eh: attempt to prevent resource leaks

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I28d716bd37d17dd96731c7863b3383416a6a6964

eh/src/command.rs

@@ -2,6 +2,7 @@ use std::{
   collections::VecDeque,
   io::{self, Read, Write},
   process::{Command, ExitStatus, Output, Stdio},
+  time::{Duration, Instant},
 };
 
 use crate::error::{EhError, Result};
@@ -27,6 +28,9 @@ impl LogInterceptor for StdIoInterceptor {
 /// Default buffer size for reading command output
 const DEFAULT_BUFFER_SIZE: usize = 4096;
 
+/// Default timeout for command execution
+const DEFAULT_TIMEOUT: Duration = Duration::from_secs(300); // 5 minutes
+
 /// Builder and executor for Nix commands.
 pub struct NixCommand {
   subcommand:       String,
@@ -147,10 +151,19 @@ impl NixCommand {
 
     let mut out_queue = VecDeque::new();
     let mut err_queue = VecDeque::new();
+    let start_time = Instant::now();
 
     loop {
       let mut did_something = false;
 
+      // Check for timeout
+      if start_time.elapsed() > DEFAULT_TIMEOUT {
+        let _ = child.kill();
+        return Err(EhError::CommandFailed {
+          command: format!("nix {} timed out after 5 minutes", self.subcommand),
+        });
+      }
+
       match stdout.read(&mut out_buf) {
         Ok(0) => {},
         Ok(n) => {
@@ -176,6 +189,11 @@ impl NixCommand {
       if !did_something && child.try_wait()?.is_some() {
         break;
       }
+
+      // Prevent busy waiting when no data is available
+      if !did_something {
+        std::thread::sleep(Duration::from_millis(10));
+      }
     }
 
     let status = child.wait()?;

eh/src/error.rs

@@ -40,9 +40,15 @@ impl EhError {
   pub const fn exit_code(&self) -> i32 {
     match self {
       Self::ProcessExit { code } => *code,
-      Self::NixCommandFailed(_) => 1,
-      Self::CommandFailed { .. } => 1,
-      _ => 1,
+      Self::NixCommandFailed(_) => 2,
+      Self::CommandFailed { .. } => 3,
+      Self::HashExtractionFailed => 4,
+      Self::NoNixFilesFound => 5,
+      Self::HashFixFailed { .. } => 6,
+      Self::InvalidInput { .. } => 7,
+      Self::Io(_) => 8,
+      Self::Regex(_) => 9,
+      Self::Utf8(_) => 10,
     }
   }
 }