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/* libnbd golang AIO buffer.
* Copyright Red Hat
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
package libnbd
/*
#cgo pkg-config: libnbd
#cgo CFLAGS: -D_GNU_SOURCE=1
#include <stdio.h>
#include <stdlib.h>
#include "libnbd.h"
#include "wrappers.h"
*/
import "C"
import "unsafe"
/* Asynchronous I/O buffer. */
type AioBuffer struct {
P unsafe.Pointer
Size uint
}
// MakeAioBuffer makes a new buffer backed by an uninitialized C allocated
// array.
func MakeAioBuffer(size uint) AioBuffer {
return AioBuffer{C.malloc(C.ulong(size)), size}
}
// MakeAioBuffer makes a new buffer backed by a C allocated array. The
// underlying buffer is set to zero.
func MakeAioBufferZero(size uint) AioBuffer {
return AioBuffer{C.calloc(C.ulong(1), C.ulong(size)), size}
}
// FromBytes makes a new buffer backed by a C allocated array, initialized by
// copying the given Go slice.
func FromBytes(buf []byte) AioBuffer {
ret := MakeAioBuffer(uint(len(buf)))
copy(ret.Slice(), buf)
return ret
}
// Free deallocates the underlying C allocated array. Using the buffer after
// Free() will panic.
func (b *AioBuffer) Free() {
if b.P != nil {
C.free(b.P)
b.P = nil
}
}
// Bytes copies the underlying C array to Go allocated memory and return a
// slice. Modifying the returned slice does not modify the underlying buffer
// backing array.
func (b *AioBuffer) Bytes() []byte {
if b.P == nil {
panic("Using AioBuffer after Free()")
}
return C.GoBytes(b.P, C.int(b.Size))
}
// Slice creates a slice backed by the underlying C array. The slice can be
// used to access or modify the contents of the underlying array. The slice
// must not be used after calling Free().
func (b *AioBuffer) Slice() []byte {
if b.P == nil {
panic("Using AioBuffer after Free()")
}
return unsafe.Slice((*byte)(b.P), b.Size)
}
// Get returns a pointer to a byte in the underlying C array. The pointer can
// be used to modify the underlying array. The pointer must not be used after
// calling Free().
func (b *AioBuffer) Get(i uint) *byte {
if b.P == nil {
panic("Using AioBuffer after Free()")
}
return (*byte)(unsafe.Pointer(uintptr(b.P) + uintptr(i)))
}
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