Escaped braces aren't handled properly

[micimize]

It seems that \{ and \} are not handled properly in both pattern patching and path evaluation:

• The pattern **/log file \{????-??-??\}.txt will fail with a syntax error
• The input path src/logs/log file {2021-05-11}.txt will fail with any pattern (this is a valid path)

If I remove both from my test the other patterns and path combinations work fine. This does not seem to be the case for brackets, e.g. src/logs/log file [2021-05-11].txt
and **/log file [????-??-??].txt. I am using doublestar.Match.

[bmatcuk]

Hmm, are you using doublestar v4? What OS are you on? How are you building your pattern? You'll need to double the backslashes to get them to stay in the string, ie "**/log file \\{????-??-??\\}.txt".

I cannot reproduce this issue using v4 on macOS.

[micimize]

I think I was maybe mistaken as to the exact issue – there is an issue with both \[ and \{ escaping.
If there is a match, they succeed, but if not, they return a syntax error. See https://play.golang.org/p/Saso864XooB

copied for reference

package main

import (
	"fmt"

	"github.com/bmatcuk/doublestar/v4"
)

func main() {
	patterns := []string{
		//`\{????-??-??\}.txt`,
		//`\[????-??-??\].txt`,
		`\{*\}.txt`,
		`\[*\].txt`,
	}
	names := []string{
		`{2021-05-01}.txt`,
		`[2021-05-01].txt`,
		`normal text`,
	}
	for _, p := range patterns {
		for _, n := range names {
			match, err := doublestar.Match(p, n)
			fmt.Println(p, n, match, err)
		}
	}

}

/* output
\{*\}.txt {2021-05-01}.txt true <nil>
\{*\}.txt [2021-05-01].txt false syntax error in pattern
\{*\}.txt normal text false syntax error in pattern
\[*\].txt {2021-05-01}.txt false syntax error in pattern
\[*\].txt [2021-05-01].txt true <nil>
\[*\].txt normal text false syntax error in pattern
*/

[micimize]

@bmatcuk I found the issue – every iteration of the loop consuming pattern validates the remaining pattern:

doublestar/match.go

Lines 279 to 281 in 1fd2e2d

	if validate && patIdx < patLen && !doValidatePattern(pattern[patIdx:], separator) {
	return false, ErrBadPattern
	}

The default fallthrough after '\\' is matched breaks before bumping patIdx when a match is rejected, resulting in an invalid pattern at validation time:

doublestar/match.go

Lines 241 to 245 in 1fd2e2d

	if patRune != nameRune {
	break
	}
	patIdx += patRuneLen

Why validate the pattern every loop? doValidatePattern is called nameLen * patLen times this way

[bmatcuk]

Hey @micimize! I'm so sorry I didn't see your reply back in May! I never got a notification from github that you replied! Your test cases were most helpful and I was able to fix the bug fairly quickly. I only wish I would have seen your reply a month ago so I could have fixed it then 😢

Anyway, I just released v4.0.2 with the fix. Let me know if you have any trouble with it.

By the way, doValidatePattern is only called if all else fails. Everything in the loop above it will either return or continue the loop before reaching that point. So, it will only reach that if the pattern has been valid up until now, but a match could not be made, and neither ** or * backtracking is possible. At that point, we already know we're returning false, we just want to know if we're also returning an error.

[bmatcuk]

I'm going to close this issue since there hasn't been any activity. Let me know if you run into trouble with the fix!

[micimize]

will do! Sorry I haven't gotten around to actually testing it but will ping here if there are any issues when I do