1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) International Business Machines  Corp., 2006
4 * Copyright (c) Cyril Hrubis 2014 <chrubis@suse.cz>
5 * Copyright (c) Linux Test Project, 2003-2023
6 * Author: Yi Yang <yyangcdl@cn.ibm.com>
7 */
8
9/*\
10 * [Description]
11 *
12 * Check the basic functionality of the readlinkat() system call.
13 *
14 * - readlinkat() passes if dirfd is directory file descriptor
15 *   and the pathname is relative.
16 * - readlinkat() passes if the pathname is abspath, then dirfd
17 *   is ignored.
18 * - readlinkat() passes if dirfd is the special value AT_FDCWD
19 *   and the pathname is relative.
20 * - readlinkat() passes if pathname is an empty string, in which
21 *   case the call operates on the symbolic link referred to by dirfd.
22 */
23
24#include <stdlib.h>
25#include <stdio.h>
26#include "tst_test.h"
27#include "lapi/fcntl.h"
28
29#define TEST_FILE       "readlink_file"
30#define TEST_SYMLINK    "readlink_symlink"
31
32static int file_fd, dir_fd, dir_fd2;
33static int fd_atcwd = AT_FDCWD;
34static const char *abspath;
35static const char *testsymlink;
36static const char *emptypath;
37
38static struct tcase {
39	int *fd;
40	const char **path;
41} tcases[] = {
42	{&dir_fd, &testsymlink},
43	{&dir_fd, &abspath},
44	{&file_fd, &abspath},
45	{&fd_atcwd, &abspath},
46	{&fd_atcwd, &testsymlink},
47	{&dir_fd2, &emptypath},
48};
49
50static void verify_readlinkat(unsigned int i)
51{
52	char buf[1024];
53	struct tcase *tc = &tcases[i];
54
55	memset(buf, 0, sizeof(buf));
56
57	TST_EXP_POSITIVE(readlinkat(*tc->fd, *tc->path, buf, sizeof(buf)),
58		     "readlinkat(%d, %s, %s, %ld)",
59		     *tc->fd, *tc->path, buf, sizeof(buf));
60
61	if (strcmp(buf, TEST_FILE) == 0)
62		tst_res(TPASS, "The filename in buffer is correct");
63	else
64		tst_res(TFAIL, "Wrong filename in buffer '%s'", buf);
65}
66
67static void setup(void)
68{
69	char *tmpdir = tst_get_tmpdir();
70
71	abspath = tst_aprintf("%s/" TEST_SYMLINK, tmpdir);
72	free(tmpdir);
73
74	file_fd = SAFE_OPEN(TEST_FILE, O_CREAT, 0600);
75	SAFE_SYMLINK(TEST_FILE, TEST_SYMLINK);
76	dir_fd = SAFE_OPEN(".", O_DIRECTORY);
77	dir_fd2 = SAFE_OPEN(TEST_SYMLINK, O_PATH | O_NOFOLLOW);
78}
79
80static void cleanup(void)
81{
82	if (file_fd > -1)
83		SAFE_CLOSE(file_fd);
84
85	if (dir_fd > -1)
86		SAFE_CLOSE(dir_fd);
87
88	if (dir_fd2 > -1)
89		SAFE_CLOSE(dir_fd2);
90}
91
92static struct tst_test test = {
93	.test = verify_readlinkat,
94	.needs_tmpdir = 1,
95	.setup = setup,
96	.cleanup = cleanup,
97	.bufs = (struct tst_buffers []) {
98		{&testsymlink, .str = TEST_SYMLINK},
99		{&emptypath, .str = ""},
100		{},
101	},
102	.tcnt = ARRAY_SIZE(tcases),
103};
104