path/filepath: Match incorrectly reports a pattern as malformed #13396

0xmohit · 2015-11-25T11:12:08Z

$ go version
go version go1.5.1 linux/amd64

Match doesn't accept a hyphen inside a character class except when it is a part of a range, e.g. [0-5] or when it is escaped [\-]. A hyphen at the beginning or the end of the character class should ideally work without escaping.

$ cd $(mktemp -d)
$ touch foo.bar
$ touch foo-bar
$ touch foobar
$ ls -l
total 0
-rw-rw-r-- 1 mohit mohit 0 Nov 25 10:05 foobar
-rw-rw-r-- 1 mohit mohit 0 Nov 25 10:05 foo-bar
-rw-rw-r-- 1 mohit mohit 0 Nov 25 10:05 foo.bar

Test program:

package main

import (
    "fmt"
    "path/filepath"
)

func main() {
    m, e := filepath.Glob(`foo*[.-]*`)
    if e != nil {
        panic(e)
    }
    for _, v := range m {
        fmt.Printf("%v\n", v)
    }
}

Executing it results in:

panic: syntax error in pattern

goroutine 1 [running]:
main.main()
    /tmp/tmp.ijbcwjChbR/z.go:11 +0xa1
exit status 2

The same glob pattern yields results in the shell:

$ ls -l -- foo[.-]*
-rw-rw-r-- 1 mohit mohit 0 Nov 25 10:05 foo-bar
-rw-rw-r-- 1 mohit mohit 0 Nov 25 10:05 foo.bar

Similar globs appear to work in other languages too:

>>> from glob import glob
>>> glob("foo[.-]*")
['foo.bar', 'foo-bar']
>>>

import std.path;

void main()
{
    assert(globMatch("foo-bar", `foo[-]*`) == true);
    assert(globMatch("foo.bar-baz", `foo[-.]*`) == true);
}

The text was updated successfully, but these errors were encountered:

gopherbot · 2015-11-25T13:02:13Z

CL https://golang.org/cl/17213 mentions this issue.

ianlancetaylor · 2015-11-25T17:00:50Z

rsc commented on the CL: "Thanks but no. While it's true that some regexp packages do accept [-] or [x-] as equivalent to [-] or [x-], it's not universal. Go is not adhering to some external spec here. We defined a specific grammar (see the doc comment on filepath.Match) and that grammar does not admit [-] nor [x-]."

mattn · 2015-11-26T03:20:28Z

However, on windows, we can't escape - as \- because go disable escape of [] on windows. So we can't glob the files with this pattern.

ianlancetaylor closed this as completed Nov 25, 2015

golang locked and limited conversation to collaborators Nov 27, 2016

gopherbot added the FrozenDueToAge label Nov 27, 2016

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path/filepath: Match incorrectly reports a pattern as malformed #13396

path/filepath: Match incorrectly reports a pattern as malformed #13396

0xmohit commented Nov 25, 2015

gopherbot commented Nov 25, 2015

ianlancetaylor commented Nov 25, 2015

mattn commented Nov 26, 2015

path/filepath: Match incorrectly reports a pattern as malformed #13396

path/filepath: Match incorrectly reports a pattern as malformed #13396

Comments

0xmohit commented Nov 25, 2015

gopherbot commented Nov 25, 2015

ianlancetaylor commented Nov 25, 2015

mattn commented Nov 26, 2015