remote: Fetch shell on ssh remote to use for preparing commands (#36690)

Prerequisite for https://github.com/zed-industries/zed/pull/36576 to
allow us to differentiate the shell in a remote.

Release Notes:

- N/A

crates/remote/src/remote.rs

@@ -4,6 +4,6 @@ pub mod proxy;
 pub mod ssh_session;
 
 pub use ssh_session::{
-    ConnectionState, SshClientDelegate, SshConnectionOptions, SshPlatform, SshRemoteClient,
-    SshRemoteEvent,
+    ConnectionState, SshClientDelegate, SshConnectionOptions, SshInfo, SshPlatform,
+    SshRemoteClient, SshRemoteEvent,
 };

crates/remote/src/ssh_session.rs

@@ -89,11 +89,19 @@ pub struct SshConnectionOptions {
     pub upload_binary_over_ssh: bool,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct SshArgs {
     pub arguments: Vec<String>,
     pub envs: Option<HashMap<String, String>>,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct SshInfo {
+    pub args: SshArgs,
+    pub path_style: PathStyle,
+    pub shell: String,
+}
+
 #[macro_export]
 macro_rules! shell_script {
     ($fmt:expr, $($name:ident = $arg:expr),+ $(,)?) => {{
@@ -471,6 +479,16 @@ impl SshSocket {
 
         Ok(SshPlatform { os, arch })
     }
+
+    async fn shell(&self) -> String {
+        match self.run_command("sh", &["-c", "echo $SHELL"]).await {
+            Ok(shell) => shell.trim().to_owned(),
+            Err(e) => {
+                log::error!("Failed to get shell: {e}");
+                "sh".to_owned()
+            }
+        }
+    }
 }
 
 const MAX_MISSED_HEARTBEATS: usize = 5;
@@ -1152,12 +1170,16 @@ impl SshRemoteClient {
         cx.notify();
     }
 
-    pub fn ssh_info(&self) -> Option<(SshArgs, PathStyle)> {
+    pub fn ssh_info(&self) -> Option<SshInfo> {
         self.state
             .lock()
             .as_ref()
             .and_then(|state| state.ssh_connection())
-            .map(|ssh_connection| (ssh_connection.ssh_args(), ssh_connection.path_style()))
+            .map(|ssh_connection| SshInfo {
+                args: ssh_connection.ssh_args(),
+                path_style: ssh_connection.path_style(),
+                shell: ssh_connection.shell(),
+            })
     }
 
     pub fn upload_directory(
@@ -1392,6 +1414,7 @@ trait RemoteConnection: Send + Sync {
     fn ssh_args(&self) -> SshArgs;
     fn connection_options(&self) -> SshConnectionOptions;
     fn path_style(&self) -> PathStyle;
+    fn shell(&self) -> String;
 
     #[cfg(any(test, feature = "test-support"))]
     fn simulate_disconnect(&self, _: &AsyncApp) {}
@@ -1403,6 +1426,7 @@ struct SshRemoteConnection {
     remote_binary_path: Option<RemotePathBuf>,
     ssh_platform: SshPlatform,
     ssh_path_style: PathStyle,
+    ssh_shell: String,
     _temp_dir: TempDir,
 }
 
@@ -1429,6 +1453,10 @@ impl RemoteConnection for SshRemoteConnection {
         self.socket.connection_options.clone()
     }
 
+    fn shell(&self) -> String {
+        self.ssh_shell.clone()
+    }
+
     fn upload_directory(
         &self,
         src_path: PathBuf,
@@ -1642,6 +1670,7 @@ impl SshRemoteConnection {
             "windows" => PathStyle::Windows,
             _ => PathStyle::Posix,
         };
+        let ssh_shell = socket.shell().await;
 
         let mut this = Self {
             socket,
@@ -1650,6 +1679,7 @@ impl SshRemoteConnection {
             remote_binary_path: None,
             ssh_path_style,
             ssh_platform,
+            ssh_shell,
         };
 
         let (release_channel, version, commit) = cx.update(|cx| {
@@ -2686,6 +2716,10 @@ mod fake {
         fn path_style(&self) -> PathStyle {
             PathStyle::current()
         }
+
+        fn shell(&self) -> String {
+            "sh".to_owned()
+        }
     }
 
     pub(super) struct Delegate;