modus 0.1.7

A language for building container images
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// Modus, a language for building container images
// Copyright (C) 2022 University College London

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

use serde::Deserialize;
use std::{
    fs, io,
    process::{Command, Stdio},
};

fn try_get_sha() -> Result<String, String> {
    match fs::read_to_string(".cargo_vcs_info.json") {
        Ok(vcs_json) => {
            #[derive(Debug, Clone, Deserialize)]
            struct VcsInfo {
                git: VcsInfoGit,
            }
            #[derive(Debug, Clone, Deserialize)]
            struct VcsInfoGit {
                sha1: String,
            }

            let vcs_info = serde_json::from_str::<VcsInfo>(&vcs_json)
                .map_err(|e| format!("Failed to parse .cargo_vcs_info.json: {}", e))?;

            Ok(vcs_info.git.sha1)
        }
        Err(e) if e.kind() == io::ErrorKind::NotFound => {
            let cmd = Command::new("git")
                .stdin(Stdio::null())
                .stderr(Stdio::inherit())
                .stdout(Stdio::piped())
                .args(&["rev-parse", "HEAD"])
                .output()
                .map_err(|e| format!("Unable to run git: {}", e))?;
            if !cmd.status.success() {
                return Err(format!("git rev-parse failed with {}", cmd.status));
            }
            let sha = std::str::from_utf8(&cmd.stdout)
                .map_err(|e| format!("git output: {}", e))?
                .trim();
            Ok(sha.to_owned())
        }
        Err(e) => {
            return Err(format!("Failed to read .cargo_vcs_info.json: {}", e));
        }
    }
}

fn main() -> Result<(), String> {
    let short = &try_get_sha()?[0..10];
    println!("cargo:rustc-env=GIT_SHA={}", short);
    println!("cargo:rerun-if-changed=../.git");
    Ok(())
}