[PATCH] t1402: test forbidden characters in refnames

[PATCH] t1402: test forbidden characters in refnames

[Nikolaus Schuetz via GitGitGadget]

From: Nikolaus Schuetz <nikolauspschuetz@gmail.com>

git-check-ref-format(1) documents that a refname cannot contain a
space, tilde, caret, colon, question-mark, asterisk or open-bracket,
and that it cannot be the single character "@".  Of these, only "?"
was tested as a character embedded in an otherwise-valid refname;
"*" was checked only as a lone character or with --refspec-pattern.

Add the remaining forbidden characters in that embedded form, and
check that "@" alone is rejected even with --allow-onelevel -- where
"@" is otherwise a valid refname component, as "refs/@" confirms.

Signed-off-by: Nikolaus Schuetz <nikolauspschuetz@gmail.com>
---
    t1402: test forbidden characters in refnames
    
    git-check-ref-format(1) documents the characters that a refname may not
    contain (space, tilde, caret, colon, question-mark, asterisk,
    open-bracket) and the rule that it may not be the single character "@".
    t1402 only exercised a few of these directly.
    
    This adds the remaining forbidden characters in embedded form, and
    checks that "@" alone is rejected even with --allow-onelevel, where "@"
    is otherwise a valid refname component (as "refs/@" confirms).
    
    Test-only; documents existing behaviour, in the spirit of 919eb8ace
    (t1402: check for refs ending with a dot).

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2203%2Fnikolauspschuetz%2Fns%2Ft1402-forbidden-characters-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2203/nikolauspschuetz/ns/t1402-forbidden-characters-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2203

 t/t1402-check-ref-format.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
index cabc516ae9..bc1e878a0f 100755
--- a/t/t1402-check-ref-format.sh
+++ b/t/t1402-check-ref-format.sh
@@ -51,12 +51,20 @@ invalid_ref '.refs/foo'
 invalid_ref 'refs/heads/foo.'
 invalid_ref 'heads/foo..bar'
 invalid_ref 'heads/foo?bar'
+invalid_ref 'heads/foo~bar'
+invalid_ref 'heads/foo^bar'
+invalid_ref 'heads/foo:bar'
+invalid_ref 'heads/foo*bar'
+invalid_ref 'heads/foo[bar'
+invalid_ref 'heads/foo bar'
 valid_ref 'foo./bar'
 invalid_ref 'heads/foo.lock'
 invalid_ref 'heads///foo.lock'
 invalid_ref 'foo.lock/bar'
 invalid_ref 'foo.lock///bar'
 valid_ref 'heads/foo@bar'
+valid_ref 'refs/@'
+invalid_ref '@' --allow-onelevel
 invalid_ref 'heads/v@{ation'
 invalid_ref 'heads/foo\bar'
 invalid_ref "$(printf 'heads/foo\t')"

base-commit: 745601a9a94110d74769ab605ccd4f61339758d2
-- 
gitgitgadget

Re: [PATCH] t1402: test forbidden characters in refnames

[Patrick Steinhardt]

On Thu, Aug 13, 2026 at 08:43:56PM +0000, Nikolaus Schuetz via GitGitGadget wrote:
> From: Nikolaus Schuetz <nikolauspschuetz@gmail.com>
> 
> git-check-ref-format(1) documents that a refname cannot contain a
> space, tilde, caret, colon, question-mark, asterisk or open-bracket,
> and that it cannot be the single character "@".  Of these, only "?"
> was tested as a character embedded in an otherwise-valid refname;
> "*" was checked only as a lone character or with --refspec-pattern.
> 
> Add the remaining forbidden characters in that embedded form, and
> check that "@" alone is rejected even with --allow-onelevel -- where
> "@" is otherwise a valid refname component, as "refs/@" confirms.

Okay.

> diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
> index cabc516ae9..bc1e878a0f 100755
> --- a/t/t1402-check-ref-format.sh
> +++ b/t/t1402-check-ref-format.sh
> @@ -51,12 +51,20 @@ invalid_ref '.refs/foo'
>  invalid_ref 'refs/heads/foo.'
>  invalid_ref 'heads/foo..bar'
>  invalid_ref 'heads/foo?bar'
> +invalid_ref 'heads/foo~bar'
> +invalid_ref 'heads/foo^bar'
> +invalid_ref 'heads/foo:bar'
> +invalid_ref 'heads/foo*bar'
> +invalid_ref 'heads/foo[bar'
> +invalid_ref 'heads/foo bar'

This feels a tiny bit excessive, but I guess it does not hurt to enforce
this property, especially now that it's so easy to add new backends.

One thing I was briefly wondering is whether we could maybe have a
simple loop here, as this feels quite repetitive. We could for example:

    for c in '?' '~' '^' ':' '*' '[' ' '
    do
        invalid_ref "heads/foo${c}bar"
    done

By the way, one weird bit: is it intentional that all of these really
use "heads/something" instead of "refs/heads/something"? I guess it
ultimately doesn't matter.

>  valid_ref 'foo./bar'
>  invalid_ref 'heads/foo.lock'
>  invalid_ref 'heads///foo.lock'
>  invalid_ref 'foo.lock/bar'
>  invalid_ref 'foo.lock///bar'
>  valid_ref 'heads/foo@bar'
> +valid_ref 'refs/@'
> +invalid_ref '@' --allow-onelevel

This one certainly is a good addition, as these are quite a bit more
subtle.

Thanks!

Patrick

Re: [PATCH] t1402: test forbidden characters in refnames

[Junio C Hamano]

Patrick Steinhardt <ps@pks.im> writes:

> On Thu, Aug 13, 2026 at 08:43:56PM +0000, Nikolaus Schuetz via GitGitGadget wrote:
>> From: Nikolaus Schuetz <nikolauspschuetz@gmail.com>
>> 
>> git-check-ref-format(1) documents that a refname cannot contain a
>> space, tilde, caret, colon, question-mark, asterisk or open-bracket,
>> and that it cannot be the single character "@".  Of these, only "?"
>> was tested as a character embedded in an otherwise-valid refname;
>> "*" was checked only as a lone character or with --refspec-pattern.
>> 
>> Add the remaining forbidden characters in that embedded form, and
>> check that "@" alone is rejected even with --allow-onelevel -- where
>> "@" is otherwise a valid refname component, as "refs/@" confirms.
>
> Okay.
>
>> diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
>> index cabc516ae9..bc1e878a0f 100755
>> --- a/t/t1402-check-ref-format.sh
>> +++ b/t/t1402-check-ref-format.sh
>> @@ -51,12 +51,20 @@ invalid_ref '.refs/foo'
>>  invalid_ref 'refs/heads/foo.'
>>  invalid_ref 'heads/foo..bar'
>>  invalid_ref 'heads/foo?bar'
>> +invalid_ref 'heads/foo~bar'
>> +invalid_ref 'heads/foo^bar'
>> +invalid_ref 'heads/foo:bar'
>> +invalid_ref 'heads/foo*bar'
>> +invalid_ref 'heads/foo[bar'
>> +invalid_ref 'heads/foo bar'
>
> This feels a tiny bit excessive, but I guess it does not hurt to enforce
> this property, especially now that it's so easy to add new backends.

"Why would we even care to check these insane cases?" was my first
reaction, but I agree with you that these are to protect authors of
new backends from stupid mistakes.

> One thing I was briefly wondering is whether we could maybe have a
> simple loop here, as this feels quite repetitive. We could for example:
>
>     for c in '?' '~' '^' ':' '*' '[' ' '
>     do
>         invalid_ref "heads/foo${c}bar"
>     done

True.  And c does not have to be a single byte. ".." can also be
part of the repertoire.

> By the way, one weird bit: is it intentional that all of these really
> use "heads/something" instead of "refs/heads/something"? I guess it
> ultimately doesn't matter.
>
>>  valid_ref 'foo./bar'
>>  invalid_ref 'heads/foo.lock'
>>  invalid_ref 'heads///foo.lock'
>>  invalid_ref 'foo.lock/bar'
>>  invalid_ref 'foo.lock///bar'
>>  valid_ref 'heads/foo@bar'
>> +valid_ref 'refs/@'
>> +invalid_ref '@' --allow-onelevel
>
> This one certainly is a good addition, as these are quite a bit more
> subtle.
>
> Thanks!
>
> Patrick

Re: [PATCH] t1402: test forbidden characters in refnames

[Nikolaus Schuetz]

> True.  And c does not have to be a single byte. ".." can also be
> part of the repertoire.

Agreed and updated accordingly: forbidden chars are looped over,
and I folded ".." in along with "\" (the same forbidden-char list).
The other refname rules enforced by refs.c are well covered,
so I kept the loop to the embedded forbidden tokens.

> By the way, one weird bit: is it intentional that all of these really
> use "heads/something" instead of "refs/heads/something"?

Not intentional -- the file already mixes them (e.g. 'refs/heads/foo.'
vs 'heads/foo..bar'). check-ref-format validates each component
regardless of a refs/ prefix, so it doesn't change what's tested; I
kept 'heads/' to match the neighbours.

Thanks,
Nikolaus

[PATCH v2] t1402: test forbidden characters in refnames

[Nikolaus Schuetz via GitGitGadget]

From: Nikolaus Schuetz <nikolauspschuetz@gmail.com>

git-check-ref-format(1) documents that a refname cannot contain a
space, tilde, caret, colon, question-mark, asterisk, open-bracket or
backslash, nor the sequence "..", and cannot be the single character
"@".  Of these, only "?", "\" and ".." were tested embedded in an
otherwise-valid refname; "*" was checked only as a lone character or
with --refspec-pattern.

Test all of them in that embedded form with a single loop, and check
that "@" alone is rejected even with --allow-onelevel -- where "@" is
otherwise a valid refname component, as "refs/@" confirms.

Signed-off-by: Nikolaus Schuetz <nikolauspschuetz@gmail.com>
---
    t1402: test forbidden characters in refnames
    
    git-check-ref-format(1) documents the characters that a refname may not
    contain (space, tilde, caret, colon, question-mark, asterisk,
    open-bracket) and the rule that it may not be the single character "@".
    t1402 only exercised a few of these directly.
    
    This adds the remaining forbidden characters in embedded form, and
    checks that "@" alone is rejected even with --allow-onelevel, where "@"
    is otherwise a valid refname component (as "refs/@" confirms).
    
    Test-only; documents existing behaviour, in the spirit of 919eb8ace
    (t1402: check for refs ending with a dot).

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2203%2Fnikolauspschuetz%2Fns%2Ft1402-forbidden-characters-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2203/nikolauspschuetz/ns/t1402-forbidden-characters-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2203

Range-diff vs v1:

 1:  f254db5b09 ! 1:  cc013499f9 t1402: test forbidden characters in refnames
     @@ Commit message
          t1402: test forbidden characters in refnames
      
          git-check-ref-format(1) documents that a refname cannot contain a
     -    space, tilde, caret, colon, question-mark, asterisk or open-bracket,
     -    and that it cannot be the single character "@".  Of these, only "?"
     -    was tested as a character embedded in an otherwise-valid refname;
     -    "*" was checked only as a lone character or with --refspec-pattern.
     +    space, tilde, caret, colon, question-mark, asterisk, open-bracket or
     +    backslash, nor the sequence "..", and cannot be the single character
     +    "@".  Of these, only "?", "\" and ".." were tested embedded in an
     +    otherwise-valid refname; "*" was checked only as a lone character or
     +    with --refspec-pattern.
      
     -    Add the remaining forbidden characters in that embedded form, and
     -    check that "@" alone is rejected even with --allow-onelevel -- where
     -    "@" is otherwise a valid refname component, as "refs/@" confirms.
     +    Test all of them in that embedded form with a single loop, and check
     +    that "@" alone is rejected even with --allow-onelevel -- where "@" is
     +    otherwise a valid refname component, as "refs/@" confirms.
      
          Signed-off-by: Nikolaus Schuetz <nikolauspschuetz@gmail.com>
      
       ## t/t1402-check-ref-format.sh ##
     -@@ t/t1402-check-ref-format.sh: invalid_ref '.refs/foo'
     +@@ t/t1402-check-ref-format.sh: invalid_ref 'foo/./bar'
     + invalid_ref 'foo/bar/.'
     + invalid_ref '.refs/foo'
       invalid_ref 'refs/heads/foo.'
     - invalid_ref 'heads/foo..bar'
     - invalid_ref 'heads/foo?bar'
     -+invalid_ref 'heads/foo~bar'
     -+invalid_ref 'heads/foo^bar'
     -+invalid_ref 'heads/foo:bar'
     -+invalid_ref 'heads/foo*bar'
     -+invalid_ref 'heads/foo[bar'
     -+invalid_ref 'heads/foo bar'
     +-invalid_ref 'heads/foo..bar'
     +-invalid_ref 'heads/foo?bar'
     ++for c in '?' '~' '^' ':' '*' '[' ' ' '\' '..'
     ++do
     ++	invalid_ref "heads/foo${c}bar"
     ++done
       valid_ref 'foo./bar'
       invalid_ref 'heads/foo.lock'
       invalid_ref 'heads///foo.lock'
     @@ t/t1402-check-ref-format.sh: invalid_ref '.refs/foo'
      +valid_ref 'refs/@'
      +invalid_ref '@' --allow-onelevel
       invalid_ref 'heads/v@{ation'
     - invalid_ref 'heads/foo\bar'
     +-invalid_ref 'heads/foo\bar'
       invalid_ref "$(printf 'heads/foo\t')"
     + invalid_ref "$(printf 'heads/foo\177')"
     + valid_ref "$(printf 'heads/fu\303\237')"


 t/t1402-check-ref-format.sh | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
index cabc516ae9..9dd64662b2 100755
--- a/t/t1402-check-ref-format.sh
+++ b/t/t1402-check-ref-format.sh
@@ -49,16 +49,19 @@ invalid_ref 'foo/./bar'
 invalid_ref 'foo/bar/.'
 invalid_ref '.refs/foo'
 invalid_ref 'refs/heads/foo.'
-invalid_ref 'heads/foo..bar'
-invalid_ref 'heads/foo?bar'
+for c in '?' '~' '^' ':' '*' '[' ' ' '\' '..'
+do
+	invalid_ref "heads/foo${c}bar"
+done
 valid_ref 'foo./bar'
 invalid_ref 'heads/foo.lock'
 invalid_ref 'heads///foo.lock'
 invalid_ref 'foo.lock/bar'
 invalid_ref 'foo.lock///bar'
 valid_ref 'heads/foo@bar'
+valid_ref 'refs/@'
+invalid_ref '@' --allow-onelevel
 invalid_ref 'heads/v@{ation'
-invalid_ref 'heads/foo\bar'
 invalid_ref "$(printf 'heads/foo\t')"
 invalid_ref "$(printf 'heads/foo\177')"
 valid_ref "$(printf 'heads/fu\303\237')"

base-commit: 745601a9a94110d74769ab605ccd4f61339758d2
-- 
gitgitgadget

Re: [PATCH v2] t1402: test forbidden characters in refnames

[Junio C Hamano]

"Nikolaus Schuetz via GitGitGadget" <gitgitgadget@gmail.com> writes:

>     This adds the remaining forbidden characters in embedded form, and
>     checks that "@" alone is rejected even with --allow-onelevel, where "@"
>     is otherwise a valid refname component (as "refs/@" confirms).

Many funny characters are not allowed between 'foo' and 'bar', but
are there characters other than dot that are not allowed at the
beginning or at the end (e.g., "refs/heads/foo." and "foo.lock")?

IOW are we testing exhaustive now?

>  invalid_ref '.refs/foo'
>  invalid_ref 'refs/heads/foo.'
> -invalid_ref 'heads/foo..bar'
> -invalid_ref 'heads/foo?bar'
> +for c in '?' '~' '^' ':' '*' '[' ' ' '\' '..'
> +do
> +	invalid_ref "heads/foo${c}bar"
> +done
>  valid_ref 'foo./bar'
>  invalid_ref 'heads/foo.lock'
>  invalid_ref 'heads///foo.lock'

Re: [PATCH v2] t1402: test forbidden characters in refnames

[Nikolaus Schuetz]

> Many funny characters are not allowed between 'foo' and 'bar', but
> are there characters other than dot that are not allowed at the
> beginning or at the end (e.g., "refs/heads/foo." and "foo.lock")?
>
> IOW are we testing exhaustive now?

No -- dot is the only character with position-specific rules,
and every other character in the forbidden set is rejected
anywhere in a component.

The file already exercises each of those rules on its own -- the
leading/trailing-dot, ".lock", empty-component, single-level and
--normalize cases are all present. So this isn't reaching for
exhaustiveness; the coverage was already broad, and this just
fills the untested gap -- of the "forbidden anywhere" characters,
only "?", "\" and ".." were tested embedded, so I folded the rest
into the loop.

Thanks,
Nikolaus