Implement support -z global linker option. It marks the shared object

as always participating in the global symbols namespace, regardless of
the way the object was brought into the process address space.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

2 files changed, 31 insertions, 17 deletions

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 44b63a7..78f823c 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -1158,8 +1158,8 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
 		    obj->z_noopen = true;
 		if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
 		    obj->z_origin = true;
-		/*if (dynp->d_un.d_val & DF_1_GLOBAL)
-		    XXX ;*/
+		if (dynp->d_un.d_val & DF_1_GLOBAL)
+		    obj->z_global = true;
 		if (dynp->d_un.d_val & DF_1_BIND_NOW)
 		    obj->bind_now = true;
 		if (dynp->d_un.d_val & DF_1_NODELETE)
@@ -1790,22 +1790,35 @@ init_dag(Obj_Entry *root)
 }
 
 static void
-process_nodelete(Obj_Entry *root)
+process_z(Obj_Entry *root)
 {
 	const Objlist_Entry *elm;
+	Obj_Entry *obj;
 
 	/*
-	 * Walk over object DAG and process every dependent object that
-	 * is marked as DF_1_NODELETE. They need to grow their own DAG,
-	 * which then should have its reference upped separately.
+	 * Walk over object DAG and process every dependent object
+	 * that is marked as DF_1_NODELETE or DF_1_GLOBAL. They need
+	 * to grow their own DAG.
+	 *
+	 * For DF_1_GLOBAL, DAG is required for symbol lookups in
+	 * symlook_global() to work.
+	 *
+	 * For DF_1_NODELETE, the DAG should have its reference upped.
 	 */
 	STAILQ_FOREACH(elm, &root->dagmembers, link) {
-		if (elm->obj != NULL && elm->obj->z_nodelete &&
-		    !elm->obj->ref_nodel) {
-			dbg("obj %s nodelete", elm->obj->path);
-			init_dag(elm->obj);
-			ref_dag(elm->obj);
-			elm->obj->ref_nodel = true;
+		obj = elm->obj;
+		if (obj == NULL)
+			continue;
+		if (obj->z_nodelete && !obj->ref_nodel) {
+			dbg("obj %s -z nodelete", obj->path);
+			init_dag(obj);
+			ref_dag(obj);
+			obj->ref_nodel = true;
+		}
+		if (obj->z_global && objlist_find(&list_global, obj) == NULL) {
+			dbg("obj %s -z global", obj->path);
+			objlist_push_tail(&list_global, obj);
+			init_dag(obj);
 		}
 	}
 }
@@ -3044,13 +3057,13 @@ dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
 		initlist_add_objects(obj, &obj->next, &initlist);
 	    }
 	    /*
-	     * Process all no_delete objects here, given them own
-	     * DAGs to prevent their dependencies from being unloaded.
-	     * This has to be done after we have loaded all of the
-	     * dependencies, so that we do not miss any.
+	     * Process all no_delete or global objects here, given
+	     * them own DAGs to prevent their dependencies from being
+	     * unloaded.  This has to be done after we have loaded all
+	     * of the dependencies, so that we do not miss any.
 	     */
 	    if (obj != NULL)
-		process_nodelete(obj);
+		process_z(obj);
 	} else {
 	    /*
 	     * Bump the reference counts for objects on this DAG.  If
diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h
index d207a92..d75d0ab 100644
--- a/libexec/rtld-elf/rtld.h
+++ b/libexec/rtld-elf/rtld.h
@@ -264,6 +264,7 @@ typedef struct Struct_Obj_Entry {
     bool z_loadfltr : 1;	/* Immediately load filtees */
     bool z_interpose : 1;	/* Interpose all objects but main */
     bool z_nodeflib : 1;	/* Don't search default library path */
+    bool z_global : 1;		/* Make the object global */
     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
     bool init_scanned: 1;	/* Object is already on init list. */
     bool on_fini_list: 1;	/* Object is already on fini list. */