Build script causes permission errors during build

[DrRuhe]

Hi, I am trying to package samply using crane. My current Progress is located in a fork of that repo.

Sadly I am getting build errors pointing to the custom build commands of libc and memchr:

@nix { "action": "setPhase", "phase": "unpackPhase" }
unpacking sources
unpacking source archive /nix/store/8n7vs04zypwrl4chxgmf7dapkch98yqz-source
source root is source
@nix { "action": "setPhase", "phase": "patchPhase" }
patching sources
Executing configureCargoCommonVars
copying cargo artifacts from /nix/store/yjv7iqq139arf84grpl4n9wf0yy4n6kl-cargo-package-deps-0.0.1/target to target
@nix { "action": "setPhase", "phase": "configurePhase" }
configuring
will append /build/source/.cargo-home/config.toml with contents of /nix/store/1j8f3b068qkgpbaa8zcn51aarp0hqyx2-vendor-cargo-deps/config.toml
default configurePhase, nothing to do
@nix { "action": "setPhase", "phase": "buildPhase" }
building
++ command cargo --version
cargo 1.65.0 (4bc8f24d3 2022-10-20)
++ command cargo build --profile release --message-format json-render-diagnostics --target x86_64-unknown-linux-gnu
warning: profiles for the non root package will be ignored, specify profiles at the workspace root:
package:   /build/source/samply-mac-preload/Cargo.toml
workspace: /build/source/Cargo.toml
warning: profiles for the non root package will be ignored, specify profiles at the workspace root:
package:   /build/source/samply/Cargo.toml
workspace: /build/source/Cargo.toml
warning: profiles for the non root package will be ignored, specify profiles at the workspace root:
package:   /build/source/tools/query_api/Cargo.toml
workspace: /build/source/Cargo.toml
   Compiling cfg-if v1.0.0
   Compiling libc v0.2.138
   Compiling memchr v2.5.0
   Compiling bitflags v1.3.2
   Compiling pin-project-lite v0.2.9
   Compiling once_cell v1.16.0
error: failed to run custom build command for `libc v0.2.138`

Caused by:
  could not execute process `/build/source/target/release/build/libc-0060f76ec4165424/build-script-build` (never executed)

Caused by:
  Permission denied (os error 13)
warning: build failed, waiting for other jobs to finish...
error: failed to run custom build command for `memchr v2.5.0`

Caused by:
  could not execute process `/build/source/target/release/build/memchr-7d105e9cb14f44f9/build-script-build` (never executed)

Caused by:
  Permission denied (os error 13)

I looked for examples/documentation for this but could not find anything relevant. I'd appreciate any feedback regarding my attempts to package it and hints as to how this issue might be solved.

[ipetkov]

Hi @DrRuhe!

What platform are you trying to build the project on? I see that the flake sets cargoExtraArgs = "--target x86_64-unknown-linux-gnu" yet it also aims to support darwin and linux builds. Judging from the attempt at building libc in the logs, it feels like a failed cross compile (i.e. cargo produces an executable for a platform different than the host trying to execute it).

If you are looking to set up an actual cross-compiled target this example may be useful

[ipetkov]

It looks like samply-mac-preload is meant to compile on darwin, I wonder if the eh_personality stuff is expected to come from the platform-dependent SDKs, but when built under Linux it fails with that error. My suggestion is to avoid building that crate (e.g. via cargo build --workspace --exclude samply-mac-preload) on non-darwin platforms

[DrRuhe]

I got the package to build 🥳
So, instead of excluding only sampy-mac-preload I thought "shouldn't cargo just ignore it anyway when I try building only the samply binary on a non-darwin platform?". So now I just use --bin samply as a cargo extra arg and it only builds the required libs, thus excluding samply-mac-preload.

Now I am just having trouble getting to actually run this:

$ nix run .#
error: unable to execute '/nix/store/2pdnvpfx7sgy691xkfv60pgp9hzjq7xn-cargo-package-0.0.1/bin/cargo-package': No such file or directory

So how can I change the following, such that It works the same "as usual"?

samply = craneLib.buildPackage {
          inherit cargoArtifacts src buildInputs;
          cargoExtraArgs = "--bin samply";
        };

This boils down to the difference in handling crates as opposed to workspaces. I am having trouble finding documentation regarding this.

[ipetkov]

@DrRuhe nix run assumes that if you have a derivation named foo then it can run an executable at ${foo}/bin/foo. In this case it looks like it is trying to run a binary from ./bin/cargo-package which doesn't exist. If you tweak the executable path (and I believe flake-utils has a mkApp utility to make that easier) it should fix the nix run .# invocation

[DrRuhe]

Ok, so after some more tinkering, I got it to work as I want it to. I solved it by adding a pname to the craneLib.buildPackage invocation like this:

samply = craneLib.buildPackage {
          inherit cargoArtifacts src buildInputs;
          pname = "samply";
          cargoExtraArgs = "--bin samply";
};

I took the inspiration to try this from the fedimint flake.nix.

[DrRuhe]

Thanks for the help :)