/* Dainius Saltenis IFF-6/13 daisal*/
/* Failas: daisal_aio01.c */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <aio.h>
#define BUFFLEN 1048576

int daisal_test_open(const char *name, int flags);
int daisal_test_close(int fd);
int daisal_test_aio_read( const int d, struct aiocb *aiorp, void *buf, const int count, int write_dskr );

int daisal_test_open(const char *name, int flags){
   int dskr;
   dskr = open( name, flags);
   if( dskr == -1 ){
      perror( name );
      exit(1);
   }
   printf( "dskr = %d\n", dskr );
   return dskr;
}

int daisal_test_close(int fd){
   int rv;
   rv = close( fd );
   if( rv != 0 ) perror ( "close() failed" );
   else puts( "closed" );
   return rv;
}

int daisal_test_aio_read( const int d, struct aiocb *aiorp, void *buf, const int count, const int write_dskr ){
	int rv = 0;
	int read_count = 0;
	memset( (void *)aiorp, 0, sizeof( struct aiocb ) );
	const struct aiocb *aioptr[1];
	while (read_count < count)
	{
		aiorp->aio_fildes = d;
		aiorp->aio_buf = buf;
		aiorp->aio_nbytes = count - read_count;
		aiorp->aio_offset = read_count;
		rv = aio_read( aiorp );
		printf( "read %d\n", rv );
		if( rv != 0 ){
			perror( "aio_read failed" );
			abort();
		}
		aioptr[0] = aiorp;
		rv = aio_suspend( aioptr, 1, NULL );
		if( rv != 0 ){
			perror( "aio_suspend failed" );
			abort();
		}
		read_count += aio_return( aiorp );
		if (read_count > count)
			pwrite(write_dskr, buf, sizeof(buf) - (read_count - count), read_count);
		else
			pwrite(write_dskr, buf, sizeof(buf), read_count);
	}

	return rv;
}


int main( int argc, char * argv[] ){
   int d, dw;
   int flags_d = O_RDONLY;
   int flags_dw = O_WRONLY | O_CREAT | O_TRUNC;
   struct aiocb aior;
   char buffer[BUFFLEN];

   printf( "(C) 2018 Dainius Saltenis, %s\n", __FILE__ );
   d = daisal_test_open( "/dev/urandom", flags_d );
   dw = daisal_test_open( argv[1] , flags_dw);
   daisal_test_aio_read ( d, &aior, buffer, BUFFLEN, dw );
   daisal_test_close( d );
   daisal_test_close( dw );
   return 0;
}