// SPDX-License-Identifier: GPL-2.0-or-later

#define _GNU_SOURCE
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <syscall.h>
#include <unistd.h>

#include "kselftest.h"

struct testdir {
        char *dirname;
        int dfd;
};

int sys_fchmodat2(int dfd, const char *filename, mode_t mode, int flags)
{
        int ret = syscall(__NR_fchmodat2, dfd, filename, mode, flags);

        return ret >= 0 ? ret : -errno;
}

static void setup_testdir(struct testdir *testdir)
{
        int ret, dfd;
        char dirname[] = "/tmp/ksft-fchmodat2.XXXXXX";

        /* Make the top-level directory. */
        if (!mkdtemp(dirname))
                ksft_exit_fail_msg("%s: failed to create tmpdir\n", __func__);

        dfd = open(dirname, O_PATH | O_DIRECTORY);
        if (dfd < 0) {
                ksft_perror("failed to open tmpdir");
                goto err;
        }

        ret = openat(dfd, "regfile", O_CREAT | O_WRONLY | O_TRUNC, 0644);
        if (ret < 0) {
                ksft_perror("failed to create file in tmpdir");
                goto err;
        }
        close(ret);

        ret = symlinkat("regfile", dfd, "symlink");
        if (ret < 0) {
                ksft_perror("symlinkat() failed");
                goto err_regfile;
        }

        testdir->dirname = strdup(dirname);
        if (!testdir->dirname) {
                ksft_perror("Out of memory");
                goto err_symlink;
        }
        testdir->dfd = dfd;

        return;

err_symlink:
        unlinkat(testdir->dfd, "symlink", 0);
err_regfile:
        unlinkat(testdir->dfd, "regfile", 0);
err:
        unlink(dirname);
        ksft_exit_fail();
}

static void cleanup_testdir(struct testdir *testdir)
{
        unlinkat(testdir->dfd, "regfile", 0);
        unlinkat(testdir->dfd, "symlink", 0);
        rmdir(testdir->dirname);
        free(testdir->dirname);
}

int expect_mode(int dfd, const char *filename, mode_t expect_mode)
{
        struct stat st;
        int ret = fstatat(dfd, filename, &st, AT_SYMLINK_NOFOLLOW);

        if (ret) {
                ksft_perror("fstatat() failed\n");
                return 0;
        }

        return (st.st_mode == expect_mode);
}

void test_regfile(void)
{
        struct testdir testdir;
        int ret;

        setup_testdir(&testdir);

        ret = sys_fchmodat2(testdir.dfd, "regfile", 0640, 0);

        if (ret < 0) {
                ksft_perror("fchmodat2(noflag) failed");
                goto out;
        }

        if (!expect_mode(testdir.dfd, "regfile", 0100640)) {
                ksft_print_msg("%s: wrong file mode bits after fchmodat2\n",
                                __func__);
                ret = 1;
                goto out;
        }

        ret = sys_fchmodat2(testdir.dfd, "regfile", 0600, AT_SYMLINK_NOFOLLOW);

        if (ret < 0) {
                ksft_perror("fchmodat2(AT_SYMLINK_NOFOLLOW) failed");
                goto out;
        }

        if (!expect_mode(testdir.dfd, "regfile", 0100600)) {
                ksft_print_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",
                               __func__);
                ret = 1;
        }

out:
        ksft_test_result(ret == 0, "fchmodat2(regfile)\n");
        cleanup_testdir(&testdir);
}

void test_symlink(void)
{
        struct testdir testdir;
        int ret;

        setup_testdir(&testdir);

        ret = sys_fchmodat2(testdir.dfd, "symlink", 0640, 0);

        if (ret < 0) {
                ksft_perror("fchmodat2(noflag) failed");
                goto err;
        }

        if (!expect_mode(testdir.dfd, "regfile", 0100640)) {
                ksft_print_msg("%s: wrong file mode bits after fchmodat2\n",
                               __func__);
                goto err;
        }

        if (!expect_mode(testdir.dfd, "symlink", 0120777)) {
                ksft_print_msg("%s: wrong symlink mode bits after fchmodat2\n",
                               __func__);
                goto err;
        }

        ret = sys_fchmodat2(testdir.dfd, "symlink", 0600, AT_SYMLINK_NOFOLLOW);

        /*
         * On certain filesystems (xfs or btrfs), chmod operation fails. So we
         * first check the symlink target but if the operation fails we mark the
         * test as skipped.
         *
         * https://sourceware.org/legacy-ml/libc-alpha/2020-02/msg00467.html
         */
        if (ret == 0 && !expect_mode(testdir.dfd, "symlink", 0120600)) {
                ksft_print_msg("%s: wrong symlink mode bits after fchmodat2 with nofollow\n",
                                __func__);
                ret = 1;
                goto err;
        }

        if (!expect_mode(testdir.dfd, "regfile", 0100640)) {
                ksft_print_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",
                               __func__);
        }

        if (ret != 0)
                ksft_test_result_skip("fchmodat2(symlink)\n");
        else
                ksft_test_result_pass("fchmodat2(symlink)\n");
        cleanup_testdir(&testdir);
        return;

err:
        ksft_test_result_fail("fchmodat2(symlink)\n");
        cleanup_testdir(&testdir);
}

#define NUM_TESTS 2

int main(int argc, char **argv)
{
        ksft_print_header();
        ksft_set_plan(NUM_TESTS);

        test_regfile();
        test_symlink();

        ksft_finished();
}