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

SPT_READUPDATEX(2) OSS System Calls Ref
erence Manual
NAME
SPT_READUPDATEX - Reads data from a Guardian disk or process file in anticipation of a
subsequent write to the 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_READUPDATEX (
short filenum,
char *buffer,
short read_count,
[short *count_read ],
[long tag ]
);
PARAMETERS
filenum specifies the file number of a Guardian file open instance that identifies
the file to be read.
buffer specifies an array in the application process in which the information
read from the file is returned.
read_count specifies the number of bytes to be read.
count_read is for waited I/O only. This parameter returns a count of the number of
bytes returned from the file into 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 pro-
vide it, it is ignored.
DESCRIPTION
The SPT_READUPDATEX() function is the thread-aware version of the Guardian READUP-
DATEX procedure.
This function reads data from a disk or process file in anticipation of a subsequent write to the
file. The values of the current-record and next-record pointers do not change. This function has
the following uses:
Disk files SPT_READUPDATEX() is used for random processing. Data is read
from the file at the position of the current-record pointer. A call to this
function typically follows a corresponding call to the Guardian POSI-
TION or KEYPOSITION procedure.
Queue Files SPT_READUPDATEX() is not supported on queue files. An attempt
to use SPT_READUPDATEX() is rejected with Guardian file-system
error 2.
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