[Pkg-telepathy-commits] [libnice] 161/265: agent: Fix a potential re-entrancy situation

[Simon McVittie]

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smcv pushed a commit to branch debian
in repository libnice.

commit e62d47d6b4e955f21c15c95cb78fdd823853dd80
Author: Philip Withnall <philip.withnall at collabora.co.uk>
Date:   Tue Mar 4 13:48:03 2014 +0000

    agent: Fix a potential re-entrancy situation
    
    If we emit signals from component_io_cb() in the middle of a read, it’s
    possible that one of those signals will be picked up by the client to
    perform another read. A likely candidate (and what was triggering the
    re-entrancy here) would be component-state-changed. Since signals are
    emitted synchronously, the second read would being inside the first, and
    trigger the anti-re-entrancy assertion.
---
 agent/agent.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/agent/agent.c b/agent/agent.c
index 689a2f6..3c22959 100644
--- a/agent/agent.c
+++ b/agent/agent.c
@@ -3876,8 +3876,14 @@ component_io_cb (GSocket *socket, GIOCondition condition, gpointer user_data)
   }
 
 done:
-
-  agent_unlock_and_emit (agent);
+  /* If we’re in the middle of a read, don’t emit any signals, or we could cause
+   * re-entrancy by (e.g.) emitting component-state-changed and having the
+   * client perform a read. */
+  if (component->n_recv_messages == 0 && component->recv_messages == NULL) {
+    agent_unlock_and_emit (agent);
+  } else {
+    agent_unlock ();
+  }
 
   g_object_unref (agent);
 

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