src/tools/build_helper/src/git.rs

   1 use std::{path::Path, process::Command};
   2
   3 /// Finds the remote for rust-lang/rust.
   4 /// For example for these remotes it will return `upstream`.
   5 /// ```text
   6 /// origin  https://github.com/Nilstrieb/rust.git (fetch)
   7 /// origin  https://github.com/Nilstrieb/rust.git (push)
   8 /// upstream        https://github.com/rust-lang/rust (fetch)
   9 /// upstream        https://github.com/rust-lang/rust (push)
  10 /// ```
  11 pub fn get_rust_lang_rust_remote(git_dir: Option<&Path>) -> Result<String, String> {
  12     let mut git = Command::new("git");
  13     if let Some(git_dir) = git_dir {
  14         git.current_dir(git_dir);
  15     }
  16     git.args(["config", "--local", "--get-regex", "remote\\..*\\.url"]);
  17
  18     let output = git.output().map_err(|err| format!("{err:?}"))?;
  19     if !output.status.success() {
  20         return Err("failed to execute git config command".to_owned());
  21     }
  22
  23     let stdout = String::from_utf8(output.stdout).map_err(|err| format!("{err:?}"))?;
  24
  25     let rust_lang_remote = stdout
  26         .lines()
  27         .find(|remote| remote.contains("rust-lang"))
  28         .ok_or_else(|| "rust-lang/rust remote not found".to_owned())?;
  29
  30     let remote_name =
  31         rust_lang_remote.split('.').nth(1).ok_or_else(|| "remote name not found".to_owned())?;
  32     Ok(remote_name.into())
  33 }
  34
  35 pub fn rev_exists(rev: &str, git_dir: Option<&Path>) -> Result<bool, String> {
  36     let mut git = Command::new("git");
  37     if let Some(git_dir) = git_dir {
  38         git.current_dir(git_dir);
  39     }
  40     git.args(["rev-parse", rev]);
  41     let output = git.output().map_err(|err| format!("{err:?}"))?;
  42
  43     match output.status.code() {
  44         Some(0) => Ok(true),
  45         Some(128) => Ok(false),
  46         None => {
  47             return Err(format!(
  48                 "git didn't exit properly: {}",
  49                 String::from_utf8(output.stderr).map_err(|err| format!("{err:?}"))?
  50             ));
  51         }
  52         Some(code) => {
  53             return Err(format!(
  54                 "git command exited with status code: {code}: {}",
  55                 String::from_utf8(output.stderr).map_err(|err| format!("{err:?}"))?
  56             ));
  57         }
  58     }
  59 }
  60
  61 /// Returns the master branch from which we can take diffs to see changes.
  62 /// This will usually be rust-lang/rust master, but sometimes this might not exist.
  63 /// This could be because the user is updating their forked master branch using the GitHub UI
  64 /// and therefore doesn't need an upstream master branch checked out.
  65 /// We will then fall back to origin/master in the hope that at least this exists.
  66 pub fn updated_master_branch(git_dir: Option<&Path>) -> Result<String, String> {
  67     let upstream_remote = get_rust_lang_rust_remote(git_dir)?;
  68     let upstream_master = format!("{upstream_remote}/master");
  69     if rev_exists(&upstream_master, git_dir)? {
  70         return Ok(upstream_master);
  71     }
  72
  73     // We could implement smarter logic here in the future.
  74     Ok("origin/master".into())
  75 }