Test aliasing in |BN_add| and |BN_sub|.
Also update the documentation for |BN_sub|.
Change-Id: I544dbfc56f22844f6ca08e9e472ec13e76baf8c4
Reviewed-on: https://boringssl-review.googlesource.com/8592
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/crypto/bn/bn_test.cc b/crypto/bn/bn_test.cc
index 0c9d74e..6248aaa 100644
--- a/crypto/bn/bn_test.cc
+++ b/crypto/bn/bn_test.cc
@@ -312,6 +312,30 @@
return false;
}
+ // Test that the functions work when |r| and |a| point to the same |BIGNUM|,
+ // or when |r| and |b| point to the same |BIGNUM|. TODO: Test the case where
+ // all of |r|, |a|, and |b| point to the same |BIGNUM|.
+ if (!BN_copy(ret.get(), a.get()) ||
+ !BN_add(ret.get(), ret.get(), b.get()) ||
+ !ExpectBIGNUMsEqual(t, "A + B (r is a)", sum.get(), ret.get()) ||
+ !BN_copy(ret.get(), b.get()) ||
+ !BN_add(ret.get(), a.get(), ret.get()) ||
+ !ExpectBIGNUMsEqual(t, "A + B (r is b)", sum.get(), ret.get()) ||
+ !BN_copy(ret.get(), sum.get()) ||
+ !BN_sub(ret.get(), ret.get(), a.get()) ||
+ !ExpectBIGNUMsEqual(t, "Sum - A (r is a)", b.get(), ret.get()) ||
+ !BN_copy(ret.get(), a.get()) ||
+ !BN_sub(ret.get(), sum.get(), ret.get()) ||
+ !ExpectBIGNUMsEqual(t, "Sum - A (r is b)", b.get(), ret.get()) ||
+ !BN_copy(ret.get(), sum.get()) ||
+ !BN_sub(ret.get(), ret.get(), b.get()) ||
+ !ExpectBIGNUMsEqual(t, "Sum - B (r is a)", a.get(), ret.get()) ||
+ !BN_copy(ret.get(), b.get()) ||
+ !BN_sub(ret.get(), sum.get(), ret.get()) ||
+ !ExpectBIGNUMsEqual(t, "Sum - B (r is b)", a.get(), ret.get())) {
+ return false;
+ }
+
// Test with |BN_add_word| and |BN_sub_word| if |b| is small enough.
BN_ULONG b_word = BN_get_word(b.get());
if (!BN_is_negative(b.get()) && b_word != (BN_ULONG)-1) {
