Import the DragonFly BSD commit 4f0bc915b65fcf5a23214f6d221d65c80be68ad4

by John Marino <draco@marino.st>, with the following (edited) commit
message
Date: Sat, 24 Mar 2012 06:40:50 +0100
Subject: [PATCH 1/1] rtld: Implement DT_RUNPATH and -z nodefaultlib

DT_RUNPATH is incorrectly being considered as an alias of DT_RPATH.  The
purpose of DT_RUNPATH is to have two different types of rpath: one that
can be overridden by the environment variable LD_LIBRARY_PATH and one that
can't.  With the currently implementation, LD_LIBRARY_PATH will always
trump any embedded rpath or runpath tags.

Current path search order by rtld:
==================================
LD_LIBRARY_PATH
DT_RPATH / DT_RUNPATH (always the same)
ldconfig hints file (default: /var/run/ld-elf.so.hints)
/usr/lib

New path search order by rtld:
==============================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file
/usr/lib

The new path search matches how the linux runtime loader works.  The other
major added feature is support for linker flag "-z nodefaultlib".  When
this flag is passed to the linker, rtld will skip all references to the
standard library search path ("/usr/lib" in this case but it could handle
more color delimited paths) except in DT_RPATH and DT_RUNPATH.

New path search order by rtld with -z nodefaultlib flag set:
============================================================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file (skips all references to /usr/lib)

FreeBSD notes:
- we fixed some bugs which were submitted to DragonFly and merged there
  as commit 1ff8a2bd3eb6e5587174c6a983303ea3a79e0002;
- we added LD_LIBRARY_PATH_RPATH environment variable to switch to
  the previous behaviour of considering DT_RPATH a synonym for DT_RUNPATH;
- the FreeBSD default search path is /lib:/usr/lib and not /usr/lib.

Reviewed by:   kan
MFC after:     1 month
MFC note:      flip the ld_library_path_rpath default value for stable/9

1 files changed, 10 insertions, 0 deletions

diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h
index 47389fe..0aba7cd 100644
--- a/libexec/rtld-elf/rtld.h
+++ b/libexec/rtld-elf/rtld.h
@@ -222,6 +222,7 @@ typedef struct Struct_Obj_Entry {
     const Elf_Hashelt *chain_zero_gnu;	/* GNU hash table value array (Zeroed) */
 
     char *rpath;		/* Search path specified in object */
+    char *runpath;		/* Search path with different priority */
     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
     Needed_Entry *needed_filtees;
     Needed_Entry *needed_aux_filtees;
@@ -258,6 +259,7 @@ typedef struct Struct_Obj_Entry {
     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
     bool z_noopen : 1;		/* Do not load on dlopen */
     bool z_loadfltr : 1;	/* Immediately load filtees */
+    bool z_nodeflib : 1;	/* Don't search default library path */
     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. */
@@ -321,6 +323,14 @@ struct Struct_RtldLockState {
 	sigjmp_buf env;
 };
 
+struct fill_search_info_args {
+	int request;
+	unsigned int flags;
+	struct dl_serinfo *serinfo;
+	struct dl_serpath *serpath;
+	char *strspace;
+};
+
 /*
  * The pack of arguments and results for the symbol lookup functions.
  */