86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
package restic
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import (
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"context"
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"github.com/restic/restic/internal/errors"
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)
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// ErrNoIDPrefixFound is returned by Find() when no ID for the given prefix
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// could be found.
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var ErrNoIDPrefixFound = errors.New("no ID found")
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// ErrMultipleIDMatches is returned by Find() when multiple IDs with the given
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// prefix are found.
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var ErrMultipleIDMatches = errors.New("multiple IDs with prefix found")
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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(be Lister, t FileType, prefix string) (string, error) {
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match := ""
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ctx, cancel := context.WithCancel(context.TODO())
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defer cancel()
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err := be.List(ctx, t, func(fi FileInfo) error {
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if 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 ErrMultipleIDMatches
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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 "", ErrNoIDPrefixFound
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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(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(context.TODO())
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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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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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