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WINDOWS SERVICES: A SUPPLEMENTARY NOTE

 

 

 

 

 

 

Windows Service: Structures used in program examples ofWindows Services 1 andWindows Services 2, where ever applicable. To learn about structure you can jump tostruct, enum, typedef etc.   The Page Index SERVICE_STATUS SERVICE_TABLE_ENTRY STARTUPINFO QUERY_SERVICE_CONFIG QUERY_SERVICE_LOCK_STATUS ENUM_SERVICE_STATUS SERVICE_DESCRIPTION SERVICE_FAILURE_ACTIONS SC_ACTION     SERVICE_STATUS   Item Description Structure SERVICE_STATUS. Info Contains information about a service. The ControlService(),EnumDependentServices(),EnumServicesStatus(), and QueryServiceStatus() functions use this structure to return information about a service. A service uses this structure in theSetServiceStatus() function to report its current status to the service control manager. Definition typedef struct _SERVICE_STATUS {   DWORD dwServiceType;   DWORD dwCurrentState;   DWORD dwControlsAccepted;   DWORD dwWin32ExitCode;   DWORD dwServiceSpecificExitCode;   DWORD dwCheckPoint;   DWORD dwWaitHint; } SERVICE_STATUS, *LPSERVICE_STATUS; Members See below. Header file <windows.h> Remark -   Table 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

Members

 

dwServiceType - Type of service. This member can be one of the following values.

 

 

If the service type is either SERVICE_WIN32_OWN_PROCESS or SERVICE_WIN32_SHARE_PROCESS, and the service is running in the context of the LocalSystem account, the following type may also be specified.

 

 

dwCurrentState - Current state of the service. This member can be one of the following values.

 

 

dwControlsAccepted - Control codes the service accepts and processes in its handler function (Handler() and HandlerEx()). A user interface process can control a service by specifying a control command in the ControlService() function. By default, all services accept the SERVICE_CONTROL_INTERROGATE value. The following are the control codes.

 

 

This value can also contain the following extended control codes, which are supported only by HandlerEx().

 

 

dwWin32ExitCode - Error code the service uses to report an error that occurs when it is starting or stopping. To return an error code specific to the service, the service must set this value to ERROR_SERVICE_SPECIFIC_ERROR to indicate that the dwServiceSpecificExitCode member contains the error code. The service should set this value toNO_ERROR when it is running and on normal termination. dwServiceSpecificExitCode - Service-specific error code that the service returns when an error occurs while the service is starting or stopping. This value is ignored unless thedwWin32ExitCode member is set to ERROR_SERVICE_SPECIFIC_ERROR. dwCheckPoint - Check-point value the service increments periodically to report its progress during a lengthy start, stop, pause, or continue operation. For example, the service should increment this value as it completes each step of its initialization when it is starting up. The user interface program that invoked the operation on the service uses this value to track the progress of the service during a lengthy operation. This value is not valid and should be zero when the service does not have a start, stop, pause, or continue operation pending. dwWaitHint - Estimated time required for a pending start, stop, pause, or continue operation, in milliseconds. Before the specified amount of time has elapsed, the service should make its next call to the SetServiceStatus() function with either an incremented dwCheckPoint value or a change in dwCurrentState. If the amount of time specified by dwWaitHint passes, and dwCheckPoint has not been incremented or dwCurrentState has not changed, the service control manager or service control program can assume that an error has occurred and the service should be stopped.

 

SERVICE_TABLE_ENTRY

 

 

STARTUPINFO

 

 

Members   cb - Size of the structure, in bytes. lpReserved - Reserved. Set this member to NULL before passing the structure to CreateProcess(). lpDesktop - Pointer to a null-terminated string that specifies either the name of the desktop or the name of both the desktop and window station for this process. A backslash in the string indicates that the string includes both the desktop and window station names. For CreateProcess() and CreateProcessAsUser(), if this member is NULL, the new process inherits the desktop and window station of its parent process. If this member is an empty string, the process does not inherit the desktop and window station of its parent process; instead, the system determines if a new desktop and window station need to be created. If the impersonated user already has a desktop, the system uses the existing desktop. ForCreateProcessWithLogonW(), if this member is NULL or an empty string, the new process inherits the desktop and window station of its parent process. It is the responsibility of the application to add permission for the specified user account to the inherited window station and desktop, even for WinSta0\Default. Windows Me/98/95:  Desktops and window stations are not supported. lpTitle - For console processes, this is the title displayed in the title bar if a new console window is created. If NULL, the name of the executable file is used as the window title instead. This parameter must be NULL for GUI or console processes that do not create a new console window.

dwX - If dwFlags specifiesSTARTF_USEPOSITION, this member is the x offset of the upper left corner of a window if a new window is created, in pixels. Otherwise, this member is ignored. The offset is from the upper left corner of the screen. For GUI processes, the specified position is used the first time the new process calls CreateWindow() to create an overlapped window if the x parameter of CreateWindow() is CW_USEDEFAULT.

dwY - If dwFlags specifiesSTARTF_USEPOSITION, this member is the y offset of the upper left corner of a window if a new window is created, in pixels. Otherwise, this member is ignored. The offset is from the upper left corner of the screen. For GUI processes, the specified position is used the first time the new process calls CreateWindow() to create an overlapped window if the y parameter of CreateWindow() is CW_USEDEFAULT.

dwXSize - If dwFlags specifiesSTARTF_USESIZE, this member is the width of the window if a new window is created, in pixels. Otherwise, this member is ignored. For GUI processes, this is used only the first time the new process calls CreateWindow() to create an overlapped window if the nWidth parameter of CreateWindow() is CW_USEDEFAULT.

dwYSize - If dwFlags specifiesSTARTF_USESIZE, this member is the height of the window if a new window is created, in pixels. Otherwise, this member is ignored. For GUI processes, this is used only the first time the new process calls CreateWindow() to create an overlapped window if the nHeight parameter of CreateWindow() is CW_USEDEFAULT.

dwXCountChars - If dwFlags specifiesSTARTF_USECOUNTCHARS, if a new console window is created in a console process, this member specifies the screen buffer width, in character columns. Otherwise, this member is ignored.

dwYCountChars - If dwFlags specifiesSTARTF_USECOUNTCHARS, if a new console window is created in a console process, this member specifies the screen buffer height, in character rows. Otherwise, this member is ignored.

dwFillAttribute - If dwFlags specifiesSTARTF_USEFILLATTRIBUTE, this member is the initial text and background colors if a new console window is created in a console application. Otherwise, this member is ignored. This value can be any combination of the following values:

FOREGROUND_BLUE, FOREGROUND_GREEN, FOREGROUND_RED, FOREGROUND_INTENSITY, BACKGROUND_BLUE, BACKGROUND_GREEN, BACKGROUND_RED, and BACKGROUND_INTENSITY

For example, the following combination of values produces red text on a white background:

 

FOREGROUND_RED| BACKGROUND_RED| BACKGROUND_GREEN| BACKGROUND_BLUE

 

dwFlags - Bit field that determines whether certain STARTUPINFO members are used when the process creates a window. This member can be one or more of the following values.

 

 

wShowWindow - If dwFlags specifies STARTF_USESHOWWINDOW, this member can be any of the SW_ constants defined inWinuser.h. Otherwise, this member is ignored. For GUI processes, wShowWindow specifies the default value the first time ShowWindow() is called. ThenCmdShow parameter of ShowWindow() is ignored. In subsequent calls to ShowWindow(), the wShowWindow member is used if the nCmdShow parameter of ShowWindow() is set to SW_SHOWDEFAULT.

cbReserved2 - Reserved for use by the C Runtime; must be zero.

lpReserved2 - Reserved for use by the C Runtime; must be NULL.

hStdInput - If dwFlags specifiesSTARTF_USESTDHANDLES, this member is a handle to be used as the standard input handle for the process. Otherwise, this member is ignored.

hStdOutput - If dwFlags specifiesSTARTF_USESTDHANDLES, this member is a handle to be used as the standard output handle for the process. Otherwise, this member is ignored.

hStdError - If dwFlags specifiesSTARTF_USESTDHANDLES, this member is a handle to be used as the standard error handle for the process. Otherwise, this member is ignored.

 

QUERY_SERVICE_CONFIG

 

 

 

Members

 

dwServiceType - Type of service. This member can be one of the following values.

 

 

If the value is SERVICE_WIN32_OWN_PROCESS or SERVICE_WIN32_SHARE_PROCESS, and the service is running in the context of the LocalSystem account, the following type may also be specified.

 

 

dwStartType - When to start the service. This member can be one of the following values.

 

 

dwErrorControl - Severity of the error, and action taken, if this service fails to start. This member can be one of the following values.

 

 

lpBinaryPathName - Pointer to a null-terminated string that contains the fully qualified path to the service binary file. The path can also include arguments for an auto-start service. These arguments are passed to the service entry point (typically the main function).

lpLoadOrderGroup - Pointer to a null-terminated string that names the load ordering group to which this service belongs. If the member is NULL or an empty string, the service does not belong to a load ordering group. The startup program uses load ordering groups to load groups of services in a specified order with respect to the other groups. The list of load ordering groups is contained in the following registry value:

 

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\ServiceGroupOrder

 

dwTagId - Unique tag value for this service in the group specified by the lpLoadOrderGroup parameter. A value of zero indicates that the service has not been assigned a tag. You can use a tag for ordering service startup within a load order group by specifying a tag order vector in the registry located at:

 

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\GroupOrderList

 

Tags are only evaluated for SERVICE_KERNEL_DRIVER and SERVICE_FILE_SYSTEM_DRIVER type services that have SERVICE_BOOT_START or SERVICE_SYSTEM_START start types.

lpDependencies - Pointer to an array of null-separated names of services or load ordering groups that must start before this service. The array is doubly null-terminated. If the pointer is NULL or if it points to an empty string, the service has no dependencies. If a group name is specified, it must be prefixed by theSC_GROUP_IDENTIFIER (defined in Winsvc.h) character to differentiate it from a service name, because services and service groups share the same name space. Dependency on a service means that this service can only run if the service it depends on is running. Dependency on a group means that this service can run if at least one member of the group is running after an attempt to start all members of the group.

lpServiceStartName - Pointer to a null-terminated string. If the service type is SERVICE_WIN32_OWN_PROCESS or SERVICE_WIN32_SHARE_PROCESS, this name is the account name in the form of "DomainName\Username", which the service process will be logged on as when it runs. If the account belongs to the built-in domain, ".\Username" can be specified. If this member is NULL, the service is to be logged on as the LocalSystem account. Windows XP:  If this member is NT AUTHORITY\LocalService,CreateService() uses the LocalService account. If the parameter is NT AUTHORITY\NetworkService,CreateService() uses the NetworkService account. If the service type is SERVICE_KERNEL_DRIVER or SERVICE_FILE_SYSTEM_DRIVER, this name is the driver object name (that is,\FileSystem\Rdr or \Driver\Xns) which the input and output (I/O) system uses to load the device driver. If this member is NULL, the driver is to be run with a default object name created by the I/O system, based on the service name.

lpDisplayName - Pointer to a null-terminated string that specifies the display name to be used by service control programs to identify the service. This string has a maximum length of 256 characters. The name is case-preserved in the service control manager. Display name comparisons are always case-insensitive.

 

QUERY_SERVICE_LOCK_STATUS

 

 

ENUM_SERVICE_STATUS

 

 

SERVICE_DESCRIPTION

 

 

SERVICE_FAILURE_ACTIONS

 

 

SC_ACTION

 

 

Members

 

Type - Action to be performed. This member can be one of the following values.

 

 

Delay - Time to wait before performing the specified action, in milliseconds.

 

 

-----------------------------------------End Windows Services Structures---------------------------------------

 

 

 

 

 

 

Further reading and digging:

 

1. Microsoft Visual C++, on-line MSDN.

2. Structure, enum, union and typedef story can be foundatC enum, typedef, define etc..

3. For Multi-bytes, Unicode characters and Localization please refer toUnicode & Multi byte 1 (Story) andUnicode & Multi-byte 2 (Implementation).

4. Windows data type information isinWindows data type.

5. Check the best selling C / C++ and Windows books at Amazon.com.

 

 

 

 

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