Building rust-openssl to wasm32 on MacOS fails

[alex-coinfund]

Reposting from rust-lang/rust#95057 just in case anyone in the openssl community encountered something similar.

I am working on project that uses openssl and compiles to wasm (wasm32-unknown-emscripten toolchain). It builds on Linux just fine, but when I try building it on my MacOS Big Sur, I get the following error (removing some irrelevant information from the output):

error: failed to run custom build command for `openssl-sys v0.9.72`

Caused by:
  process didn't exit successfully: `/Users/alex/projects/mufl-poc-cpp/src/external/nitroattest/aws-nitroattest/target/debug/build/openssl-sys-c48c44c33a472711/build-script-main` (exit status: 101)
  --- stdout
  cargo:rustc-cfg=const_fn
  cargo:rerun-if-env-changed=WASM32_UNKNOWN_EMSCRIPTEN_OPENSSL_NO_VENDOR
  WASM32_UNKNOWN_EMSCRIPTEN_OPENSSL_NO_VENDOR unset
  cargo:rerun-if-env-changed=OPENSSL_NO_VENDOR
  OPENSSL_NO_VENDOR unset
  CC_wasm32-unknown-emscripten = None
  CC_wasm32_unknown_emscripten = None
  TARGET_CC = None
  CC = None
  CFLAGS_wasm32-unknown-emscripten = None
  CFLAGS_wasm32_unknown_emscripten = None
  TARGET_CFLAGS = None
  CFLAGS = None
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("true")
  CARGO_CFG_TARGET_FEATURE = None
  running "perl" "./Configure" "--prefix=/Users/alex/projects/mufl-poc-cpp/src/external/nitroattest/aws-nitroattest/target/wasm32-unknown-emscripten/debug/build/openssl-sys-85f599ecbb1dcfeb/out/openssl-build/install" "no-dso" "no-shared" "no-ssl3" "no-unit-test" "no-comp" "no-zlib" "no-zlib-dynamic" "no-md2" "no-rc5" "no-weak-ssl-ciphers" "no-camellia" "no-idea" "no-seed" "gcc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-D__STDC_NO_ATOMICS__"
  Configuring OpenSSL version 1.1.1n (0x101010efL) for gcc
  Using os-specific seed configuration
  Creating configdata.pm
  Creating Makefile

[SNIP]

  --- stderr
  ar: creating archive apps/libapps.a
  warning: /Library/Developer/CommandLineTools/usr/bin/ranlib: archive library: apps/libapps.a the table of contents is empty (no object file members in the library define global symbols)
  ar: creating archive libcrypto.a
  warning: /Library/Developer/CommandLineTools/usr/bin/ranlib: archive library: libcrypto.a the table of contents is empty (no object file members in the library define global symbols)
  ar: creating archive libssl.a
  warning: /Library/Developer/CommandLineTools/usr/bin/ranlib: archive library: libssl.a the table of contents is empty (no object file members in the library define global symbols)
  LLVM ERROR: malformed uleb128, extends past end
  /bin/sh: line 1: 64526 Abort trap: 6           ranlib "/Users/alex/projects/mufl-poc-cpp/src/external/nitroattest/aws-nitroattest/target/wasm32-unknown-emscripten/debug/build/openssl-sys-85f599ecbb1dcfeb/out/openssl-build/install/lib/$fn.new"
  make: *** [install_dev] Error 134
  thread 'main' panicked at '


  Error installing OpenSSL:
      Command: "make" "install_dev"
      Exit status: exit status: 2

Obviously, it is incorrectly using Apple's native libraries and tools where it should be using those provided by emscripten. My workaround was to link emscripten's llvm-ar as ar (same for ranlib) and put them temporarily on the front of my $PATH, which works. Yet, I still wanted to report, or see if I'm missing something obvious wrt building wasm on MacOS.

[yihuang]

#1016

[Skepfyr]

@alex-coinfund I'm surprised it compiled fine on Linux! A bunch of discussion about getting OpenSSL working on WASM is happening in #1016, I suspect they'd appreciate a description of how you got it working on Linux.

[alex-coinfund]

This was a while back, I don’t remember off-hand. Maybe @shakhvit remembers?

[shakhvit]

@Skepfyr
As @yihuang suggested in #1016 I've added vendored feature to my cargo.toml.
Also, I am using wasm32-unknown-emsrcipten target, while in #1016 wasm32-unknown-unknown and wasm32-wasi are mainly discussed. Hope it will help.

[johnkeates]

For some reason it doesn't build on Linux or Darwin at all for me, regardless of which with llvm and native vs. packaged libraries and tools I configure. Did you add any other specific changes to make it wasm compatible?

[shakhvit]

@johnkeates I've created a repository with an example configuration. Please take a look at the build instructions in README.md and if you have any questions please feel free to contact me.

But I am not using anything specific. Just as I said vendored feature and wasm32-unknown-emscripten target.

Here is the link to the repo:
https://github.com/shakhvit/rust_openssl_wasm_build

[johnkeates]

@shakhvit Thanks! I'll try it out in a clean environment. I just noticed that there is a slight difference in our targets as I'm using wasm32-unknown-unknown so that might be the culprit and maybe my defect doesn't belong in this issue after all ✂️

Update: this totally works for emscripten, so that's a nice improvement, it means that technically the wasm32 or a wasi SDK could do the same if there was an environment injector available. I did spot someone talking about this yesterday but I can't find the comment right now. It looks like WASI support in generally is getting plenty of traction so this would likely just be a matter of time to get a more easy-to-find implementation.

[johnkeates]

Turns out that wasi as a target now works so this also works 😎

[Skepfyr]

Given everything above I'm going to claim this works now, feel free to reopen if that's not true.