libcras: Expose try_with_socket_type API

Allow users to select different server sockets while creating the
clients.

* Add with_type in CrasServerSocket
* Add with_type in CrasClient
* Expose enum CrasSocketType for users

BUG=b:155048379
TEST=Apply full patch set and test with VMs

Change-Id: Ic2020d9f9e0cf1c1321772baa339934989db145f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/2167813
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Commit-Queue: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

2 files changed, 41 insertions, 5 deletions

diff --git a/cras/client/libcras/src/cras_server_socket.rs b/cras/client/libcras/src/cras_server_socket.rs
index 6fa84fbd..34e8cbd4 100644
--- a/cras/client/libcras/src/cras_server_socket.rs
+++ b/cras/client/libcras/src/cras_server_socket.rs
@@ -9,7 +9,23 @@ use sys_util::{net::UnixSeqpacket, ScmSocket};
 
 use data_model::DataInit;
 
-const CRAS_SERVER_SOCKET_PATH: &str = "/run/cras/.cras_socket";
+/// Server socket type to connect.
+pub enum CrasSocketType {
+    /// A server socket type supports only playback function.
+    Legacy,
+    /// A server socket type supports both playback and capture functions.
+    Unified,
+}
+
+impl CrasSocketType {
+    fn sock_path(&self) -> &str {
+        match self {
+            Self::Legacy => "/run/cras/.cras_socket",
+            Self::Unified => "/run/cras/.cras_unified",
+        }
+    }
+}
+
 /// A socket connecting to the CRAS audio server.
 pub struct CrasServerSocket {
     socket: UnixSeqpacket,
@@ -17,8 +33,18 @@ pub struct CrasServerSocket {
 
 impl CrasServerSocket {
     pub fn new() -> io::Result<CrasServerSocket> {
-        let socket = UnixSeqpacket::connect(CRAS_SERVER_SOCKET_PATH)?;
-        Ok(CrasServerSocket { socket })
+        Self::with_type(CrasSocketType::Legacy)
+    }
+
+    /// Creates a `CrasServerSocket` with given `CrasSocketType`.
+    ///
+    /// # Errors
+    ///
+    /// Returns the `io::Error` generated when connecting to the socket on failure.
+    pub fn with_type(socket_type: CrasSocketType) -> io::Result<CrasServerSocket> {
+        Ok(CrasServerSocket {
+            socket: UnixSeqpacket::connect(socket_type.sock_path())?,
+        })
     }
 
     /// Sends a sized and packed server messge to the server socket. The message
diff --git a/cras/client/libcras/src/libcras.rs b/cras/client/libcras/src/libcras.rs
index cdad706f..69a06ace 100644
--- a/cras/client/libcras/src/libcras.rs
+++ b/cras/client/libcras/src/libcras.rs
@@ -142,6 +142,7 @@ mod audio_socket;
 use crate::audio_socket::AudioSocket;
 mod cras_server_socket;
 use crate::cras_server_socket::CrasServerSocket;
+pub use crate::cras_server_socket::CrasSocketType;
 mod cras_shm;
 use crate::cras_shm::CrasServerState;
 pub mod cras_shm_stream;
@@ -227,9 +228,18 @@ impl<'a> CrasClient<'a> {
     /// Returns error if error occurs while handling server message or message
     /// type is incorrect
     pub fn new() -> Result<Self> {
-        // Create a connection to the server.
-        let mut server_socket = CrasServerSocket::new()?;
+        Self::with_type(CrasSocketType::Legacy)
+    }
 
+    /// Tries to create a `CrasClient` with a given `CrasSocketType`.
+    ///
+    /// # Errors
+    ///
+    /// Returns error if error occurs while handling server message or message
+    /// type is incorrect.
+    pub fn with_type(socket_type: CrasSocketType) -> Result<Self> {
+        // Create a connection to the server.
+        let mut server_socket = CrasServerSocket::with_type(socket_type)?;
         // Gets client ID and server state fd from server
         if let ServerResult::Connected(client_id, server_state_fd) =
             CrasClient::wait_for_message(&mut server_socket)?