iox-eclipse-iceoryx#32 refactor message queue existance check and add…

…ed static unlink function

Signed-off-by: Kraus Mathias (CC-AD/ESW1) <[email protected]>

iceoryx_posh/source/runtime/message_queue_interface.cpp

@@ -175,14 +175,7 @@ bool MqBase::closeMessageQueue() noexcept
 
 bool MqBase::reopen() noexcept
 {
-    if (posix::MessageQueue::exists(m_interfaceName).get_value_or(false))
-    {
-        return openMessageQueue(m_channelSide);
-    }
-    else
-    {
-        return false;
-    }
+    return openMessageQueue(m_channelSide);
 }
 
 bool MqBase::mqMapsToFile() noexcept
@@ -197,21 +190,16 @@ bool MqBase::hasClosableMessageQueue() const noexcept
 
 void MqBase::cleanupOutdatedMessageQueue(const std::string& name) noexcept
 {
-    // if the message queue already exists, take ownership and use RAII for cleanup
-    if (posix::MessageQueue::exists(name).get_value_or(false))
+    if (posix::MessageQueue::unlinkIfExists(name).get_value_or(false))
     {
         LogWarn() << "MQ still there, doing an unlink of " << name;
-        posix::MessageQueue::create(name, posix::IpcChannelMode::BLOCKING, posix::IpcChannelSide::SERVER);
     }
 }
 
 MqInterfaceUser::MqInterfaceUser(const std::string& name, const long maxMessages, const long messageSize) noexcept
     : MqBase(name, maxMessages, messageSize)
 {
-    if (posix::MessageQueue::exists(name).get_value_or(false))
-    {
-        openMessageQueue(posix::IpcChannelSide::CLIENT);
-    }
+    openMessageQueue(posix::IpcChannelSide::CLIENT);
 }
 
 MqInterfaceCreator::MqInterfaceCreator(const std::string& name, const long maxMessages, const long messageSize) noexcept

iceoryx_utils/include/iceoryx_utils/internal/posix_wrapper/message_queue.hpp

@@ -50,6 +50,7 @@ class MessageQueue : public DesignPattern::Creation<MessageQueue, IpcChannelErro
   public:
     static constexpr mqd_t INVALID_DESCRIPTOR = -1;
     static constexpr int32_t ERROR_CODE = -1;
+    static constexpr size_t SHORTEST_VALID_QUEUE_NAME = 2;
     static constexpr size_t NULL_TERMINATOR_SIZE = 1;
     static constexpr size_t MAX_MESSAGE_SIZE = 4096;
 
@@ -67,7 +68,7 @@ class MessageQueue : public DesignPattern::Creation<MessageQueue, IpcChannelErro
 
     ~MessageQueue();
 
-    static cxx::expected<bool, IpcChannelError> exists(const std::string& name);
+    static cxx::expected<bool, IpcChannelError> unlinkIfExists(const std::string& name);
 
     /// close and remove message queue.
     cxx::expected<IpcChannelError> destroy();

iceoryx_utils/source/posix_wrapper/message_queue.cpp

@@ -43,6 +43,18 @@ MessageQueue::MessageQueue(const std::string& name,
     }
     else
     {
+        if (channelSide == IpcChannelSide::SERVER)
+        {
+            auto mqCall = cxx::makeSmartC(
+                mq_unlink, cxx::ReturnMode::PRE_DEFINED_ERROR_CODE, {ERROR_CODE}, {ENOENT}, m_name.c_str());
+            if (!mqCall.hasErrors())
+            {
+                if (mqCall.getErrNum() != ENOENT)
+                {
+                    std::cout << "MQ still there, doing an unlink of " << name << std::endl;
+                }
+            }
+        }
         // fields have a different order in QNX,
         // so we need to initialize by name
         m_attributes.mq_flags = (mode == IpcChannelMode::NON_BLOCKING) ? O_NONBLOCK : 0;
@@ -103,34 +115,19 @@ MessageQueue& MessageQueue::operator=(MessageQueue&& other)
     return *this;
 }
 
-cxx::expected<bool, IpcChannelError> MessageQueue::exists(const std::string& name)
+cxx::expected<bool, IpcChannelError> MessageQueue::unlinkIfExists(const std::string& name)
 {
-    if (name.empty() || name.at(0) != '/')
+    if (name.size() < SHORTEST_VALID_QUEUE_NAME || name.at(0) != '/')
     {
         return cxx::error<IpcChannelError>(IpcChannelError::INVALID_CHANNEL_NAME);
     }
 
-    int32_t openFlags = O_RDWR;
-
-    // the mask will be applied to the permissions, therefore we need to set it to 0
-    mode_t umaskSaved = umask(0);
-
-    struct mq_attr attributes;
-
-    auto mqCall = cxx::makeSmartC(mq_open,
-                                  cxx::ReturnMode::PRE_DEFINED_ERROR_CODE,
-                                  {ERROR_CODE},
-                                  {ENOENT},
-                                  name.c_str(),
-                                  openFlags,
-                                  MessageQueue::m_filemode,
-                                  &attributes);
-
-    umask(umaskSaved);
+    auto mqCall =
+        cxx::makeSmartC(mq_unlink, cxx::ReturnMode::PRE_DEFINED_ERROR_CODE, {ERROR_CODE}, {ENOENT}, name.c_str());
 
     if (!mqCall.hasErrors())
     {
-        // ENOENT is set if the message queue could not be opened
+        // ENOENT is set if the message queue could not be unlinked
         return cxx::success<bool>(mqCall.getErrNum() != ENOENT);
     }
     else
@@ -209,7 +206,7 @@ cxx::expected<std::string, IpcChannelError> MessageQueue::receive() const
 cxx::expected<int32_t, IpcChannelError>
 MessageQueue::open(const std::string& name, const IpcChannelMode mode, const IpcChannelSide channelSide)
 {
-    if (name.empty() || name.at(0) != '/')
+    if (name.size() < SHORTEST_VALID_QUEUE_NAME || name.at(0) != '/')
     {
         return cxx::error<IpcChannelError>(IpcChannelError::INVALID_CHANNEL_NAME);
     }
@@ -227,7 +224,7 @@ MessageQueue::open(const std::string& name, const IpcChannelMode mode, const Ipc
     auto mqCall = cxx::makeSmartC(mq_open,
                                   cxx::ReturnMode::PRE_DEFINED_ERROR_CODE,
                                   {ERROR_CODE},
-                                  {},
+                                  {ENOENT},
                                   name.c_str(),
                                   openFlags,
                                   m_filemode,
@@ -237,7 +234,18 @@ MessageQueue::open(const std::string& name, const IpcChannelMode mode, const Ipc
 
     if (!mqCall.hasErrors())
     {
-        return cxx::success<int32_t>(mqCall.getReturnValue());
+        if (mqCall.getErrNum() == 0)
+        {
+            return cxx::success<int32_t>(mqCall.getReturnValue());
+        }
+        else if (mqCall.getErrNum() == ENOENT)
+        {
+            return cxx::error<IpcChannelError>(IpcChannelError::NO_SUCH_CHANNEL);
+        }
+        else
+        {
+            return createErrorFromErrnum(mqCall.getErrNum());
+        }
     }
     else
     {