Difference between revisions of "DosCloseVDD"

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(Created page with "==Description== Closes the specified virtual device driver (VDD) handle. ==Syntax== <PRE> #define INCL_DOSMVDM #include <os2.h> HVDD hvdd; /* The handle of the virtua...")
 
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ulrc = DosCloseVDD(hvdd);
 
ulrc = DosCloseVDD(hvdd);
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</PRE>
  
</PRE>
 
 
==Parameters==
 
==Parameters==
; hvdd (HVDD) - input : The handle of the virtual device driver to be closed.
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;hvdd (HVDD) - input : The handle of the virtual device driver to be closed.
 +
Specify the handle that was returned by a previous call to DosOpenVDD.
  
Specify the handle that was returned by a previous call to DosOpenVDD.
 
 
==Return Code==
 
==Return Code==
 
  ulrc (APIRET) - returns
 
  ulrc (APIRET) - returns
 
 
DosCloseVDD returns one of the following values:
 
DosCloseVDD returns one of the following values:
 
+
* 0 NO_ERROR
* 0         NO_ERROR  
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* 6 ERROR_INVALID_HANDLE
* 6         ERROR_INVALID_HANDLE  
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* 644 ERROR_INVALID_CALLER
* 644       ERROR_INVALID_CALLER
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==Remarks==
 
==Remarks==
Line 70: Line 68:
 
         return 1;
 
         return 1;
 
     }
 
     }
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</PRE>
  
</PRE>
 
 
==Related Functions==
 
==Related Functions==
* [[OS2 API:CPI:DosOpenVDD|DosOpenVDD]]
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*[[DosOpenVDD]]
* [[OS2 API:CPI:DosRequestVDD|DosRequestVDD]]
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*[[DosRequestVDD]]
 
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[[Category:The OS/2 API Project]]
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[[Category:Dos]]

Revision as of 14:12, 6 December 2016

Description

Closes the specified virtual device driver (VDD) handle.

Syntax

#define INCL_DOSMVDM
#include <os2.h>

HVDD      hvdd;  /*  The handle of the virtual device driver to be closed. */
APIRET    ulrc;  /*  Return Code. */

ulrc = DosCloseVDD(hvdd);

Parameters

hvdd (HVDD) - input 
The handle of the virtual device driver to be closed.

Specify the handle that was returned by a previous call to DosOpenVDD.

Return Code

ulrc (APIRET) - returns

DosCloseVDD returns one of the following values:

  • 0 NO_ERROR
  • 6 ERROR_INVALID_HANDLE
  • 644 ERROR_INVALID_CALLER

Remarks

DosCloseVDD closes the specified virtual device driver (VDD) handle.

Example Code

The following is NOT a complete C program. It is simply intended to provide an idea of how a protected-mode OS/2 process can communicate with a virtual device driver (VDD).

This example shows a protected-mode process calling a hypothetical VDD with a request to read a string of bytes from the VDD. Assume that the session identifier of the specified DOS session has been placed into SessionID already and that the sample virtual device driver has registered the name "VDD007" with the operating system.

 #define INCL_DOSMVDM     /* Multiple DOS sessions values */
 #define INCL_DOSERRORS   /* DOS Error values */
 #include <os2.h>
 #include <stdio.h>

 UCHAR   VDDName[10] = "VDD007";    /* Name of VDD */
 HVDD    VDDHandle   = NULLHANDLE;  /* Handle of VDD */
 SGID    SessionID   = 0;  /* Session identifier (should be initialized */
 ULONG   Command     = 3;           /* VDD function code (hypothetical) */
 APIRET  rc          = NO_ERROR;    /* Return code */
 UCHAR   InputBuffer[30]  = "Your command here";  /* Command information    */
 UCHAR   OutputBuffer[30] = "";                   /* Output data (returned) */

    rc = DosOpenVDD(VDDName, &VDDHandle);
    if (rc != NO_ERROR) {
       printf("VDD %s was not found.\n", rc);
       return 1;
    }

    rc = DosRequestVDD(VDDHandle,              /* Handle of VDD */
                       SessionID,              /* Session ID */
                       Command,                /* Command to send to VDD */
                       sizeof(InputBuffer),    /* Length of input */
                       InputBuffer,            /* Input buffer */
                       sizeof(OutputBuffer),   /* Length of output area */
                       OutputBuffer);          /* Output from command */
    if (rc != NO_ERROR) {
        printf("DosRequestVDD error: return code = %u\n", rc);
        return 1;
    }

    rc = DosCloseVDD(VDDHandle);               /* Close the VDD */
    if (rc != NO_ERROR) {
        printf("DosCloseVDD error: return code = %u\n", rc);
        return 1;
    }

Related Functions