sparse-checkout: warn on incorrect '*' in 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 is invalid. Add checks to disable cone mode when seeing these
values.

A later change will properly handle escaped asterisks.

Signed-off-by: Derrick Stolee <[email protected]>

Author: derrickstolee

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;
@@ -652,13 +653,42 @@ 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. */
 		pl->use_cone_patterns = 0;
 		warning(_("unrecognized pattern: '%s'"), given->pattern);
 		goto clear_hashmaps;
 	}
 
+	prev = given->pattern;
+	cur = given->pattern + 1;
+	next = given->pattern + 2;
+
+	while (*cur) {
+		/* We care about *cur == '*' */
+		if (*cur != '*')
+			goto increment;
+
+		/* But only if *prev != '\\' */
+		if (*prev == '\\')
+			goto increment;
+
+		/* But a trailing '/' then '*' is fine */
+		if (*prev == '/' && *next == 0)
+			goto increment;
+
+		/* Not a cone pattern. */
+		pl->use_cone_patterns = 0;
+		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)) {

t/t1091-sparse-checkout-builtin.sh

@@ -348,4 +348,31 @@ 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: escaped "*"' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/does\*not\*exist/
+	EOF
+	check_read_tree_errors repo "a" ""
+'
+
 test_done