compilation error because of deprecated BIGNUM functions in openssl 1.1

[akhenakh]

as of 8a8746c

compilation is failing on Arch because of openssl 1.1:

In file included from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29:0,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:516:10: error: field ‘bn_’ has incomplete type ‘BIGNUM {aka bignum_st}’
   BIGNUM bn_;
          ^~~
In file included from /usr/include/openssl/bn.h:32:0,
                 from /home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:119,
                 from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/usr/include/openssl/ossl_typ.h:80:16: note: forward declaration of ‘BIGNUM {aka struct bignum_st}’
 typedef struct bignum_st BIGNUM;
                ^~~~~~~~~
In file included from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29:0,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h: In constructor ‘ExactFloat::ExactFloat()’:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:576:3: error: ‘BN_init’ was not declared in this scope
   BN_init(&bn_);
   ^~~~~~~
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:576:3: note: suggested alternative: ‘BN_print’
   BN_init(&bn_);
   ^~~~~~~
   BN_print
make[2]: *** [CMakeFiles/s2.dir/build.make:879: CMakeFiles/s2.dir/src/s2/s2edge_crossings.cc.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:105: CMakeFiles/s2.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

BN_init() was removed in OpenSSL 1.1.0; use BN_new() instead.
source https://www.openssl.org/docs/man1.1.0/crypto/BN_new.html

Solution for Arch is:
cmake -DOPENSSL_INCLUDE_DIR="/usr/include/openssl-1.0" -DOPENSSL_SSL_LIBRARY=/usr/lib/openssl-1.0/libssl.so ..

It will become an issue for every distribution with recent openssl.

[jmr]

Ok, working on it.

[akhenakh]

in the meantime here is an AUR pkg for Arch https://aur.archlinux.org/packages/s2geometry-git

[jmr]

We're seeing a ~40% slowdown and 75% more allocs on some ExactFloat benchmarks with a simple BN_init -> BN_new fix. Do you know if there's an easy fix?

[akhenakh]

I don't, I've only tried this without any performance measurement:

BN_init() is no longer available as of OpenSSL 1.1.0. It was used to initialize an existing uninitialized BIGNUM. Typically this would be done as follows:

 BIGNUM a;
 BN_init(&a);

Applications should replace use of BN_init with BN_new instead:

 BIGNUM *a;
 a = BN_new();
 if(!a) /* Handle error */
 ...
 BN_free(a);

[jmr]

Can you put this before ExactFloat::ExactFloat in exactfloat.h and let me know if it works / what the error is?

#if defined(OPENSSL_API_COMPAT) && OPENSSL_API_COMPAT >= 0x10100000L
extern "C" void bn_init(BIGNUM *a);
#define BN_init bn_init
#endif

[akhenakh]

diff --git a/src/s2/util/math/exactfloat/exactfloat.h b/src/s2/util/math/exactfloat/exactfloat.h
index 050b75f..ab849d2 100644
--- a/src/s2/util/math/exactfloat/exactfloat.h
+++ b/src/s2/util/math/exactfloat/exactfloat.h
@@ -571,6 +571,10 @@ class ExactFloat {
 
 /////////////////////////////////////////////////////////////////////////
 // Implementation details follow:
+#if defined(OPENSSL_API_COMPAT) && OPENSSL_API_COMPAT >= 0x10100000L
+extern "C" void bn_init(BIGNUM *a);
+#define BN_init bn_init
+#endif
 
 inline ExactFloat::ExactFloat() : sign_(1), bn_exp_(kExpZero) {
   BN_init(&bn_);

In file included from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29:0,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:516:10: error: field ‘bn_’ has incomplete type ‘BIGNUM {aka bignum_st}’
   BIGNUM bn_;
          ^~~
In file included from /usr/include/openssl/bn.h:32:0,
                 from /home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:119,
                 from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/usr/include/openssl/ossl_typ.h:80:16: note: forward declaration of ‘BIGNUM {aka struct bignum_st}’
 typedef struct bignum_st BIGNUM;
                ^~~~~~~~~
In file included from /home/akh/tmp/s2geometry/src/s2/s2predicates_internal.h:29:0,
                 from /home/akh/tmp/s2geometry/src/s2/s2edge_crossings.cc:28:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h: In constructor ‘ExactFloat::ExactFloat()’:
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:580:3: error: ‘BN_init’ was not declared in this scope
   BN_init(&bn_);
   ^~~~~~~
/home/akh/tmp/s2geometry/src/s2/util/math/exactfloat/exactfloat.h:580:3: note: suggested alternative: ‘BN_print’
   BN_init(&bn_);
   ^~~~~~~
   BN_print
make[2]: *** [CMakeFiles/s2.dir/build.make:879: CMakeFiles/s2.dir/src/s2/s2edge_crossings.cc.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:105: CMakeFiles/s2.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

[jmr]

Ok, now there's support for both BN_init and BN_new, depending on the OpenSSL version.

[jmr]

@akhenakh Does this actually work for you with openssl 1.1? I'm seeing errors for bn->top and bn->d since BIGNUM is an incomplete type.

[mkatsevVR]

yup, also getting the same errors with 1.1

[jmr]

Now it should be working. Let me know if you find otherwise.

[mkatsevVR]

works for me now, thanks