From 34e2788ee8bdc075c997b5698fe55d0b1bdcfd86 Mon Sep 17 00:00:00 2001
From: Arne Goedeke <el@laramies.com>
Date: Fri, 11 Jan 2013 15:56:59 +0100
Subject: [PATCH] `%: add overflow checks
---
src/bignum.h | 10 ++++++++++
src/operators.c | 46 +++++++++++++++++++++++++++++++++++-----------
src/testsuite.in | 2 ++
3 files changed, 47 insertions(+), 11 deletions(-)
diff --git a/src/bignum.h b/src/bignum.h
index 4e4f326216..cfbb024625 100644
--- a/src/bignum.h
+++ b/src/bignum.h
@@ -167,6 +167,16 @@ static INLINE int type ## _SUB_OVERFLOW(type a, type b) { \
int of = 0; \
DO_ ## type ## _SUB_OVERFLOW(a, b, &of); \
return of; \
+} \
+static INLINE int type ## _MOD_OVERFLOW(type a, type b) { \
+ return type ## _DIV_OVERFLOW(a, b); \
+} \
+static INLINE type DO_ ## type ## _MOD_OVERFLOW(type a, type b, int * of) { \
+ if (type ## _MOD_OVERFLOW(a, b)) { \
+ *of = 1; \
+ return 0; \
+ } \
+ return a % b; \
}
diff --git a/src/operators.c b/src/operators.c
index 7f94cb370e..32f1ca487b 100644
--- a/src/operators.c
+++ b/src/operators.c
@@ -4231,6 +4231,9 @@ PMOD_EXPORT void o_mod(void)
{
if(TYPEOF(sp[-2]) != TYPEOF(sp[-1]) && !float_promote())
{
+#ifdef AUTO_BIGNUM
+do_lfun_modulo:
+#endif
if(call_lfun(LFUN_MOD, LFUN_RMOD))
return;
@@ -4305,28 +4308,49 @@ PMOD_EXPORT void o_mod(void)
return;
}
case T_INT:
- if (sp[-1].u.integer == 0)
+ {
+ int of = 0;
+ INT_TYPE a = sp[-2].u.integer,
+ b = sp[-1].u.integer;
+ INT_TYPE res;
+ if (b == 0)
OP_MODULO_BY_ZERO_ERROR("`%");
- sp--;
- if(sp[-1].u.integer>=0)
+ if(a>=0)
{
- if(sp[0].u.integer>=0)
+ if(b>=0)
{
- sp[-1].u.integer %= sp[0].u.integer;
+ res = a % b;
}else{
- sp[-1].u.integer=((sp[-1].u.integer+~sp[0].u.integer)%-sp[0].u.integer)-~sp[0].u.integer;
+ /* res = ((a+~b)%-b)-~b */
+ res = DO_INT_TYPE_ADD_OVERFLOW(a, ~b, &of);
+ res = DO_INT_TYPE_MOD_OVERFLOW(res, b, &of);
+ res = DO_INT_TYPE_SUB_OVERFLOW(res, ~b, &of);
}
}else{
- if(sp[0].u.integer>=0)
+ if(b>=0)
{
- sp[-1].u.integer=sp[0].u.integer+~((~sp[-1].u.integer) % sp[0].u.integer);
+ /* res = b+~((~a) % b) */
+ res = DO_INT_TYPE_MOD_OVERFLOW(~a, b, &of);
+ res = DO_INT_TYPE_ADD_OVERFLOW(b, ~res, &of);
}else{
- sp[-1].u.integer=-(-sp[-1].u.integer % -sp[0].u.integer);
+ /* a % b and a % -b are equivalent, if overflow does not
+ * happen
+ * res = -(-a % -b) = a % b; */
+ res = DO_INT_TYPE_MOD_OVERFLOW(a, b, &of);
}
}
- SET_SVAL_SUBTYPE(sp[-1], NUMBER_NUMBER);
+#ifdef AUTO_BIGNUM
+ if (of) {
+ stack_swap();
+ convert_stack_top_to_bignum();
+ stack_swap();
+ goto do_lfun_modulo;
+ }
+#endif
+ sp--;
+ SET_SVAL(sp[-1], T_INT, NUMBER_NUMBER, integer, res);
return;
-
+ }
default:
PIKE_ERROR("`%", "Bad argument 1.\n", sp, 2);
}
diff --git a/src/testsuite.in b/src/testsuite.in
index f03d6f84fa..e6a656d430 100644
--- a/src/testsuite.in
+++ b/src/testsuite.in
@@ -8374,6 +8374,8 @@ test_eq(0 ? "a" : 0 ? "b" : 1 ? "c" : 1, "c")
// testing overflow checks
test_eq(-1 - 0x7fffffff, -0x80000000)
+test_eq(Int.NATIVE_MIN % -1, 0)
+test_eq(Int.NATIVE_MAX % Int.NATIVE_MIN, -1)
// testing indexing
test_eq("foo"[0],'f')
--
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