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fix(Mutex_POSIX): prevent deadlocks when logging inside signal handlers #4944

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fix(Mutex_POSIX): prevent deadlocks when logging inside signal handlers #4944

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6 changes: 6 additions & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -247,6 +247,12 @@ option(POCO_ENABLE_STD_MUTEX "Set to OFF|NO using mutex from standard library (d
if (POCO_ENABLE_STD_MUTEX)
add_definitions(-DPOCO_ENABLE_STD_MUTEX)
endif ()

option(POCO_ENABLE_SIG_LOCK "Set to ON if signal handlers use code that lock mutexes to prevent deadlocks (default OFF)" OFF)

if (POCO_ENABLE_SIG_LOCK)
add_definitions(-DPOCO_ENABLE_SIG_LOCK)
endif ()
include(DefinePlatformSpecifc)

# Collect the built libraries and include dirs, the will be used to create the PocoConfig.cmake file
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13 changes: 13 additions & 0 deletions Foundation/include/Poco/Mutex_POSIX.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@
#include <pthread.h>
#include <errno.h>

#ifdef POCO_ENABLE_SIG_LOCK
#include <signal.h>
#endif


namespace Poco {

Expand All @@ -40,6 +44,7 @@ class Foundation_API MutexImpl

private:
pthread_mutex_t _mutex;
sigset_t set, oldset;
};


Expand All @@ -56,6 +61,10 @@ class Foundation_API FastMutexImpl: public MutexImpl
//
inline void MutexImpl::lockImpl()
{
#ifdef POCO_ENABLE_SIG_LOCK
sigfillset(&set);
pthread_sigmask(SIG_BLOCK, &set, &oldset);
#endif
if (pthread_mutex_lock(&_mutex))
throw SystemException("cannot lock mutex");
}
Expand All @@ -77,6 +86,10 @@ inline void MutexImpl::unlockImpl()
{
if (pthread_mutex_unlock(&_mutex))
throw SystemException("cannot unlock mutex");

#ifdef POCO_ENABLE_SIG_LOCK
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
#endif
}


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