FLOCK

NOTE: The file system does not guarantee exclusive access, even when FLOCK and FUNLOCK are used, unless all programs that access the file cooperate by using locking. A program that opens the file with dynamic locking enabled will still be allowed to modify the file, even if it never calls FLOCK.

Syntax

         I16V     U16V
  FLOCK (filenum, lockflag);

Parameters

filenum

16-bit signed integer by value (required)

Passes the file number of the file whose global resource identification number (RIN) is to be locked.

lockflag

16-bit unsigned integer by value (required)

Specify either conditional or unconditional locking by setting bit (15:1) as follows:

Value

Meaning

0

Locking takes place only if the file's global RIN is not currently locked. If the RIN is locked, control returns immediately to the calling process, with condition code CCG.

1

Locking takes place unconditionally. If the file cannot be locked immediately, the calling process suspends until the file can be locked.

Operation Notes

Condition Codes

CCE

Request granted.

CCG

Not returned.

CCL

Request denied. This file was not opened with the dynamic locking aoption bit (10:1) specified in the FOPEN/HPFOPEN intrinsic.