then use gcc's (hidden) Unwind_Backtrace() function.  Note that this
+ *    function doesn't work for C programs on many other architectures. 
+ * 3. Otherwise, if the architecture x86 or x86_64, try to unwind the stack
+ *    frame following frame pointers.  This assumes the executable binary
+ *    compiled with frame pointers; this is not always true for x86_64 (rather,
+ *    compiler optimizations often disable frame pointers).  The validation
+ *    checks in getnextframeptr() hopefully rejects bogus values stored in
+ *    the RBP register in such a case.  If the backtrace function itself crashes
+ *    due to this problem, the whole package should be rebuilt with
+ *    --disable-backtrace.
+ */
+#ifdef HAVE_LIBCTRACE
+#define BACKTRACE_LIBC
+#elif defined(__GNUC__) && (defined(__x86_64__) || defined(__ia64__))
+#define BACKTRACE_GCC
+#elif defined(__x86_64__) || defined(__i386__)
+#define BACKTRACE_X86STACK
+#else
+#define BACKTRACE_DISABLED
+#endif  /* HAVE_LIBCTRACE */
+#else	/* !ISC_PLATFORM_USEBACKTRACE */
+#define BACKTRACE_DISABLED
+#endif	/* ISC_PLATFORM_USEBACKTRACE */
+
+#ifdef BACKTRACE_LIBC
+isc_result_t
+isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+	int n;
+
+	/*
+	 * Validate the arguments: intentionally avoid using REQUIRE().
+	 * See notes in backtrace.h.
+	 */
+	if (addrs == NULL || nframes == NULL)
+		return (ISC_R_FAILURE);
+
+	/*
+	 * backtrace(3) includes this function itself in the address array,
+	 * which should be eliminated from the returned sequence.
+	 */
+	n = backtrace(addrs, maxaddrs);
+	if (n < 2)
+		return (ISC_R_NOTFOUND);
+	n--;
+	memmove(addrs, &addrs[1], sizeof(void *) * n);
+	*nframes = n;
+	return (ISC_R_SUCCESS);
+}
+#elif defined(BACKTRACE_GCC)
+extern int _Unwind_Backtrace(void* fn, void* a);
+extern void* _Unwind_GetIP(void* ctx);
+
+typedef struct {
+	void **result;
+	int max_depth;
+	int skip_count;
+	int count;
+} trace_arg_t;
+
+static int
+btcallback(void *uc, void *opq) {
+	trace_arg_t *arg = (trace_arg_t *)opq;
+
+	if (arg->skip_count > 0)
+		arg->skip_count--;
+	else
+		arg->result[arg->count++] = (void *)_Unwind_GetIP(uc);
+	if (arg->count == arg->max_depth)
+		return (5); /* _URC_END_OF_STACK */
+
+	return (0); /* _URC_NO_REASON */
+}
+
+isc_result_t
+isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+	trace_arg_t arg;
+
+	/* Argument validation: see above. */
+	if (addrs == NULL || nframes == NULL)
+		return (ISC_R_FAILURE);
+
+	arg.skip_count = 1;
+	arg.result = addrs;
+	arg.max_depth = maxaddrs;
+	arg.count = 0;
+	_Unwind_Backtrace(btcallback, &arg);
+
+	*nframes = arg.count;
+
+	return (ISC_R_SUCCESS);
+}
+#elif defined(BACKTRACE_X86STACK)
+#ifdef __x86_64__
+static unsigned long
+getrbp() {
+	__asm("movq %rbp, %rax\n");
+}
+#endif
+
+static void **
+getnextframeptr(void **sp) {
+	void **newsp = (void **)*sp;
+
+	/*
+	 * Perform sanity check for the new frame pointer, derived from
+	 * google glog.  This can actually be bogus depending on compiler.
+	 */
+
+	/* prohibit the stack frames from growing downwards */
+	if (newsp <= sp)
+		return (NULL);
+
+	/* A heuristics to reject "too large" frame: this actually happened. */
+	if ((char *)newsp - (char *)sp > 100000)
+		return (NULL);
+
+	/*
+	 * Not sure if other checks used in glog are needed at this moment.
+	 * For our purposes we don't have to consider non-contiguous frames,
+	 * for example.
+	 */
+
+	return (newsp);
+}
+
+isc_result_t
+isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+	int i = 0;
+	void **sp;
+
+	/* Argument validation: see above. */
+	if (addrs == NULL || nframes == NULL)
+		return (ISC_R_FAILURE);
+
+#ifdef __x86_64__
+	sp = (void **)getrbp();
+	if (sp == NULL)
+		return (ISC_R_NOTFOUND);
+	/*
+	 * sp is the frame ptr of this function itself due to the call to
+	 * getrbp(), so need to unwind one frame for consistency.
+	 */
+	sp = getnextframeptr(sp);
+#else
+	/*
+	 * i386: the frame pointer is stored 2 words below the address for the
+	 * first argument.  Note that the body of this function cannot be
+	 * inlined since it depends on the address of the function argument.
+	 */
+	sp = (void **)&addrs - 2;
+#endif
+
+	while (sp != NULL && i < maxaddrs) {
+		addrs[i++] = *(sp + 1);
+		sp = getnextframeptr(sp);
+	}
+
+	*nframes = i;
+
+	return (ISC_R_SUCCESS);
+}
+#elif defined(BACKTRACE_DISABLED)
+isc_result_t
+isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
+	/* Argument validation: see above. */
+	if (addrs == NULL || nframes == NULL)
+		return (ISC_R_FAILURE);
+
+	UNUSED(maxaddrs);
+
+	return (ISC_R_NOTIMPLEMENTED);
+}
+#endif
+
+isc_result_t
+isc_backtrace_getsymbolfromindex(int index, const void **addrp,
+				 const char **symbolp)
+{
+	REQUIRE(addrp != NULL && *addrp == NULL);
+	REQUIRE(symbolp != NULL && *symbolp == NULL);
+
+	if (index < 0 || index >= isc__backtrace_nsymbols)
+		return (ISC_R_RANGE);
+
+	*addrp = isc__backtrace_symtable[index].addr;
+	*symbolp = isc__backtrace_symtable[index].symbol;
+	return (ISC_R_SUCCESS);
+}
+
+static int
+symtbl_compare(const void *addr, const void *entryarg) {
+	const isc_backtrace_symmap_t *entry = entryarg;
+	const isc_backtrace_symmap_t *end =
+		&isc__backtrace_symtable[isc__backtrace_nsymbols - 1];
+
+	if (isc__backtrace_nsymbols == 1 || entry == end) {
+		if (addr >= entry->addr) {
+			/*
+			 * If addr is equal to or larger than that of the last
+			 * entry of the table, we cannot be sure if this is
+			 * within a valid range so we consider it valid.
+			 */
+			return (0);
+		}
+		return (-1);
+	}
+
+	/* entry + 1 is a valid entry from now on. */
+	if (addr < entry->addr)
+		return (-1);
+	else if (addr >= (entry + 1)->addr)
+		return (1);
+	return (0);
+}
+
+isc_result_t
+isc_backtrace_getsymbol(const void *addr, const char **symbolp,
+			unsigned long *offsetp)
+{
+	isc_result_t result = ISC_R_SUCCESS;
+	isc_backtrace_symmap_t *found;
+
+	/*
+	 * Validate the arguments: intentionally avoid using REQUIRE().
+	 * See notes in backtrace.h.
+	 */
+	if (symbolp == NULL || *symbolp != NULL || offsetp == NULL)
+		return (ISC_R_FAILURE);
+
+	if (isc__backtrace_nsymbols < 1)
+		return (ISC_R_NOTFOUND);
+
+	/*
+	 * Search the table for the entry that meets:
+	 * entry.addr <= addr < next_entry.addr.
+	 */
+	found = bsearch(addr, isc__backtrace_symtable, isc__backtrace_nsymbols,
+			sizeof(isc__backtrace_symtable[0]), symtbl_compare);
+	if (found == NULL)
+		result = ISC_R_NOTFOUND;
+	else {
+		*symbolp = found->symbol;
+		*offsetp = (const char *)addr - (char *)found->addr;
+	}
+
+	return (result);
+}
diff --git a/lib/isc/include/isc/backtrace.h b/lib/isc/include/isc/backtrace.h
new file mode 100644
index 0000000000..c0e98c0b75
--- /dev/null
+++ b/lib/isc/include/isc/backtrace.h
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: backtrace.h,v 1.2 2009/09/01 18:40:25 jinmei Exp $ */
+
+/*! \file isc/backtrace.h
+ * \brief provide a back trace of the running process to help debug problems.
+ *
+ * This module tries to get a back trace of the process using some platform
+ * dependent way when available.  It also manages an internal symbol table
+ * that maps function addresses used in the process to their textual symbols.
+ * This module is expected to be used to help debug when some fatal error
+ * happens.
+ *
+ * IMPORTANT NOTE: since the (major) intended use case of this module is
+ * dumping a back trace on a fatal error, normally followed by self termination,
+ * functions defined in this module generally doesn't employ assertion checks
+ * (if it did, a program bug could cause infinite recursive calls to a
+ * backtrace function).  These functions still perform minimal checks and return
+ * ISC_R_FAILURE if they detect an error, but the caller should therefore be
+ * very careful about the use of these functions, and generally discouraged to
+ * use them except in an exit path.  The exception is
+ * isc_backtrace_getsymbolfromindex(), which is expected to be used in a
+ * non-error-handling context and validates arguments with assertion checks.
+ */
+
+#ifndef ISC_BACKTRACE_H
+#define ISC_BACKTRACE_H 1
+
+/***
+ ***	Imports
+ ***/
+
+#include <isc/types.h>
+
+/***
+ *** Types
+ ***/
+struct isc_backtrace_symmap {
+	void		*addr;
+	const char	*symbol;
+};
+
+extern const int isc__backtrace_nsymbols;
+extern const isc_backtrace_symmap_t isc__backtrace_symtable[];
+
+/***
+ *** Functions
+ ***/
+
+ISC_LANG_BEGINDECLS
+isc_result_t
+isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes);
+/*%<
+ * Get a back trace of the running process above this function itself.  On
+ * success, addrs[i] will store the address of the call point of the i-th
+ * stack frame (addrs[0] is the caller of this function).  *nframes will store
+ * the total number of frames.
+ *
+ * Requires (note that these are not ensured by assertion checks, see above):
+ *
+ *\li	'addrs' is a valid array containing at least 'maxaddrs' void * entries.
+ *
+ *\li	'nframes' must be non NULL.
+ *
+ * Returns:
+ *
+ *\li	#ISC_R_SUCCESS
+ *\li	#ISC_R_FAILURE
+ *\li	#ISC_R_NOTFOUND
+ *\li	#ISC_R_NOTIMPLEMENTED
+ */
+
+isc_result_t
+isc_backtrace_getsymbolfromindex(int index, const void **addrp,
+				 const char **symbolp);
+/*%<
+ * Returns the content of the internal symbol table of the given index.
+ * On success, *addrsp and *symbolp point to the address and the symbol of
+ * the 'index'th entry of the table, respectively.  If 'index' is not in the
+ * range of the symbol table, ISC_R_RANGE will be returned.
+ *
+ * Requires
+ *
+ *\li	'addrp' must be non NULL && '*addrp' == NULL.
+ *
+ *\li	'symbolp' must be non NULL && '*symbolp' == NULL.
+ *
+ * Returns:
+ *
+ *\li	#ISC_R_SUCCESS
+ *\li	#ISC_R_RANGE
+ */
+
+isc_result_t
+isc_backtrace_getsymbol(const void *addr, const char **symbolp,
+			unsigned long *offsetp);
+/*%<
+ * Searches the internal symbol table for the symbol that most matches the
+ * given 'addr'.  On success, '*symbolp' will point to the name of function
+ * to which the address 'addr' belong, and '*offsetp' will store the offset
+ * from the function's entry address to 'addr'.
+ *
+ * Requires (note that these are not ensured by assertion checks, see above):
+ *
+ *\li	'symbolp' must be non NULL && '*symbolp' == NULL.
+ *
+ *\li	'offsetp' must be non NULL.
+ *
+ * Returns:
+ *
+ *\li	#ISC_R_SUCCESS
+ *\li	#ISC_R_FAILURE
+ *\li	#ISC_R_NOTFOUND
+ */
+ISC_LANG_ENDDECLS
+
+#endif	/* ISC_BACKTRACE_H */
diff --git a/lib/isc/include/isc/platform.h.in b/lib/isc/include/isc/platform.h.in
index fd5461e4b1..ef49d3298d 100644
--- a/lib/isc/include/isc/platform.h.in
+++ b/lib/isc/include/isc/platform.h.in
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: platform.h.in,v 1.51 2009/02/06 23:47:42 tbox Exp $ */
+/* $Id: platform.h.in,v 1.52 2009/09/01 18:40:25 jinmei Exp $ */
 
 #ifndef ISC_PLATFORM_H
 #define ISC_PLATFORM_H 1
@@ -146,6 +146,11 @@
  */
 @ISC_PLATFORM_HAVEDEVPOLL@
 
+/*! \brief
+ * Define if we want to log backtrace
+ */
+@ISC_PLATFORM_USEBACKTRACE@
+
 /*
  *** Printing.
  ***/
diff --git a/lib/isc/include/isc/types.h b/lib/isc/include/isc/types.h
index dd60d76a20..03ada89a1c 100644
--- a/lib/isc/include/isc/types.h
+++ b/lib/isc/include/isc/types.h
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: types.h,v 1.49 2009/09/01 00:22:28 jinmei Exp $ */
+/* $Id: types.h,v 1.50 2009/09/01 18:40:25 jinmei Exp $ */
 
 #ifndef ISC_TYPES_H
 #define ISC_TYPES_H 1
@@ -43,6 +43,7 @@
 /* Core Types.  Alphabetized by defined type. */
 
 typedef struct isc_appctx		isc_appctx_t;	 	/*%< Application context */
+typedef struct isc_backtrace_symmap	isc_backtrace_symmap_t; /*%< Symbol Table Entry */
 typedef struct isc_bitstring		isc_bitstring_t; 	/*%< Bitstring */
 typedef struct isc_buffer		isc_buffer_t;		/*%< Buffer */
 typedef ISC_LIST(isc_buffer_t)		isc_bufferlist_t;	/*%< Buffer List */
diff --git a/make/rules.in b/make/rules.in
index 4191ef038f..2bd67556a7 100644
--- a/make/rules.in
+++ b/make/rules.in
@@ -13,7 +13,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: rules.in,v 1.67 2009/09/01 00:22:28 jinmei Exp $
+# $Id: rules.in,v 1.68 2009/09/01 18:40:25 jinmei Exp $
 
 ###
 ### Common Makefile rules for BIND 9.
@@ -136,12 +136,83 @@ PURIFY = @PURIFY@
 
 MKDEP = ${SHELL} ${top_builddir}/make/mkdep
 
+###
+### This is a template compound command to build an executable binary with
+### an internal symbol table.
+### This process is tricky.  We first link all objects including a tentative
+### empty symbol table, then get a tentative list of symbols from the resulting
+### binary ($@tmp0).  Next, we re-link all objects, but this time with the
+### symbol table just created ($tmp@1).  The set of symbols should be the same,
+### but the corresponding addresses would be changed due to the difference on
+### the size of symbol tables.  So we create the symbol table and re-create the
+### objects once again.  Finally, we check the symbol table embedded in the
+### final binaryis consistent with the binary itself; otherwise the process is
+### terminated.
+###
+### To minimize the overhead of creating symbol tables, the autoconf switch
+### --enable-symtable takes an argument so that the symbol table can be created
+### on a per application basis: unless the argument is set to "all", the symbol
+### table is created only when a shell (environment) variable "MAKE_SYMTABLE" is
+### set to a non-null value in the rule to build the executable binary.
+###
+### Each Makefile.in that uses this macro is expected to define "LIBS" and
+### "NOSYMLIBS"; the former includes libisc with an empty symbol table, and
+### the latter includes libisc without the definition of a symbol table.
+### The rule to make the executable binary will look like this
+### binary@EXEEXT@: ${OBJS}
+###     #export MAKE_SYMTABLE="yes"; \  <- enable if symtable is always needed
+###	export BASEOBJS="${OBJS}"; \
+###	${FINALBUILDCMD}
+###
+### Normally, ${LIBS} includes all necessary libraries to build the binary;
+### there are some exceptions however, where the rule lists some of the
+### necessary libraries explicitly in addition to (or instead of) ${LIBS},
+### like this:
+### binary@EXEEXT@: ${OBJS}
+###     cc -o $@ ${OBJS} ${OTHERLIB1} ${OTHERLIB2} ${lIBS}
+### in order to modify such a rule to use this compound command, a separate
+### variable "LIBS0" should be deinfed for the explicitly listed libraries,
+### while making sure ${LIBS} still includes libisc.  So the above rule would
+### be modified as follows:
+### binary@EXEEXT@: ${OBJS}
+###	export BASEOBJS="${OBJS}"; \
+###	export LIBS0="${OTHERLIB1} ${OTHERLIB2}"; \
+###     ${FINALBUILDCMD}
+### See bin/check/Makefile.in for a complete example of the use of LIBS0.
+###
+FINALBUILDCMD = if [ X"${MKSYMTBL_PROGRAM}" = X -o X"$${MAKE_SYMTABLE:-${ALWAYS_MAKE_SYMTABLE}}" = X ] ; then \
+		${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} \
+		-o $@ $${BASEOBJS} $${LIBS0} ${LIBS}; \
+	else \
+		rm -f $@tmp0; \
+		${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} \
+		-o $@tmp0 $${BASEOBJS} $${LIBS0} ${LIBS} || exit 1; \
+		rm -f $@-symtbl.c $@-symtbl.@O@; \
+		${MKSYMTBL_PROGRAM} ${top_srcdir}/util/mksymtbl.pl \
+		-o $@-symtbl.c $@tmp0 || exit 1; \
+		$(MAKE) $@-symtbl.@O@ || exit 1; \
+		rm -f $@tmp1; \
+		${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} \
+		-o $@tmp1 $${BASEOBJS} $@-symtbl.@O@ $${LIBS0} ${NOSYMLIBS} || exit 1; \
+		rm -f $@-symtbl.c $@-symtbl.@O@; \
+		${MKSYMTBL_PROGRAM} ${top_srcdir}/util/mksymtbl.pl \
+		-o $@-symtbl.c $@tmp1 || exit 1; \
+		$(MAKE) $@-symtbl.@O@ || exit 1; \
+		${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} \
+		-o $@tmp2 $${BASEOBJS} $@-symtbl.@O@ $${LIBS0} ${NOSYMLIBS}; \
+		${MKSYMTBL_PROGRAM} ${top_srcdir}/util/mksymtbl.pl \
+		-o $@-symtbl2.c $@tmp2; \
+		diff $@-symtbl.c $@-symtbl2.c || exit 1;\
+		mv $@tmp2 $@; \
+		rm -f $@tmp0 $@tmp1 $@tmp2 $@-symtbl2.c; \
+	fi
+
 cleandir: distclean
 superclean: maintainer-clean
 
 clean distclean maintainer-clean::
-	rm -f *.@O@ *.o *.lo *.la core *.core .depend
-	rm -rf .libs
+	rm -f *.@O@ *.o *.lo *.la core *.core *-symtbl.c *tmp0 *tmp1 *tmp2
+	rm -rf .depend .libs
 
 distclean maintainer-clean::
 	rm -f Makefile
@@ -218,6 +289,16 @@ LATEX =			@LATEX@
 PDFLATEX =		@PDFLATEX@
 W3M =			@W3M@
 
+###
+### Script language program used to create internal symbol tables
+###
+MKSYMTBL_PROGRAM =	@MKSYMTBL_PROGRAM@
+
+###
+### Switch to create internal symbol table selectively
+###
+ALWAYS_MAKE_SYMTABLE =	@ALWAYS_MAKE_SYMTABLE@
+
 ###
 ### DocBook -> HTML
 ### DocBook -> man page