restic/internal/backend/utils.go

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package backend
import (
"bytes"
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"context"
"io"
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"github.com/restic/restic/internal/restic"
)
// LoadAll reads all data stored in the backend for the handle into the given
// buffer, which is truncated. If the buffer is not large enough or nil, a new
// one is allocated.
func LoadAll(ctx context.Context, buf []byte, be restic.Backend, h restic.Handle) ([]byte, error) {
err := be.Load(ctx, h, 0, 0, func(rd io.Reader) error {
// make sure this is idempotent, in case an error occurs this function may be called multiple times!
wr := bytes.NewBuffer(buf[:0])
_, cerr := io.Copy(wr, rd)
if cerr != nil {
return cerr
}
buf = wr.Bytes()
return nil
})
if err != nil {
return nil, err
}
return buf, nil
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}
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// LimitedReadCloser wraps io.LimitedReader and exposes the Close() method.
type LimitedReadCloser struct {
io.ReadCloser
io.Reader
}
// Read reads data from the limited reader.
func (l *LimitedReadCloser) Read(p []byte) (int, error) {
return l.Reader.Read(p)
}
// LimitReadCloser returns a new reader wraps r in an io.LimitReader, but also
// exposes the Close() method.
func LimitReadCloser(r io.ReadCloser, n int64) *LimitedReadCloser {
return &LimitedReadCloser{ReadCloser: r, Reader: io.LimitReader(r, n)}
}
// DefaultLoad implements Backend.Load using lower-level openReader func
func DefaultLoad(ctx context.Context, h restic.Handle, length int, offset int64,
openReader func(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error),
fn func(rd io.Reader) error) error {
rd, err := openReader(ctx, h, length, offset)
if err != nil {
return err
}
err = fn(rd)
if err != nil {
rd.Close() // ignore secondary errors closing the reader
return err
}
return rd.Close()
}