Fixes #20729 (#22048)

### What does this PR do?

Fixes #20729

### How did you verify your code works?

There is a test

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

packages/bun-types/sql.d.ts

@@ -272,14 +272,11 @@ declare module "bun" {
        */
       ssl?: TLSOptions | boolean | undefined;
 
-      // `.path` is currently unsupported in Bun, the implementation is
-      // incomplete.
-      //
-      // /**
-      //  * Unix domain socket path for connection
-      //  * @default ""
-      //    */
-      // path?: string | undefined;
+      /**
+       * Unix domain socket path for connection
+       * @default undefined
+       */
+      path?: string | undefined;
 
       /**
        * Callback executed when a connection attempt completes

src/js/internal/sql/shared.ts

@@ -305,7 +305,7 @@ function parseOptions(
     onclose: ((client: Bun.SQL) => void) | undefined,
     max: number | null | undefined,
     bigint: boolean | undefined,
-    path: string | string[],
+    path: string,
     adapter: Bun.SQL.__internal.Adapter;
 
   let prepare = true;
@@ -421,9 +421,19 @@ function parseOptions(
   port ||= Number(options.port || env.PGPORT || (adapter === "mysql" ? 3306 : 5432));
 
   path ||= (options as { path?: string }).path || "";
-  // add /.s.PGSQL.${port} if it doesn't exist
-  if (path && path?.indexOf("/.s.PGSQL.") === -1 && adapter === "postgres") {
-    path = `${path}/.s.PGSQL.${port}`;
+
+  if (adapter === "postgres") {
+    // add /.s.PGSQL.${port} if the unix domain socket is listening on that path
+    if (path && Number.isSafeInteger(port) && path?.indexOf("/.s.PGSQL.") === -1) {
+      const pathWithSocket = `${path}/.s.PGSQL.${port}`;
+
+      // Only add the path if it actually exists. It would be better to just
+      // always respect whatever the user passes in, but that would technically
+      // be a breakpoint change at this point.
+      if (require("node:fs").existsSync(pathWithSocket)) {
+        path = pathWithSocket;
+      }
+    }
   }
 
   username ||=
@@ -579,6 +589,12 @@ function parseOptions(
     ret.onclose = onclose;
   }
 
+  if (path) {
+    if (require("node:fs").existsSync(path)) {
+      ret.path = path;
+    }
+  }
+
   return ret;
 }
 

test/js/sql/sql.test.ts

@@ -147,9 +147,88 @@ if (isDockerEnabled()) {
   // --- Expected pg_hba.conf ---
   process.env.DATABASE_URL = `postgres://bun_sql_test@localhost:${container.port}/bun_sql_test`;
 
+  const net = require("node:net");
+  const fs = require("node:fs");
+  const path = require("node:path");
+  const os = require("node:os");
+
+  // Create a temporary unix domain socket path
+  const socketPath = path.join(os.tmpdir(), `postgres_echo_${Date.now()}.sock`);
+
+  // Clean up any existing socket file
+  try {
+    fs.unlinkSync(socketPath);
+  } catch {}
+
+  // Create a unix domain socket server that proxies to the PostgreSQL container
+  const socketServer = net.createServer(clientSocket => {
+    console.log("PostgreSQL connection received on unix socket");
+
+    // Create connection to the actual PostgreSQL container
+    const containerSocket = net.createConnection({
+      host: login.host,
+      port: login.port,
+    });
+
+    // Handle container connection
+    containerSocket.on("connect", () => {
+      console.log("Connected to PostgreSQL container");
+    });
+
+    containerSocket.on("error", err => {
+      console.error("Container connection error:", err);
+      clientSocket.destroy();
+    });
+
+    containerSocket.on("close", () => {
+      console.log("Container connection closed");
+      clientSocket.end();
+    });
+
+    // Handle client socket
+    clientSocket.on("data", data => {
+      // Forward client data to container
+      containerSocket.write(data);
+    });
+
+    clientSocket.on("error", err => {
+      console.error("Client socket error:", err);
+      containerSocket.destroy();
+    });
+
+    clientSocket.on("close", () => {
+      console.log("Client connection closed");
+      containerSocket.end();
+    });
+
+    // Forward container responses back to client
+    containerSocket.on("data", data => {
+      clientSocket.write(data);
+    });
+  });
+
+  socketServer.listen(socketPath, () => {
+    console.log(`Unix domain socket server listening on ${socketPath}`);
+  });
+
+  // Clean up the socket on exit
+  afterAll(() => {
+    socketServer.close();
+    try {
+      fs.unlinkSync(socketPath);
+    } catch {}
+  });
+
   const login: Bun.SQL.PostgresOrMySQLOptions = {
     username: "bun_sql_test",
     port: container.port,
+    path: socketPath,
+  };
+
+  const login_domain_socket: Bun.SQL.PostgresOrMySQLOptions = {
+    username: "bun_sql_test",
+    port: container.port,
+    path: socketPath,
   };
 
   const login_md5: Bun.SQL.PostgresOrMySQLOptions = {
@@ -1036,6 +1115,11 @@ if (isDockerEnabled()) {
     expect((await sql`select true as x`)[0].x).toBe(true);
   });
 
+  test("unix domain socket can send query", async () => {
+    await using sql = postgres({ ...options, ...login_domain_socket });
+    expect((await sql`select true as x`)[0].x).toBe(true);
+  });
+
   test("Login using MD5", async () => {
     await using sql = postgres({ ...options, ...login_md5 });
     expect(await sql`select true as x`).toEqual([{ x: true }]);