minio/pkg/wildcard/match.go
karthic rao 2e0742e309 bucket policy: Support for '?' wildcard. (#2353)
- Support for '?' wildcard for resource matching.

- Wildcard package is added with Match functions.

- Wildcard.Match supports '*' and wild.MatchExtended supports both '*'
  and '?' wildcards in the pattern string.

- Tests for the same for the wide range of cases.
2016-08-04 00:41:32 -07:00

139 lines
3.5 KiB
Go

/*
* Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package wildcard
import (
"strings"
"unicode/utf8"
)
// Match - finds whether the text matches/satisfies the pattern string.
// supports only '*' wildcard in the pattern.
// considers a file system path as a flat name space.
func Match(pattern, text string) bool {
if pattern == "" {
return text == pattern
}
if pattern == "*" {
return true
}
parts := strings.Split(pattern, "*")
if len(parts) == 1 {
return text == pattern
}
tGlob := strings.HasSuffix(pattern, "*")
end := len(parts) - 1
if !strings.HasPrefix(text, parts[0]) {
return false
}
for i := 1; i < end; i++ {
if !strings.Contains(text, parts[i]) {
return false
}
idx := strings.Index(text, parts[i]) + len(parts[i])
text = text[idx:]
}
return tGlob || strings.HasSuffix(text, parts[end])
}
// MatchExtended - finds whether the text matches/satisfies the pattern string.
// supports '*' and '?' wildcards in the pattern string.
// unlike path.Match(), considers a path as a flat name space while matching the pattern.
// The difference is illustrated in the example here https://play.golang.org/p/Ega9qgD4Qz .
func MatchExtended(pattern, name string) (matched bool) {
Pattern:
for len(pattern) > 0 {
var star bool
var chunk string
star, chunk, pattern = scanChunk(pattern)
if star && chunk == "" {
// Trailing * matches rest of string.
return true
}
// Look for match at current position.
t, ok := matchChunk(chunk, name)
// if we're the last chunk, make sure we've exhausted the name
// otherwise we'll give a false result even if we could still match
// using the star
if ok && (len(t) == 0 || len(pattern) > 0) {
name = t
continue
}
if star {
// Look for match skipping i+1 bytes.
for i := 0; i < len(name); i++ {
t, ok := matchChunk(chunk, name[i+1:])
if ok {
// if we're the last chunk, make sure we exhausted the name
if len(pattern) == 0 && len(t) > 0 {
continue
}
name = t
continue Pattern
}
}
}
return false
}
return len(name) == 0
}
// scanChunk gets the next segment of pattern, which is a non-star string
// possibly preceded by a star.
func scanChunk(pattern string) (star bool, chunk, rest string) {
for len(pattern) > 0 && pattern[0] == '*' {
pattern = pattern[1:]
star = true
}
inrange := false
var i int
Scan:
for i = 0; i < len(pattern); i++ {
switch pattern[i] {
case '*':
if !inrange {
break Scan
}
}
}
return star, pattern[0:i], pattern[i:]
}
// matchChunk checks whether chunk matches the beginning of s.
// If so, it returns the remainder of s (after the match).
// Chunk is all single-character operators: literals, char classes, and ?.
func matchChunk(chunk, s string) (rest string, ok bool) {
for len(chunk) > 0 {
if len(s) == 0 {
return
}
switch chunk[0] {
case '?':
_, n := utf8.DecodeRuneInString(s)
s = s[n:]
chunk = chunk[1:]
default:
if chunk[0] != s[0] {
return
}
s = s[1:]
chunk = chunk[1:]
}
}
return s, true
}