forked from TrueCloudLab/restic
c7b770eb1f
Ideally, code that uses a repository shouldn't directly interact with the underlying backend. Thus, move MemorizeList one layer up.
76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
package backend
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import (
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"bytes"
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"context"
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"encoding/hex"
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"fmt"
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"io"
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"github.com/minio/sha256-simd"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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)
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func verifyContentMatchesName(s string, data []byte) (bool, error) {
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if len(s) != hex.EncodedLen(sha256.Size) {
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return false, fmt.Errorf("invalid length for ID: %q", s)
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}
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b, err := hex.DecodeString(s)
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if err != nil {
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return false, fmt.Errorf("invalid ID: %s", err)
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}
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var id [sha256.Size]byte
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copy(id[:], b)
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hashed := sha256.Sum256(data)
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return id == hashed, nil
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}
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// LoadAll reads all data stored in the backend for the handle into the given
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// buffer, which is truncated. If the buffer is not large enough or nil, a new
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// one is allocated.
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func LoadAll(ctx context.Context, buf []byte, be Backend, h Handle) ([]byte, error) {
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retriedInvalidData := false
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err := be.Load(ctx, h, 0, 0, func(rd io.Reader) error {
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// make sure this is idempotent, in case an error occurs this function may be called multiple times!
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wr := bytes.NewBuffer(buf[:0])
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_, cerr := io.Copy(wr, rd)
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if cerr != nil {
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return cerr
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}
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buf = wr.Bytes()
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// retry loading damaged data only once. If a file fails to download correctly
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// the second time, then it is likely corrupted at the backend. Return the data
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// to the caller in that case to let it decide what to do with the data.
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if !retriedInvalidData && h.Type != ConfigFile {
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if matches, err := verifyContentMatchesName(h.Name, buf); err == nil && !matches {
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debug.Log("retry loading broken blob %v", h)
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retriedInvalidData = true
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return errors.Errorf("loadAll(%v): invalid data returned", h)
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}
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}
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return nil
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})
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if err != nil {
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return nil, err
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}
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return buf, nil
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}
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// LimitedReadCloser wraps io.LimitedReader and exposes the Close() method.
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type LimitedReadCloser struct {
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io.Closer
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io.LimitedReader
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}
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// LimitReadCloser returns a new reader wraps r in an io.LimitedReader, but also
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// exposes the Close() method.
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func LimitReadCloser(r io.ReadCloser, n int64) *LimitedReadCloser {
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return &LimitedReadCloser{Closer: r, LimitedReader: io.LimitedReader{R: r, N: n}}
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}
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