Added a "mustNotExist" argument to NamedPipe creation

modules/juce_core/native/juce_posix_NamedPipe.cpp

@@ -33,6 +33,8 @@ public:
        : pipeInName  (pipePath + "_in"),
          pipeOutName (pipePath + "_out"),
          pipeIn (-1), pipeOut (-1),
+         createdFifoIn (false),
+         createdFifoOut (false),
          createdPipe (createPipe),
          stopReadOperation (false)
     {
@@ -47,8 +49,8 @@ public:
 
         if (createdPipe)
         {
-            unlink (pipeInName.toUTF8());
-            unlink (pipeOutName.toUTF8());
+            if (createdFifoIn)  unlink (pipeInName.toUTF8());
+            if (createdFifoOut) unlink (pipeOutName.toUTF8());
         }
     }
 
@@ -119,14 +121,22 @@ public:
         return bytesWritten;
     }
 
-    bool createFifos() const
+    static bool createFifo (const String& name, bool mustNotExist)
     {
-        return (mkfifo (pipeInName .toUTF8(), 0666) == 0 || errno == EEXIST)
-            && (mkfifo (pipeOutName.toUTF8(), 0666) == 0 || errno == EEXIST);
+        return mkfifo (name.toUTF8(), 0666) == 0 || ((! mustNotExist) && errno == EEXIST);
+    }
+
+    bool createFifos (bool mustNotExist)
+    {
+        createdFifoIn  = createFifo (pipeInName, mustNotExist);
+        createdFifoOut = createFifo (pipeOutName, mustNotExist);
+
+        return createdFifoIn && createdFifoOut;
     }
 
     const String pipeInName, pipeOutName;
     int pipeIn, pipeOut;
+    bool createdFifoIn, createdFifoOut;
 
     const bool createdPipe;
     bool stopReadOperation;
@@ -188,7 +198,7 @@ void NamedPipe::close()
     }
 }
 
-bool NamedPipe::openInternal (const String& pipeName, const bool createPipe)
+bool NamedPipe::openInternal (const String& pipeName, const bool createPipe, bool mustNotExist)
 {
    #if JUCE_IOS
     pimpl = new Pimpl (File::getSpecialLocation (File::tempDirectory)
@@ -202,7 +212,7 @@ bool NamedPipe::openInternal (const String& pipeName, const bool createPipe)
     pimpl = new Pimpl (file, createPipe);
    #endif
 
-    if (createPipe && ! pimpl->createFifos())
+    if (createPipe && ! pimpl->createFifos (mustNotExist))
     {
         pimpl = nullptr;
         return false;

modules/juce_core/native/juce_win32_Files.cpp

@@ -788,7 +788,7 @@ void File::revealToUser() const
 class NamedPipe::Pimpl
 {
 public:
-    Pimpl (const String& pipeName, const bool createPipe)
+    Pimpl (const String& pipeName, const bool createPipe, bool mustNotExist)
         : filename ("\\\\.\\pipe\\" + File::createLegalFileName (pipeName)),
           pipeH (INVALID_HANDLE_VALUE),
           cancelEvent (CreateEvent (0, FALSE, FALSE, 0)),
@@ -800,7 +800,7 @@ public:
                                      PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED, 0,
                                      PIPE_UNLIMITED_INSTANCES, 4096, 4096, 0, 0);
 
-            if (GetLastError() == ERROR_ALREADY_EXISTS)
+            if (mustNotExist && GetLastError() == ERROR_ALREADY_EXISTS)
                 closePipeHandle();
         }
     }
@@ -995,9 +995,9 @@ void NamedPipe::close()
     }
 }
 
-bool NamedPipe::openInternal (const String& pipeName, const bool createPipe)
+bool NamedPipe::openInternal (const String& pipeName, const bool createPipe, bool mustNotExist)
 {
-    pimpl = new Pimpl (pipeName, createPipe);
+    pimpl = new Pimpl (pipeName, createPipe, mustNotExist);
 
     if (createPipe && pimpl->pipeH == INVALID_HANDLE_VALUE)
     {

modules/juce_core/network/juce_NamedPipe.cpp

@@ -41,7 +41,7 @@ bool NamedPipe::openExisting (const String& pipeName)
 
     ScopedWriteLock sl (lock);
     currentPipeName = pipeName;
-    return openInternal (pipeName, false);
+    return openInternal (pipeName, false, false);
 }
 
 bool NamedPipe::isOpen() const
@@ -49,13 +49,13 @@ bool NamedPipe::isOpen() const
     return pimpl != nullptr;
 }
 
-bool NamedPipe::createNewPipe (const String& pipeName)
+bool NamedPipe::createNewPipe (const String& pipeName, bool mustNotExist)
 {
     close();
 
     ScopedWriteLock sl (lock);
     currentPipeName = pipeName;
-    return openInternal (pipeName, true);
+    return openInternal (pipeName, true, mustNotExist);
 }
 
 String NamedPipe::getName() const

modules/juce_core/network/juce_NamedPipe.h

@@ -56,8 +56,10 @@ public:
 
     /** Tries to create a new pipe.
         Returns true if it succeeds.
+        If mustNotExist is true then it will fail if a pipe is already
+        open with the same name.
     */
-    bool createNewPipe (const String& pipeName);
+    bool createNewPipe (const String& pipeName, bool mustNotExist = false);
 
     /** Closes the pipe, if it's open. */
     void close();
@@ -95,7 +97,7 @@ private:
     String currentPipeName;
     ReadWriteLock lock;
 
-    bool openInternal (const String& pipeName, const bool createPipe);
+    bool openInternal (const String& pipeName, bool createPipe, bool mustNotExist);
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NamedPipe)
 };

modules/juce_events/interprocess/juce_InterprocessConnection.cpp

@@ -91,13 +91,13 @@ bool InterprocessConnection::connectToPipe (const String& pipeName, const int ti
     return false;
 }
 
-bool InterprocessConnection::createPipe (const String& pipeName, const int timeoutMs)
+bool InterprocessConnection::createPipe (const String& pipeName, const int timeoutMs, bool mustNotExist)
 {
     disconnect();
 
     ScopedPointer<NamedPipe> newPipe (new NamedPipe());
 
-    if (newPipe->createNewPipe (pipeName))
+    if (newPipe->createNewPipe (pipeName, mustNotExist))
     {
         const ScopedLock sl (pipeAndSocketLock);
         pipeReceiveMessageTimeout = timeoutMs;

modules/juce_events/interprocess/juce_InterprocessConnection.h

@@ -108,13 +108,14 @@ public:
         This creates a pipe with the given name, so that other processes can use
         connectToPipe() to connect to the other end.
 
-        @param pipeName     the name to use for the pipe - this should be unique to your app
+        @param pipeName       the name to use for the pipe - this should be unique to your app
         @param pipeReceiveMessageTimeoutMs  a timeout length to be used when reading or writing
-                                            to the pipe, or -1 for an infinite timeout.
+                                            to the pipe, or -1 for an infinite timeout
+        @param mustNotExist   if set to true, the method will fail if the pipe already exists
         @returns true if the pipe was created, or false if it fails (e.g. if another process is
-                 already using using the pipe).
+                 already using using the pipe)
     */
-    bool createPipe (const String& pipeName, int pipeReceiveMessageTimeoutMs);
+    bool createPipe (const String& pipeName, int pipeReceiveMessageTimeoutMs, bool mustNotExist = false);
 
     /** Disconnects and closes any currently-open sockets or pipes. */
     void disconnect();