4D Doc Center : VOLUME ATTRIBUTES

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4D v14.3

VOLUME ATTRIBUTES


VOLUME ATTRIBUTES ( volume ; size ; used ; free )

Parameter	Type	Description
volume	String	Volume name
size	Real	Volume size expressed in bytes
used	Real	Used space expressed in bytes
free	Real	Free space expressed in bytes

Description

The VOLUME ATTRIBUTES command returns, expressed in bytes, the size, the used space and the free space for the volume whose name you pass in volume.

Note: If volume indicates a non-mounted remote volume, the OK variable is set to 0 and the three parameters return -1.

Your application includes some batch operations running the night or the week-end that store huge temporary files on disk. To make this process as automatic and flexible as possible, you write a routine that will automatically find the first volume whose free space is sufficient for your temporary files. You might write the following project method:

  ` Find volume for space Project Method

  ` Find volume for space ( Real ) -> String

  ` Find volume for space ( Space needed in bytes ) -> Volume name or Empty string

 

 C_STRING(31;$0)

 C_STRING(255;$vsDocName)

 C_LONGINT($vlNbVolumes;$vlVolume)

 C_REAL($1;$vlSize;$vlUsed;$vlFree)

 C_TIME($vhDocRef)

 

  ` Initialize function result

 $0:=""

  ` Protect all I/O operations with an error interruption method

 ON ERR CALL("ERROR METHOD")

  ` Get the list of the volumes

 ARRAY STRING(31;$asVolumes;0)

 gError:=0

 VOLUME LIST($asVolumes)

 If(gError=0)

  ` If running on windows, skip the (usual) two floppy drives

    If(On Windows)

       $vlVolume:=Find in array($asVolumes;"A:\\")

       If($vlVolume>0)

          DELETE FROM ARRAY($asVolumes;$vlVolume)

       End if

       $vlVolume:=Find in array($asVolumes;"B:\\")

       If($vlVolume>0)

          DELETE FROM ARRAY($asVolumes;$vlVolume)

       End if

    End if

    $vlNbVolumes:=Size of array($asVolumes)

  ` For each volume

    For($vlVolume;1;$vlNbVolumes)

  ` Get the size, used space and free space

       gError:=0

       VOLUME ATTRIBUTES($asVolumes{$vlVolume};$vlSize;$vlUsed;$vlFree)

       If(gError=0)

  ` Is the free space large enough (plus an extra 32K) ?

          If($vlFree>=($1+32768))

  ` If so, check if the volume is unlocked...

             $vsDocName:=$asVolumes{$vlVolume}+Char(Directory symbol)+"XYZ"+String(Random)+".TXT"

             $vhDocRef:=Create document($vsDocName)

             If(OK=1)

                CLOSE DOCUMENT($vhDocRef)

                DELETE DOCUMENT($vsDocName)

  ` If everything's fine, return the name of the volume

                $0:=$asVolumes{$vlVolume}

                $vlVolume:=$vlNbVolumes+1

             End if

          End if

       End if

    End for

 End if

 ON ERR CALL("")

Once this project method is added to your application, you can for instance write:

 $vsVolume:=Find volume for space(100*1024*1024)

 If($vsVolume#"")

  ` Continue

 Else

    ALERT("A volume with at least 100 MB of free space is required!")

 End if

4D v14.3

VOLUME ATTRIBUTES

VOLUME ATTRIBUTES

Description

Example