Format
#include <recio.h>
_RIOFB_T *_Rreads(_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
The _Rreads() function reads the current record in the access path that is currently being used for the file that is associated with 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 _Rreads() function locks the record positioned to unless __NO_LOCK is specified.
If the current position in the file that is associated with fp has no record associated with it, the _Rreads() function will fail.
The _Rreads() function is not valid when the file is open for record blocking.
The following are valid parameters for the _Rreads() function.
The _Rreads() function is valid for database and DDM files.
Return Value
The _Rreads() function returns a pointer to the _RIOFB_T structure that is associated with fp. If the _Rreads() 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 are also updated. If it is unsuccessful, the num_bytes field is set to a value less than size, and errno is changed.
The value of errno may be set to:
See Table 12 and Table 14 for errno settings.
Example that uses _Rreads()
#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) );
/* Get the same record without locking it. */
_Rreads ( fp, NULL, 20, __NO_LOCK);
printf ( "Same record: %10.10s\n", *(fp->in_buf) );
_Rclose ( fp );
}
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