From 372d62d4e1738431d33c1318be1ee4305c74649d Mon Sep 17 00:00:00 2001
From: "David N. Welton" <davidw@dedasys.com>
Date: Mon, 15 Dec 2014 17:53:09 +0100
Subject: Do not accept Nan and Infinity values

Erlang does not accept these values, so we return an error in the C
interface rather than letting them through to the Erlang VM, which
rejects the message with a somewhat cryptic "bad external term".
---
 lib/erl_interface/configure.in               | 12 ++++++++++++
 lib/erl_interface/src/encode/encode_double.c | 12 ++++++++++++
 lib/erl_interface/src/legacy/erl_eterm.c     | 10 ++++++++++
 3 files changed, 34 insertions(+)

(limited to 'lib')

diff --git a/lib/erl_interface/configure.in b/lib/erl_interface/configure.in
index ef78f0f87b..076170c648 100644
--- a/lib/erl_interface/configure.in
+++ b/lib/erl_interface/configure.in
@@ -139,6 +139,18 @@ esac
 AC_CHECK_LIB([nsl], [gethostbyname])
 AC_CHECK_LIB([socket], [getpeername])
 
+AC_MSG_CHECKING([for isfinite])
+AC_TRY_LINK([#include <math.h>],
+            [isfinite(0);], have_isfinite=yes, have_isfinite=no),
+
+if test $have_isfinite = yes; then
+    AC_DEFINE(HAVE_ISFINITE,[1],
+              [Define to 1 if you have the `isfinite' function.])
+    AC_MSG_RESULT(yes)
+else
+    AC_MSG_RESULT(no)
+fi
+
 # Checks for header files.
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
diff --git a/lib/erl_interface/src/encode/encode_double.c b/lib/erl_interface/src/encode/encode_double.c
index 148a49f73a..a19a871eda 100644
--- a/lib/erl_interface/src/encode/encode_double.c
+++ b/lib/erl_interface/src/encode/encode_double.c
@@ -18,6 +18,9 @@
  */
 #include <stdio.h>
 #include <string.h>
+#if defined(HAVE_ISFINITE)
+#include <math.h>
+#endif
 #include "eidef.h"
 #include "eiext.h"
 #include "putget.h"
@@ -27,6 +30,15 @@ int ei_encode_double(char *buf, int *index, double p)
   char *s = buf + *index;
   char *s0 = s;
 
+  /* Erlang does not handle Inf and NaN, so we return an error rather
+   * than letting the Erlang VM complain about a bad external
+   * term. */
+#if defined(HAVE_ISFINITE)
+  if(!isfinite(p)) {
+      return -1;
+  }
+#endif
+
   if (!buf)
     s += 9;
   else {
diff --git a/lib/erl_interface/src/legacy/erl_eterm.c b/lib/erl_interface/src/legacy/erl_eterm.c
index 636d26b24b..c167fd1f78 100644
--- a/lib/erl_interface/src/legacy/erl_eterm.c
+++ b/lib/erl_interface/src/legacy/erl_eterm.c
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <math.h>
 
 #include "ei_locking.h"
 #include "ei_resolve.h"
@@ -125,6 +126,15 @@ ETERM *erl_mk_float (double d)
 {
     ETERM *ep;
 
+    /* Erlang does not handle Inf and NaN, so we return an error
+     * rather than letting the Erlang VM complain about a bad external
+     * term. */
+    switch(fpclassify(d)) {
+        case FP_NAN:
+        case FP_INFINITE:
+            return NULL;
+    }
+
     ep = erl_alloc_eterm(ERL_FLOAT);
     ERL_COUNT(ep) = 1;
     ERL_FLOAT_VALUE(ep) = d;
-- 
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