mirror of https://github.com/octoleo/restic.git
103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
package restic
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import (
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"context"
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"fmt"
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"github.com/restic/restic/internal/debug"
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)
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// A MultipleIDMatchesError is returned by Find() when multiple IDs with a
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// given prefix are found.
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type MultipleIDMatchesError struct{ prefix string }
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func (e *MultipleIDMatchesError) Error() string {
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return fmt.Sprintf("multiple IDs with prefix %q found", e.prefix)
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}
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// A NoIDByPrefixError is returned by Find() when no ID for a given prefix
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// could be found.
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type NoIDByPrefixError struct{ prefix string }
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func (e *NoIDByPrefixError) Error() string {
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return fmt.Sprintf("no matching ID found for prefix %q", e.prefix)
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}
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// Find loads the list of all files of type t and searches for names which
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// start with prefix. If none is found, nil and ErrNoIDPrefixFound is returned.
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// If more than one is found, nil and ErrMultipleIDMatches is returned.
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func Find(ctx context.Context, be Lister, t FileType, prefix string) (string, error) {
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match := ""
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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err := be.List(ctx, t, func(fi FileInfo) error {
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// ignore filename which are not an id
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_, err := ParseID(fi.Name)
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if err != nil {
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debug.Log("unable to parse %v as an ID", fi.Name)
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return nil
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}
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if len(fi.Name) >= len(prefix) && prefix == fi.Name[:len(prefix)] {
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if match == "" {
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match = fi.Name
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} else {
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return &MultipleIDMatchesError{prefix}
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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 "", err
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}
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if match != "" {
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return match, nil
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}
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return "", &NoIDByPrefixError{prefix}
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}
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const minPrefixLength = 8
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// PrefixLength returns the number of bytes required so that all prefixes of
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// all names of type t are unique.
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func PrefixLength(ctx context.Context, be Lister, t FileType) (int, error) {
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// load all IDs of the given type
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list := make([]string, 0, 100)
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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err := be.List(ctx, t, func(fi FileInfo) error {
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list = append(list, fi.Name)
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return nil
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})
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if err != nil {
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return 0, err
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}
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// select prefixes of length l, test if the last one is the same as the current one
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var id ID
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outer:
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for l := minPrefixLength; l < len(id); l++ {
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var last string
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for _, name := range list {
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if last == name[:l] {
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continue outer
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}
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last = name[:l]
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}
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return l, nil
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}
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return len(id), nil
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}
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