[4/8] sparse-checkout: cone mode does not recognize "**"
diff mbox series

Message ID dfa7e204449c8958d35cc01261d2dc8099d7ce0c.1579029963.git.gitgitgadget@gmail.com
State New
Headers show
Series
  • Harden the sparse-checkout builtin
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Commit Message

starlord via GitGitGadget Jan. 14, 2020, 7:25 p.m. UTC
From: Derrick Stolee <dstolee@microsoft.com>

When core.sparseCheckoutCone is enabled, the 'git sparse-checkout set'
command creates a restricted set of possible patterns that are used
by a custom algorithm to quickly match those patterns.

If a user manually edits the sparse-checkout file, then they could
create patterns that do not match these expectations. The cone-mode
matching algorithm can return incorrect results. The solution is to
detect these incorrect patterns, warn that we do not recognize them,
and revert to the standard algorithm.

Check each pattern for the "**" substring, and revert to the old
logic if seen. While technically a "/<dir>/**" pattern matches
the meaning of "/<dir>/", it is not one that would be written by
the sparse-checkout builtin in cone mode. Attempting to accept that
pattern change complicates the logic and instead we punt and do
not accept any instance of "**".

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 dir.c                              |  7 ++++++
 t/t1091-sparse-checkout-builtin.sh | 34 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

Comments

Jeff King Jan. 14, 2020, 9:16 p.m. UTC | #1
On Tue, Jan 14, 2020 at 07:25:58PM +0000, Derrick Stolee via GitGitGadget wrote:

> From: Derrick Stolee <dstolee@microsoft.com>
> 
> When core.sparseCheckoutCone is enabled, the 'git sparse-checkout set'
> command creates a restricted set of possible patterns that are used
> by a custom algorithm to quickly match those patterns.
> 
> If a user manually edits the sparse-checkout file, then they could
> create patterns that do not match these expectations. The cone-mode
> matching algorithm can return incorrect results. The solution is to
> detect these incorrect patterns, warn that we do not recognize them,
> and revert to the standard algorithm.
> 
> Check each pattern for the "**" substring, and revert to the old
> logic if seen. While technically a "/<dir>/**" pattern matches
> the meaning of "/<dir>/", it is not one that would be written by
> the sparse-checkout builtin in cone mode. Attempting to accept that
> pattern change complicates the logic and instead we punt and do
> not accept any instance of "**".

That all makes sense.

> diff --git a/dir.c b/dir.c
> index 22d08e61c2..f8e350dda2 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -651,6 +651,13 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
>  		return;
>  	}
>  
> +	if (strstr(given->pattern, "**")) {
> +		/* Not a cone pattern. */
> +		pl->use_cone_patterns = 0;
> +		warning(_("unrecognized pattern: '%s'"), given->pattern);
> +		goto clear_hashmaps;
> +	}

The clear_hashmaps label already unsets pl->use_cone_patterns, so the
first line is redundant (the same is true of existing goto jumps, as
well, though).

I wondered whether this warning could be triggered accidentally by
somebody who just happened to add such a pattern. But we'd exit
immediately from add_pattern_to_hashsets() immediately unless the user
has set core.sparseCheckoutCone. And if that's set, then warning is
definitely the right thing to do.

-Peff

Patch
diff mbox series

diff --git a/dir.c b/dir.c
index 22d08e61c2..f8e350dda2 100644
--- a/dir.c
+++ b/dir.c
@@ -651,6 +651,13 @@  static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 		return;
 	}
 
+	if (strstr(given->pattern, "**")) {
+		/* Not a cone pattern. */
+		pl->use_cone_patterns = 0;
+		warning(_("unrecognized pattern: '%s'"), given->pattern);
+		goto clear_hashmaps;
+	}
+
 	if (given->patternlen > 2 &&
 	    !strcmp(given->pattern + given->patternlen - 2, "/*")) {
 		if (!(given->flags & PATTERN_FLAG_NEGATIVE)) {
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index 58d9c69163..e532a52f89 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -305,4 +305,38 @@  test_expect_success 'different sparse-checkouts with worktrees' '
 	check_files worktree "a deep"
 '
 
+check_read_tree_errors () {
+	REPO=$1
+	FILES=$2
+	ERRORS=$3
+	git -C $REPO read-tree -mu HEAD 2>err &&
+	if test -z "$ERRORS"
+	then
+		test_must_be_empty err
+	else
+		test_i18ngrep "$ERRORS" err
+	fi &&
+	check_files $REPO "$FILES"
+}
+
+test_expect_success 'pattern-checks: /A/**' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/folder1/**
+	EOF
+	check_read_tree_errors repo "a folder1" "disabling cone pattern matching"
+'
+
+test_expect_success 'pattern-checks: /A/**/B/' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/deep/**/deepest
+	EOF
+	check_read_tree_errors repo "a deep" "disabling cone pattern matching" &&
+	check_files repo/deep "deeper1" &&
+	check_files repo/deep/deeper1 "deepest"
+'
+
 test_done