add Exiv2

[Crghilardi]

Add a build_tarballs.jl for the Exiv2 library

Tested locally on linux-gnu, linux-musl and mingw with no issues.

[Crghilardi]

I don't quite understand what is going on with the i686-linux-musl-cxx11 check, especially when the i686-linux-musl-cxx03 one passes?

[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o: In function `Exiv2::FileIo::write(Exiv2::BasicIo&) [clone .part.25] [clone .constprop.97]':
[19:28:21] basicio.cpp:(.text+0xa64): undefined reference to `__stack_chk_fail_local'
[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o: In function `Exiv2::RemoteIo::path[abi:cxx11]() const':
[19:28:21] basicio.cpp:(.text+0xc44): undefined reference to `__stack_chk_fail_local'
[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o: In function `Exiv2::FileIo::path[abi:cxx11]() const [clone .localalias.80]':
[19:28:21] basicio.cpp:(.text+0xd14): undefined reference to `__stack_chk_fail_local'
[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o: In function `Exiv2::FileIo::Impl::Impl(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
[19:28:21] basicio.cpp:(.text+0xf75): undefined reference to `__stack_chk_fail_local'
[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o: In function `Exiv2::FileIo::Impl::stat(Exiv2::FileIo::Impl::StructStat&) const':
[19:28:21] basicio.cpp:(.text+0x165c): undefined reference to `__stack_chk_fail_local'
[19:28:21] CMakeFiles/exiv2lib.dir/basicio.cpp.o:basicio.cpp:(.text+0x16f9): more undefined references to `__stack_chk_fail_local' follow
[19:28:21] collect2: error: ld returned 1 exit status

I tried adding a preferred_gcc version with 5,6,and 7 unsuccessfully (edit: also tried 8 and 9, didn't work....). I have also tried adding a -DBUILD_WITH_STACK_PROTECTOR flag with the same result.

The 0.27.4 release is listed as 499 commit behind master so I haven't been able to find any patches in master worth pulling out yet.

[giordano]

I don't quite understand what is going on with the i686-linux-musl-cxx11 check,

We've got the same issues with __stack_chk_fail_local in #845 and #3249, in both cases I think we ended up not going through that code path

especially when the i686-linux-musl-cxx03 one passes?

That uses GCC 4.8, the C++11 string ABI necessarily requires GCC 5 (well, 4.9 but we don't have it), maybe that's relevant

[Crghilardi]

So the issue came down to the addition of a -fstack-protector-strong flag in i686-linux-musl-cxx11 build from a series of check_cxx_compiler_flag statements that was not included in the cxx03 build. Apparently, gcc emits slightly different code for 32 bit stack stuff and musl takes a slightly different stance on how this should all be handled.

i686-linux-musl-cxx11 CMake output

[19:28:14] -- Performing Test HAS_FSTACK_CLASH_PROTECTION
[19:28:14] -- Performing Test HAS_FSTACK_CLASH_PROTECTION - Failed
[19:28:14] -- Performing Test HAS_FCF_PROTECTION
[19:28:14] -- Performing Test HAS_FCF_PROTECTION - Failed
[19:28:14] -- Performing Test HAS_FSTACK_PROTECTOR_STRONG
[19:28:15] -- Performing Test HAS_FSTACK_PROTECTOR_STRONG - Success


[19:28:16] -- CMAKE_CXX_STANDARD:
[19:28:16] --  --- Compiler flags --- 
[19:28:16] -- General:           
[19:28:16] 	 -fstack-protector-strong
[19:28:16] 	 -Wp,-D_GLIBCXX_ASSERTIONS
[19:28:16] 	 -Wp,-D_FORTIFY_SOURCE=2
[19:28:16] 	 -Wall
[19:28:16] 	 -Wcast-align
[19:28:16] 	 -Wpointer-arith
[19:28:16] 	 -Wformat-security
[19:28:16] 	 -Wmissing-format-attribute
[19:28:16] 	 -Woverloaded-virtual
[19:28:16] 	 -W

i686-linux-musl-cxx03 CMake output

[19:27:18] -- Performing Test HAS_FSTACK_CLASH_PROTECTION
[19:27:18] -- Performing Test HAS_FSTACK_CLASH_PROTECTION - Failed
[19:27:18] -- Performing Test HAS_FCF_PROTECTION
[19:27:18] -- Performing Test HAS_FCF_PROTECTION - Failed
[19:27:18] -- Performing Test HAS_FSTACK_PROTECTOR_STRONG
[19:27:18] -- Performing Test HAS_FSTACK_PROTECTOR_STRONG - Failed

[19:27:20] -- CMake Generator:   Unix Makefiles
[19:27:20] -- CMAKE_BUILD_TYPE:  Release
[19:27:20] -- Compiler info: GNU (/opt/bin/i686-linux-musl-libgfortran3-cxx03/i686-linux-musl-g++) ; version: 4.8.5
[19:27:20] -- CMAKE_CXX_STANDARD:
[19:27:20] --  --- Compiler flags --- 
[19:27:20] -- General:           
[19:27:20] 	 -Wp,-D_GLIBCXX_ASSERTIONS
[19:27:20] 	 -Wp,-D_FORTIFY_SOURCE=2
[19:27:20] 	 -Wall
[19:27:20] 	 -Wcast-align
[19:27:20] 	 -Wpointer-arith
[19:27:20] 	 -Wformat-security
[19:27:20] 	 -Wmissing-format-attribute
[19:27:20] 	 -Woverloaded-virtual
[19:27:20] 	 -W

[Crghilardi]

@giordano I was reading in this thread that this might be handled in some form by libssp (or -libssp_nonshared?). It looks like that gets disabled in the BB musl builds?. Am I understanding that correctly and we are disabling libssp for BB?

Edit: #739 related

[giordano]

Thanks for the great detective work! I think this is a good solution for the time being, also because i686-linux-musl is the only platform for which Julia doesn't really work, so not many people are going to complain anyway if this breaks anything 😄