package filter import ( "path/filepath" "strings" "github.com/restic/restic/internal/errors" ) // ErrBadString is returned when Match is called with the empty string as the // second argument. var ErrBadString = errors.New("filter.Match: string is empty") type patternPart struct { pattern string // First is "/" for absolute pattern; "" for "**". isSimple bool } // Pattern represents a preparsed filter pattern type Pattern []patternPart func prepareStr(str string) ([]string, error) { if str == "" { return nil, ErrBadString } return splitPath(str), nil } func preparePattern(pattern string) Pattern { parts := splitPath(filepath.Clean(pattern)) patterns := make([]patternPart, len(parts)) for i, part := range parts { isSimple := !strings.ContainsAny(part, "\\[]*?") // Replace "**" with the empty string to get faster comparisons // (length-check only) in hasDoubleWildcard. if part == "**" { part = "" } patterns[i] = patternPart{part, isSimple} } return patterns } // Split p into path components. Assuming p has been Cleaned, no component // will be empty. For absolute paths, the first component is "/". func splitPath(p string) []string { parts := strings.Split(filepath.ToSlash(p), "/") if parts[0] == "" { parts[0] = "/" } return parts } // Match returns true if str matches the pattern. When the pattern is // malformed, filepath.ErrBadPattern is returned. The empty pattern matches // everything, when str is the empty string ErrBadString is returned. // // Pattern can be a combination of patterns suitable for filepath.Match, joined // by filepath.Separator. // // In addition patterns suitable for filepath.Match, pattern accepts a // recursive wildcard '**', which greedily matches an arbitrary number of // intermediate directories. func Match(pattern, str string) (matched bool, err error) { if pattern == "" { return true, nil } patterns := preparePattern(pattern) strs, err := prepareStr(str) if err != nil { return false, err } return match(patterns, strs) } // ChildMatch returns true if children of str can match the pattern. When the pattern is // malformed, filepath.ErrBadPattern is returned. The empty pattern matches // everything, when str is the empty string ErrBadString is returned. // // Pattern can be a combination of patterns suitable for filepath.Match, joined // by filepath.Separator. // // In addition patterns suitable for filepath.Match, pattern accepts a // recursive wildcard '**', which greedily matches an arbitrary number of // intermediate directories. func ChildMatch(pattern, str string) (matched bool, err error) { if pattern == "" { return true, nil } patterns := preparePattern(pattern) strs, err := prepareStr(str) if err != nil { return false, err } return childMatch(patterns, strs) } func childMatch(patterns Pattern, strs []string) (matched bool, err error) { if patterns[0].pattern != "/" { // relative pattern can always be nested down return true, nil } ok, pos := hasDoubleWildcard(patterns) if ok && len(strs) >= pos { // cut off at the double wildcard strs = strs[:pos] } // match path against absolute pattern prefix l := 0 if len(strs) > len(patterns) { l = len(patterns) } else { l = len(strs) } return match(patterns[0:l], strs) } func hasDoubleWildcard(list Pattern) (ok bool, pos int) { for i, item := range list { if item.pattern == "" { return true, i } } return false, 0 } func match(patterns Pattern, strs []string) (matched bool, err error) { if ok, pos := hasDoubleWildcard(patterns); ok { // gradually expand '**' into separate wildcards newPat := make(Pattern, len(strs)) // copy static prefix once copy(newPat, patterns[:pos]) for i := 0; i <= len(strs)-len(patterns)+1; i++ { // limit to static prefix and already appended '*' newPat := newPat[:pos+i] // in the first iteration the wildcard expands to nothing if i > 0 { newPat[pos+i-1] = patternPart{"*", false} } newPat = append(newPat, patterns[pos+1:]...) matched, err := match(newPat, strs) if err != nil { return false, err } if matched { return true, nil } } return false, nil } if len(patterns) == 0 && len(strs) == 0 { return true, nil } // an empty pattern never matches a non-empty path if len(patterns) == 0 { return false, nil } if len(patterns) <= len(strs) { minOffset := 0 maxOffset := len(strs) - len(patterns) // special case absolute patterns if patterns[0].pattern == "/" { maxOffset = 0 } else if strs[0] == "/" { // skip absolute path marker if pattern is not rooted minOffset = 1 } outer: for offset := maxOffset; offset >= minOffset; offset-- { for i := len(patterns) - 1; i >= 0; i-- { var ok bool if patterns[i].isSimple { ok = patterns[i].pattern == strs[offset+i] } else { ok, err = filepath.Match(patterns[i].pattern, strs[offset+i]) if err != nil { return false, errors.Wrap(err, "Match") } } if !ok { continue outer } } return true, nil } } return false, nil } // ParsePatterns prepares a list of patterns for use with List. func ParsePatterns(patterns []string) []Pattern { patpat := make([]Pattern, 0) for _, pat := range patterns { if pat == "" { continue } pats := preparePattern(pat) patpat = append(patpat, pats) } return patpat } // List returns true if str matches one of the patterns. Empty patterns are ignored. func List(patterns []Pattern, str string) (matched bool, err error) { matched, _, err = list(patterns, false, str) return matched, err } // ListWithChild returns true if str matches one of the patterns. Empty patterns are ignored. func ListWithChild(patterns []Pattern, str string) (matched bool, childMayMatch bool, err error) { return list(patterns, true, str) } // List returns true if str matches one of the patterns. Empty patterns are ignored. func list(patterns []Pattern, checkChildMatches bool, str string) (matched bool, childMayMatch bool, err error) { if len(patterns) == 0 { return false, false, nil } strs, err := prepareStr(str) if err != nil { return false, false, err } for _, pat := range patterns { m, err := match(pat, strs) if err != nil { return false, false, err } var c bool if checkChildMatches { c, err = childMatch(pat, strs) if err != nil { return false, false, err } } else { c = true } matched = matched || m childMayMatch = childMayMatch || c if matched && childMayMatch { return true, true, nil } } return matched, childMayMatch, nil }