support clean up the historical control_directory (#126)

* support clean up the historical control_directory before creating a SessionBuilder

* Update src/builder.rs

Co-authored-by: Jiahao XU <[email protected]>

* Update src/builder.rs

Co-authored-by: Jiahao XU <[email protected]>

* Update src/builder.rs

Co-authored-by: Jiahao XU <[email protected]>

* optimizing code

---------

Co-authored-by: Jiahao XU <[email protected]>

src/builder.rs

@@ -2,11 +2,11 @@ use super::{Error, Session};
 
 use std::borrow::Cow;
 use std::ffi::OsString;
-use std::fs;
 use std::iter::IntoIterator;
 use std::path::{Path, PathBuf};
 use std::process::Stdio;
 use std::str;
+use std::{fs, io};
 
 use dirs::state_dir;
 use once_cell::sync::OnceCell;
@@ -34,6 +34,26 @@ fn get_default_control_dir<'a>() -> Result<&'a Path, Error> {
         })
 }
 
+fn clean_history_control_dir(socketdir: &Path, prefix: &str) -> io::Result<()> {
+    // Read the entries in the parent directory
+    fs::read_dir(socketdir)?
+        // Filter out and keep only the valid entries
+        .filter_map(Result::ok)
+        // Filter the entries to only include files that start with prefix
+        .filter(|entry| {
+            if let Ok(file_type) = entry.file_type() {
+                file_type.is_dir() && entry.file_name().to_string_lossy().starts_with(prefix)
+            } else {
+                false
+            }
+        })
+        // For each matching entry, remove the directory
+        .for_each(|entry| {
+            let _ = fs::remove_dir_all(entry.path());
+        });
+    Ok(())
+}
+
 /// Build a [`Session`] with options.
 #[derive(Debug, Clone)]
 pub struct SessionBuilder {
@@ -44,6 +64,7 @@ pub struct SessionBuilder {
     server_alive_interval: Option<u64>,
     known_hosts_check: KnownHosts,
     control_dir: Option<PathBuf>,
+    clean_history_control_dir: bool,
     config_file: Option<PathBuf>,
     compression: Option<bool>,
     jump_hosts: Vec<Box<str>>,
@@ -61,6 +82,7 @@ impl Default for SessionBuilder {
             server_alive_interval: None,
             known_hosts_check: KnownHosts::Add,
             control_dir: None,
+            clean_history_control_dir: false,
             config_file: None,
             compression: None,
             jump_hosts: Vec::new(),
@@ -133,6 +155,20 @@ impl SessionBuilder {
         self
     }
 
+    /// Clean up the temporary directories with the `.ssh-connection` prefix
+    /// in directory specified by [`SessionBuilder::control_directory`], created by
+    /// previous `openssh::Session` that is not cleaned up for some reasons
+    /// (e.g. process getting killed, abort on panic, etc)
+    ///
+    /// Use this with caution, do not enable this if you don't understand
+    /// what it does,
+    #[cfg(not(windows))]
+    #[cfg_attr(docsrs, doc(cfg(not(windows))))]
+    pub fn clean_history_control_directory(&mut self, clean: bool) -> &mut Self {
+        self.clean_history_control_dir = clean;
+        self
+    }
+
     /// Set an alternative per-user configuration file.
     ///
     /// By default, ssh uses `~/.ssh/config`. This is equivalent to `ssh -F <p>`.
@@ -295,8 +331,14 @@ impl SessionBuilder {
             get_default_control_dir()?
         };
 
+        let prefix = ".ssh-connection";
+
+        if self.clean_history_control_dir {
+            let _ = clean_history_control_dir(&socketdir, prefix);
+        }
+
         let dir = Builder::new()
-            .prefix(".ssh-connection")
+            .prefix(prefix)
             .tempdir_in(socketdir)
             .map_err(Error::Master)?;