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mirror of https://github.com/octoleo/restic.git synced 2024-12-24 11:55:28 +00:00
restic/internal/filter/filter.go
Michael Eischer 88c8e903d2 filter: Fix glob matching on absolute path marker on windows
A pattern part containing "/" is used to mark a path or a pattern as
absolute. However, on Windows the path separator is "\" such that glob
patterns like "?" could match the marker. The code now explicitly skips
the marker when the pattern does not represent an absolute path.
2020-10-09 16:11:05 +02:00

266 lines
6.4 KiB
Go

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
}
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
}