forked from TrueCloudLab/restic
266 lines
7.1 KiB
Go
266 lines
7.1 KiB
Go
package main
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import (
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"bytes"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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"sync"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/filter"
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"github.com/restic/restic/internal/fs"
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"github.com/restic/restic/internal/repository"
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)
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type rejectionCache struct {
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m map[string]bool
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mtx sync.Mutex
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}
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// Lock locks the mutex in rc.
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func (rc *rejectionCache) Lock() {
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if rc != nil {
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rc.mtx.Lock()
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}
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}
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// Unlock unlocks the mutex in rc.
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func (rc *rejectionCache) Unlock() {
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if rc != nil {
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rc.mtx.Unlock()
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}
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}
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// Get returns the last stored value for dir and a second boolean that
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// indicates whether that value was actually written to the cache. It is the
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// callers responsibility to call rc.Lock and rc.Unlock before using this
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// method, otherwise data races may occur.
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func (rc *rejectionCache) Get(dir string) (bool, bool) {
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if rc == nil || rc.m == nil {
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return false, false
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}
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v, ok := rc.m[dir]
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return v, ok
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}
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// Store stores a new value for dir. It is the callers responsibility to call
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// rc.Lock and rc.Unlock before using this method, otherwise data races may
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// occur.
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func (rc *rejectionCache) Store(dir string, rejected bool) {
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if rc == nil {
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return
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}
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if rc.m == nil {
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rc.m = make(map[string]bool)
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}
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rc.m[dir] = rejected
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}
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// RejectFunc is a function that takes a filename and os.FileInfo of a
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// file that would be included in the backup. The function returns true if it
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// should be excluded (rejected) from the backup.
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type RejectFunc func(path string, fi os.FileInfo) bool
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// rejectByPattern returns a RejectFunc which rejects files that match
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// one of the patterns.
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func rejectByPattern(patterns []string) RejectFunc {
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return func(item string, fi os.FileInfo) bool {
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matched, _, err := filter.List(patterns, item)
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if err != nil {
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Warnf("error for exclude pattern: %v", err)
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}
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if matched {
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debug.Log("path %q excluded by an exclude pattern", item)
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return true
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}
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return false
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}
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}
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// rejectIfPresent returns a RejectFunc which itself returns whether a path
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// should be excluded. The RejectFunc considers a file to be excluded when
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// it resides in a directory with an exclusion file, that is specified by
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// excludeFileSpec in the form "filename[:content]". The returned error is
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// non-nil if the filename component of excludeFileSpec is empty. If rc is
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// non-nil, it is going to be used in the RejectFunc to expedite the evaluation
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// of a directory based on previous visits.
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func rejectIfPresent(excludeFileSpec string, rc *rejectionCache) (RejectFunc, error) {
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if excludeFileSpec == "" {
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return nil, errors.New("name for exclusion tagfile is empty")
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}
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colon := strings.Index(excludeFileSpec, ":")
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if colon == 0 {
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return nil, fmt.Errorf("no name for exclusion tagfile provided")
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}
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tf, tc := "", ""
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if colon > 0 {
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tf = excludeFileSpec[:colon]
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tc = excludeFileSpec[colon+1:]
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} else {
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tf = excludeFileSpec
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}
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debug.Log("using %q as exclusion tagfile", tf)
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fn := func(filename string, _ os.FileInfo) bool {
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return isExcludedByFile(filename, tf, tc, rc)
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}
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return fn, nil
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}
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// isExcludedByFile interprets filename as a path and returns true if that file
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// is in a excluded directory. A directory is identified as excluded if it contains a
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// tagfile which bears the name specified in tagFilename and starts with
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// header. If rc is non-nil, it is used to expedite the evaluation of a
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// directory based on previous visits.
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func isExcludedByFile(filename, tagFilename, header string, rc *rejectionCache) bool {
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if tagFilename == "" {
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return false
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}
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dir, base := filepath.Split(filename)
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if base == tagFilename {
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return false // do not exclude the tagfile itself
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}
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rc.Lock()
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defer rc.Unlock()
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rejected, visited := rc.Get(dir)
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if visited {
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return rejected
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}
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rejected = isDirExcludedByFile(dir, tagFilename, header)
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rc.Store(dir, rejected)
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return rejected
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}
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func isDirExcludedByFile(dir, tagFilename, header string) bool {
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tf := filepath.Join(dir, tagFilename)
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_, err := fs.Lstat(tf)
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if os.IsNotExist(err) {
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return false
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}
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if err != nil {
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Warnf("could not access exclusion tagfile: %v", err)
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return false
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}
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// when no signature is given, the mere presence of tf is enough reason
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// to exclude filename
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if len(header) == 0 {
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return true
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}
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// From this stage, errors mean tagFilename exists but it is malformed.
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// Warnings will be generated so that the user is informed that the
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// indented ignore-action is not performed.
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f, err := os.Open(tf)
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if err != nil {
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Warnf("could not open exclusion tagfile: %v", err)
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return false
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}
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defer f.Close()
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buf := make([]byte, len(header))
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_, err = io.ReadFull(f, buf)
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// EOF is handled with a dedicated message, otherwise the warning were too cryptic
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if err == io.EOF {
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Warnf("invalid (too short) signature in exclusion tagfile %q\n", tf)
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return false
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}
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if err != nil {
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Warnf("could not read signature from exclusion tagfile %q: %v\n", tf, err)
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return false
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}
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if bytes.Compare(buf, []byte(header)) != 0 {
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Warnf("invalid signature in exclusion tagfile %q\n", tf)
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return false
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}
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return true
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}
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// gatherDevices returns the set of unique device ids of the files and/or
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// directory paths listed in "items".
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func gatherDevices(items []string) (deviceMap map[string]uint64, err error) {
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deviceMap = make(map[string]uint64)
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for _, item := range items {
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fi, err := fs.Lstat(item)
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if err != nil {
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return nil, err
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}
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id, err := fs.DeviceID(fi)
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if err != nil {
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return nil, err
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}
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deviceMap[item] = id
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}
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if len(deviceMap) == 0 {
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return nil, errors.New("zero allowed devices")
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}
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return deviceMap, nil
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}
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// rejectByDevice returns a RejectFunc that rejects files which are on a
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// different file systems than the files/dirs in samples.
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func rejectByDevice(samples []string) (RejectFunc, error) {
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allowed, err := gatherDevices(samples)
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if err != nil {
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return nil, err
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}
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debug.Log("allowed devices: %v\n", allowed)
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return func(item string, fi os.FileInfo) bool {
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if fi == nil {
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return false
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}
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id, err := fs.DeviceID(fi)
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if err != nil {
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// This should never happen because gatherDevices() would have
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// errored out earlier. If it still does that's a reason to panic.
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panic(err)
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}
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for dir := item; dir != ""; dir = filepath.Dir(dir) {
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debug.Log("item %v, test dir %v", item, dir)
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allowedID, ok := allowed[dir]
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if !ok {
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continue
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}
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if allowedID != id {
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debug.Log("path %q on disallowed device %d", item, id)
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return true
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}
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return false
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}
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panic(fmt.Sprintf("item %v, device id %v not found, allowedDevs: %v", item, id, allowed))
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}, nil
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}
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// rejectResticCache returns a RejectFunc that rejects the restic cache
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// directory (if set).
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func rejectResticCache(repo *repository.Repository) (RejectFunc, error) {
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if repo.Cache == nil {
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return func(string, os.FileInfo) bool {
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return false
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}, nil
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}
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cacheBase := repo.Cache.BaseDir()
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if cacheBase == "" {
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return nil, errors.New("cacheBase is empty string")
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}
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return func(item string, _ os.FileInfo) bool {
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if fs.HasPathPrefix(cacheBase, item) {
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debug.Log("rejecting restic cache directory %v", item)
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return true
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}
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return false
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}, nil
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}
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