Merge lp:~afrantzis/mir/fix-lp-1163368 into lp:~mir-team/mir/trunk

[Alexandros Frantzis]

server: Properly handle EOF when reading from SignalDispatcher socket

server: Properly handle EOF when reading from SignalDispatcher socket

The handling is not ideal (e.g. we use an exception for a non-exceptional situation (EOF)) but certainly an improvement... and it doesn't crash :)

[Alan Griffiths (alan-griffiths)]

good

review: Approve

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:552
http://jenkins.qa.ubuntu.com/job/mir-ci/279/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-android-raring-i386-build/232
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-clang-raring-amd64-build/115
    SUCCESS: http://jenkins.qa.ubuntu.com/job/mir-quantal-amd64-ci/281
        deb: http://jenkins.qa.ubuntu.com/job/mir-quantal-amd64-ci/281/artifact/work/output/*zip*/output.zip

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review: Approve (continuous-integration)

=== modified file 'src/server/signal_dispatcher.cpp'
--- src/server/signal_dispatcher.cpp	2013-03-28 12:13:18 +0000
+++ src/server/signal_dispatcher.cpp	2013-04-02 16:11:38 +0000
@@ -60,9 +60,20 @@
 
     int read_signal_from(SocketIdentifier id)
     {
-        int signal;
-        if (::read(sockets[id], &signal, sizeof(signal)) < 0)
-            throw std::runtime_error("Problem reading_from socket");
+        int signal{0};
+        ssize_t nread{0};
+
+        while (nread <= 0)
+        {
+            nread = ::read(sockets[id], &signal, sizeof(signal));
+
+            if (nread == 0)
+                throw std::runtime_error("Write end of socket has been closed");
+            else if (nread > 0 && nread < static_cast<ssize_t>(sizeof(signal)))
+                throw std::runtime_error("Incomplete message retrieved");
+            else if (nread < 0 && errno != EINTR)
+                throw std::runtime_error("Problem reading from socket");
+        }
 
         return signal;
     }