From 9abc60f8015d060d3f3433b105648a4725c97bd1 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Fri, 31 Jan 2020 20:16:08 +0000
Subject: sparse-checkout: warn on globs in cone patterns

In cone mode, the sparse-checkout commmand will write patterns that
allow faster pattern matching. This matching only works if the patterns
in the sparse-checkout file are those written by that command. Users
can edit the sparse-checkout file and create patterns that cause the
cone mode matching to fail.

The cone mode patterns may end in "/*" but otherwise an un-escaped
asterisk or other glob character is invalid. Add checks to disable
cone mode when seeing these values.

A later change will properly handle escaped globs.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/dir.c b/dir.c
index c2e5856..71d2833 100644
--- a/dir.c
+++ b/dir.c
@@ -635,6 +635,7 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 	struct pattern_entry *translated;
 	char *truncated;
 	char *data = NULL;
+	const char *prev, *cur, *next;
 
 	if (!pl->use_cone_patterns)
 		return;
@@ -652,12 +653,47 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 	}
 
 	if (given->patternlen <= 2 ||
+	    *given->pattern == '*' ||
 	    strstr(given->pattern, "**")) {
 		/* Not a cone pattern. */
 		warning(_("unrecognized pattern: '%s'"), given->pattern);
 		goto clear_hashmaps;
 	}
 
+	prev = given->pattern;
+	cur = given->pattern + 1;
+	next = given->pattern + 2;
+
+	while (*cur) {
+		/* Watch for glob characters '*', '\', '[', '?' */
+		if (!is_glob_special(*cur))
+			goto increment;
+
+		/* But only if *prev != '\\' */
+		if (*prev == '\\')
+			goto increment;
+
+		/* But allow the initial '\' */
+		if (*cur == '\\' &&
+		    is_glob_special(*next))
+			goto increment;
+
+		/* But a trailing '/' then '*' is fine */
+		if (*prev == '/' &&
+		    *cur == '*' &&
+		    *next == 0)
+			goto increment;
+
+		/* Not a cone pattern. */
+		warning(_("unrecognized pattern: '%s'"), given->pattern);
+		goto clear_hashmaps;
+
+	increment:
+		prev++;
+		cur++;
+		next++;
+	}
+
 	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 2e57534..c732abe 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -348,4 +348,43 @@ test_expect_success 'pattern-checks: too short' '
 	check_read_tree_errors repo "a" "disabling cone pattern matching"
 '
 
+test_expect_success 'pattern-checks: trailing "*"' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/a*
+	EOF
+	check_read_tree_errors repo "a" "disabling cone pattern matching"
+'
+
+test_expect_success 'pattern-checks: starting "*"' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	*eep/
+	EOF
+	check_read_tree_errors repo "a deep" "disabling cone pattern matching"
+'
+
+test_expect_success 'pattern-checks: contained glob characters' '
+	for c in "[a]" "\\" "?" "*"
+	do
+		cat >repo/.git/info/sparse-checkout <<-EOF &&
+		/*
+		!/*/
+		something$c-else/
+		EOF
+		check_read_tree_errors repo "a" "disabling cone pattern matching"
+	done
+'
+
+test_expect_success 'pattern-checks: escaped "*"' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/does\*not\*exist/
+	EOF
+	check_read_tree_errors repo "a" ""
+'
+
 test_done
-- 
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