From 0238e9ef50f115d98cf860a476bff8b5edff12ff Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sun, 6 Aug 2017 21:10:06 +0200
Subject: Handle the case where machine is shutdown/rebooted from within

---
 bbot/agent/machine.cxx | 149 +++++++++++++++++++++++++------------------------
 1 file changed, 77 insertions(+), 72 deletions(-)

diff --git a/bbot/agent/machine.cxx b/bbot/agent/machine.cxx
index c2ded27..9502021 100644
--- a/bbot/agent/machine.cxx
+++ b/bbot/agent/machine.cxx
@@ -180,8 +180,10 @@ namespace bbot
     print_info (diag_record&) override;
 
   private:
+    // Throw system_error in case of communication errors.
+    //
     void
-    monitor_command (const string&, bool fail_hard = true);
+    monitor_command (const string&);
 
   private:
     path kvm;     // Hypervisor binary.
@@ -333,44 +335,55 @@ namespace bbot
   bool kvm_machine::
   shutdown (size_t& seconds)
   {
-    monitor_command ("system_powerdown");
-
     // Wait for up to the specified number if seconds for the machine to
-    // shutdown.
-    //
-    // Since things sometimes get stuck for no apparent reason, keep repeating
-    // the the request every minute.
+    // shutdown. And handle the case where it was shutdown from within.
     //
-    for (size_t s;; )
+    try
     {
-      s = 60;
-      bool r (seconds < s ? wait (seconds) : wait (s));
-      seconds -= (60 - s);
-
-      if (r || seconds == 0)
-        return r;
+      monitor_command ("system_powerdown");
+    }
+    catch (const system_error& e)
+    {
+      size_t t (0);
+      if (wait (t))
+        return true;
 
-      try
-      {
-        monitor_command ("system_powerdown", false);
-      }
-      catch (const failed&) {}
+      fail << "unable to communicate with qemu monitor: " << e;
     }
 
-    return false;
+    return wait (seconds);
   }
 
   void kvm_machine::
   forcedown (bool fh)
   {
-    monitor_command ("system_reset", fh);
+    try
+    {
+      monitor_command ("system_reset");
+    }
+    catch (const system_error& e)
+    {
+      size_t t (0);
+      if (wait (t, fh))
+        return;
+
+      fail (fh) << "unable to communicate with qemu monitor: " << e;
+    }
+
     wait (fh);
   }
 
   void kvm_machine::
   suspend ()
   {
-    monitor_command ("stop");
+    try
+    {
+      monitor_command ("stop");
+    }
+    catch (const system_error& e)
+    {
+      fail << "unable to communicate with qemu monitor: " << e;
+    }
   }
 
   void kvm_machine::
@@ -408,70 +421,62 @@ namespace bbot
   }
 
   void kvm_machine::
-  monitor_command (const string& c, bool fh)
+  monitor_command (const string& c)
   {
-    try
-    {
-      sockaddr_un addr;
-      addr.sun_family = AF_LOCAL;
-      strcpy (addr.sun_path, monitor.string ().c_str ()); // Size check in ctor
+    sockaddr_un addr;
+    addr.sun_family = AF_LOCAL;
+    strcpy (addr.sun_path, monitor.string ().c_str ()); // Size check in ctor
 
-      auto_fd sock (socket (AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0));
+    auto_fd sock (socket (AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0));
 
-      if (sock.get () == -1)
-        throw_system_error (errno);
+    if (sock.get () == -1)
+      throw_system_error (errno);
 
-      if (connect (sock.get (),
-                   reinterpret_cast<sockaddr*> (&addr),
-                   sizeof (addr)) == -1)
-        throw_system_error (errno);
+    if (connect (sock.get (),
+                 reinterpret_cast<sockaddr*> (&addr),
+                 sizeof (addr)) == -1)
+      throw_system_error (errno);
 
-      // Read until we get something.
-      //
-      auto readsome = [&sock] ()
+    // Read until we get something.
+    //
+    auto readsome = [&sock] ()
+    {
+      ifdstream ifs (move (sock),
+                     fdstream_mode::non_blocking,
+                     ostream::badbit);
+
+      char buf[256];
+      for (streamsize n (0), m (0);
+           n == 0 || m != 0;
+           m = ifs.readsome (buf, sizeof (buf) - 1))
       {
-        ifdstream ifs (move (sock),
-                       fdstream_mode::non_blocking,
-                       ostream::badbit);
-
-        char buf[256];
-        for (streamsize n (0), m (0);
-             n == 0 || m != 0;
-             m = ifs.readsome (buf, sizeof (buf) - 1))
+        if (m != 0)
         {
-          if (m != 0)
-          {
-            n += m;
+          n += m;
 
-            //buf[m] = '\0';
-            //text << buf;
-          }
+          //buf[m] = '\0';
+          //text << buf;
         }
+      }
 
-        sock = ifs.release ();
-      };
-
-      // Read QEMU welcome.
-      //
-      readsome ();
+      sock = ifs.release ();
+    };
 
-      // Write our command.
-      //
-      {
-        ofdstream ofs (move (sock), fdstream_mode::blocking);
-        ofs << c << endl;
-        sock = ofs.release ();
-      }
+    // Read QEMU welcome.
+    //
+    readsome ();
 
-      // Read QEMU reply (may hit eof).
-      //
-      readsome ();
-      return;
-    }
-    catch (const system_error& e)
+    // Write our command.
+    //
     {
-      fail (fh) << "unable to communicate with qemu monitor: " << e;
+      ofdstream ofs (move (sock), fdstream_mode::blocking);
+      ofs << c << endl;
+      sock = ofs.release ();
     }
+
+    // Read QEMU reply (may hit eof).
+    //
+    readsome ();
   }
 
   unique_ptr<machine>
-- 
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