ld.so: add RTLD_LOCAL, RTLD_DEEPBIND notes + example

1 files changed, 23 insertions, 0 deletions

diff --git a/src/development/ldso/deepbind/lib.c b/src/development/ldso/deepbind/lib.c
new file mode 100644
index 0000000..e18a4ce
--- /dev/null
+++ b/src/development/ldso/deepbind/lib.c
@@ -0,0 +1,23 @@
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <stdio.h>
+
+#ifndef NAME
+#define NAME ""
+#endif
+
+void test() {
+  puts(NAME ":test()");
+
+  // Lookup next symbol from the libraries scope, which will search only in the
+  // libraries LOCAL scope, starting from the next object after the current one.
+  (void)dlsym(RTLD_NEXT, "next_lib" NAME);
+
+  // Global lookup from the libraries scope, which will search libraries in the
+  // GLOBAL scope and the libraries LOCAL scope. The order in which the scopes
+  // are searched depends on whether the library was loaded (a) with DEEPBIND or
+  // (b) not. whether this library was loaded with DEEPBIND). In the first case,
+  // the LOCAL scope is searched first, where in the latter, the GLOBAL scope is
+  // searched first.
+  (void)dlsym(RTLD_DEFAULT, "default_lib" NAME);
+}