1 files changed, 68 insertions, 0 deletions
diff --git a/lib/libc/tests/gen/fts_blocks_test.c b/lib/libc/tests/gen/fts_blocks_test.c
new file mode 100644
index 000000000000..f020dd8dea45
--- /dev/null
+++ b/lib/libc/tests/gen/fts_blocks_test.c
@@ -0,0 +1,68 @@
+/*-
+ * Copyright (c) 2025 Klara, Inc.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/stat.h>
+
+#include <fcntl.h>
+#include <fts.h>
+
+#include <atf-c.h>
+
+/*
+ * Create two directories with three files each in lexicographical order,
+ * then call FTS with a sort block that sorts in reverse lexicographical
+ * order.  This has the least chance of getting a false positive due to
+ * differing file system semantics.  UFS will return the files in the
+ * order they were created while ZFS will sort them lexicographically; in
+ * both cases, the order we expect is the reverse.
+ */
+ATF_TC(fts_blocks_test);
+ATF_TC_HEAD(fts_blocks_test, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "Test FTS with a block in lieu of a comparison function");
+}
+ATF_TC_BODY(fts_blocks_test, tc)
+{
+	char *args[] = {
+		"bar", "foo", NULL
+	};
+	char *paths[] = {
+		"foo", "z", "y", "x", "foo",
+		"bar", "c", "b", "a", "bar",
+		NULL
+	};
+	char **expect = paths;
+	FTS *fts;
+	FTSENT *ftse;
+
+	ATF_REQUIRE_EQ(0, mkdir("bar", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("bar/a", 0644)));
+	ATF_REQUIRE_EQ(0, close(creat("bar/b", 0644)));
+	ATF_REQUIRE_EQ(0, close(creat("bar/c", 0644)));
+	ATF_REQUIRE_EQ(0, mkdir("foo", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("foo/x", 0644)));
+	ATF_REQUIRE_EQ(0, close(creat("foo/y", 0644)));
+	ATF_REQUIRE_EQ(0, close(creat("foo/z", 0644)));
+	fts = fts_open_b(args, 0,
+	    ^(const FTSENT * const *a, const FTSENT * const *b) {
+		    return (strcmp((*b)->fts_name, (*a)->fts_name));
+	    });
+	ATF_REQUIRE_MSG(fts != NULL, "fts_open_b(): %m");
+	while ((ftse = fts_read(fts)) != NULL && *expect != NULL) {
+		ATF_CHECK_STREQ(*expect, ftse->fts_name);
+		expect++;
+	}
+	ATF_CHECK_EQ(NULL, ftse);
+	ATF_CHECK_EQ(NULL, *expect);
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, fts_blocks_test);
+	return (atf_no_error());
+}