Q32219: DosGetPid and DosGetInfoSeg Get Process Identification (PID)

Article: Q32219
Product(s): See article
Version(s): 6.00 6.00b 7.00
Operating System(s): OS/2
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 1-FEB-1990

Two MS OS/2 API calls return the process identification (PID) of the
current process. The two calls are DosGetPid and DosGetInfoSeg, which
are illustrated in a code example below.

This information applies to Microsoft BASIC Compiler Versions 6.00 and
6.00b for MS OS/2, and to Microsoft BASIC Professional Development
System (PDS) Version 7.00 for MS OS/2.

DosGetPid is the simplest and most direct way of retrieving the
current PID. This function is passed the address of a structure
containing three integers or words. The function declarations are as
follows:

      TYPE PidInfo
           Pid as integer        'Process Pid
           Tid as integer        'Thread Pid
           pidParent as integer 'Parent Pid
      END TYPE

      DECLARE FUNCTION DosGetPid%(_
                   SEG P1 AS PidInfo)

The PID information is returned in the structure.

The information returned by DosGetInfoSeg also helps find the PID, but
the procedure is more difficult. This function returns the address of
both the GDT and LDT. The LDT contains the process information. To
locate the PID, you must set the segment to the LDT (DEF SEG=address
of LDT), then look at the bytes that contain the desired information.
The program below demonstrates this method. (This program also
contains an example of DosGetPid.)

       'Declarations used below can be found in BSDOSPC.BI
       TYPE PidInfo
            Pid as integer
            Tid as integer
            pidParent as integer
       END TYPE
       DECLARE FUNCTION DosGetInfoSeg%(_
                    SEG P1 AS INTEGER,_
                    SEG P2 AS INTEGER)
       DECLARE FUNCTION DosGetPid%(_
                    SEG P1 AS PidInfo)

       DEFINT A-Z
       CLS
       DIM info AS PidInfo

       x=DosGetInfoSeg%(global,localo)

       IF (x) THEN
         Print "Error, the number is : ";x
       ELSE
         Print "The Global Segment : ";Global
         Print "The Local Segment : ";localo
         def seg=localo            'Change Segment
         pid1=peek(0)+(256*(peek(1))) 'First Word in segment
         pid2=peek(2)+(256*(peek(3))) 'Second Word
         pid3=peek(6)+(256*(peek(7))) 'Fourth Word
         def seg
         print "         Current Process ID : ";pid1
         print "       Process ID of Parent : ";pid2
         print "Thread ID of Current Thread : ";pid3
       END IF

       x=DosGetPid%(info)

       IF (x) THEN
         Print "Error, the number is : ";x
       ELSE
         print "         Current Process ID : ";info.pid
         print "       Process ID of Parent : ";info.pidParent
         print "Thread ID of Current Thread : ";info.tid
       END IF

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