TdhQueryProviderFieldInformation function (tdh.h)

Retrieves information for the specified field from the event descriptions for those field values that match the given value.

Syntax

TDHSTATUS TdhQueryProviderFieldInformation(
  [in]      LPGUID                    pGuid,
  [in]      ULONGLONG                 EventFieldValue,
  [in]      EVENT_FIELD_TYPE          EventFieldType,
  [out]     PPROVIDER_FIELD_INFOARRAY pBuffer,
  [in, out] ULONG                     *pBufferSize
);

Parameters

[in] pGuid

GUID that identifies the provider whose information you want to retrieve.

[in] EventFieldValue

Retrieve information about the field if the field's value matches this value. If the field type is a keyword, the information is retrieved for each event keyword bit contained in the mask.

[in] EventFieldType

Specify the type of field for which you want to retrieve information. For possible values, see the EVENT_FIELD_TYPE enumeration.

[out] pBuffer

User-allocated buffer to receive the field information. For details, see the PROVIDER_FIELD_INFOARRAY structure.

[in, out] pBufferSize

Size, in bytes, of the pBuffer buffer. If the function succeeds, this parameter receives the size of the buffer used. If the buffer is too small, the function returns ERROR_INSUFFICIENT_BUFFER and sets this parameter to the required buffer size. If the buffer size is zero on input, no data is returned in the buffer and this parameter receives the required buffer size.

Return value

Returns ERROR_SUCCESS if successful. Otherwise, this function returns one of the following return codes in addition to others.

Remarks

This function uses the XML manifest or WMI MOF class to retrieve the information.

Examples

The following example shows how to query information contained in the manifest or MOF class for the requested field.

#include <windows.h>
#include <stdio.h>
#include <wmistr.h>
#include <evntrace.h>
#include <tdh.h>

#pragma comment(lib, "tdh.lib")

DWORD QueryFieldInfo(LPGUID pProvider, EVENT_FIELD_TYPE fieldType, ULONGLONG fieldValue);

// GUID of the provider whose metadata you want to enumerate.

EXTERN_C __declspec(selectany) const GUID ProviderGuid = {0xd8909c24, 0x5be9, 0x4502, {0x98, 0xca, 0xab, 0x7b, 0xdc, 0x24, 0x89, 0x9d}};

void wmain(void)
{
    DWORD status = ERROR_SUCCESS;

    // Retrieve channel information if the provider defines a channel
    // whose value is 17. Returns one entry if the channel exists.

    wprintf(L"Retrieve EventChannelInformation for channel value 17.\n");

    status = QueryFieldInfo((LPGUID)&ProviderGuid, EventChannelInformation, 17);
    if (ERROR_SUCCESS != status)
    {
        wprintf(L"Failed to retrieve EventChannelInformation (%lu).\n\n", status);
    }

    // Retrieve keyword information for keywords whose value is 2 or 8.

    wprintf(L"Retrieve EventKeywordInformation for keywords 2 and 8.\n");

    status = QueryFieldInfo((LPGUID)&ProviderGuid, EventKeywordInformation, 0xA);
    if (ERROR_SUCCESS != status)
    {
        wprintf(L"Failed to retrieve EventKeywordInformation (%lu).\n\n", status);
    }
}

// Prints the information associated with the specified field type.
DWORD QueryFieldInfo(LPGUID pProvider, EVENT_FIELD_TYPE fieldType, ULONGLONG fieldValue)
{
    DWORD status = ERROR_SUCCESS;
    PROVIDER_FIELD_INFOARRAY* penum = NULL;
    DWORD bufferSize = 0;

    // Retrieve the required buffer size. If the status is ERROR_INSUFFICIENT_BUFFER,
    // use bufferSize to allocate the buffer.

    status = TdhQueryProviderFieldInformation(pProvider, fieldValue, fieldType, penum, &bufferSize);
    if (ERROR_INSUFFICIENT_BUFFER == status)
    {
        penum = (PROVIDER_FIELD_INFOARRAY*) malloc(bufferSize);
        if (penum == NULL)
        {
            wprintf(L"Allocation failed (size=%lu).\n", bufferSize);
            status = ERROR_OUTOFMEMORY;
            goto cleanup;
        }

        // Retrieve the information for the field type and value.

        status = TdhQueryProviderFieldInformation(pProvider, fieldValue, fieldType, penum, &bufferSize);
    }

    // The first call can fail with ERROR_NOT_FOUND if none of the provider's event
    // descriptions contain the requested field type information.

    if (ERROR_SUCCESS == status)
    {
        // Loop through the list of field information and print the field's name,
        // description (if it exists), and value. 

        for (DWORD i = 0; i < penum->NumberOfElements; i++)
        {
            wprintf(L"Field name: %s\nDescription: %s\nValue: %I64u\n\n",
                (PWCHAR)((PBYTE)(penum) + penum->FieldInfoArray[i].NameOffset),
                (penum->FieldInfoArray[i].DescriptionOffset) ? 
                    (PWCHAR)((PBYTE)(penum) + penum->FieldInfoArray[i].DescriptionOffset): L"",
                penum->FieldInfoArray[i].Value);
        }
    }
    else
    {
        if (ERROR_NOT_FOUND == status)
        {
            wprintf(L"Requested field type not found.\n");
        }
        else
        {
            wprintf(L"TdhQueryProviderFieldInformation failed with %lu.\n", status);
        }

        goto cleanup;
    }

cleanup:

    if (penum)
    {
        free(penum);
        penum = NULL;
    }

    return status;
}

Requirements

See also

TdhEnumerateProviderFieldInformation