C # Start an external program (3)-CreateProcess

Today, let's continue to talk about C # calling the system API to start the external Program Method, today we are talking about the CreateProcess API function, compared to the first two Article (1 and 2) the CreateProcess parameter is more complex, but more flexible to use.
1. Using System. runtime. interopservices;

2. Several struct types are used in CreateProcess. declare them first:

[System. runtime. interopservices. structlayout (layoutkind. Sequential)]
Public   Class Security_attributes
{
Public   Int Nlength;
Public   String Lpsecuritydescriptor;
Public   Bool Binherithandle;
}

[Structlayout (layoutkind. Sequential)]
Public   Struct Startupinfo
{
Public   Int CB;
Public   String Lpreserved;
Public   String Lpdesktop;
Public   Int Lptitle;
Public   Int Dwx;
Public   Int Dwy;
Public   Int Dwxsize;
Public   Int Dwysize;
Public   Int Dwxcountchars;
Public   Int Dwycountchars;
Public   Int Dwfillattribute;
Public   Int Dwflags;
Public   Int Wshowwindow;
Public   Int Cbreserved2;
Public   Byte Lpreserved2;
Public Intptr hstdinput;
Public Intptr hstdoutput;
Public Intptr hstderror;
}

[Structlayout (layoutkind. Sequential)]
Public   Struct Process_information
{
Public Intptr hprocess;
Public Intptr hthread;
Public   Int Dwprocessid;
Public   Int Dwthreadid;
}

3. Declare CreateProcess

[Dllimport ( " Kernel32.dll " , Charset = Charset. ANSI)]
Public   Static   Extern   Bool CreateProcess (
Stringbuilder lpapplicationname, stringbuilder lpcommandline,
Security_attributes lpprocessattributes,
Security_attributes lpthreadattributes,
Bool Binherithandles,
Int Dwcreationflags,
Stringbuilder lpenvironment,
Stringbuilder lpcurrentdirectory,
Ref Startupinfo lpstartupinfo,
Ref Process_information lpprocessinformation
);

4. The three below are also APIs. For more information, see annotations.

# Region Win32 API: waitforsingleobject
// Detect the Signal Status of a system core object (thread, event, signal). When the object execution time exceeds dwmilliseconds, it returns; otherwise, it waits until the object returns a signal.
[Dllimport ("kernel32.dll")]
Public static extern uint waitforsingleobject (system. intptr hhandle, uint dwmilliseconds );

# Endregion

# Region Win32 API: closehandle
// Close a kernel object and release the system resources occupied by the object. This includes file, file ing, process, thread, security, and synchronization objects.
[Dllimport ("kernel32.dll")]
Public static extern bool closehandle (system. intptr hobject );

# Endregion

# Region Win32 API: getexitcodeprocess
// Obtain the exit of an interrupted processCode, Non-zero indicates success, and zero indicates failure.
// The hprocess parameter. To obtain the handle of a process that exits the code, the lpexitcode parameter is used to load a long integer variable of the process exit code.
[Dllimport ("kernel32.dll")]
Static extern bool getexitcodeprocess (system. intptr hprocess, ref uint lpexitcode );

# Endregion

5. If the execution time of the program specified by argm In the example is long, the process will be blocked to the waitforsingleobject line until the command execution is complete or the process is aborted.

String Argm =   " Cmd.exe " ;

Startupinfo SINFO= NewStartupinfo ();
Process_information pinfo= NewProcess_information ();

If ( ! CreateProcess ( Null , New Stringbuilder (argm ), Null , Null , False , 0 , Null , Null , Ref SINFO, Ref Pinfo ))
{
Throw   New Exception ( " Call failed " );
}
Uint I =   0 ;
Waitforsingleobject (pinfo. hprocess, Int . Maxvalue );
Getexitcodeprocess (pinfo. hprocess, Ref I );
Closehandle (pinfo. hprocess );
Closehandle (pinfo. hthread );