_Rreadl() — Read the Last Record

Format 

#include <recio.h>

_RIOFB_T *_Rreadl(_RFILE *fp, void *buf, size_t size, int opts);

Language Level: ILE C Extension

Threadsafe: Yes. However, if the file pointer is passed among threads, the I/O feedback area is shared among those threads.

Description

Start of changeThe _Rreadl() function reads the last record in the access path currently being used for the file specified by fp. The access path may be keyed sequence or arrival sequence. Up to size number of bytes are copied from the record into buf (move mode only). If the file is opened for updating, the _Rreadl() function locks the last record unless __NO_LOCK is specified.End of change

The following parameters are valid for the _Rreadl() function.

buf
Points to the buffer where the data that is read is to be stored. If locate mode is used, this parameter must be set to NULL.
size
Specifies the number of bytes that are to be read and stored in buf. If locate mode is used, this parameter is ignored.
opts
Specifies the processing options for the file. Possible values are:
__DFT
If the file is opened for updating, then the record being read or positioned to is locked. The previously locked record will no longer be locked.
__NO_LOCK
Do not lock the record being positioned to.

The _Rreadl() function is valid for database and DDM files.

Return Value

The _Rreadl() function returns a pointer to the _RIOFB_T structure that is associated with fp. If the _Rreadl() operation is successful the num_bytes field is set to the number of bytes transferred from the system buffer to the user's buffer (move mode) or the record length of the file (locate mode). The key and rrn fields will be updated. If record blocking is taking place, the blk_count and blk_filled_by fields will be updated. If the file is empty, the num_bytes field is set to EOF. If it is unsuccessful, the num_bytes field is set to a value less than size and errno will be changed.

The value of errno may be set to:

Value
Meaning
ENOTREAD
The file is not open for read operations.
ETRUNC
Truncation occurred on an I/O operation.
EIOERROR
A non-recoverable I/O error occurred.
EIORECERR
A recoverable I/O error occurred.

See Table 12 and Table 14 for errno settings.

Example that uses _Rreadl()

#include <stdio.h>
#include <stdlib.h>
#include <recio.h>
 
int main(void)
{
    _RFILE      *fp;
    _XXOPFB_T   *opfb;
 
    /* Open the file for processing in arrival sequence.             */
    if (( fp = _Ropen ( "MYLIB/T1677RD1", "rr+, arrseq=Y" )) == NULL )
    {
        printf ( "Open failed\n" );
        exit ( 1 );
    }
 
    /* Get the library and file names of the file opened.            */
    opfb = _Ropnfbk ( fp );
    printf ( "Library: %10.10s\nFile:    %10.10s\n",
              opfb->library_name,
              opfb->file_name);
 
    /* Get the last record.                                          */
    _Rreadl ( fp, NULL, 20, __DFT );
    printf ( "Last record: %10.10s\n", *(fp->in_buf) );
 
    _Rclose ( fp );
}

Related Information


[ Top of Page | Previous Page | Next Page | Contents | Index ]