Simplify _dl_find_symbol(). Currently, it returns three values:

 - the symbol it found, returned via the second argument
 - the base offset of the the object it was found in, via the return value
 - optionally: the object it was found in, returned via the last argument

Instead, return a struct with the symbol and object pointers and let the
caller get the base offset from the object's obj_base member.  On at least
aarch64, amd64, mips64, powerpc, and sparc64, a two word struct like this
is passed in registers.

ok mpi@, kettenis@

1 files changed, 20 insertions, 26 deletions

diff --git a/libexec/ld.so/loader.c b/libexec/ld.so/loader.c
index e7b4e031b54..918c299aa61 100644
--- a/libexec/ld.so/loader.c
+++ b/libexec/ld.so/loader.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: loader.c,v 1.183 2019/07/21 03:54:16 guenther Exp $ */
+/*	$OpenBSD: loader.c,v 1.184 2019/08/04 23:51:45 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -847,6 +847,23 @@ _dl_unsetenv(const char *var, char **env)
 	}
 }
 
+static inline void
+fixup_sym(struct elf_object *dummy_obj, const char *name, void *addr)
+{
+	struct sym_res sr;
+
+	sr = _dl_find_symbol(name, SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT,
+	    NULL, dummy_obj);
+	if (sr.sym != NULL) {
+		void *p = (void *)(sr.sym->st_value + sr.obj->obj_base);
+		if (p != addr) {
+			DL_DEB(("setting %s %p@%s[%p] from %p\n", name,
+			    p, sr.obj->load_name, (void *)sr.obj, addr));
+			*(void **)p = *(void **)addr;
+		}
+	}
+}
+
 /*
  * _dl_fixup_user_env()
  *
@@ -856,35 +873,12 @@ _dl_unsetenv(const char *var, char **env)
 void
 _dl_fixup_user_env(void)
 {
-	const struct elf_object *obj;
-	const Elf_Sym *sym;
-	Elf_Addr ooff;
 	struct elf_object dummy_obj;
 
 	dummy_obj.dyn.symbolic = 0;
 	dummy_obj.load_name = "ld.so";
-
-	sym = NULL;
-	ooff = _dl_find_symbol("environ", &sym,
-	    SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT, NULL, &dummy_obj, &obj);
-	if (sym != NULL) {
-		DL_DEB(("setting environ %p@%s[%p] from %p\n",
-		    (void *)(sym->st_value + ooff), obj->load_name,
-		    (void *)obj, (void *)&environ));
-		if ((char ***)(sym->st_value + ooff) != &environ)
-			*((char ***)(sym->st_value + ooff)) = environ;
-	}
-
-	sym = NULL;
-	ooff = _dl_find_symbol("__progname", &sym,
-	    SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT, NULL, &dummy_obj, &obj);
-	if (sym != NULL) {
-		DL_DEB(("setting __progname %p@%s[%p] from %p\n",
-		    (void *)(sym->st_value + ooff), obj->load_name,
-		    (void *)obj, (void *)&__progname));
-		if ((char **)(sym->st_value + ooff) != &__progname)
-			*((char **)(sym->st_value + ooff)) = __progname;
-	}
+	fixup_sym(&dummy_obj, "environ", &environ);
+	fixup_sym(&dummy_obj, "__progname", &__progname);
 }
 
 const void *