detect.c

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/*
 * PROJECT:     ReactOS Sound System "MME Buddy" NT4 Library
 * LICENSE:     GPL - See COPYING in the top level directory
 * FILE:        lib/drivers/sound/mment4/detect.c
 *
 * PURPOSE:     Assists in locating Windows NT4 compatible sound devices,
 *              which mostly use the same device naming convention and/or
 *              store their created device names within their service key
 *              within the registry.
 *
 * PROGRAMMERS: Andrew Greenwood (silverblade@reactos.org)
*/

#include "precomp.h"

/*
    This is the "nice" way to discover audio devices in NT4 - go into the
    service registry key and enumerate the Parameters\Device*\Devices
    values. The value names represent the device name, whereas the data
    assigned to them identifies the type of device.
*/
MMRESULT
EnumerateNt4ServiceSoundDevices(
    IN  LPWSTR ServiceName,
    IN  MMDEVICE_TYPE DeviceType,
    IN  SOUND_DEVICE_DETECTED_PROC SoundDeviceDetectedProc)
{
    HKEY Key;
    DWORD KeyIndex = 0;

    VALIDATE_MMSYS_PARAMETER( ServiceName );

    /* Device type zero means "all" */
    VALIDATE_MMSYS_PARAMETER( IsValidSoundDeviceType(DeviceType) ||
                              DeviceType == 0 );

    while ( OpenSoundDeviceRegKey(ServiceName, KeyIndex, &Key) == MMSYSERR_NOERROR )
    {
        HKEY DevicesKey;
        DWORD ValueType = REG_NONE, ValueIndex = 0;
        DWORD MaxNameLength = 0, ValueNameLength = 0;
        PWSTR DevicePath = NULL, ValueName = NULL;
        DWORD ValueDataLength = sizeof(DWORD);
        DWORD ValueData;

        if ( RegOpenKeyEx(Key,
                          REG_DEVICES_KEY_NAME_U,
                          0,
                          KEY_READ,
                          &DevicesKey) == ERROR_SUCCESS )
        {
            /* Find out how much memory is needed for the key name */
            if ( RegQueryInfoKey(DevicesKey,
                                 NULL, NULL, NULL, NULL, NULL, NULL, NULL,
                                 &MaxNameLength,
                                 NULL, NULL, NULL) != ERROR_SUCCESS )
            {
                SND_ERR(L"Failed to query registry key information\n");
                RegCloseKey(DevicesKey);
                RegCloseKey(Key);

                return MMSYSERR_ERROR;
            }

            DevicePath = AllocateWideString(MaxNameLength +
                                            strlen("\\\\.\\"));

            /* Check that the memory allocation was successful */
            if ( ! DevicePath )
            {
                /* There's no point in going further */
                RegCloseKey(DevicesKey);
                RegCloseKey(Key);

                return MMSYSERR_NOMEM;
            }

            /* Insert the device path prefix */
            wsprintf(DevicePath, L"\\\\.\\");

            /* The offset of the string following this prefix */
            ValueName = DevicePath + strlen("\\\\.\\");

            /* Copy this so that it may be overwritten - include NULL */
            ValueNameLength = MaxNameLength + sizeof(WCHAR);

            SND_TRACE(L"Interested in devices beginning with %wS\n", DevicePath);

            while ( RegEnumValue(DevicesKey,
                                 ValueIndex,
                                 ValueName,
                                 &ValueNameLength,
                                 NULL,
                                 &ValueType,
                                 (LPBYTE) &ValueData,
                                 &ValueDataLength) == ERROR_SUCCESS )
            {
                /* Device types are stored as DWORDs */
                if ( ( ValueType == REG_DWORD ) &&
                     ( ValueDataLength == sizeof(DWORD) ) )
                {
                    if ( ( DeviceType == 0 ) ||
                         ( DeviceType == ValueData ) )
                    {
                        SND_TRACE(L"Found device: %wS\n", DevicePath);
                        SoundDeviceDetectedProc(ValueData, DevicePath);
                    }
                }

                /* Reset variables for the next iteration */
                ValueNameLength = MaxNameLength + sizeof(WCHAR);
                ZeroMemory(ValueName, (MaxNameLength+1)*sizeof(WCHAR));
                /*ZeroWideString(ValueName);*/
                ValueDataLength = sizeof(DWORD);
                ValueData = 0;
                ValueType = REG_NONE;

                ++ ValueIndex;
            }

            FreeMemory(DevicePath);

            RegCloseKey(DevicesKey);
        }
        else
        {
            SND_WARN(L"Unable to open the Devices key!\n");
        }

        ++ KeyIndex;

        RegCloseKey(Key);
    }

    return MMSYSERR_NOERROR;
}

/*
    Brute-force device detection, using a base device name (eg: \\.\WaveOut).

    This will add the device number as a suffix to the end of the string and
    attempt to open the device based on that name. On success, it will
    increment the device number and repeat this process.

    When it runs out of devices, it will give up.
*/
MMRESULT
DetectNt4SoundDevices(
    IN  MMDEVICE_TYPE DeviceType,
    IN  PWSTR BaseDeviceName,
    IN  SOUND_DEVICE_DETECTED_PROC SoundDeviceDetectedProc)
{
    ULONG DeviceNameLength = 0;
    PWSTR DeviceName = NULL;
    ULONG Index = 0;
    HANDLE DeviceHandle;
    BOOLEAN DoSearch = TRUE;

    VALIDATE_MMSYS_PARAMETER( IsValidSoundDeviceType(DeviceType) );

    DeviceNameLength = wcslen(BaseDeviceName);
    /* Consider the length of the number */
    DeviceNameLength += GetDigitCount(Index);

    DeviceName = AllocateWideString(DeviceNameLength);

    if ( ! DeviceName )
    {
        return MMSYSERR_NOMEM;
    }

    while ( DoSearch )
    {
        /* Nothing like a nice clean device name */
        ZeroWideString(DeviceName);
        wsprintf(DeviceName, L"%ls%d", BaseDeviceName, Index);

        if ( OpenKernelSoundDeviceByName(DeviceName,
                                         TRUE,
                                         &DeviceHandle) == MMSYSERR_NOERROR )
        {
            /* Notify the callback function */
            SND_TRACE(L"Found device: %wS\n", DeviceName);
            SoundDeviceDetectedProc(DeviceType, DeviceName);

            CloseHandle(DeviceHandle);

            ++ Index;
        }
        else
        {
            DoSearch = FALSE;
        }
    }

    FreeMemory(DeviceName);

    return MMSYSERR_NOERROR;
}