github.com/mckael/restic@v0.8.3/internal/restic/readerat.go (about) 1 package restic 2 3 import ( 4 "context" 5 "io" 6 7 "github.com/restic/restic/internal/debug" 8 "github.com/restic/restic/internal/errors" 9 ) 10 11 type backendReaderAt struct { 12 be Backend 13 h Handle 14 } 15 16 func (brd backendReaderAt) ReadAt(p []byte, offset int64) (n int, err error) { 17 return ReadAt(context.TODO(), brd.be, brd.h, offset, p) 18 } 19 20 // ReaderAt returns an io.ReaderAt for a file in the backend. 21 func ReaderAt(be Backend, h Handle) io.ReaderAt { 22 return backendReaderAt{be: be, h: h} 23 } 24 25 // ReadAt reads from the backend handle h at the given position. 26 func ReadAt(ctx context.Context, be Backend, h Handle, offset int64, p []byte) (n int, err error) { 27 debug.Log("ReadAt(%v) at %v, len %v", h, offset, len(p)) 28 29 err = be.Load(ctx, h, len(p), offset, func(rd io.Reader) (ierr error) { 30 n, ierr = io.ReadFull(rd, p) 31 32 return ierr 33 }) 34 if err != nil { 35 return 0, err 36 } 37 38 debug.Log("ReadAt(%v) ReadFull returned %v bytes", h, n) 39 40 return n, errors.Wrapf(err, "ReadFull(%v)", h) 41 }