Open System Services System Calls Reference Manual (G06.28+, H06.05+)

SPT_WRITEREADX(2) OSS System Calls Reference Manual
Use on files opened for nowait I/O
— If the buffer is in an extended data segment, you cannot
deallocate or reduce the size of the extended data seg-
ment before the I/O completes with a call to the Guar-
dian AWAITIOX procedure or is canceled by a call to
the SPT_CANCEL() function or the Guardian CAN-
CELREQ procedure.
— You must not modify the buffer before the I/O completes
with a call to the Guardian AWAITIOX procedure. This
restriction also applies to other processes that might
share the segment. It is the application’s responsibility
to ensure this.
— If you initiated the I/O with SPT_WRITEREADX(),
the I/O must be completed with a call to the Guardian
AWAITIOX procedure.
— A selectable extended data segment containing the
buffer need not be in use at the time of the call to
AWAITIOX.
— You can call SPT_CANCEL() or CANCELREQ to
cancel nowait I/O initiated with
SPT_WRITEREADX(). The I/O is canceled if the file
is closed before the I/O completes or if you call the
Guardian AWAITIOX procedure with a positive time
limit and specific file number and the request times out.
Bounds checking
If the extended address of buffer is odd, bounds checking rounds
the address to the next lower word boundary and also checks an
extra byte. The odd address is used for the transfer.
RETURN VALUES
The SPT_WRITEREADX( ) function returns 0 (zero) upon successful completion. Otherwise,
this function returns a nonzero Guardian file-system error number that indicates the outcome of
the operation.
For information about Guardian file-system error numbers, see the Guardian Procedure Errors
and Messages Manual.
ERRORS
None. This function does not set the errno variable.
RELATED INFORMATION
Functions: SPT_CANCEL(2), SPT_CONTROL(2), SPT_FILE_CLOSE_(2),
SPT_FILE_OPEN_(2), SPT_LOCKFILE(2), SPT_LOCKREC(2), SPT_READLOCKX(2),
SPT_READUPDATELOCKX(2), SPT_READUPDATEX(2), SPT_READX(2),
SPT_SETMODE(2), SPT_UNLOCKFILE(2), SPT_UNLOCKREC(2),
SPT_WRITEUPDATEUNLOCKX(2), SPT_WRITEUPDATEX(2), SPT_WRITEX(2).
7−350 Hewlett-Packard Company 527186-007