From e5693d4ccda7f1ac184f671d2001d2426cd9f721 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Fri, 7 Mar 2014 09:46:03 +0000
Subject: [PATCH] avoid large alloca on Complex/Rational calls

* complex.c (parse_comp): replace ALLOCA_N with ALLOCV_N/ALLOCV_END
* rational.c (read_digits): ditto

This fixes segfaults on:

	Rational("1" * 16 * 1024 * 1024)
	Complex("1" * 16 * 1024 * 1024)

On my system where my stack size is only 8M.
---
 complex.c  | 23 +++++++++++++++--------
 rational.c |  4 +++-
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/complex.c b/complex.c
index 3e9d631..c36d890 100644
--- a/complex.c
+++ b/complex.c
@@ -1774,19 +1774,26 @@ parse_comp(const char *s, int strict,
 	   VALUE *num)
 {
     char *buf, *b;
+    VALUE tmp;
+    int ret = 1;
 
-    buf = ALLOCA_N(char, strlen(s) + 1);
+    buf = ALLOCV_N(char, tmp, strlen(s) + 1);
     b = buf;
 
     skip_ws(&s);
-    if (!read_comp(&s, strict, num, &b))
-	return 0;
-    skip_ws(&s);
+    if (!read_comp(&s, strict, num, &b)) {
+	ret = 0;
+    }
+    else {
+	skip_ws(&s);
 
-    if (strict)
-	if (*s != '\0')
-	    return 0;
-    return 1;
+	if (strict)
+	    if (*s != '\0')
+		ret = 0;
+    }
+    ALLOCV_END(tmp);
+
+    return ret;
 }
 
 static VALUE
diff --git a/rational.c b/rational.c
index fe2d11e..a03fcd9 100644
--- a/rational.c
+++ b/rational.c
@@ -2167,13 +2167,14 @@ read_digits(const char **s, int strict,
 {
     char *b, *bb;
     int us = 1, ret = 1;
+    VALUE tmp;
 
     if (!isdecimal(**s)) {
 	*num = ZERO;
 	return 0;
     }
 
-    bb = b = ALLOCA_N(char, strlen(*s) + 1);
+    bb = b = ALLOCV_N(char, tmp, strlen(*s) + 1);
 
     while (isdecimal(**s) || **s == '_') {
 	if (**s == '_') {
@@ -2200,6 +2201,7 @@ read_digits(const char **s, int strict,
   conv:
     *b = '\0';
     *num = rb_cstr_to_inum(bb, 10, 0);
+    ALLOCV_END(tmp);
     return ret;
 }
 
-- 
1.9.rc1