Add support to build the MCP SDK using Linux

Dockerfile

@@ -0,0 +1,6 @@
+FROM swift:6.0-noble AS build
+
+WORKDIR /app
+COPY . ./
+RUN ["swift", "package", "clean"]
+CMD ["swift", "test", "--parallel"]

Package.swift

@@ -1,6 +1,4 @@
 // swift-tools-version:6.0
-// The swift-tools-version declares the minimum version of Swift required to build this package.
-
 import PackageDescription
 
 let package = Package(
@@ -14,30 +12,34 @@ let package = Package(
         .visionOS("1.0"),
     ],
     products: [
-        // Products define the executables and libraries a package produces, making them visible to other packages.
-        .library(
-            name: "MCP",
-            targets: ["MCP"])
+        .library(name: "MCP", targets: ["MCP"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-system.git", from: "1.0.0"),
-        .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
+        .package(url: "https://github.com/apple/swift-system", from: "1.0.0"),
+        .package(url: "https://github.com/apple/swift-log", from: "1.5.0"),
     ],
     targets: [
-        // Targets are the basic building blocks of a package, defining a module or a test suite.
-        // Targets can depend on other targets in this package and products from dependencies.
         .target(
             name: "MCP",
             dependencies: [
                 .product(name: "SystemPackage", package: "swift-system"),
                 .product(name: "Logging", package: "swift-log"),
-            ]),
+                .target(name: "libmcp"),
+            ]
+        ),
+        .target(
+            name: "libmcp",
+            dependencies: [
+
+            ]
+        ),
         .testTarget(
             name: "MCPTests",
             dependencies: [
                 "MCP",
                 .product(name: "SystemPackage", package: "swift-system"),
                 .product(name: "Logging", package: "swift-log"),
-            ]),
+            ]
+        ),
     ]
 )

Sources/MCP/Base/Transports.swift

@@ -1,6 +1,5 @@
-import Darwin
+import libmcp
 import Logging
-
 import struct Foundation.Data
 
 #if canImport(System)
@@ -72,11 +71,11 @@ public actor StdioTransport: Transport {
     }
 
     private func setNonBlocking(fileDescriptor: FileDescriptor) throws {
-        let flags = fcntl(fileDescriptor.rawValue, F_GETFL)
+        let flags = fcntl_int(fileDescriptor.rawValue, F_GETFL)
         guard flags >= 0 else {
             throw MCPError.transportError(Errno.badFileDescriptor)
         }
-        let result = fcntl(fileDescriptor.rawValue, F_SETFL, flags | O_NONBLOCK)
+        let result = fcntl_int_long(fileDescriptor.rawValue, F_SETFL, Int(flags | O_NONBLOCK))
         guard result >= 0 else {
             throw MCPError.transportError(Errno.badFileDescriptor)
         }

Sources/libmcp/include/shims.h

@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/types.h>
+
+/* open functions */
+int open_int(const char *path, int oflag);
+int open_int_mode(const char *path, int oflag, mode_t mode);
+
+/* fcntl functions */
+int fcntl_int(int fildes, int cmd);
+int fcntl_int_flock(int fildes, int cmd, struct flock* flock);
+int fcntl_int_long(int fildes, int cmd, long arg);
+
+/* ioctl functions */
+int ioctl_long(int fd, unsigned long request);
+int ioctl_long_void(int fd, unsigned long request, void* data);

Sources/libmcp/module.modulemap

@@ -0,0 +1,5 @@
+module libmcp [system] {
+    header "/usr/local/include/shims.h"
+    link "libmcp"
+    export *
+}

Sources/libmcp/shims.c

@@ -0,0 +1,35 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include "shims.h"
+
+/* open functions */
+int open_int(const char *path, int oflag) {
+    return open(path, oflag);
+}
+int open_int_mode(const char *path, int oflag, mode_t mode) {
+    return open(path, oflag, mode);
+}
+
+/* fcntl functions */
+int fcntl_int(int fildes, int cmd) {
+    return fcntl(fildes, cmd);
+}
+int fcntl_int_flock(int fildes, int cmd, struct flock* flock) {
+    return fcntl(fildes, cmd, flock);
+}
+int fcntl_int_long(int fildes, int cmd, long arg) {
+    return fcntl(fildes, cmd, arg);
+}
+
+/* ioctl functions */
+int ioctl_long(int fd, unsigned long request) {
+    return ioctl(fd, request);
+}
+int ioctl_long_void(int fd, unsigned long request, void* data) {
+    return ioctl(fd, request, data);
+}

Tests/MCPTests/RoundtripTests.swift

@@ -127,7 +127,7 @@ struct RoundtripTests {
         let pingTask = Task {
             try await client.ping()
             // Ping doesn't return anything, so just getting here without throwing is success
-            #expect(true)  // Test passed if we reach this point
+            #expect(Bool(true))  // Test passed if we reach this point
         }
 
         try await withThrowingTaskGroup(of: Void.self) { group in