From 8203c955c8bde94bba609d20abb39c576acf3e38 Mon Sep 17 00:00:00 2001
From: Tommi Rantala <tt.rantala@gmail.com>
Date: Fri, 31 Aug 2012 11:29:26 +0300
Subject: [PATCH] Change test-varargs to check libunwind backtracing

test-varargs is checking how `backtrace()' provided by the system
behaves when varargs are used. Let's make the test more useful by
changing it to test the `backtrace()' provided by libunwind.

Change the testcase to return 0/1 for success/failure, and add it to the
set of checks, so that it gets run on `make check'. Also call
`unw_backtrace()' explicitly so that we do not need to bother with
`execinfo.h' and `backtrace()' prototype.
---
 configure.in         |  2 --
 tests/Makefile.am    |  6 +++---
 tests/test-varargs.c | 45 ++++++++++++++++++++++++++++++++++++--------
 3 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/configure.in b/configure.in
index f577bc71..0a7577b6 100644
--- a/configure.in
+++ b/configure.in
@@ -303,7 +303,6 @@ old_LIBS="$LIBS"
 LIBS=""
 AC_SEARCH_LIBS(backtrace, execinfo)
 AM_CONDITIONAL(HAVE_BACKTRACE, test "x$ac_cv_search_backtrace" != xno)
-BACKTRACELIB="$LIBS"
 LIBS="$old_LIBS"
 
 AC_SUBST(build_arch)
@@ -319,7 +318,6 @@ AC_SUBST(PKG_MAINTAINER)
 AC_SUBST(enable_cxx_exceptions)
 AC_SUBST(enable_debug_frame)
 AC_SUBST(DLLIB)
-AC_SUBST(BACKTRACELIB)
 
 AC_CONFIG_FILES(Makefile src/Makefile tests/Makefile tests/check-namespace.sh
 		doc/Makefile doc/common.tex include/libunwind-common.h
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 987f22b1..c96d8a58 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -46,13 +46,13 @@ endif #ARCH_IA64
 			Gtest-dyn1 Ltest-dyn1				 \
 			Gtest-trace Ltest-trace				 \
 			test-async-sig test-flush-cache test-init-remote \
-			test-mem test-setjmp test-ptrace		 \
+			test-mem test-setjmp test-ptrace test-varargs	 \
 			Ltest-nomalloc Ltest-nocalloc rs-race
  noinst_PROGRAMS_cdep = forker crasher mapper test-ptrace-misc		 \
 			Gperf-simple Lperf-simple
 
 if HAVE_BACKTRACE
- noinst_PROGRAMS_cdep += Gperf-trace Lperf-trace test-varargs
+ noinst_PROGRAMS_cdep += Gperf-trace Lperf-trace
 endif
 
 if SUPPORT_CXX_EXCEPTIONS
@@ -148,7 +148,7 @@ test_proc_info_LDADD = $(LIBUNWIND)
 test_static_link_LDADD = $(LIBUNWIND)
 test_strerror_LDADD = $(LIBUNWIND)
 rs_race_LDADD = $(LIBUNWIND) -lpthread
-test_varargs_LDADD = @BACKTRACELIB@
+test_varargs_LDADD = $(LIBUNWIND_local)
 
 Gtest_bt_LDADD = $(LIBUNWIND) $(LIBUNWIND_local)
 Gtest_concurrent_LDADD = $(LIBUNWIND) $(LIBUNWIND_local) -lpthread
diff --git a/tests/test-varargs.c b/tests/test-varargs.c
index 9366461e..bf5cee30 100644
--- a/tests/test-varargs.c
+++ b/tests/test-varargs.c
@@ -1,28 +1,44 @@
+#include <libunwind.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
-extern int backtrace (void **, int);
+int ok;
+int verbose;
 
-static void
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 3)
+void a (int, ...) __attribute__((noinline, optimize(0)));
+void b (void) __attribute__((noinline, optimize(0)));
+void c (void) __attribute__((noinline, optimize(0)));
+#endif
+
+void
 b (void)
 {
   void *v[20];
   int i, n;
 
-  n = backtrace(v, 20);
-  for (i = 0; i < n; ++i)
-    printf ("[%d] %p\n", i, v[i]);
+  n = unw_backtrace(v, 20);
+
+  /* Check that the number of addresses given by unw_backtrace() looks
+   * reasonable. If the compiler inlined everything, then this check will also
+   * break. */
+  if (n >= 7)
+    ok = 1;
+
+  if (verbose)
+    for (i = 0; i < n; ++i)
+      printf ("[%d] %p\n", i, v[i]);
 }
 
-static void
+void
 c (void)
 {
     b ();
 }
 
-static void
+void
 a (int d, ...)
 {
   switch (d)
@@ -45,8 +61,21 @@ a (int d, ...)
 }
 
 int
-main (void)
+main (int argc, char **argv __attribute__((unused)))
 {
+  if (argc > 1)
+    verbose = 1;
+
   a (5, 3, 4, 5, 6);
+
+  if (!ok)
+    {
+      fprintf (stderr, "FAILURE: expected deeper backtrace.\n");
+      return 1;
+    }
+
+  if (verbose)
+    printf ("SUCCESS.\n");
+
   return 0;
 }