1 files changed, 142 insertions, 0 deletions
diff --git a/crates/mozart-vcs/src/process.rs b/crates/mozart-vcs/src/process.rs
new file mode 100644
index 0000000..91741a8
--- /dev/null
+++ b/crates/mozart-vcs/src/process.rs
@@ -0,0 +1,142 @@
+use std::collections::HashMap;
+use std::path::Path;
+use std::process::Command;
+use std::time::{Duration, Instant};
+
+use anyhow::{Result, bail};
+
+/// Output from a process execution.
+#[derive(Debug, Clone)]
+pub struct ProcessOutput {
+    pub status: i32,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+/// Wrapper around `std::process::Command` for executing external programs.
+///
+/// Corresponds to Composer's `ProcessExecutor`.
+pub struct ProcessExecutor {
+    timeout: Option<Duration>,
+    env_overrides: HashMap<String, Option<String>>,
+}
+
+impl Default for ProcessExecutor {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl ProcessExecutor {
+    pub fn new() -> Self {
+        Self {
+            timeout: None,
+            env_overrides: HashMap::new(),
+        }
+    }
+
+    pub fn with_timeout(secs: u64) -> Self {
+        Self {
+            timeout: Some(Duration::from_secs(secs)),
+            env_overrides: HashMap::new(),
+        }
+    }
+
+    /// Set an environment variable override for all subsequent executions.
+    pub fn set_env(&mut self, key: impl Into<String>, value: impl Into<String>) {
+        self.env_overrides.insert(key.into(), Some(value.into()));
+    }
+
+    /// Remove an environment variable for all subsequent executions.
+    pub fn remove_env(&mut self, key: impl Into<String>) {
+        self.env_overrides.insert(key.into(), None);
+    }
+
+    /// Execute a command. Does not error on non-zero exit status.
+    pub fn execute(&self, args: &[&str], cwd: Option<&Path>) -> Result<ProcessOutput> {
+        if args.is_empty() {
+            bail!("No command specified");
+        }
+
+        let mut cmd = Command::new(args[0]);
+        if args.len() > 1 {
+            cmd.args(&args[1..]);
+        }
+        if let Some(dir) = cwd {
+            cmd.current_dir(dir);
+        }
+
+        for (key, value) in &self.env_overrides {
+            match value {
+                Some(v) => {
+                    cmd.env(key, v);
+                }
+                None => {
+                    cmd.env_remove(key);
+                }
+            }
+        }
+
+        if let Some(timeout) = self.timeout {
+            let mut child = cmd
+                .stdout(std::process::Stdio::piped())
+                .stderr(std::process::Stdio::piped())
+                .spawn()?;
+
+            let start = Instant::now();
+            loop {
+                match child.try_wait()? {
+                    Some(status) => {
+                        let mut stdout = String::new();
+                        let mut stderr = String::new();
+                        if let Some(ref mut out) = child.stdout {
+                            std::io::Read::read_to_string(out, &mut stdout)?;
+                        }
+                        if let Some(ref mut err) = child.stderr {
+                            std::io::Read::read_to_string(err, &mut stderr)?;
+                        }
+                        return Ok(ProcessOutput {
+                            status: status.code().unwrap_or(-1),
+                            stdout,
+                            stderr,
+                        });
+                    }
+                    None => {
+                        if start.elapsed() > timeout {
+                            let _ = child.kill();
+                            bail!("Process timed out after {} seconds", timeout.as_secs());
+                        }
+                        std::thread::sleep(Duration::from_millis(50));
+                    }
+                }
+            }
+        } else {
+            let output = cmd.output()?;
+            Ok(ProcessOutput {
+                status: output.status.code().unwrap_or(-1),
+                stdout: String::from_utf8_lossy(&output.stdout).into_owned(),
+                stderr: String::from_utf8_lossy(&output.stderr).into_owned(),
+            })
+        }
+    }
+
+    /// Execute a command, returning an error if the exit status is non-zero.
+    pub fn execute_checked(&self, args: &[&str], cwd: Option<&Path>) -> Result<ProcessOutput> {
+        let output = self.execute(args, cwd)?;
+        if output.status != 0 {
+            bail!(
+                "Command `{}` failed with exit code {}\nstdout: {}\nstderr: {}",
+                args.join(" "),
+                output.status,
+                output.stdout.trim(),
+                output.stderr.trim(),
+            );
+        }
+        Ok(output)
+    }
+
+    /// Split output into non-empty lines.
+    pub fn split_lines(output: &str) -> Vec<&str> {
+        output.lines().filter(|l| !l.is_empty()).collect()
+    }
+}