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Reliably obtain C Strings for names, fixes #29
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@brunchboy
brunchboy committed Sep 2, 2019
1 parent 6f80497 commit 4d3bc01
Showing 1 changed file with 101 additions and 56 deletions.
157 changes: 101 additions & 56 deletions CoreMIDI4J/Native/CoreMidi4J/CoreMidiDeviceProvider.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,47 @@ JNIEXPORT jint JNICALL Java_uk_co_xfactorylibrarians_coremidi4j_CoreMidiDevicePr

}

/*
* Safely obtains a C string pointer from a CFStringRef. We must do it this way, because CFStringGetCStringPtr
* is free to return NULL for a variety of reasons, including simply not having an efficient way to respond.
* However, this means that it is the responsibility of the caller to free() the returned pointer when it is
* no longer needed, unless we returned NULL.
*
* @param aString The CFStringRef
*
* @return A newly allocated C string holding the contents of str, or NULL
*
*/
char * safeCFStringCopyUTF8String(CFStringRef aString) {
if (aString == NULL) {
return NULL;
}

CFIndex length = CFStringGetLength(aString);
CFIndex maxSize = CFStringGetMaximumSizeForEncoding(length, kCFStringEncodingUTF8) + 1;
char *buffer = (char *)malloc(maxSize);
if (CFStringGetCString(aString, buffer, maxSize, kCFStringEncodingUTF8)) {
return buffer;
}
free(buffer); // We failed
return NULL;
}

/*
* Safely prints a line describing a retrieved string for debugging purposes.
* If the string is null, also reports that.
*
* @param label Describes the string being printed
* @param aString The CFStringRef to be printed
*
*/
// Uncomment this if you want to perform the (also commented out) debug printing in the function below.
//void debugPrintCFString(std::string label, CFStringRef aString) {
// char *cString = safeCFStringCopyUTF8String(aString);
// std::cout << label << ((cString != NULL)? cString : "<NULL pointer>") << std::endl;
// free(cString);
//}

/*
* Creates and gets a MidiDevice.Info object for the specified end point reference
*
Expand Down Expand Up @@ -183,7 +224,7 @@ JNIEXPORT jobject JNICALL Java_uk_co_xfactorylibrarians_coremidi4j_CoreMidiDevic
SInt32 endpointOffline = NULL;
SInt32 endpointUniqueID = 0;
SInt32 endpointDriverVersion = 0;

// Find the Java CoreMIDIDeviceInfo class and its constructor
jclass javaClass = env->FindClass("uk/co/xfactorylibrarians/coremidi4j/CoreMidiDeviceInfo");
jmethodID constructor = env->GetMethodID(javaClass, "<init>", "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;IILjava/lang/String;IILjava/lang/String;II)V");
Expand Down Expand Up @@ -215,88 +256,86 @@ JNIEXPORT jobject JNICALL Java_uk_co_xfactorylibrarians_coremidi4j_CoreMidiDevic
MIDIObjectGetIntegerProperty(deviceReference, kMIDIPropertyOffline, &deviceOffline);
MIDIObjectGetIntegerProperty(deviceReference, kMIDIPropertyUniqueID, &deviceUniqueID);
MIDIObjectGetIntegerProperty(deviceReference, kMIDIPropertyDriverVersion, &deviceDriverVersion);

long numberOfEntities = MIDIDeviceGetNumberOfEntities(deviceReference);

// Uncomment these lines if you wish to view information as received on the native side during debugging.
//CFStringRef nullPointerText = CFSTR("** NULL POINTER **");
//
//std::cout << "End Point " << std::endl;
//std::cout << " End Point Reference " << endPointReference << std::endl;
//std::cout << " End Point kMIDIPropertyName " << CFStringGetCStringPtr ( ( endpointName != NULL ) ? endpointName : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " End Point kMIDIPropertyModel " << CFStringGetCStringPtr ( ( endpointModel != NULL ) ? endpointModel : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " End Point kMIDIPropertyManufacturer " << CFStringGetCStringPtr ( ( endpointManufacturer != NULL ) ? endpointManufacturer : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " End Point kMIDIPropertyOffline " << endpointOffline << std::endl;
//std::cout << " End Point kMIDIPropertyUniqueID " << endpointUniqueID << std::endl;
//std::cout << " End Point kMIDIPropertyDriverVersion " << endpointDriverVersion << std::endl;
//std::cout << std::endl;
//std::cout << " Entity Reference " << entityReference << std::endl;
//std::cout << " Entity kMIDIPropertyName " << CFStringGetCStringPtr ( ( entityName != NULL ) ? entityName : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Entity kMIDIPropertyModel " << CFStringGetCStringPtr ( ( entityModel != NULL ) ? entityModel : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Entity kMIDIPropertyManufacturer " << CFStringGetCStringPtr ( ( entityManufacturer != NULL ) ? entityManufacturer : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Entity kMIDIPropertyOffline " << entityOffline << std::endl;
//std::cout << " Entity kMIDIPropertyUniqueID " << entityUniqueID << std::endl;
//std::cout << " Entity kMIDIPropertyDriverVersion " << entityDriverVersion << std::endl;
//std::cout << std::endl;
//std::cout << " Device Reference " << deviceReference << std::endl;
//std::cout << " Device kMIDIPropertyName " << CFStringGetCStringPtr ( ( deviceName != NULL ) ? deviceName : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Device kMIDIPropertyModel " << CFStringGetCStringPtr ( ( deviceModel != NULL ) ? deviceModel : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Device kMIDIPropertyManufacturer " << CFStringGetCStringPtr ( ( deviceManufacturer != NULL ) ? deviceManufacturer : nullPointerText, CFStringGetSystemEncoding() ) << std::endl;
//std::cout << " Device kMIDIPropertyOffline " << deviceOffline << std::endl;
//std::cout << " Device kMIDIPropertyUniqueID " << deviceUniqueID << std::endl;
//std::cout << " Device kMIDIPropertyDriverVersion " << deviceDriverVersion << std::endl;
//std::cout << std::endl;
//std::cout << " Number of entities " << numberOfEntities << std::endl;
//std::cout << std::endl;

// Uncomment these lines and debugPrintCFString (above) if you wish to view information as received on the native side during debugging.
// std::cout << "End Point " << std::endl;
// std::cout << " End Point Reference " << endPointReference << std::endl;
// debugPrintCFString(" End Point kMIDIPropertyName ", endpointName);
// debugPrintCFString(" End Point kMIDIPropertyModel ", endpointModel);
// debugPrintCFString(" End Point kMIDIPropertyManufacturer ", endpointManufacturer);
// std::cout << " End Point kMIDIPropertyOffline " << endpointOffline << std::endl;
// std::cout << " End Point kMIDIPropertyUniqueID " << endpointUniqueID << std::endl;
// std::cout << " End Point kMIDIPropertyDriverVersion " << endpointDriverVersion << std::endl;
// std::cout << std::endl;
// std::cout << " Entity Reference " << entityReference << std::endl;
// debugPrintCFString(" Entity kMIDIPropertyName ", entityName);
// debugPrintCFString(" Entity kMIDIPropertyModel ", entityModel);
// debugPrintCFString(" Entity kMIDIPropertyManufacturer ", entityManufacturer);
// std::cout << " Entity kMIDIPropertyOffline " << entityOffline << std::endl;
// std::cout << " Entity kMIDIPropertyUniqueID " << entityUniqueID << std::endl;
// std::cout << " Entity kMIDIPropertyDriverVersion " << entityDriverVersion << std::endl;
// std::cout << std::endl;
// std::cout << " Device Reference " << deviceReference << std::endl;
// debugPrintCFString(" Device kMIDIPropertyName ", deviceName);
// debugPrintCFString(" Device kMIDIPropertyModel ", deviceModel);
// debugPrintCFString(" Device kMIDIPropertyManufacturer ", deviceManufacturer);
// std::cout << " Device kMIDIPropertyOffline " << deviceOffline << std::endl;
// std::cout << " Device kMIDIPropertyUniqueID " << deviceUniqueID << std::endl;
// std::cout << " Device kMIDIPropertyDriverVersion " << deviceDriverVersion << std::endl;
// std::cout << std::endl;
// std::cout << " Number of entities " << numberOfEntities << std::endl;
// std::cout << std::endl;

// Build the Device Info name. Add "CoreMIDI4J - " to the start of our device name if we can
// And if the device has more than one entity then add the entity name
CFMutableStringRef buildName = CFStringCreateMutable(NULL, 0);
CFStringRef deviceInfoName;

if ( buildName != NULL ) {

if ( deviceName != NULL ) {

CFStringAppend(buildName, (deviceName != NULL ) ? deviceName : CFSTR("<Unknown Device>") );

if ( numberOfEntities > 1 ) {

CFStringAppend(buildName, CFSTR(" "));
CFStringAppend(buildName, (endpointName != NULL ) ? endpointName : CFSTR("<Unknown Endpoint>") );

}

} else {

CFStringAppend(buildName, (endpointName != NULL ) ? endpointName : CFSTR("<Unknown Device>") );

}

// Overwrite the deviceName with our updated one
deviceInfoName = CFStringCreateCopy(NULL, buildName);

// And release the temporary string
CFRelease(buildName);

} else {

// Overwrite the deviceName with our updated one
deviceInfoName = CFStringCreateCopy(NULL, deviceName);

}
const char *deviceInfoNamePtr = CFStringGetCStringPtr ( deviceInfoName, CFStringGetSystemEncoding() );
const char *deviceInfoManufacturerPtr = CFStringGetCStringPtr ( endpointManufacturer, CFStringGetSystemEncoding() ); // The end point manufacturer name is always present
const char *deviceInfoDescriptionPtr = CFStringGetCStringPtr ( endpointModel, CFStringGetSystemEncoding() ); // The end point model name is always present
const char *deviceNamePtr = CFStringGetCStringPtr ( deviceName, CFStringGetSystemEncoding() );
const char *entityNamePtr = CFStringGetCStringPtr ( entityName, CFStringGetSystemEncoding() );
const char *endPointNamePtr = CFStringGetCStringPtr ( endpointName, CFStringGetSystemEncoding() );

char *deviceInfoNamePtr = safeCFStringCopyUTF8String ( deviceInfoName );
char *deviceInfoManufacturerPtr = safeCFStringCopyUTF8String ( endpointManufacturer ); // The end point manufacturer name is always present
char *deviceInfoDescriptionPtr = safeCFStringCopyUTF8String ( endpointModel ); // The end point model name is always present

char *deviceNamePtr = safeCFStringCopyUTF8String ( deviceName );
char *entityNamePtr = safeCFStringCopyUTF8String ( entityName );
char *endPointNamePtr = safeCFStringCopyUTF8String ( endpointName );

// TODO - Have seen reference that the device neds to be initialised to get the version. As we are still getting zero, force the string for now
const char *deviceInfoVersion = "Unknown Version";

// Create the Java Object
jobject info = env->NewObject(javaClass,
constructor,
Expand All @@ -314,7 +353,13 @@ JNIEXPORT jobject JNICALL Java_uk_co_xfactorylibrarians_coremidi4j_CoreMidiDevic
endPointReference,
endpointUniqueID);

free(deviceInfoNamePtr);
free(deviceInfoManufacturerPtr);
free(deviceInfoDescriptionPtr);
free(deviceNamePtr);
free(entityNamePtr);
free(endPointNamePtr);

return info;

}

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