[Mammoth] Add Channel object for simple IPC messages

lib/mammoth/src/channel.cpp

@@ -0,0 +1,61 @@
+#include "mammoth/channel.h"
+
+#include <zcall.h>
+
+#include "mammoth/debug.h"
+
+namespace {
+
+uint64_t strlen(const char* ptr) {
+  uint64_t len = 0;
+  while (*ptr != '\0') {
+    len++;
+    ptr++;
+  }
+  return len;
+}
+
+}  // namespace
+
+void Channel::adopt_cap(uint64_t id) {
+  if (chan_cap_ != 0) {
+    crash("Adopting over channel.", Z_ERR_EXISTS);
+  }
+  chan_cap_ = id;
+}
+uint64_t Channel::release_cap() {
+  uint64_t cap = chan_cap_;
+  chan_cap_ = 0;
+  return cap;
+}
+
+z_err_t Channel::WriteStr(const char* msg) {
+  if (!chan_cap_) {
+    return Z_ERR_NULL;
+  }
+  uint64_t type = 11;
+  return ZChannelSend(chan_cap_, type, strlen(msg),
+                      reinterpret_cast<const uint8_t*>(msg), 0, 0);
+}
+
+z_err_t Channel::ReadStr(char* buffer, uint64_t* size) {
+  if (!chan_cap_) {
+    return Z_ERR_NULL;
+  }
+  uint64_t type;
+  uint64_t num_caps;
+  return ZChannelRecv(chan_cap_, *size, reinterpret_cast<uint8_t*>(buffer), 0,
+                      0, &type, size, &num_caps);
+}
+
+z_err_t CreateChannels(Channel& c1, Channel& c2) {
+  uint64_t chan1, chan2;
+  z_err_t err = ZChannelCreate(&chan1, &chan2);
+  if (err != Z_OK) {
+    return err;
+  }
+
+  c1.adopt_cap(chan1);
+  c2.adopt_cap(chan2);
+  return Z_OK;
+}