askpass: Shell escape Zed path in askpass script (cherry-pick #29447)

crates/askpass/Cargo.toml

@@ -15,6 +15,7 @@ path = "src/askpass.rs"
 anyhow.workspace = true
 futures.workspace = true
 gpui.workspace = true
+shlex.workspace = true
 smol.workspace = true
 tempfile.workspace = true
 util.workspace = true

crates/askpass/src/askpass.rs

@@ -72,8 +72,7 @@ impl AskPassSession {
         let (askpass_opened_tx, askpass_opened_rx) = oneshot::channel::<()>();
         let listener =
             UnixListener::bind(&askpass_socket).context("failed to create askpass socket")?;
-        let zed_path = std::env::current_exe()
-            .context("Failed to figure out current executable path for use in askpass")?;
+        let zed_path = get_shell_safe_zed_path()?;
 
         let (askpass_kill_master_tx, askpass_kill_master_rx) = oneshot::channel::<()>();
         let mut kill_tx = Some(askpass_kill_master_tx);
@@ -115,7 +114,7 @@ impl AskPassSession {
         // Create an askpass script that communicates back to this process.
         let askpass_script = format!(
             "{shebang}\n{print_args} | {zed_exe} --askpass={askpass_socket} 2> /dev/null \n",
-            zed_exe = zed_path.display(),
+            zed_exe = zed_path,
             askpass_socket = askpass_socket.display(),
             print_args = "printf '%s\\0' \"$@\"",
             shebang = "#!/bin/sh",
@@ -161,6 +160,32 @@ impl AskPassSession {
     }
 }
 
+#[cfg(unix)]
+fn get_shell_safe_zed_path() -> anyhow::Result<String> {
+    let zed_path = std::env::current_exe()
+        .context("Failed to figure out current executable path for use in askpass")?
+        .to_string_lossy()
+        .to_string();
+
+    // sanity check on unix systems that the path exists and is executable
+    // todo(windows): implement this check for windows (or just use `is-executable` crate)
+    use std::os::unix::fs::MetadataExt;
+    let metadata = std::fs::metadata(&zed_path)
+        .context("Failed to check metadata of Zed executable path for use in askpass")?;
+    let is_executable = metadata.is_file() && metadata.mode() & 0o111 != 0;
+    anyhow::ensure!(
+        is_executable,
+        "Failed to verify Zed executable path for use in askpass"
+    );
+    // As of writing, this can only be fail if the path contains a null byte, which shouldn't be possible
+    // but shlex has annotated the error as #[non_exhaustive] so we can't make it a compile error if other
+    // errors are introduced in the future :(
+    let zed_path_escaped = shlex::try_quote(&zed_path)
+        .context("Failed to shell-escape Zed executable path for use in askpass")?;
+
+    return Ok(zed_path_escaped.to_string());
+}
+
 /// The main function for when Zed is running in netcat mode for use in askpass.
 /// Called from both the remote server binary and the zed binary in their respective main functions.
 #[cfg(unix)]