How to build openssl for M1 and for Intel? - macos

Question

I have a project which needs to use Libcrypto - and I have two versions of Libcrypto (libcrypto.a (from OpenSSL 1.1.1) built for ARM64) and (lcrypto.a (from OpenSSL 1.0.2) for Intel). Leaving aside the issues of whether it's good practice or not to have two different versions, I can say that if I include libcrypto.a then I can build and run on M1 and it works fine on M1. If I include lcrypto.a then I can build and run on Intel and it works fine on Intel. What I can't do is include them both (linker error - The linked library 'lcrypto.a' is missing one or more architectures required by this target: arm64.) - and if I can't include them both then I can't build a fat binary, and my app is less than entirely useful!
My question is How can I include both in my project - or where can I get (and how can I include) a fat version of Libcrypto? I've looked at this https://github.com/balthisar/openssl-xcframeworks/releases and this https://developer.apple.com/forums/thread/670631 but I'm none the wiser. I think I built a Fat Binary - but the Fat Binary I thought that I built doesn't work for either architecture!

Answer 1

Use command lipo to combine binaries
Compile Intel and ARM versions separately (arm version requires Xcode 12).
export MACOSX_DEPLOYMENT_TARGET=10.9
cp -r openssl-1.1.1t openssl-1.1.1t-arm64
cp -r openssl-1.1.1t openssl-1.1.1t-x86_x64
Build the Intel half
cd openssl-1.1.1t-x86_x64
./Configure darwin64-x86_64-cc shared
make
NOTE: For openssl-1.1.1q use -Wno-error=implicit-function-declaration as a configure parameter
Build the Arm half
export MACOSX_DEPLOYMENT_TARGET=10.15 /* arm64 only with Big Sur -> minimum might be 10.16 or 11.0 */)
cd ../openssl-1.1.1t-arm64
./Configure enable-rc5 zlib darwin64-arm64-cc no-asm
make
NOTE: For openssl-1.1.1q use -Wno-error=implicit-function-declaration as a configure parameter
To create universal binary use command lipo:
cd ..
mkdir openssl-mac
lipo -create openssl-1.1.1t-arm64/libcrypto.a openssl-1.1.1t-x86_x64/libcrypto.a -output openssl-mac/libcrypto.a
lipo -create openssl-1.1.1t-arm64/libssl.a openssl-1.1.1t-x86_x64/libssl.a -output openssl-mac/libssl.a
Verify that resulting binary contains both architectures:
file libcrypto.a libssl.a
libcrypto.a: Mach-O universal binary with 2 architectures: [x86_64:current ar archive random library] [arm64]
libcrypto.a (for architecture x86_64): current ar archive random library
libcrypto.a (for architecture arm64): current ar archive random library
libssl.a: Mach-O universal binary with 2 architectures: [x86_64:current ar archive random library] [arm64]
libssl.a (for architecture x86_64): current ar archive random library
libssl.a (for architecture arm64): current ar archive random library
PS: If you plan to use dynamic library combine dylib files using lipo and run instal_name_tool
cd openssl-mac
install_name_tool -id '#rpath/libcrypto.1.1.1.dylib' libcrypto.1.1.1.dylib
install_name_tool -id '#rpath/libssl.1.1.dylib' libssl.1.1.dylib
otool -D libssl.1.1.dylib /* to verify */
Result:
libssl.1.1.dylib:
#rpath/libssl.1.1.dylib

Answer 2

Even though this question already has an accepted answer, I'd like to mention that I found an easier way to do this that doesn't require using lipo, just in case it helps make someone else's life easier.
The trick is to force it to compile for both architectures simultaneously.
Before calling Configure in the openssl source directory, create a file somewhere convenient (for the purposes of explaining I'll just have it in the home folder) named cc, and have it contain the following text:
#!/bin/bash
if [[ $* == *-arch\ x86_64* ]] && ! [[ $* == *-arch\ arm64* ]]; then
echo Forcing compilation with arm64
cc -arch arm64 $#
else
cc $#
fi
That script will automatically add -arch arm64 to any compilation command that only includes -arch x86_64, and leave all other compilation commands unmodified.
Give it execute permissions:
chmod a+x ~/cc
Then execute the following in your shell to force compilation with this shell script:
export CC=/Users/yourname/cc
Then proceed with configuring and building as though for arm64, but tell it to compile as x86_64:
./Configure enable-rc5 zlib no-asm darwin64-x86_64-cc
make
make install
The resulting static libs and dylibs will already be x86_64 / arm64 universal!