tst_require_root()

tst_res(TPASS, "getenv(" ENV1 ") = ‘"ENV_VAL "‘");
tst_res(TFAIL, "getenv(" ENV1 ") = ‘%s‘, expected ‘"ENV_VAL "‘", ret);

SAFE_MKDIR(MNTPOINT, 0777);
SAFE_MKFS(tst_device->dev, tst_device->fs_type, NULL, NULL);
fd1 = SAFE_OPEN(cleanup, FILE1, O_CREAT | O_RDWR, 0666);
SAFE_CLOSE(fd1);

/*
 *   Copyright (c) International Business Machines  Corp., 2001
 *    07/2001 Ported by Wayne Boyer
 *    06/2017 Modified by Guangwen Feng <fenggw-fnst@cn.fujitsu.com>
 *
 *   This program is free software;  you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
这段是当你提交代码到开源社区时（ltp），必须声明，遵循GNU General Public License协议（不知道的可以搜一下）。主要规定代码是否可供别人使用，是否可允许修改，是否可商业使用等等。
 */

/*
 * DESCRIPTION
 *      Open a file with oflag = O_CREAT set, does it set the sticky bit off?
 *      Open a dir with O_DIRECTORY, does it set the S_IFDIR bit on?
 *
 * ALGORITHM
 *      1. open a new file with O_CREAT, fstat.st_mode should not have the
 *         01000 bit on. In Linux, the save text bit is *NOT* cleared.
 *      2. open a new dir with O_DIRECTORY, fstat.st_mode should have the
 *         040000 bit on.
 */
用例描述性文字，如果自己提交，记得写清楚哈

#define _GNU_SOURCE             /* for O_DIRECTORY */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include "tst_test.h"
包含有文件，其中"tst_test.h"是调用框架接口，必须包含

#define TEST_FILE       "testfile"
#define TEST_DIR        "testdir"

static int fd;

static struct tcase {
        char *filename;
        int flag;
        mode_t mode;
        unsigned short tst_bit;
        char *desc;
} tcases[] = {
        {TEST_FILE, O_RDWR | O_CREAT, 01444, S_ISVTX, "Sticky bit"},
        {TEST_DIR, O_DIRECTORY, 0, S_IFDIR, "Directory bit"}
};
变量和用例初始化，这里提一下，为了代码的可扩展性，系统调用参数尽量提取出来，使用结构体数组存储，方便新增或者删除用例。用例执行部分直接open(tcases[0]->filename,tcases[0]->flag…)。

static void verify_open(unsigned int n)
{
        struct tcase *tc = &tcases[n];
        struct stat buf;

        TEST(open(tc->filename, tc->flag, tc->mode));
        fd = TEST_RETURN;
        if (fd == -1) {
                tst_res(TFAIL, "Cannot open a file");
                return;
        }

        SAFE_FSTAT(fd, &buf);
        if (!(buf.st_mode & tc->tst_bit))
                tst_res(TFAIL, "%s is cleared unexpectedly", tc->desc);
        else
                tst_res(TPASS, "%s is set as expected", tc->desc);

        SAFE_CLOSE(fd);
        if (S_ISREG(buf.st_mode))
    SAFE_UNLINK(tc->filename);
}
verify_open（）用例主体

static void setup(void)
{
        SAFE_MKDIR(TEST_DIR, 0755);
}
setup初始化

static void cleanup(void)
{
        if (fd > 0)
                SAFE_CLOSE(fd);
}
cleanup清理环境

static struct tst_test test = {
        .tcnt = ARRAY_SIZE(tcases),
        .needs_tmpdir = 1,
        .setup = setup,
        .cleanup = cleanup,
        .test = verify_open,
};
架构声明，声明用例数组，函数等，框架会直接调用执行。