Build shared libraries using Visual Studio

[madebr]

The Visual Studio makefile does not support building shared libraries.

libtommath/makefile.msvc

Line 20 in 44ee82c

#Libraries to be created (this makefile builds only static libraries)

Would a patch adding this be accepted?

[sjaeckel]

sure!

hint: it will be accepted even faster if the PR also adds corresponding CI jobs

ping @karel-m ping @nijtmans

I'm closing this and wait for the PR!

[madebr]

I will open one in the coming days.
I suppose the exports in tommath.def will be kept up to date?

[madebr]

Creating the implib+dll is not hard, but linking the test to the dll is harder.
After adding some missing exports to tommath.def, linking the test to the dll fails.
This is because the test is using private symbols.

        cl /nologo /I./ /D_CRT_SECURE_NO_WARNINGS /D_CRT_NONSTDC_NO_DEPRECATE /D__STDC_WANT_SECURE_LIB__=1 /D_CRT_HAS_CXX17=0 /Wall /wd4146 /wd4127 /wd4668 /wd4710 /wd4711 /wd4820 /wd5045 /WX /Ox  tommath.dll.lib  advapi32.lib demo/shared.c demo/test.c /Fetest_dll.exe
shared.c
test.c
Generating Code...
test.obj : error LNK2019: unresolved external symbol s_mp_div_3 referenced in function very_random_source
test.obj : error LNK2019: unresolved external symbol s_mp_div_recursive referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_div_school referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_div_small referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_mul referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_mul_balance referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_mul_karatsuba referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_mul_toom referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_sqr referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_sqr_karatsuba referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_sqr_toom referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_radix_size_overestimate referenced in function s_rs
test.obj : error LNK2019: unresolved external symbol s_mp_rand_jenkins referenced in function very_random_source
test.obj : error LNK2019: unresolved external symbol s_mp_rand_jenkins_init referenced in function unit_tests
test.obj : error LNK2019: unresolved external symbol s_mp_rand_source referenced in function rand_long
test_dll.exe : fatal error LNK1120: 15 unresolved externals
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\HostX64\x64\cl.EXE"' : return code '0x2'
Stop.

@sjaeckel
Any advice about how to continue?
I will open a pr with my changes thus far.

[sjaeckel]

I see ... the tests of the private functions ... which isn't done at all for shared libraries ... well then no CI for this ;)

[madebr]

I see ... the tests of the private functions ... which isn't done at all for shared libraries ... well then no CI for this ;)

That's too bad, because linking the tests to the dll gave me a linking error about some missing exported symbols in the export file.

mp_rand_source
MP_MUL_KARATSUBA_CUTOFF
MP_SQR_KARATSUBA_CUTOFF
MP_MUL_TOOM_CUTOFF
MP_SQR_TOOM_CUTOFF

[sjaeckel]

Indeed it is ...

[madebr]

Splitting the tests could fix that, but that will be a lot of work.

[sjaeckel]

Splitting the tests could fix that, but that will be a lot of work.

#490 adds a testrun with the shared library in travis ... now we only need MSVC to be fixed ... or maybe use the correct options to compile the tests?!

[madebr]

@sjaeckel
You can simulate the behaviour of windows shared libraries by adding -fvisibility=hidden to CFLAGS and LDFLAGS on gcc/clang. Then, only the exported symbols are visible.

[sjaeckel]

The private symbols are hidden by default in the shared libraries!? No need to simulate anything.

$ make clean && make -j9  -f makefile.shared &>/dev/null
$ comm -3 <(nm --demangle --defined-only .libs/libtommath.a | cut -d ' ' -f 2- | grep '^[DRT]' | cut -d ' ' -f 2- | sort | uniq) <(nm -D --defined-only .libs/libtommath.so | cut -d ' ' -f 3- | sort | uniq)
s_mp_add
s_mp_copy_digs
s_mp_div_3
s_mp_div_recursive
s_mp_div_school
s_mp_div_small
s_mp_exptmod
s_mp_exptmod_fast
s_mp_get_bit
s_mp_invmod
s_mp_invmod_odd
s_mp_log
s_mp_log_2expt
s_mp_log_d
s_mp_montgomery_reduce_comba
s_mp_mul
s_mp_mul_balance
s_mp_mul_comba
s_mp_mul_high
s_mp_mul_high_comba
s_mp_mul_karatsuba
s_mp_mul_toom
s_mp_prime_is_divisible
s_mp_prime_tab
s_mp_radix_map
s_mp_radix_map_reverse
s_mp_radix_size_overestimate
s_mp_rand_platform
s_mp_rand_source
s_mp_sqr
s_mp_sqr_comba
s_mp_sqr_karatsuba
s_mp_sqr_toom
s_mp_sub
s_mp_zero_buf
s_mp_zero_digs