Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

SPT_WRITEUPDATEX(2) OSS System Calls Reference Manual
NAME
SPT_WRITEUPDATEX - Transfers data from an array in the application program to a Guar-
dian file
LIBRARY
G-series native OSS processes: /G/system/sysnn/zsptsrl
H-series OSS processes: /G/system/zdllnnn/zsptdll
SYNOPSIS
[#include <cextdecs.h>]
#include <spthread.h>
short SPT_WRITEUPDATEX (
short filenum,
char *buffer,
unsigned short write_count,
[unsigned short *count_written ],
[long tag ]
);
PARAMETERS
filenum specifies the file number of a Guardian file open instance that identifies the file to
be written.
buffer specifies an array in the application process in which the information to be writ-
ten to the file is stored before the call.
write_count specifies the number of bytes to be written.
count_written returns a count of the number of bytes written to the file from buffer.
tag is for nowait I/O only. The tag value you define uniquely identifies the operation
associated with this call.
This parameter is supported only for program compatibility; if you provide it, it
is ignored.
DESCRIPTION
The SPT_WRITEUPDATEX() function is the thread-aware version of the Guardian WRI-
TEUPDATEX procedure.
The SPT_WRITEUPDATEX() function performs random processing of records in a Guardian
disk file. SPT_WRITEUPDATEX() has two purposes:
• To alter the contents of the record at the current position
• To delete the record at the current position in a key-sequenced or relative file
Data from the application process’s array is written in the position indicated by the setting of the
current-record pointer. A call to this procedure typically follows a corresponding call to the
SPT_READX( ) or SPT_READUPDATEX() function. The current-record and next-record
pointers are not affected by the SPT_WRITEUPDATEX() procedure.
For magnetic tapes, SPT_WRITEUPDATEX() is used to replace a record in an already written
tape. The tape is backspaced one record; the data from the application process’s array is written
in that area.
For programming information about the WRITEUPDATEX procedure, see the Enscribe
Programmer’s Guide and the Guardian Programmer’s Guide.
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