From 12b25c01ba0fbe7706bada2519c28193d73f7061 Mon Sep 17 00:00:00 2001
From: Alex Shinn <ashinn@users.noreply.github.com>
Date: Sun, 3 Aug 2014 20:45:26 +0900
Subject: [PATCH] Giving a proper OOM error on arithmetic-shift with a huge
 shift.

---
 bignum.c          | 12 ++++++++----
 lib/srfi/33/bit.c | 30 +++++++++++++++++-------------
 2 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/bignum.c b/bignum.c
index c80e3603..023bdfe1 100644
--- a/bignum.c
+++ b/bignum.c
@@ -19,15 +19,19 @@ static int hex_digit (int n) {
 sexp sexp_make_bignum (sexp ctx, sexp_uint_t len) {
   sexp_uint_t size = sexp_sizeof(bignum) + len*sizeof(sexp_uint_t);
   sexp res = sexp_alloc_tagged(ctx, size, SEXP_BIGNUM);
-  sexp_bignum_length(res) = len;
-  sexp_bignum_sign(res) = 1;
+  if (!sexp_exceptionp(res)) {
+    sexp_bignum_length(res) = len;
+    sexp_bignum_sign(res) = 1;
+  }
   return res;
 }
 
 sexp sexp_fixnum_to_bignum (sexp ctx, sexp a) {
   sexp res = sexp_make_bignum(ctx, 1);
-  sexp_bignum_data(res)[0] = sexp_unbox_fixnum(sexp_fx_abs(a));
-  sexp_bignum_sign(res) = sexp_fx_sign(a);
+  if (!sexp_exceptionp(res)) {
+    sexp_bignum_data(res)[0] = sexp_unbox_fixnum(sexp_fx_abs(a));
+    sexp_bignum_sign(res) = sexp_fx_sign(a);
+  }
   return res;
 }
 
diff --git a/lib/srfi/33/bit.c b/lib/srfi/33/bit.c
index 6e026238..b81f5d77 100644
--- a/lib/srfi/33/bit.c
+++ b/lib/srfi/33/bit.c
@@ -215,12 +215,14 @@ static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, s
         res = sexp_make_fixnum(sexp_bignum_sign(i) > 0 ? 0 : -1);
       } else {
         res = sexp_make_bignum(ctx, len - offset + 1);
-        sexp_bignum_sign(res) = sexp_bignum_sign(i);
-        for (j=len-offset-1, tmp=0; j>=0; j--) {
-          sexp_bignum_data(res)[j]
-            = (sexp_bignum_data(i)[j+offset] >> bit_shift)+ tmp;
-          tmp = sexp_bignum_data(i)[j+offset]
-            << (sizeof(sexp_uint_t)*CHAR_BIT-bit_shift);
+        if (!sexp_exceptionp(res)) {
+          sexp_bignum_sign(res) = sexp_bignum_sign(i);
+          for (j=len-offset-1, tmp=0; j>=0; j--) {
+            sexp_bignum_data(res)[j]
+              = (sexp_bignum_data(i)[j+offset] >> bit_shift)+ tmp;
+            tmp = sexp_bignum_data(i)[j+offset]
+              << (sizeof(sexp_uint_t)*CHAR_BIT-bit_shift);
+          }
         }
       }
     } else {
@@ -228,14 +230,16 @@ static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, s
       bit_shift = c - offset*(sizeof(sexp_uint_t)*CHAR_BIT);
       tail_shift = (sizeof(sexp_uint_t)*CHAR_BIT-bit_shift);
       res = sexp_make_bignum(ctx, len + offset + 1);
-      sexp_bignum_sign(res) = sexp_bignum_sign(i);
-      for (j=tmp=0; j<len; j++) {
-        sexp_bignum_data(res)[j+offset]
-          = (sexp_bignum_data(i)[j] << bit_shift) + tmp;
-        if (bit_shift != 0)
-          tmp = sexp_bignum_data(i)[j] >> tail_shift;
+      if (!sexp_exceptionp(res)) {
+        sexp_bignum_sign(res) = sexp_bignum_sign(i);
+        for (j=tmp=0; j<len; j++) {
+          sexp_bignum_data(res)[j+offset]
+            = (sexp_bignum_data(i)[j] << bit_shift) + tmp;
+          if (bit_shift != 0)
+            tmp = sexp_bignum_data(i)[j] >> tail_shift;
+        }
+        if (bit_shift != 0) sexp_bignum_data(res)[len+offset] = tmp;
       }
-      if (bit_shift != 0) sexp_bignum_data(res)[len+offset] = tmp;
     }
 #endif
   } else {