[Mammoth] Create userspace mutex capability.

lib/mammoth/CMakeLists.txt

@@ -5,6 +5,7 @@ add_library(mammoth STATIC
   src/endpoint_server.cpp
   src/init.cpp
   src/memory_region.cpp
+  src/mutex.cpp
   src/new.cpp
   src/process.cpp
   src/port_client.cpp

lib/mammoth/include/mammoth/mutex.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <glacier/status/error_or.h>
+#include <ztypes.h>
+
+class Mutex {
+ public:
+  Mutex(const Mutex&) = delete;
+  Mutex(Mutex&&);
+  Mutex& operator=(Mutex&&);
+
+  static glcr::ErrorOr<Mutex> Create();
+
+  glcr::ErrorCode Lock();
+  glcr::ErrorCode Release();
+
+ private:
+  z_cap_t mutex_cap_;
+
+  Mutex(z_cap_t mutex_cap) : mutex_cap_(mutex_cap) {}
+};

lib/mammoth/src/mutex.cpp

@@ -0,0 +1,23 @@
+#include "mammoth/mutex.h"
+
+#include <zcall.h>
+
+Mutex::Mutex(Mutex&& other) : mutex_cap_(other.mutex_cap_) {
+  other.mutex_cap_ = 0;
+}
+
+Mutex& Mutex::operator=(Mutex&& other) {
+  // TODO: Release existing mutex if it exists.
+  mutex_cap_ = other.mutex_cap_;
+  other.mutex_cap_ = 0;
+  return *this;
+}
+
+glcr::ErrorOr<Mutex> Mutex::Create() {
+  z_cap_t mutex_cap;
+  RET_ERR(ZMutexCreate(&mutex_cap));
+  return Mutex(mutex_cap);
+}
+
+glcr::ErrorCode Mutex::Lock() { return ZMutexLock(mutex_cap_); }
+glcr::ErrorCode Mutex::Release() { return ZMutexRelease(mutex_cap_); }