[Pdns-dev] [PATCH] Handle EINTR in Semaphore::wait()

Anders Kaseorg andersk at ksplice.com
Mon Dec 13 21:19:09 CET 2010


Can I get a developer to look at this patch to make Semaphore::wait() 
handle EINTR?

Right now the callers of wait() ignore its return value, which leads to 
crashes, for example, when sending SIGSTOP and SIGCONT to a running 
pdns_server.  The callers should also be updated to notice errors, but 
this fixes the most common case, since EINTR can happen at any time during 
normal operation.

I also submitted it to the Trac: http://wiki.powerdns.com/trac/ticket/326


diff -ur pdns-2.9.22.orig/pdns/unix_semaphore.cc pdns-2.9.22/pdns/unix_semaphore.cc
--- pdns-2.9.22.orig/pdns/unix_semaphore.cc	2008-11-15 15:32:46.000000000 -0500
+++ pdns-2.9.22/pdns/unix_semaphore.cc	2010-11-12 18:24:00.815081488 -0500
@@ -156,7 +156,11 @@
 int Semaphore::wait()
-  return sem_wait(m_pSemaphore);
+  int ret;
+  do
+    ret = sem_wait(m_pSemaphore);
+  while (ret == -1 && errno == EINTR);
+  return ret;
 int Semaphore::tryWait()

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