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spawnl function fails?

Posted on 1999-01-29
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Last Modified: 2008-03-06
I am working on NT Server.I execute a program inside another with the spawnl function.
I wrote:
       father_pid = getpid ();
       if( (pid = spawnl (P_NOWAIT, argv[0], argv[0], NULL ) ) == -1 )
          printf( "Spawn failed" );

The pid must to be the pid of de called program and the father_pid the pid of the calling program.  I start the Task Manager and can see that the father_pid is correct, but the pid of the called program is different, so I only can know the pid of the called program if I see the Task Manager.

Has the spawnl function failed?. Thanks.

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Question by:riclueje
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Accepted Solution

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hougaard earned 50 total points
ID: 1258499
Use CreateProcess instead ... That is the official function within win32 to do a spawn!

BOOL CreateProcess(

    LPCTSTR lpApplicationName,      // pointer to name of executable module
    LPTSTR lpCommandLine,      // pointer to command line string
    LPSECURITY_ATTRIBUTES lpProcessAttributes,      // pointer to process security attributes
    LPSECURITY_ATTRIBUTES lpThreadAttributes,      // pointer to thread security attributes
    BOOL bInheritHandles,      // handle inheritance flag
    DWORD dwCreationFlags,      // creation flags
    LPVOID lpEnvironment,      // pointer to new environment block
    LPCTSTR lpCurrentDirectory,      // pointer to current directory name
    LPSTARTUPINFO lpStartupInfo,      // pointer to STARTUPINFO
    LPPROCESS_INFORMATION lpProcessInformation       // pointer to PROCESS_INFORMATION  
   );


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Author Comment

by:riclueje
ID: 1258500
I can´t because I need the pid to kill the process.
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LVL 2

Expert Comment

by:hougaard
ID: 1258501
The PROCESS_INFORMATION structure returned will give you the PID in the dwProcessId member!

typedef struct _PROCESS_INFORMATION { // pi
    HANDLE hProcess;
    HANDLE hThread;
    DWORD dwProcessId;
    DWORD dwThreadId;
} PROCESS_INFORMATION;
 

Members

hProcess

Returns a handle to the newly created process. The handle is used to specify the process in all functions that perform operations on the process object.

hThread

Returns a handle to the primary thread of the newly created process. The handle is used to specify the thread in all functions that perform operations on the thread object.

dwProcessId

Returns a global process identifier that can be used to identify a process. The value is valid from the time the process is created until the time the process is terminated.

dwThreadId

Returns a global thread identifiers that can be used to identify a thread. The value is valid from the time the thread is created until the time the thread is terminated.


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Author Comment

by:riclueje
ID: 1258502
Can you send me an example? I can´t do it.
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LVL 2

Expert Comment

by:hougaard
ID: 1258503
STARTUPINFO         si;
PROCESS_INFORMATION pi;

    si.cb=sizeof(STARTUPINFO);
    si.lpReserved=NULL;
    si.lpTitle=NULL;
    si.lpDesktop=NULL;
    si.dwX=si.dwY=si.dwYSize=si.dwXSize=0;
    si.dwFlags=0;
    si.wShowWindow=SW_SHOW;
    si.lpReserved2=NULL;
    si.cbReserved2=0;

if (CreateProcess(NULL,
            "C:\WINNT\SYSTEM32\TELNET.EXE",
            NULL,
            NULL,
            FALSE,
            CREATE_NEW_CONSOLE,
            NORMAL_PRIORITY_CLASS,
           NULL,
           NULL,
           &si,
           &pi))
{
  printf("Process ID = %i\n",pi.dwProcessId);
}
}
           
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