[Build] Generalize POSIX platform guards

Most non-Windows code paths use standard POSIX APIs (sockets, signals,
dlopen, threading) that work on any POSIX platform. Change Linux-specific
guards to !WIN32 or #else where the code is portable. Linux-specific
APIs (SIGRTMIN, Vulkan/X11, fontconfig/GTK) remain Linux-guarded.

src/xenia/kernel/xam/xam_net.cc

@@ -23,10 +23,11 @@
 // NOTE: must be included last as it expects windows.h to already be included.
 #define _WINSOCK_DEPRECATED_NO_WARNINGS  // inet_addr
 #include <winsock2.h>                    // NOLINT(build/include_order)
-#elif XE_PLATFORM_LINUX
+#else
 #include <arpa/inet.h>
 #include <netinet/in.h>
 #include <netinet/ip.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #endif
 

src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc

@@ -244,7 +244,7 @@ dword_result_t NtSuspendThread_entry(dword_t handle,
       } else {
         return X_STATUS_THREAD_IS_TERMINATING;
       }
-#elif XE_PLATFORM_LINUX
+#else
       // Handle self-suspension specially to avoid deadlock.
       if (!thread->guest_object<X_KTHREAD>()->terminated) {
         bool is_self_suspend =
@@ -261,8 +261,6 @@ dword_result_t NtSuspendThread_entry(dword_t handle,
       } else {
         return X_STATUS_THREAD_IS_TERMINATING;
       }
-#else
-#error "Unsupported platform"
 #endif
     } else {
       return X_STATUS_OBJECT_TYPE_MISMATCH;

src/xenia/kernel/xsocket.cc

@@ -86,7 +86,7 @@ X_STATUS XSocket::Initialize(AddressFamily af, Type type, Protocol proto) {
 X_STATUS XSocket::Close() {
 #if XE_PLATFORM_WIN32
   int ret = closesocket(native_handle_);
-#elif XE_PLATFORM_LINUX
+#else
   int ret = close(native_handle_);
 #endif
 
@@ -166,7 +166,7 @@ X_STATUS XSocket::IOControl(uint32_t cmd, uint8_t* arg_ptr) {
     return X_STATUS_UNSUCCESSFUL;
   }
   return X_STATUS_SUCCESS;
-#elif XE_PLATFORM_LINUX
+#else
   int native_cmd = cmd;
 
   assert_false(!supported_controls.contains(cmd));

src/xenia/kernel/xthread.cc

@@ -9,7 +9,7 @@
 
 #include "xenia/kernel/xthread.h"
 
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
 #include <signal.h>
 #endif
 
@@ -556,17 +556,19 @@ void XThread::Execute() {
   // On Windows, setjmp/longjmp is used because MSVC's longjmp performs SEH
   // stack unwinding which already calls destructors.
   uint32_t next_address;
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
   try {
     exit_code = static_cast<int>(kernel_state()->processor()->Execute(
         thread_state_, address, args.data(), args.size()));
     next_address = 0;
   } catch (const FiberReentryException& e) {
+#if XE_PLATFORM_LINUX
     // Ensure SIGRTMIN (used for thread suspend) is not left blocked.
     sigset_t set;
     sigemptyset(&set);
     sigaddset(&set, SIGRTMIN);
     pthread_sigmask(SIG_UNBLOCK, &set, nullptr);
+#endif
     next_address = e.address;
   }
 
@@ -578,10 +580,12 @@ void XThread::Execute() {
         exit_code = static_cast<int>(thread_state_->context()->r[3]);
       }
     } catch (const FiberReentryException& e) {
+#if XE_PLATFORM_LINUX
       sigset_t set;
       sigemptyset(&set);
       sigaddset(&set, SIGRTMIN);
       pthread_sigmask(SIG_UNBLOCK, &set, nullptr);
+#endif
       next_address = e.address;
     }
   }
@@ -616,7 +620,7 @@ void XThread::Reenter(uint32_t address) {
   // Called when the game switches fiber stacks (e.g., via
   // KeSetCurrentStackPointers in games like Forza Horizon 2).
   // Must unwind through all frames between here and Execute().
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
   // Throw a C++ exception that unwinds through JIT frames (using DWARF
   // .eh_frame info) and host frames (using compiler-generated DWARF),
   // calling destructors properly along the way.
@@ -767,7 +771,7 @@ X_STATUS XThread::Resume(uint32_t* out_suspend_count) {
   } else {
     return X_STATUS_UNSUCCESSFUL;
   }
-#elif XE_PLATFORM_LINUX
+#else
   // Use mutex to protect suspend_count access and coordinate with SelfSuspend.
   bool should_resume_host = false;
   {
@@ -788,8 +792,6 @@ X_STATUS XThread::Resume(uint32_t* out_suspend_count) {
     thread_->Resume(&unused_host_suspend_count);
   }
   return X_STATUS_SUCCESS;
-#else
-#error "Unsupported platform"
 #endif
 }
 
@@ -821,7 +823,7 @@ X_STATUS XThread::Suspend(uint32_t* out_suspend_count) {
   }
 }
 
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
 uint32_t XThread::SelfSuspend() {
   auto guest_thread = guest_object<X_KTHREAD>();
   std::unique_lock<std::mutex> lock(suspend_mutex_);
@@ -831,7 +833,7 @@ uint32_t XThread::SelfSuspend() {
       lock, [guest_thread]() { return guest_thread->suspend_count == 0; });
   return previous;
 }
-#endif
+#endif  // !XE_PLATFORM_WIN32
 
 X_STATUS XThread::Delay(uint32_t processor_mode, uint32_t alertable,
                         uint64_t interval) {

src/xenia/kernel/xthread.h

@@ -14,7 +14,7 @@
 #include <string>
 
 #include "xenia/base/mutex.h"
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
 #include <condition_variable>
 #include <csignal>
 #include <mutex>
@@ -343,7 +343,7 @@ struct X_KTHREAD {
 };
 static_assert_size(X_KTHREAD, 0xAB0);
 
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
 // Exception thrown by XThread::Reenter() to unwind through JIT frames.
 // C++ exception unwinding uses DWARF .eh_frame info registered for JIT code,
 // ensuring destructors and RAII guards in host C++ frames are properly called.
@@ -442,7 +442,7 @@ class XThread : public XObject, public cpu::Thread {
   X_STATUS Delay(uint32_t processor_mode, uint32_t alertable,
                  uint64_t interval);
 
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
   // Performs self-suspension: increments suspend_count and blocks until
   // another thread calls Resume() and suspend_count reaches 0.
   // Returns the previous suspend_count value.
@@ -490,7 +490,7 @@ class XThread : public XObject, public cpu::Thread {
 
   int32_t priority_ = 0;
 
-#if XE_PLATFORM_LINUX
+#if !XE_PLATFORM_WIN32
   // Condition variable for thread self-suspension.
   std::mutex suspend_mutex_;
   std::condition_variable suspend_cv_;