Replace io_list_len() with erts_iolist_size()

The io_list_len() function returns an int, where a negative return
value indicates a type error. One problem is that an int only consists
of 32 bits in a 64-bit emulator. Changing the return type to Sint
will solve that problem, but in the 32-bit emulator, a large iolist
and a iolist with a type error will both return a negative number.
(Noticed by Jon Meredith.)

Another problem is that for iolists whose total size exceed the
word size, the result would be truncated, leading to a subsequent
buffer overflow and emulator crash.

Therefore, introduce the new erts_iolist_size() function which
returns a status indication and writes the result size through
a passed pointer. If the result size does not fit in a word,
return an overflow indication.

1 files changed, 5 insertions, 8 deletions

diff --git a/erts/emulator/beam/erl_bif_ddll.c b/erts/emulator/beam/erl_bif_ddll.c
index c9cdcb87a6..9631fb50db 100644
--- a/erts/emulator/beam/erl_bif_ddll.c
+++ b/erts/emulator/beam/erl_bif_ddll.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  * 
- * Copyright Ericsson AB 2006-2010. All Rights Reserved.
+ * Copyright Ericsson AB 2006-2011. All Rights Reserved.
  * 
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
@@ -146,7 +146,7 @@ BIF_RETTYPE erl_ddll_try_load_3(Process *p, Eterm path_term,
 				Eterm name_term, Eterm options)
 {
     char *path = NULL;
-    int path_len;
+    Uint path_len;
     char *name = NULL;
     DE_Handle *dh;
     erts_driver_t *drv;
@@ -221,9 +221,7 @@ BIF_RETTYPE erl_ddll_try_load_3(Process *p, Eterm path_term,
 	goto error;
     }
 
-    path_len = io_list_len(path_term);
-
-    if (path_len <= 0) {
+    if (erts_iolist_size(path_term, &path_len)) {
 	goto error;
     }
     path = erts_alloc(ERTS_ALC_T_DDLL_TMP_BUF, path_len + 1 /* might need path separator */ + sys_strlen(name) + 1);
@@ -1878,7 +1876,7 @@ static Eterm mkatom(char *str)
 static char *pick_list_or_atom(Eterm name_term)
 { 
     char *name = NULL;
-    int name_len;
+    Uint name_len;
     if (is_atom(name_term)) {
 	Atom *ap = atom_tab(atom_val(name_term));
 	if (ap->len == 0) {
@@ -1890,8 +1888,7 @@ static char *pick_list_or_atom(Eterm name_term)
 	memcpy(name,ap->name,ap->len);
 	name[ap->len] = '\0';
     } else {
-	name_len = io_list_len(name_term);
-	if (name_len <= 0) {
+	if (erts_iolist_size(name_term, &name_len)) {
 	    goto error;
 	}
 	name = erts_alloc(ERTS_ALC_T_DDLL_TMP_BUF, name_len + 1);