// ReadAt reads len(data) bytes from the given RADOS object at the byte
// offset off. It returns the number of bytes read and the error, if any.
// ReadAt always returns a non-nil error when n < len(data).
// At the end of file, that error is io.EOF.
//
// This function adopted from the Go os.ReadAt() function.
func (c *Context) ReadAt(key string, data []byte, off uint64) (n int, err error) {
cname := C.CString(key)
defer C.free(unsafe.Pointer(cname))
for len(data) > 0 {
cdata, cdatalen := byteSliceToBuffer(data)
coff := C.uint64_t(off)
cerr := C.rados_read(c.ctx, cname, cdata, cdatalen, coff)
if cerr == 0 {
return n, io.EOF
}
if cerr < 0 {
err = radosReturnCodeError(cerr)
break
}
n += int(cerr)
data = data[cerr:]
}
return
}
// ReadAt reads len(data) bytes from the given RADOS object at the byte
// offset off. It returns the number of bytes read and the error, if any.
// ReadAt always returns a non-nil error when n < len(data).
// At the end of file, that error is io.EOF.
//
// This function adopted from the Go os.ReadAt() function.
func (o *Object) ReadAt(data []byte, off int64) (n int, err error) {
cname := C.CString(o.name)
defer C.free(unsafe.Pointer(cname))
for len(data) > 0 {
cdata, cdatalen := byteSliceToBuffer(data)
coff := C.uint64_t(off)
cerr := C.rados_read(o.c.ctx, cname, cdata, cdatalen, coff)
if cerr == 0 {
return n, io.EOF
}
if cerr < 0 {
err = fmt.Errorf("RADOS read %s: %s", o.name, strerror(cerr))
break
}
n += int(cerr)
data = data[cerr:]
off += int64(cerr)
}
return
}
func (r *RadosIoCtx) ReadRaw(oid string, length, offset uint64, buf unsafe.Pointer) int {
coid := C.CString(oid)
defer func() {
C.free(unsafe.Pointer(coid))
}()
cerr := C.rados_read(*r.ctx, coid, (*C.char)(buf), C.size_t(length), C.uint64_t(offset))
return int(cerr)
}
// Read reads a specified length of data from the object starting at the given offset.
func (o *Object) Read(length, offset uint64) (io.Reader, error) {
oid := C.CString(o.name)
defer freeString(oid)
bufAddr := bufferAddress(int(length))
ret := C.rados_read(o.ioContext, oid, bufAddr, C.size_t(length), C.uint64_t(offset))
if err := toRadosError(ret); err != nil {
err.Message = fmt.Sprintf("Unable to read object %s.", o.name)
return nil, err
}
return bufToReader(bufAddr, ret), nil
}
func (r *RadosIoCtx) Read(oid string, length, offset uint64) ([]byte, error) {
var buf = make([]byte, length)
coid := C.CString(oid)
defer func() {
C.free(unsafe.Pointer(coid))
}()
cerr := C.rados_read(*r.ctx, coid, (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(length), C.uint64_t(offset))
if cerr < 0 {
return nil, errors.New("read data failed")
}
return buf, nil
}
// Read reads up to len(data) bytes from the object with key oid starting at byte
// offset offset. It returns the number of bytes read and an error, if any.
func (ioctx *IOContext) Read(oid string, data []byte, offset uint64) (int, error) {
if len(data) == 0 {
return 0, nil
}
c_oid := C.CString(oid)
defer C.free(unsafe.Pointer(c_oid))
ret := C.rados_read(
ioctx.ioctx,
c_oid,
(*C.char)(unsafe.Pointer(&data[0])),
(C.size_t)(len(data)),
(C.uint64_t)(offset))
if ret >= 0 {
return int(ret), nil
} else {
return 0, GetRadosError(ret)
}
}
// Get reads all the data in the named object in the pool referenced by
// the given context. The data is returned as a byte slice.
//
// If the object does not exist, an error is returned.
// If the object contains no data, an empty slice is returned.
func (c *Context) Get(name string) ([]byte, error) {
obj, err := c.Stat(name)
if err != nil {
return nil, err
}
if obj.Size() == 0 {
// Return an empty slice
return make([]byte, 0), nil
}
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
data := make([]byte, obj.Size())
cdata, cdatalen := byteSliceToBuffer(data)
if cerr := C.rados_read(c.ctx, cname, cdata, cdatalen, 0); cerr < 0 {
return nil, fmt.Errorf("RADOS get %s: %s", name, strerror(cerr))
}
return data, nil
}