vmexec: create working directory if it doesn't exist (#591)

This seems like standard OCI runtime behavior, which is to create the
working directory if it doesn't exist.

Author: yibozhuang

Sources/Integration/ContainerTests.swift

@@ -4218,6 +4218,87 @@ extension IntegrationSuite {
         }
     }
 
+    func testWorkingDirCreated() async throws {
+        let id = "test-working-dir-created"
+        let bs = try await bootstrap(id)
+
+        let buffer = BufferWriter()
+        let container = try LinuxContainer(id, rootfs: bs.rootfs, vmm: bs.vmm) { config in
+            config.process.arguments = ["/bin/pwd"]
+            config.process.workingDirectory = "/does/not/exist"
+            config.process.stdout = buffer
+            config.bootLog = bs.bootLog
+        }
+
+        do {
+            try await container.create()
+            try await container.start()
+
+            let status = try await container.wait()
+            try await container.stop()
+
+            guard status.exitCode == 0 else {
+                throw IntegrationError.assert(msg: "process with non-existent workingDir failed: \(status)")
+            }
+
+            guard let output = String(data: buffer.data, encoding: .utf8)?.trimmingCharacters(in: .whitespacesAndNewlines) else {
+                throw IntegrationError.assert(msg: "failed to read stdout")
+            }
+
+            guard output == "/does/not/exist" else {
+                throw IntegrationError.assert(msg: "expected cwd '/does/not/exist', got '\(output)'")
+            }
+        } catch {
+            try? await container.stop()
+            throw error
+        }
+    }
+
+    func testWorkingDirExecCreated() async throws {
+        let id = "test-working-dir-exec-created"
+        let bs = try await bootstrap(id)
+
+        let container = try LinuxContainer(id, rootfs: bs.rootfs, vmm: bs.vmm) { config in
+            config.process.arguments = ["/bin/sleep", "1000"]
+            config.bootLog = bs.bootLog
+        }
+
+        do {
+            try await container.create()
+            try await container.start()
+
+            let buffer = BufferWriter()
+            let exec = try await container.exec("cwd-exec") { config in
+                config.arguments = ["/bin/pwd"]
+                config.workingDirectory = "/a/b/c/d"
+                config.stdout = buffer
+            }
+
+            try await exec.start()
+            let status = try await exec.wait()
+            try await exec.delete()
+
+            guard status.exitCode == 0 else {
+                throw IntegrationError.assert(msg: "exec with non-existent workingDir failed: \(status)")
+            }
+
+            guard let output = String(data: buffer.data, encoding: .utf8)?.trimmingCharacters(in: .whitespacesAndNewlines) else {
+                throw IntegrationError.assert(msg: "failed to read stdout")
+            }
+
+            guard output == "/a/b/c/d" else {
+                throw IntegrationError.assert(msg: "expected cwd '/a/b/c/d', got '\(output)'")
+            }
+
+            try await container.kill(SIGKILL)
+            try await container.wait()
+            try await container.stop()
+        } catch {
+            try? await container.stop()
+            throw error
+        }
+    }
+
     func testNoNewPrivilegesExec() async throws {
         let id = "test-no-new-privileges-exec"
 

Sources/Integration/Suite.swift

@@ -374,6 +374,8 @@ struct IntegrationSuite: AsyncParsableCommand {
                 Test("container noNewPrivileges", testNoNewPrivileges),
                 Test("container noNewPrivileges disabled", testNoNewPrivilegesDisabled),
                 Test("container noNewPrivileges exec", testNoNewPrivilegesExec),
+                Test("container workingDir created", testWorkingDirCreated),
+                Test("container workingDir exec created", testWorkingDirExecCreated),
 
                 // Pods
                 Test("pod single container", testPodSingleContainer),

vminitd/Sources/vmexec/vmexec.swift

@@ -96,6 +96,16 @@ extension App {
         let env = process.env.map { strdup($0) } + [nil]
         let cwd = process.cwd
 
+        // Create the working directory if it doesn't exist, this seems like the expected
+        // OCI runtime spec behavior.
+        if !FileManager.default.fileExists(atPath: cwd) {
+            try FileManager.default.createDirectory(
+                atPath: cwd,
+                withIntermediateDirectories: true,
+                attributes: [.posixPermissions: 0o755]
+            )
+        }
+
         guard chdir(cwd) == 0 else {
             throw App.Errno(stage: "chdir(cwd)", info: "failed to change directory to '\(cwd)'")
         }