[Mammoth] Add Channel object for simple IPC messages

lib/mammoth/include/mammoth/channel.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <stdint.h>
+#include <zerrors.h>
+
+class Channel {
+ public:
+  Channel() {}
+  void adopt_cap(uint64_t id);
+  uint64_t release_cap();
+
+  z_err_t WriteStr(const char* msg);
+  z_err_t ReadStr(char* buffer, uint64_t* size);
+
+  // FIXME: Close channel here.
+  ~Channel() {}
+
+ private:
+  uint64_t chan_cap_ = 0;
+};
+
+uint64_t CreateChannels(Channel& c1, Channel& c2);

lib/mammoth/include/mammoth/debug.h

@@ -1,9 +1,12 @@
 #pragma once
 
 #include <stdint.h>
+#include <zerrors.h>
 
 void dbgln(const char*);
 
 // Checks that the code is ok.
 // if not exits the process.
 void check(uint64_t);
+
+void crash(const char*, z_err_t);