sparse-checkout: escape all glob characters on write

The sparse-checkout patterns allow special globs according to
fnmatch(3). When writing cone-mode patterns for paths containing
these characters, they must be escaped.

Use is_glob_special() to check which characters must be escaped
this way, and add a path to the tests that contains all glob
characters at once. Note that ']' is not special, since the
initial bracket '[' is escaped.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/sparse-checkout.c

@@ -149,7 +149,7 @@ static char *escaped_pattern(char *pattern)
 	struct strbuf final = STRBUF_INIT;
 
 	while (*p) {
-		if (*p == '*' || *p == '\\')
+		if (is_glob_special(*p))
 			strbuf_addch(&final, '\\');
 
 		strbuf_addch(&final, *p);

t/t1091-sparse-checkout-builtin.sh

@@ -381,20 +381,21 @@ test_expect_success 'pattern-checks: contained glob characters' '
 	done
 '
 
-test_expect_success BSLASHPSPEC 'pattern-checks: escaped "*"' '
+test_expect_success BSLASHPSPEC 'pattern-checks: escaped characters' '
 	git clone repo escaped &&
 	TREEOID=$(git -C escaped rev-parse HEAD:folder1) &&
 	NEWTREE=$(git -C escaped mktree <<-EOF
 	$(git -C escaped ls-tree HEAD)
 	040000 tree $TREEOID	zbad\\dir
 	040000 tree $TREEOID	zdoes*exist
+	040000 tree $TREEOID	zglob[!a]?
 	EOF
 	) &&
 	COMMIT=$(git -C escaped commit-tree $NEWTREE -p HEAD) &&
 	git -C escaped reset --hard $COMMIT &&
-	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist" &&
+	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist" zglob[!a]? &&
 	git -C escaped sparse-checkout init --cone &&
-	git -C escaped sparse-checkout set zbad\\dir/bogus "zdoes*not*exist" "zdoes*exist" &&
+	git -C escaped sparse-checkout set zbad\\dir/bogus "zdoes*not*exist" "zdoes*exist" "zglob[!a]?" &&
 	cat >expect <<-\EOF &&
 	/*
 	!/*/
@@ -403,9 +404,10 @@ test_expect_success BSLASHPSPEC 'pattern-checks: escaped "*"' '
 	/zbad\\dir/bogus/
 	/zdoes\*exist/
 	/zdoes\*not\*exist/
+	/zglob\[!a]\?/
 	EOF
 	test_cmp expect escaped/.git/info/sparse-checkout &&
-	check_read_tree_errors escaped "a zbad\\dir zdoes*exist" &&
+	check_read_tree_errors escaped "a zbad\\dir zdoes*exist zglob[!a]?" &&
 	git -C escaped ls-tree -d --name-only HEAD >list-expect &&
 	git -C escaped sparse-checkout set --stdin <list-expect &&
 	cat >expect <<-\EOF &&
@@ -416,9 +418,10 @@ test_expect_success BSLASHPSPEC 'pattern-checks: escaped "*"' '
 	/folder2/
 	/zbad\\dir/
 	/zdoes\*exist/
+	/zglob\[!a]\?/
 	EOF
 	test_cmp expect escaped/.git/info/sparse-checkout &&
-	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist" &&
+	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist" zglob[!a]? &&
 	git -C escaped sparse-checkout list >list-actual &&
 	test_cmp list-expect list-actual
 '