NtQueryInformationProcess function (winternl.h)

[NtQueryInformationProcess may be altered or unavailable in future versions of Windows. Applications should use the alternate functions listed in this topic.]

Retrieves information about the specified process.

Syntax

__kernel_entry NTSTATUS NtQueryInformationProcess(
  [in]            HANDLE           ProcessHandle,
  [in]            PROCESSINFOCLASS ProcessInformationClass,
  [out]           PVOID            ProcessInformation,
  [in]            ULONG            ProcessInformationLength,
  [out, optional] PULONG           ReturnLength
);

Parameters

[in] ProcessHandle

A handle to the process for which information is to be retrieved.

[in] ProcessInformationClass

The type of process information to be retrieved. This parameter can be one of the following values from the PROCESSINFOCLASS enumeration.

[out] ProcessInformation

A pointer to a buffer supplied by the calling application into which the function writes the requested information. The size of the information written varies depending on the data type of the ProcessInformationClass parameter:

PROCESS_BASIC_INFORMATION

When the ProcessInformationClass parameter is ProcessBasicInformation, the buffer pointed to by the ProcessInformation parameter should be large enough to hold a single PROCESS_BASIC_INFORMATION structure having the following layout:

typedef struct _PROCESS_BASIC_INFORMATION {
    NTSTATUS ExitStatus;
    PPEB PebBaseAddress;
    ULONG_PTR AffinityMask;
    KPRIORITY BasePriority;
    ULONG_PTR UniqueProcessId;
    ULONG_PTR InheritedFromUniqueProcessId;
} PROCESS_BASIC_INFORMATION;

ULONG_PTR

When the ProcessInformationClass parameter is ProcessWow64Information, the buffer pointed to by the ProcessInformation parameter should be large enough to hold a ULONG_PTR. If this value is nonzero, the process is running in a WOW64 environment. Otherwise, the process is not running in a WOW64 environment.

Use the IsWow64Process2 function to determine whether a process is running in the WOW64 environment.

UNICODE_STRING

When the ProcessInformationClass parameter is ProcessImageFileName, the buffer pointed to by the ProcessInformation parameter should be large enough to hold a UNICODE_STRING structure as well as the string itself. The string stored in the Buffer member is the name of the image file.

If the buffer is too small, the function fails with the STATUS_INFO_LENGTH_MISMATCH error code and the ReturnLength parameter is set to the required buffer size.

[in] ProcessInformationLength

The size of the buffer pointed to by the ProcessInformation parameter, in bytes.

[out, optional] ReturnLength

A pointer to a variable in which the function returns the size of the requested information. If the function was successful, this is the size of the information written to the buffer pointed to by the ProcessInformation parameter (if the buffer was too small, this is the minimum size of buffer needed to receive the information successfully).

Return value

The function returns an NTSTATUS success or error code.

The forms and significance of NTSTATUS error codes are listed in the Ntstatus.h header file available in the DDK. See Logging Errors for more details.

Remarks

The NtQueryInformationProcess function and the structures that it returns are internal to the operating system and subject to change from one release of Windows to another. To maintain the compatibility of your application, it is better to use public functions mentioned in the description of the ProcessInformationClass parameter instead.

If you do use NtQueryInformationProcess, access the function through run-time dynamic linking. This gives your code an opportunity to respond gracefully if the function has been changed or removed from the operating system. Signature changes, however, may not be detectable.

This function has no associated import library. You must use the LoadLibrary and GetProcAddress functions to dynamically link to Ntdll.dll.

Requirements

See also

CheckRemoteDebuggerPresent

GetProcessId

IsDebuggerPresent

IsWow64Process

IsWow64Process2