[erlang-questions] Problem with binary_to_term on different machines

Sverker Eriksson sverker.eriksson@REDACTED
Fri Jan 20 17:17:41 CET 2017

This is indeed a problem in Erlang VM code (shallow copy of inflate state)
that has existed since R16B03, but not caused actual problem until zlib 

Fix coming up. Here is a preliminary patch for the impatient.

diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index beed847..1c4fff5 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -1431,6 +1431,10 @@ static B2TContext* b2t_export_context(Process* p, 
B2TContext* src)
      if (ctx->state >= B2TDecode && ctx->u.dc.next == &src->u.dc.res) {
          ctx->u.dc.next = &ctx->u.dc.res;
+    else if (ctx->state == B2TUncompressChunk) {
+        int cres = inflateCopy(&ctx->u.uc.stream, &src->u.uc.stream);
+        ASSERT(cres == Z_OK); (void)cres;
+    }
      hp = HAlloc(p, PROC_BIN_SIZE);
      ctx->trap_bin = erts_mk_magic_binary_term(&hp, &MSO(p), context_b);
      return ctx;

/Sverker, Erlang/OTP

On 01/19/2017 04:14 AM, Michel Boaventura wrote:
> Hi all,
> I've build erlang 19 from scratch on my gentoo machine but can't use
> dialyzer, because it complains my beam files weren't compiled with
> debug_info.
> I've read and debugged a log of dialyzer and erlang code and find out the
> issue is that for some reason erlang can't parse the abstract part of the
> files.
> To check this I save the abstract part on a file and tried to parse it on
> my gentoo machine and on a Ubuntu server I have access. For some reason I
> don't know it reads with no problem Ubuntu but gives me an invalid arg on
> gentoo.
> I'm very new to erlang and have no clue of how to debug further. The binary
> is attached and I'm reading it like:
> {ok, [Binary]} = file:consult("Abstr").
> Term = binary_to_term(Binary).
> ps: I've sent a message similar to this one on this list, but since it was
> my first one I think it wasn't accepted (and I do apologize for the double
> post if you received it). But after it I've discovered the problem with
> binary_to_term, so that message isn't so useful anyway.
> _______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
> http://erlang.org/mailman/listinfo/erlang-questions

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