Make ldd(1) work when versioned dependency file is cannot be loaded.

Instead of aborting in locate_dependency(), propagate the error to
caller. The rtld startup function does the right thing with an error
from rtld_verify_versions(), depending on the mode of operation.

Reported by:	maho
In collaboration with:	kan
MFC after:	1 week

1 files changed, 13 insertions, 4 deletions

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 11ef847..ee97708 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -3704,10 +3704,17 @@ locate_dependency(const Obj_Entry *obj, const char *name)
     }
 
     for (needed = obj->needed;  needed != NULL;  needed = needed->next) {
-	if (needed->obj == NULL)
-	    continue;
-	if (object_match_name(needed->obj, name))
-	    return needed->obj;
+	if (strcmp(obj->strtab + needed->name, name) == 0 ||
+	  (needed->obj != NULL && object_match_name(needed->obj, name))) {
+	    /*
+	     * If there is DT_NEEDED for the name we are looking for,
+	     * we are all set.  Note that object might not be found if
+	     * dependency was not loaded yet, so the function can
+	     * return NULL here.  This is expected and handled
+	     * properly in caller.
+	     */
+	    return (needed->obj);
+	}
     }
     _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
 	obj->path, name);
@@ -3833,6 +3840,8 @@ rtld_verify_object_versions(Obj_Entry *obj)
     vn = obj->verneed;
     while (vn != NULL) {
 	depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
+	if (depobj == NULL)
+	    return (-1);
 	vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
 	for (;;) {
 	    if (check_object_provided_version(obj, depobj, vna))