From 6f09971503f9bea177168d1599e925a5b22d18dd Mon Sep 17 00:00:00 2001
From: David 'Digit' Turner <digit@google.com>
Date: Wed, 21 Jul 2010 16:15:28 -0700
Subject: [PATCH] bionic: add a test for dlopen(NULL,...)

Change-Id: Iee8b33d1a046a71f5fd934912ee36371c1c9e8e5
---
 tests/bionic/libc/Android.mk                | 23 +++++++++++++++++-
 tests/bionic/libc/common/test_dlopen_null.c | 37 +++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tests/bionic/libc/common/test_dlopen_null.c

diff --git a/tests/bionic/libc/Android.mk b/tests/bionic/libc/Android.mk
index 48748508..10ed2027 100644
--- a/tests/bionic/libc/Android.mk
+++ b/tests/bionic/libc/Android.mk
@@ -32,10 +32,12 @@ define device-test
     $(eval LOCAL_MODULE := $(notdir $(file:%.c=%))) \
     $(eval LOCAL_MODULE := $(LOCAL_MODULE:%.cpp=%)) \
     $(eval LOCAL_CFLAGS += $(EXTRA_CFLAGS)) \
+    $(eval LOCAL_LDFLAGS += $(EXTRA_LDLIBS)) \
     $(eval LOCAL_MODULE_TAGS := tests) \
     $(eval include $(BUILD_EXECUTABLE)) \
   ) \
-  $(eval EXTRA_CFLAGS :=)
+  $(eval EXTRA_CFLAGS :=) \
+  $(eval EXTRA_LDLIBS :=)
 endef
 
 # same as 'device-test' but builds a host executable instead
@@ -82,6 +84,25 @@ EXTRA_CFLAGS := -D_XOPEN_SOURCE=600 -DHOST
 $(call host-test, $(sources))
 $(call device-test, $(sources))
 
+# The 'test_dlopen_null' tests requires specific linker flags
+#
+# The -Wl,--export-dynamic ensures that dynamic symbols are
+# exported from the executable.
+#
+# -Wl,-u,foo is used to ensure that symbol "foo" is not
+# garbage-collected by the gold linker, since the function
+# appears to be unused.
+#
+sources := common/test_dlopen_null.c \
+
+EXTRA_LDLIBS := -ldl -Wl,--export-dynamic -Wl,-u,foo
+EXTRA_CFLAGS := -DHOST
+$(call host-test, $(sources))
+
+EXTRA_LDLIBS := -ldl -Wl,--export-dynamic -Wl,-u,foo
+$(call device-test, $(sources))
+
+
 sources := \
     common/test_libgen.c \
 
diff --git a/tests/bionic/libc/common/test_dlopen_null.c b/tests/bionic/libc/common/test_dlopen_null.c
new file mode 100644
index 00000000..42b23dd3
--- /dev/null
+++ b/tests/bionic/libc/common/test_dlopen_null.c
@@ -0,0 +1,37 @@
+#include <dlfcn.h>
+#include <stddef.h>
+#include <stdio.h>
+
+extern int foo(void)
+{
+    return 42;
+}
+
+int (*func_ptr)(void) = foo;
+
+int main(void)
+{
+    void*  lib = dlopen(NULL, RTLD_NOW | RTLD_GLOBAL);
+    void*  symbol;
+
+#if 0
+    /* The Gold linker will garbage-collect unused global functions
+     * even if --Wl,--export-dynamic is used. So use a dummy global
+     * variable reference here to prevent this.
+     */
+    if (foo() != 42)
+        return 3;
+#endif
+
+    if (lib == NULL) {
+        fprintf(stderr, "Could not open self-executable with dlopen(NULL) !!: %s\n", dlerror());
+        return 1;
+    }
+    symbol = dlsym(lib, "foo");
+    if (symbol == NULL) {
+        fprintf(stderr, "Could not lookup symbol inside executable !!: %s\n", dlerror());
+        return 2;
+    }
+    dlclose(lib);
+    return 0;
+}
-- 
2.11.0