git » libfiu » commit 633bd2a

diff --git a/preload/posix/Makefile b/preload/posix/Makefile
index 0b07f90..a45477a 100644
--- a/preload/posix/Makefile
+++ b/preload/posix/Makefile
@@ -81,8 +81,12 @@ build-needlibdl:
 # ia64 and alpha use libc.so.6.1), so find which one to use at build-time.
 # Please note that the argument to ldd *must* start with "./", otherwise some
 # "ldd"s won't work (for example, the one in FreeBSD 8.1).
+# To find out the soname, we build a dummy shared library against the libc,
+# and use ldd to extract the version. This shared library must actually use
+# something from libc, otherwise a smart compiler/linker (such as one using
+# --as-needed) might not link it against libc.
 build-libcsoname:
-	@$(CC) -x c /dev/null -lc -shared -o build-libccheck.so
+	@$(CC) build-libccheck.c -lc -shared -fPIC -o build-libccheck.so
 	@ldd ./build-libccheck.so | grep libc.so | awk '{ print $$1 }' > $@
 	@rm build-libccheck.so
 	@test "`cat $@`" != "" || \
diff --git a/preload/posix/build-libccheck.c b/preload/posix/build-libccheck.c
new file mode 100644
index 0000000..41fad24
--- /dev/null
+++ b/preload/posix/build-libccheck.c
@@ -0,0 +1,8 @@
+/* Dummy file used at build time to find out libc's soname.
+ * It must use something from libc. See the Makefile for details. */
+
+#include <stdio.h>
+
+int use_printf(void) {
+	return printf("I'm using libc\n");
+}