lib/libc/tests/gen: add fts_set() tests

Add ATF test cases for fts_set():

fts_set:
- invalid instruction returns non-zero with EINVAL
- FTS_AGAIN revisits the current node
- FTS_AGAIN consecutive visits node three times
- FTS_FOLLOW on symlink to file yields FTS_F
- FTS_FOLLOW on symlink to directory causes descent
- FTS_FOLLOW on dead symlink yields FTS_SLNONE
- FTS_SKIP prevents descent into directory
- fts_set_clientptr/fts_get_clientptr round-trip
- fts_get_stream returns parent FTS* from FTSENT*

Sponsored by:	Google LLC (GSoC 2026)
Reviewed by:	asomers
MFC after:	2 weeks
Pull Request:	https://github.com/freebsd/freebsd-src/pull/2242

lib/libc/tests/gen/Makefile

@@ -14,6 +14,7 @@ ATF_TESTS_C+=		fts_children_test
 ATF_TESTS_C+=		fts_misc_test
 ATF_TESTS_C+=		fts_open_test
 ATF_TESTS_C+=		fts_options_test
+ATF_TESTS_C+=		fts_set_test
 ATF_TESTS_C+=		ftw_test
 ATF_TESTS_C+=		getentropy_test
 ATF_TESTS_C+=		getmntinfo_test

lib/libc/tests/gen/fts_set_test.c

@@ -0,0 +1,361 @@
+/*
+ * Copyright (c) 2026 Jitendra Bhati
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+/*
+ * Tests for fts_set(), fts_set_clientptr(), fts_get_clientptr(),
+ * and fts_get_stream().
+ */
+
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <fts.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <atf-c.h>
+
+#include "fts_test.h"
+
+/*
+ * fts_set with invalid options must return non-zero with EINVAL.
+ * Note: fts_set returns 1 (not -1) on error.
+ */
+ATF_TC(invalid_options);
+ATF_TC_HEAD(invalid_options, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "fts_set with invalid options returns non-zero with EINVAL");
+}
+ATF_TC_BODY(invalid_options, tc)
+{
+	char *paths[] = { ".", NULL };
+	FTS *fts;
+	FTSENT *ent;
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL, NULL)) != NULL);
+
+	ent = fts_read(fts);
+	ATF_REQUIRE(ent != NULL);
+	ATF_REQUIRE_ERRNO(EINVAL, fts_set(fts, ent, 99) != 0);
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_AGAIN causes the current node to be re-stat()ed and returned
+ * again on the next fts_read() call.
+ */
+ATF_TC(again);
+ATF_TC_HEAD(again, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_AGAIN causes the current node to be returned once more");
+}
+ATF_TC_BODY(again, tc)
+{
+	char *paths[] = { "dir", NULL };
+	FTS *fts;
+	FTSENT *ent;
+	int revisit_count;
+
+	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("dir/file", 0644)));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL,
+	    fts_lexical_compar)) != NULL);
+
+	revisit_count = 0;
+	while ((ent = fts_read(fts)) != NULL) {
+		if (ent->fts_info == FTS_F && revisit_count == 0) {
+			ATF_REQUIRE_EQ_MSG(0,
+			    fts_set(fts, ent, FTS_AGAIN),
+			    "fts_set(FTS_AGAIN): %m");
+			revisit_count++;
+		} else if (ent->fts_info == FTS_F && revisit_count >= 1) {
+			revisit_count++;
+		}
+	}
+	ATF_CHECK_EQ_MSG(0, errno, "traversal ended with errno %d", errno);
+	ATF_CHECK_EQ_MSG(2, revisit_count,
+	    "expected file visited twice via FTS_AGAIN, saw %d",
+	    revisit_count);
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_AGAIN set twice in a row causes the node to be visited three
+ * times total.  Each fts_read() clears fts_options, so the caller must
+ * set FTS_AGAIN again explicitly each time.
+ */
+ATF_TC(again_consecutive);
+ATF_TC_HEAD(again_consecutive, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_AGAIN set twice in a row visits the node three times");
+}
+ATF_TC_BODY(again_consecutive, tc)
+{
+	char *paths[] = { "file", NULL };
+	FTS *fts;
+	FTSENT *ent;
+	int visit_count;
+
+	ATF_REQUIRE_EQ(0, close(creat("file", 0644)));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL, NULL)) != NULL);
+
+	visit_count = 0;
+	while ((ent = fts_read(fts)) != NULL) {
+		if (ent->fts_info == FTS_F) {
+			visit_count++;
+			if (visit_count < 3)
+				ATF_REQUIRE_EQ(0,
+				    fts_set(fts, ent, FTS_AGAIN));
+		}
+	}
+	ATF_CHECK_EQ_MSG(3, visit_count,
+	    "expected 3 visits with consecutive FTS_AGAIN, got %d",
+	    visit_count);
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_FOLLOW on an FTS_SL entry pointing to a regular file yields FTS_F.
+ */
+ATF_TC(follow_symlink_to_file);
+ATF_TC_HEAD(follow_symlink_to_file, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_FOLLOW on FTS_SL to regular file yields FTS_F");
+}
+ATF_TC_BODY(follow_symlink_to_file, tc)
+{
+	char *paths[] = { "dir", NULL };
+	FTS *fts;
+	FTSENT *ent;
+	int followed;
+
+	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("dir/target", 0644)));
+	ATF_REQUIRE_EQ(0, symlink("target", "dir/link"));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL,
+	    fts_lexical_compar)) != NULL);
+
+	followed = 0;
+	while ((ent = fts_read(fts)) != NULL) {
+		if (ent->fts_info == FTS_SL &&
+		    strcmp(ent->fts_name, "link") == 0)
+			ATF_REQUIRE_EQ(0, fts_set(fts, ent, FTS_FOLLOW));
+		else if (ent->fts_info == FTS_F &&
+		    strcmp(ent->fts_name, "link") == 0)
+			followed = 1;
+	}
+	ATF_CHECK_MSG(followed != 0,
+	    "FTS_FOLLOW on symlink-to-file must yield FTS_F");
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_FOLLOW on an FTS_SL entry pointing to a directory causes descent
+ * into the target directory.
+ */
+ATF_TC(follow_symlink_to_dir);
+ATF_TC_HEAD(follow_symlink_to_dir, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_FOLLOW on FTS_SL to directory causes descent");
+}
+ATF_TC_BODY(follow_symlink_to_dir, tc)
+{
+	char *paths[] = { "dir", NULL };
+	FTS *fts;
+	FTSENT *ent;
+	int saw_inside;
+
+	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
+	ATF_REQUIRE_EQ(0, mkdir("dir/real", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("dir/real/inside", 0644)));
+	ATF_REQUIRE_EQ(0, symlink("real", "dir/link"));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL,
+	    fts_lexical_compar)) != NULL);
+
+	saw_inside = 0;
+	while ((ent = fts_read(fts)) != NULL) {
+		if (ent->fts_info == FTS_SL &&
+		    strcmp(ent->fts_name, "link") == 0)
+			ATF_REQUIRE_EQ(0, fts_set(fts, ent, FTS_FOLLOW));
+		if (ent->fts_info == FTS_F &&
+		    strcmp(ent->fts_name, "inside") == 0 &&
+		    strcmp(ent->fts_path, "dir/link/inside") == 0)
+		    saw_inside = 1;
+	}
+	ATF_CHECK_MSG(saw_inside != 0,
+	    "FTS_FOLLOW on symlink-to-dir should descend and visit 'inside'");
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_FOLLOW on a dangling symlink (FTS_SLNONE) yields FTS_SLNONE again.
+ * FTS_SLNONE requires FTS_LOGICAL — under FTS_PHYSICAL a dangling
+ * symlink is reported as FTS_SL.
+ */
+ATF_TC(follow_dead_symlink);
+ATF_TC_HEAD(follow_dead_symlink, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_FOLLOW on dead symlink yields FTS_SLNONE");
+}
+ATF_TC_BODY(follow_dead_symlink, tc)
+{
+	char *paths[] = { "dead", NULL };
+	FTS *fts;
+	FTSENT *ent;
+
+	ATF_REQUIRE_EQ(0, symlink("no-such-target", "dead"));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_LOGICAL, NULL)) != NULL);
+
+	ent = fts_read(fts);
+	ATF_REQUIRE(ent != NULL);
+	ATF_REQUIRE_EQ_MSG(FTS_SLNONE, ent->fts_info,
+	    "expected FTS_SLNONE for dead symlink, got %d", ent->fts_info);
+
+	ATF_REQUIRE_EQ(0, fts_set(fts, ent, FTS_FOLLOW));
+	ent = fts_read(fts);
+	ATF_REQUIRE(ent != NULL);
+	ATF_CHECK_EQ_MSG(FTS_SLNONE, ent->fts_info,
+	    "FTS_FOLLOW on dead symlink should still be FTS_SLNONE, got %d",
+	    ent->fts_info);
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * FTS_SKIP on an FTS_D node prevents descent into that directory.
+ * The next fts_read() converts the node to FTS_DP without visiting
+ * any children.
+ */
+ATF_TC(skip);
+ATF_TC_HEAD(skip, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "FTS_SKIP prevents descent into a directory");
+}
+ATF_TC_BODY(skip, tc)
+{
+	char *paths[] = { "dir", NULL };
+	FTS *fts;
+	FTSENT *ent;
+	int saw_inside;
+
+	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
+	ATF_REQUIRE_EQ(0, mkdir("dir/skip_me", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("dir/skip_me/inside", 0644)));
+	ATF_REQUIRE_EQ(0, close(creat("dir/sibling", 0644)));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL,
+	    fts_lexical_compar)) != NULL);
+
+	saw_inside = 0;
+	while ((ent = fts_read(fts)) != NULL) {
+		if (ent->fts_info == FTS_D &&
+		    strcmp(ent->fts_name, "skip_me") == 0)
+			ATF_REQUIRE_EQ(0, fts_set(fts, ent, FTS_SKIP));
+		if (strcmp(ent->fts_name, "inside") == 0)
+			saw_inside = 1;
+	}
+	ATF_CHECK_MSG(saw_inside == 0,
+	    "FTS_SKIP: 'inside' must not have been visited");
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * fts_set_clientptr() and fts_get_clientptr() store and retrieve an
+ * arbitrary pointer on the FTS stream.
+ */
+ATF_TC(clientptr_roundtrip);
+ATF_TC_HEAD(clientptr_roundtrip, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "fts_set_clientptr / fts_get_clientptr round-trip");
+}
+ATF_TC_BODY(clientptr_roundtrip, tc)
+{
+	char *paths[] = { ".", NULL };
+	FTS *fts;
+	int value = 42;
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL, NULL)) != NULL);
+
+	ATF_CHECK_EQ(NULL, fts_get_clientptr(fts));
+
+	fts_set_clientptr(fts, &value);
+	ATF_CHECK_EQ_MSG(&value, fts_get_clientptr(fts),
+	    "fts_get_clientptr did not return the stored pointer");
+
+	fts_set_clientptr(fts, NULL);
+	ATF_CHECK_EQ(NULL, fts_get_clientptr(fts));
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+/*
+ * fts_get_stream() returns the parent FTS* from any FTSENT* returned
+ * by fts_read().
+ */
+ATF_TC(get_stream_backpointer);
+ATF_TC_HEAD(get_stream_backpointer, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "fts_get_stream returns the parent FTS* from an FTSENT*");
+}
+ATF_TC_BODY(get_stream_backpointer, tc)
+{
+	char *paths[] = { "dir", NULL };
+	FTS *fts;
+	FTSENT *ent;
+
+	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
+	ATF_REQUIRE_EQ(0, close(creat("dir/file", 0644)));
+
+	ATF_REQUIRE((fts = fts_open(paths, FTS_PHYSICAL, NULL)) != NULL);
+
+	while ((ent = fts_read(fts)) != NULL) {
+		ATF_CHECK_EQ_MSG(fts, fts_get_stream(ent),
+		    "fts_get_stream(ent) must return the parent FTS*, "
+		    "entry: %s info: %d",
+		    ent->fts_name, ent->fts_info);
+	}
+
+	ATF_REQUIRE_EQ_MSG(0, fts_close(fts), "fts_close(): %m");
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	fts_check_debug();
+	ATF_TP_ADD_TC(tp, invalid_options);
+	ATF_TP_ADD_TC(tp, again);
+	ATF_TP_ADD_TC(tp, again_consecutive);
+	ATF_TP_ADD_TC(tp, follow_symlink_to_file);
+	ATF_TP_ADD_TC(tp, follow_symlink_to_dir);
+	ATF_TP_ADD_TC(tp, follow_dead_symlink);
+	ATF_TP_ADD_TC(tp, skip);
+	ATF_TP_ADD_TC(tp, clientptr_roundtrip);
+	ATF_TP_ADD_TC(tp, get_stream_backpointer);
+
+	return (atf_no_error());
+}