Update.

2004-09-17  Ulrich Drepper  <drepper@redhat.com>

	* include/link.h (struct link_map): Add l_used element.
	* sysdeps/generic/ldsodefs.h: Define DL_DEBUG_UNUSED.
	* elf/rtld.c (process_dl_debug): Recognize unused.
	(dl_main): When unused debug flag is set check for unused direct
	dependencies.
	When printing dependencies and SONAME starts with /, omit the SONAME =>
	part.
	* elf/dl-lookup.c (_dl_lookup_symbol_x): Mark object in which the
	symbol has been found as used.
	* elf/ldd.bash.in: Add -u option.

3 files changed, 54 insertions, 0 deletions

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 2b73da591a..d2a6976e4e 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -344,6 +344,9 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
 				  symbol_scope, version, type_class,
 				  flags, skip_map);
 
+  /* The object is used.  */
+  current_value.m->l_used = 1;
+
   if (__builtin_expect (GLRO(dl_debug_mask)
 			& (DL_DEBUG_BINDINGS|DL_DEBUG_PRELINK), 0))
     _dl_debug_bindings (undef_name, undef_map, ref, symbol_scope,
diff --git a/elf/ldd.bash.in b/elf/ldd.bash.in
index 8867211109..6ee9b60e51 100644
--- a/elf/ldd.bash.in
+++ b/elf/ldd.bash.in
@@ -50,6 +50,7 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       --version           print version information and exit
   -d, --data-relocs       process data relocations
   -r, --function-relocs   process data and function relocations
+  -u, --unused            print unused direct dependencies
   -v, --verbose           print all information
 For bug reporting instructions, please see:
 <http://www.gnu.org/software/libc/bugs.html>."
@@ -71,6 +72,9 @@ For bug reporting instructions, please see:
     verbose=yes
     shift
     ;;
+  -u | --u | --un | --unu | --unus | --unuse | --unused)
+    unused=yes
+    shift
   --v | --ve | --ver)
     echo >&2 $"ldd: option \`$1' is ambiguous"
     exit 1
@@ -97,6 +101,9 @@ nonelf ()
 
 add_env="LD_TRACE_LOADED_OBJECTS=1 LD_WARN=$warn LD_BIND_NOW=$bind_now"
 add_env="$add_env LD_VERBOSE=$verbose"
+if test "$unused" = yes; then
+  add_env="$add_env LD_DEBUG="$LD_DEBUG${LD_DEBUG:+,}unused"
+fi
 case $# in
 0)
   echo >&2 'ldd:' $"missing file arguments"
diff --git a/elf/rtld.c b/elf/rtld.c
index e015477c19..93c45311d4 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1526,6 +1526,44 @@ cannot allocate TLS data structures for initial thread");
 		_dl_printf ("\n");
 	    }
 	}
+      else if (GLRO(dl_debug_mask) & DL_DEBUG_UNUSED)
+	{
+	  /* Look through the dependencies of the main executable
+	     and determine which of them is not actually
+	     required.  */
+	  struct link_map *l = GL(dl_loaded);
+
+	  /* Relocate the main executable.  */
+	  struct relocate_args args = { .l = l, .lazy = GLRO(dl_lazy) };
+	  _dl_receive_error (print_unresolved, relocate_doit, &args);
+
+	  /* This loop depends on the dependencies of the executable to
+	     correspond in number and order to the DT_NEEDED entries.  */
+	  ElfW(Dyn) *dyn = GL(dl_loaded)->l_ld;
+	  bool first = true;
+	  while (dyn->d_tag != DT_NULL)
+	    {
+	      if (dyn->d_tag == DT_NEEDED)
+		{
+		  l = l->l_next;
+
+		  if (!l->l_used)
+		    {
+		      if (first)
+			{
+			  _dl_printf ("Unused direct dependencies:\n");
+			  first = false;
+			}
+
+		      _dl_printf ("\t%s\n", l->l_name);
+		    }
+		}
+
+	      ++dyn;
+	    }
+
+	  _exit (first != true);
+	}
       else if (! GL(dl_loaded)->l_info[DT_NEEDED])
 	_dl_printf ("\tstatically linked\n");
       else
@@ -1534,6 +1572,10 @@ cannot allocate TLS data structures for initial thread");
 	    if (l->l_faked)
 	      /* The library was not found.  */
 	      _dl_printf ("\t%s => not found\n", l->l_libname->name);
+	    else if (l->l_libname->name[0] == '/')
+	      _dl_printf ("\t%s (0x%0*Zx)\n", l->l_libname->name,
+			  (int) sizeof l->l_map_start * 2,
+			  (size_t) l->l_map_start);
 	    else
 	      _dl_printf ("\t%s => %s (0x%0*Zx)\n", l->l_libname->name,
 			  l->l_name, (int) sizeof l->l_map_start * 2,
@@ -1962,6 +2004,8 @@ process_dl_debug (const char *dl_debug)
 	| DL_DEBUG_BINDINGS | DL_DEBUG_VERSIONS | DL_DEBUG_IMPCALLS },
       { LEN_AND_STR ("statistics"), "display relocation statistics",
 	DL_DEBUG_STATISTICS },
+      { LEN_AND_STR ("unused"), "determined unused DSOs",
+	DL_DEBUG_UNUSED },
       { LEN_AND_STR ("help"), "display this help message and exit",
 	DL_DEBUG_HELP },
     };