deb: cross-compilation, ephemeral contexts, local builds

Multiple changes:
- New contexts (schroot, unshare)
- Cross-building quirks, with ephemeral contexts and repositories management
- Contexts with parents, global context manager, better lifetime handling
- Local building of binary packages
- Pull: pulling dsc files by default
- Many small bugfixes and changes

Co-authored-by: Valentin Haudiquet <valentin.haudiquet@canonical.com>
Co-committed-by: Valentin Haudiquet <valentin.haudiquet@canonical.com>

src/context/local.rs

@@ -8,17 +8,24 @@ use std::process::Command;
 pub struct LocalDriver;
 
 impl ContextDriver for LocalDriver {
-    fn ensure_available(&self, src: &Path, _dest_root: &str) -> io::Result<PathBuf> {
-        src.canonicalize()
+    fn ensure_available(&self, src: &Path, dest_root: &str) -> io::Result<PathBuf> {
+        let dest_root_path = Path::new(dest_root);
+        let dest = dest_root_path.join(src.file_name().unwrap_or(src.as_os_str()));
+
+        if src != dest {
+            // Copy src inside dest_root
+            self.copy_path(src, &dest)?;
+        }
+        dest.canonicalize()
     }
 
-    fn prepare_work_dir(&self) -> io::Result<String> {
-        // TODO: Fix that, we should not always use '..' as work directory locally
-        Ok("..".to_string())
+    fn create_temp_dir(&self) -> io::Result<String> {
+        let temp_dir = tempfile::Builder::new().prefix("pkh-").tempdir()?;
+        Ok(temp_dir.keep().to_string_lossy().to_string())
     }
 
-    fn retrieve_path(&self, _src: &Path, _dest: &Path) -> io::Result<()> {
-        Ok(())
+    fn retrieve_path(&self, src: &Path, dest: &Path) -> io::Result<()> {
+        self.copy_path(src, dest)
     }
 
     fn list_files(&self, path: &Path) -> io::Result<Vec<PathBuf>> {
@@ -30,11 +37,60 @@ impl ContextDriver for LocalDriver {
         Ok(entries)
     }
 
-    fn run(&self, program: &str, args: &[String]) -> io::Result<std::process::ExitStatus> {
-        Command::new(program).args(args).status()
+    fn run(
+        &self,
+        program: &str,
+        args: &[String],
+        env: &[(String, String)],
+        cwd: Option<&str>,
+    ) -> io::Result<std::process::ExitStatus> {
+        let mut cmd = Command::new(program);
+        cmd.args(args).envs(env.iter().map(|(k, v)| (k, v)));
+        if let Some(dir) = cwd {
+            cmd.current_dir(dir);
+        }
+        cmd.status()
     }
 
-    fn run_output(&self, program: &str, args: &[String]) -> io::Result<std::process::Output> {
-        Command::new(program).args(args).output()
+    fn run_output(
+        &self,
+        program: &str,
+        args: &[String],
+        env: &[(String, String)],
+        cwd: Option<&str>,
+    ) -> io::Result<std::process::Output> {
+        let mut cmd = Command::new(program);
+        cmd.args(args).envs(env.iter().map(|(k, v)| (k, v)));
+        if let Some(dir) = cwd {
+            cmd.current_dir(dir);
+        }
+        cmd.output()
+    }
+
+    fn copy_path(&self, src: &Path, dest: &Path) -> io::Result<()> {
+        copy_dir_recursive(src, dest)
+    }
+
+    fn read_file(&self, path: &Path) -> io::Result<String> {
+        std::fs::read_to_string(path)
+    }
+
+    fn write_file(&self, path: &Path, content: &str) -> io::Result<()> {
+        std::fs::write(path, content)
     }
 }
+
+fn copy_dir_recursive(src: &Path, dest: &Path) -> io::Result<()> {
+    if src.is_dir() {
+        std::fs::create_dir_all(dest)?;
+        for entry in std::fs::read_dir(src)? {
+            let entry = entry?;
+            let path = entry.path();
+            let dest_path = dest.join(entry.file_name());
+            copy_dir_recursive(&path, &dest_path)?;
+        }
+    } else {
+        std::fs::copy(src, dest)?;
+    }
+    Ok(())
+}