Subject: Re: [PATCH] worktree add: sanitize worktree names

From: Konstantin Kharlamov <[email-masked]>
Date: Thu, 21 Feb 2019 14:28:45 +0300

On Чт, Feb 21, 2019 at 2:00 PM, 
=?UTF-8?b?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy <[email-masked]> wrote:
> Worktree names are based on $(basename $GIT_WORK_TREE). They aren't
> significant until 3a3b9d8cde (refs: new ref types to make per-worktree
> refs visible to all worktrees - 2018-10-21), where worktree name could
> be part of a refname and must follow refname rules.
> 
> Update 'worktree add' code to remove special characters to follow
> these rules. The code could replace chars with '-' more than
> necessary, but it keeps the code simple. In the future the user will
> be able to specify the worktree name by themselves if they're not
> happy with this dumb character substitution.
> 
> Reported-by: [email-masked]
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---
>  builtin/worktree.c      | 47 
> ++++++++++++++++++++++++++++++++++++++++-
>  t/t2025-worktree-add.sh |  5 +++++
>  2 files changed, 51 insertions(+), 1 deletion(-)
> 
> diff --git a/builtin/worktree.c b/builtin/worktree.c
> index 3f9907fcc9..ff36838a33 100644
> --- a/builtin/worktree.c
> +++ b/builtin/worktree.c
> @@ -262,6 +262,46 @@ static void validate_worktree_add(const char 
> *path, const struct add_opts *opts)
>  	free_worktrees(worktrees);
>  }
> 
> +/*
> + * worktree name is part of refname and has to pass
> + * check_refname_component(). Remove unallowed characters to make it
> + * valid.
> + */
> +static void sanitize_worktree_name(struct strbuf *name)
> +{
> +	int i;
> +
> +	/* no ending with .lock */
> +	if (ends_with(name->buf, ".lock"))
> +		strbuf_remove(name, name->len - strlen(".lock"),
> +			      strlen(".lock"));
> +
> +	/*
> +	 * All special chars replaced with dashes. See
> +	 * check_refname_component() for reference.
> +	 */
> +	for (i = 0; i < name->len; i++) {
> +		if (strchr(":?[]\\~ \t@{}*/.", name->buf[i]))
> +			name->buf[i] = '-';
> +	}
> +
> +	/* remove consecutive dashes, leading or trailing dashes */
> +	for (i = 0; i < name->len; i++) {
> +		while (name->buf[i] == '-' &&
> +		       (i == 0 ||
> +			i == name->len - 1 ||
> +			(i < name->len - 1 && name->buf[i + 1] == '-')))
> +			strbuf_remove(name, i, 1);
> +	}
> +
> +	/* last resort, should never ever happen in practice */
> +	if (name->len == 0)
> +		strbuf_addstr(name, "worktree");

I assume this means a user have passed a zero-sized worktree name? But 
zero-sized file/directory names are not possible anyway, would it make 
sense to just return an error in this case?

> +
> +	if (check_refname_format(name->buf, REFNAME_ALLOW_ONELEVEL))
> +		BUG("worktree name '%s' is not a valid refname", name->buf);
> +}
> +
>  static int add_worktree(const char *path, const char *refname,
>  			const struct add_opts *opts)
>  {
> @@ -275,6 +315,7 @@ static int add_worktree(const char *path, const 
> char *refname,
>  	struct strbuf symref = STRBUF_INIT;
>  	struct commit *commit = NULL;
>  	int is_branch = 0;
> +	struct strbuf sb_name = STRBUF_INIT;
> 
>  	validate_worktree_add(path, opts);
> 
> @@ -290,7 +331,10 @@ static int add_worktree(const char *path, const 
> char *refname,
>  		die(_("invalid reference: %s"), refname);
> 
>  	name = worktree_basename(path, &len);
> -	git_path_buf(&sb_repo, "worktrees/%.*s", (int)(path + len - name), 
> name);
> +	strbuf_add(&sb_name, name, path + len - name);
> +	sanitize_worktree_name(&sb_name);
> +	name = sb_name.buf;
> +	git_path_buf(&sb_repo, "worktrees/%s", name);
>  	len = sb_repo.len;
>  	if (safe_create_leading_directories_const(sb_repo.buf))
>  		die_errno(_("could not create leading directories of '%s'"),
> @@ -415,6 +459,7 @@ static int add_worktree(const char *path, const 
> char *refname,
>  	strbuf_release(&symref);
>  	strbuf_release(&sb_repo);
>  	strbuf_release(&sb_git);
> +	strbuf_release(&sb_name);
>  	return ret;
>  }
> 
> diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
> index 286bba35d8..0d465adb54 100755
> --- a/t/t2025-worktree-add.sh
> +++ b/t/t2025-worktree-add.sh
> @@ -570,4 +570,9 @@ test_expect_success '"add" an existing locked but 
> missing worktree' '
>  	git worktree add --force --force --detach gnoo
>  '
> 
> +test_expect_success 'sanitize generated worktree name' '
> +	git worktree add --detach ".  weird*..?.lock" &&
> +	test -d .git/worktrees/weird
> +'
> +
>  test_done
> --
> 2.21.0.rc1.337.gdf7f8d0522
>