ZwQueryInformationProcess function

[ZwQueryInformationProcess 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

NTSTATUS WINAPI ZwQueryInformationProcess(
  _In_      HANDLE           ProcessHandle,
  _In_      PROCESSINFOCLASS ProcessInformationClass,
  _Out_     PVOID            ProcessInformation,
  _In_      ULONG            ProcessInformationLength,
  _Out_opt_ PULONG           ReturnLength
);

Parameters

ProcessHandle [in]

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

ProcessInformationClass [in]

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

Value	Meaning
ProcessBasicInformation 0	Retrieves a pointer to a PEB structure that can be used to determine whether the specified process is being debugged, and a unique value used by the system to identify the specified process. It is best to use the CheckRemoteDebuggerPresent and GetProcessId functions to obtain this information.
ProcessDebugPort 7	Retrieves a DWORD_PTR value that is the port number of the debugger for the process. A nonzero value indicates that the process is being run under the control of a ring 3 debugger. It is best to use the CheckRemoteDebuggerPresent or IsDebuggerPresent function.
ProcessWow64Information 26	Determines whether the process is running in the WOW64 environment (WOW64 is the x86 emulator that allows Win32-based applications to run on 64-bit Windows). It is best to use the IsWow64Process function to obtain this information.
ProcessImageFileName 27	Retrieves a UNICODE_STRING value containing the name of the image file for the process.
ProcessBreakOnTermination 29	Retrieves a ULONG value indicating whether the process is considered critical. Note: This value can be used starting in Windows XP with SP3. Starting in Windows 8.1, IsProcessCritical should be used instead.
ProcessProtectionInformation 61	Retrieves a BYTE value indicating the type of protected process and the protected process signer.

 

ProcessInformation [out]

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 value 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;

Field	Meaning
ExitStatus	Contains the same value that GetExitCodeProcess would return. However the use of GetExitCodeProcess is preferable for clarity and safety.
PebBaseAddress	Points to a PEB structure.
AffinityMask	Can be cast to a DWORD and contains the same value that GetProcessAffinityMask would return for the lpProcessAffinityMask parameter.
BasePriority	Contains the process priority as described in Scheduling Priorities.
UniqueProcessId	Can be cast to a DWORD and contains a unique identifier for this process. It is best to use the GetProcessId function to retrieve this information.
InheritedFromUniqueProcessId	Can be cast to a DWORD and contains a unique identifier for the parent process.

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, if the value is equal to zero, the process is not running in a WOW64 environment.

It is best to use the IsWow64Process 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.

PS_PROTECTION

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

typedef struct _PS_PROTECTION {
    union {
        UCHAR Level;
        struct {
            UCHAR Type   : 3;
            UCHAR Audit  : 1;                  // Reserved
            UCHAR Signer : 4;
        };
    };
} PS_PROTECTION, *PPS_PROTECTION;

The first 3 bits contain the type of protected process:

typedef enum _PS_PROTECTED_TYPE {
    PsProtectedTypeNone = 0,
    PsProtectedTypeProtectedLight = 1,
    PsProtectedTypeProtected = 2
} PS_PROTECTED_TYPE, *PPS_PROTECTED_TYPE;

The top 4 bits contain the protected process signer:

typedef enum _PS_PROTECTED_SIGNER {
    PsProtectedSignerNone = 0,
    PsProtectedSignerAuthenticode,
    PsProtectedSignerCodeGen,
    PsProtectedSignerAntimalware,
    PsProtectedSignerLsa,
    PsProtectedSignerWindows,
    PsProtectedSignerWinTcb,
    PsProtectedSignerWinSystem,
    PsProtectedSignerApp,
    PsProtectedSignerMax
} PS_PROTECTED_SIGNER, *PPS_PROTECTED_SIGNER;

ProcessInformationLength [in]

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

ReturnLength [out, optional]

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, but if the buffer was too small, this is the minimum size of buffer needed to receive the information successfully.

Return value

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, and are described in the DDK documentation under Kernel-Mode Driver Architecture / Design Guide / Driver Programming Techniques / Logging Errors.

Remarks

The ZwQueryInformationProcess 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 ZwQueryInformationProcess, 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

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
DLL	Ntdll.dll

See also

CheckRemoteDebuggerPresent

GetProcessId

IsDebuggerPresent

IsWow64Process