Refactor task OS-name setting

Task::copy_state sets the OS name of a task in the same fashion that
persistent checkpointing sets name. Refactored this functionality into
Task::set_name.

Also removed the unnecessary `update_prname` from Task::copy_state.

update_prname is not a "write to tracee"-operation but a "read from tracee"-operation; and since
we already know what name we want to set Task::prname to, we skip this reading from the tracee
in Task::copy_state and just set it to the parameter passed in to Task::set_name

src/ReplaySession.cc

@@ -2157,11 +2157,11 @@ void ReplaySession::load_checkpoint(
     Task* child = Task::os_clone(Task::SESSION_CLONE_LEADER, this, remote,
                                  taskInfo.getRecTid(), taskInfo.getSerial(),
                                  SIGCHLD, nullptr);
-    cloned_leaders.push_back((ReplayTask*)child);
+    cloned_leaders.push_back(static_cast<ReplayTask*>(child));
   }
 
   auto clone_leader_index = 0;
-
+  LOG(debug) << "Restoring " << addr_spaces.size() << " clone leaders";
   for (const auto& as : addr_spaces) {
     ReplayTask* leader = cloned_leaders[clone_leader_index++];
     const auto proc_space = as.getProcessSpace();
@@ -2272,9 +2272,7 @@ void ReplaySession::load_checkpoint(
       auto index = original_exe_name.rfind('/');
       auto name = "rr:" + original_exe_name.substr(
                               index == std::string::npos ? 0 : index + 1);
-      AutoRestoreMem mem(remote, name.c_str());
-      remote.infallible_syscall(syscall_number_for_prctl(leader->arch()),
-                                PR_SET_NAME, mem.get());
+      leader->set_name(remote, name);
     }
 
     ASSERT(leader, scratch_mem != nullptr)

src/Task.cc

@@ -2578,21 +2578,23 @@ Task::CapturedState Task::capture_state() {
   return state;
 }
 
+void Task::set_name(AutoRemoteSyscalls& remote, const std::string& name) {
+  char prname[17];
+  strncpy(prname, name.c_str(), sizeof(prname));
+  prname[16] = 0;
+  AutoRestoreMem remote_prname(remote, (const uint8_t*)prname, 16);
+  LOG(debug) << "    setting name to " << prname;
+  remote.infallible_syscall(syscall_number_for_prctl(arch()), PR_SET_NAME,
+                            remote_prname.get().as_int());
+  this->prname = name;
+}
+
 void Task::copy_state(const CapturedState& state) {
   set_regs(state.regs);
   set_extra_regs(state.extra_regs);
   {
     AutoRemoteSyscalls remote(this);
-    {
-      char prname[17];
-      strncpy(prname, state.prname.c_str(), sizeof(prname));
-      prname[16] = 0;
-      AutoRestoreMem remote_prname(remote, (const uint8_t*)prname, 16);
-      LOG(debug) << "    setting name to " << prname;
-      remote.infallible_syscall(syscall_number_for_prctl(arch()), PR_SET_NAME,
-                                remote_prname.get().as_int());
-      update_prname(remote_prname.get());
-    }
+    set_name(remote, state.prname);
 
     copy_tls(state, remote);
     thread_areas_ = state.thread_areas;

src/Task.h

@@ -1049,6 +1049,12 @@ class Task {
    */
   void forget();
 
+  /**
+   * Sets the OS-name of this task by injecting system call for PR_SET_NAME.
+   * Also updates |prname| to |name|.
+   */
+  void set_name(AutoRemoteSyscalls& remote_syscalls, const std::string& name);
+
   // Used on aarch64 to detect whether we've recorded x0 and x8 on syscall entry
   Ticks ticks_at_last_syscall_entry;
   remote_code_ptr ip_at_last_syscall_entry;