RunWait.exe - DLL Provides Synchronous Spawn Function |
Q105116
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1
SUMMARY
The sample RunWait.exe demonstrates how to use TOOLHELP.DLL to provide a dynamic-link library (DLL) function that spawns applications and waits for their termination before returning from the function call. The sample is compatible with Visual Basic (VB) and Windows 3.0. The sample loads a hidden task at DLL startup time to own the Toolhelp callback.
MORE INFORMATION
The following files are available for download from the Microsoft Download Center:
RunWait.exe
For additional information about how to download Microsoft Support files, click the article number below to view the article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft used the most current virus detection software available on the date of posting to scan this file for viruses. Once posted, the file is housed on secure servers that prevent any unauthorized changes to the file.
The following is the VB function declaration (this must be on a single line in VB):
Declare Function SpawnAndWait& Lib "RUNLIB.DLL" (ByVal parenthwnd%, ByVal lpszOp$, ByVal lpszFile$, ByVal lpszParams$, ByVal lpszDir$, ByVal nShow%) DWORD SpawnAndWait(hwnd, lpszOp, lpszFile, lpszParams, lpszDir, fsShowCmd) HWND hwnd /* Handle of parent window */ LPCSTR lpszOp /* Address of string for operation to perform */ LPCSTR lpszFile /* Address of string for filename */ LPCSTR lpszParams /* Address of string for executable-file parameters */ LPSCTR lpszDir /* Address of string for default directory */ int fsCmdShow /* Whether file is shown when opened */
The SpawnAndWait function executes and waits for termination of the specified application or associated file.
Parameter Description
hwnd Identifies the parent window. This window receives any message
boxes an application produces (for example, for error
reporting).
lpszOp Points to a null-terminated string specifying the operation to
perform. This string can be "open" or "print". If this parameter
is NULL, "open" is the default value.
lpszFile Points to a null-terminated string specifying the file to
open.
lpszParams Points to a null-terminated string specifying parameters
NULL; "open" is the default value. Passed to the application
when the lpszFile parameter specifies an executable file. If
lpszFile points to a string specifying a document file, this
parameter is NULL.
lpszDir Points to a null-terminated string specifying the default
directory.
fsShowCmd Specifies whether the application window is to be shown when
the application is opened. See ShowWindow for valid values.
Returns
HIWORD == hInstance of started application. Values less than 32 are errors
returned from ShellExecute. 0xFFFF is a general error.
LOWORD == Return code of spawned application. 0xFFFF is a general error.
Comments
The file specified by the lpszFile parameter can be a document file or an executable file. If it is a document file, this function opens or prints it, depending on the value of the lpszOp parameter. If it is an executable file, this function opens it, even if the string "print" is pointed to by lpszOp.
WARNING: This function will not wait on applications such as Word and Excel that respond to the DDE broadcast made by ShellExecute or the second instance of multiple data applications.
WARNING: This function supports only one block at a time per task. Calling tasks should not call this function when it has a prior pending SpawnAndWait call.
Sample Code
DWORD SpawnAndWaitIndirect(lpSpawnWait)
LPSPAWNWAIT lpSpawnWait /* Far reference to SPAWNWAIT structure
typedef struct tagSPAWNWAIT
{
HWND hwnd;
LPCSTR lpszOp;
LPCSTR lpszFile;
LPCSTR lpszParams;
LPCSTR lpszDir;
int fsShowCmd;
LPMSGPROC lpmsgproc;
} SPAWNWAIT;
Member Description
hwnd Handle of parent window
lpszOp Address of string for operation to perform
lpszFile Address of string for filename
lpszParams Address of string for executable-file parameters
lpszDir Address of string for default directory
fsShowCmd Whether file is shown when opened
lpmsgproc Address of application provided MessagePump (must load
DS on entry)
void CALLBACK MessagePump(lpmsg)
LPSMG lpsg /* Long pointer to MSG to process
Message Proc is a place holder for an application-provided callback function (which must load DS on entry) that will process messages retrieved in RunLib's PeekMessage loop. It allows the calling application to do modeless dialog box and accelerator message processing.
lpmsgproc should be set to NULL if it is not used. RunLib will do a default TranslateMessage/DispatchMessage instead.
The following is an example of a message processing function for a MDI application:
void CALLBACK MyMessagePump(LPMSG lpmsg)
{
if(!TranslateMDISysAccel(hClient, lpsmg) &&
!TranslateAccelerator(hFram, hAccel, lpsmg))
{
TranslateMessage(lpsmg);
DispatchMessage(lpmsg);
}
}
Returns
HIWORD == hInstance of started application. Values less than 32 are errors
returned from ShellExecute. 0xFFFF is a general error.
LOWORD == Return code of spawned application. 0xFFFF is a general
error.
Comments
The file specified by the lpszFile parameter can be a document file or an executable file. If it is a document file, this function opens or prints it, depending on the value of the lpszOp parameter. If it is an executable file, this function opens it, even if the string "print" is pointed to by lpszOp.
WARNING: This function will not wait on applications such as Word and Excel that respond to the DDE broadcast made by ShellExecute or the second instance of multiple data applications.
WARNING: This function supports only one block at a time per task. Calling tasks should not call this function when it has a prior pending SpawnAndWait call.
Additional query words:
Keywords : kbfile kbsample kb16bitonly
Issue type :
Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Last Reviewed: December 10, 1999 |
