[PATCH] ld.so: ldd crashes when __LDSO_SEARCH_INTERP_PATH__ is not #defined
Since b65c7b2c79debcb9017e31913e01eeaa280106fb, the implicit search path
can be disabled by not #defining __LDSO_SEARCH_INTERP_PATH__. This
causes _dl_ldsopath to never be set, so it remains NULL. _dl_ldsopath is
still used when __LDSO_LDD_SUPPORT__ is #defined, to strip the path off
of the beginning of the absolute path to the ld.so interpreter in use
for printing. The _dl_strlen will crash with a NULL argument.

Rather than relying on _dl_ldsopath, this change causes ldd to compute
the interpreter's basename directly.

glibc ld.so seems to print the full path to the interpreter without
any computed basename or =>. I personally prefer glibc's behavior, but
to preserve backwards compatibility with uClibc ld.so, the existing
format with the computed basename, =>, and full path is used here. This
enables simpler (and unchanged) text processing in a pipeline.

Signed-off-by: Mark Mentovai <mark at moxienet.com>
---
ldso/ldso/ldso.c |   12 +++++++++---
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -920,9 +920,15 @@
 #ifdef __LDSO_LDD_SUPPORT__
 	/* End of the line for ldd.... */
 	if (trace_loaded_objects) {
-		_dl_dprintf(1, "\t%s => %s (%x)\n",
-			    rpnt->dyn->libname + _dl_strlen(_dl_ldsopath) + 1,
-			    rpnt->dyn->libname, DL_LOADADDR_BASE(rpnt->dyn->loadaddr));
+		/* glibc ld.so/ldd would just do
+		 * _dl_dprintf(1, "\t%s (%x)\n", rpnt->dyn->libname,
+		 *	       DL_LOADADDR_BASE(rpnt->dyn->loadaddr));
+		 * but uClibc has always used the => format. */
+		char *ptmp = _dl_strrchr(rpnt->dyn->libname, '/');
+		if (ptmp != rpnt->dyn->libname)
+			++ptmp;
+		_dl_dprintf(1, "\t%s => %s (%x)\n", ptmp, rpnt->dyn->libname,
+			    DL_LOADADDR_BASE(rpnt->dyn->loadaddr));
 		_dl_exit(0);
 	}
 #endif
