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, 19 insertions, 0 deletions

diff --git a/erts/emulator/test/binary_SUITE.erl b/erts/emulator/test/binary_SUITE.erl
index 401b3c23b6..67f0ae9408 100644
--- a/erts/emulator/test/binary_SUITE.erl
+++ b/erts/emulator/test/binary_SUITE.erl
@@ -275,6 +275,25 @@ bad_list_to_binary(Config) when is_list(Config) ->
     ?line test_bad_bin(fun(X, Y) -> X*Y end),
     ?line test_bad_bin([1,fun(X) -> X + 1 end,2|fun() -> 0 end]),
     ?line test_bad_bin([fun(X) -> X + 1 end]),
+
+    %% Test iolists that do not fit in the address space.
+    %% Unfortunately, it would be too slow to test in a 64-bit emulator.
+    case erlang:system_info(wordsize) of
+	4 -> huge_iolists();
+	_ -> ok
+    end.
+
+huge_iolists() ->
+    FourGigs = 1 bsl 32,
+    ?line Sizes = [FourGigs+N || N <- lists:seq(0, 64)] ++
+	[1 bsl N || N <- lists:seq(33, 37)],
+    ?line Base = <<0:(1 bsl 20)/unit:8>>,
+    [begin
+	 L = build_iolist(Sz, Base),
+	 ?line {'EXIT',{system_limit,_}} = (catch list_to_binary([L])),
+	 ?line {'EXIT',{system_limit,_}} = (catch binary:list_to_bin([L])),
+	 ?line {'EXIT',{system_limit,_}} = (catch iolist_to_binary(L))
+	 end || Sz <- Sizes],
     ok.
 
 test_bad_bin(List) ->