Fix BN_ext_get_uint64 for OpenSSL >= 1.1 32bit

Origin: upstream
Bug: https://github.com/google/s2geometry/pull/183
Forwarded: no
Reviewed-by: Étienne Mollier <emollier@debian.org>
Last-Update: 2021-10-04

Suggested changes fix compilation error with OpenSSL >= 1.0 for 32bit target.
The algorithm is similar to what is currently being done in BN_ext_set_uint64,
but in the opposite direction.
Last-Update: 2021-10-04
Gbp-Pq: Name fix-ftbfs-on-32bit.patch

diff --git a/src/s2/util/math/exactfloat/exactfloat.cc b/src/s2/util/math/exactfloat/exactfloat.cc
index 2300ea02d6426cb1fa5867b9ad3708eb4cf51ce9..f98f8ba9a9079220f3bc2896fe18c089fd0e6797 100644 (file)
--- a/src/s2/util/math/exactfloat/exactfloat.cc
+++ b/src/s2/util/math/exactfloat/exactfloat.cc
@@ -93,6 +93,8 @@ inline static void BN_ext_set_uint64(BIGNUM* bn, uint64 v) {
 #endif
 }
 
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
 // Return the absolute value of a BIGNUM as a 64-bit unsigned integer.
 // Requires that BIGNUM fits into 64 bits.
 inline static uint64 BN_ext_get_uint64(const BIGNUM* bn) {
@@ -108,8 +110,6 @@ inline static uint64 BN_ext_get_uint64(const BIGNUM* bn) {
 #endif
 }
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L
-
 // Count the number of low-order zero bits in the given BIGNUM (ignoring its
 // sign).  Returns 0 if the argument is zero.
 static int BN_ext_count_low_zero_bits(const BIGNUM* bn) {
@@ -130,6 +130,22 @@ static int BN_ext_count_low_zero_bits(const BIGNUM* bn) {
 
 #else  // OPENSSL_VERSION_NUMBER >= 0x10100000L
 
+// Return the absolute value of a BIGNUM as a 64-bit unsigned integer.
+// Requires that BIGNUM fits into 64 bits.
+inline static uint64 BN_ext_get_uint64(const BIGNUM* bn) {
+  uint64 r;
+#ifdef IS_LITTLE_ENDIAN
+  S2_CHECK_EQ(BN_bn2lebinpad(bn, reinterpret_cast<unsigned char*>(&r),
+              sizeof(r)), sizeof(r));
+#elif IS_BIG_ENDIAN
+  S2_CHECK_EQ(BN_bn2binpad(bn, reinterpret_cast<unsigned char*>(&r),
+              sizeof(r)), sizeof(r));
+#else
+#error one of IS_LITTLE_ENDIAN or IS_BIG_ENDIAN should be defined!
+#endif
+  return r;
+}
+
 static int BN_ext_count_low_zero_bits(const BIGNUM* bn) {
   // In OpenSSL >= 1.1, BIGNUM is an opaque type, so d and top
   // cannot be accessed.  The bytes must be copied out at a ~25%