1/*
2 * Copyright �� 2018 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16// Test /proc/*/fd lookup.
17
18#undef NDEBUG
19#include <assert.h>
20#include <dirent.h>
21#include <errno.h>
22#include <limits.h>
23#include <sched.h>
24#include <stdio.h>
25#include <unistd.h>
26#include <sys/types.h>
27#include <sys/stat.h>
28#include <fcntl.h>
29
30#include "proc.h"
31
32/* lstat(2) has more "coverage" in case non-symlink pops up somehow. */
33static void test_lookup_pass(const char *pathname)
34{
35	struct stat st;
36	ssize_t rv;
37
38	memset(&st, 0, sizeof(struct stat));
39	rv = lstat(pathname, &st);
40	assert(rv == 0);
41	assert(S_ISLNK(st.st_mode));
42}
43
44static void test_lookup_fail(const char *pathname)
45{
46	struct stat st;
47	ssize_t rv;
48
49	rv = lstat(pathname, &st);
50	assert(rv == -1 && errno == ENOENT);
51}
52
53static void test_lookup(unsigned int fd)
54{
55	char buf[64];
56	unsigned int c;
57	unsigned int u;
58	int i;
59
60	snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
61	test_lookup_pass(buf);
62
63	/* leading junk */
64	for (c = 1; c <= 255; c++) {
65		if (c == '/')
66			continue;
67		snprintf(buf, sizeof(buf), "/proc/self/fd/%c%u", c, fd);
68		test_lookup_fail(buf);
69	}
70
71	/* trailing junk */
72	for (c = 1; c <= 255; c++) {
73		if (c == '/')
74			continue;
75		snprintf(buf, sizeof(buf), "/proc/self/fd/%u%c", fd, c);
76		test_lookup_fail(buf);
77	}
78
79	for (i = INT_MIN; i < INT_MIN + 1024; i++) {
80		snprintf(buf, sizeof(buf), "/proc/self/fd/%d", i);
81		test_lookup_fail(buf);
82	}
83	for (i = -1024; i < 0; i++) {
84		snprintf(buf, sizeof(buf), "/proc/self/fd/%d", i);
85		test_lookup_fail(buf);
86	}
87	for (u = INT_MAX - 1024; u <= (unsigned int)INT_MAX + 1024; u++) {
88		snprintf(buf, sizeof(buf), "/proc/self/fd/%u", u);
89		test_lookup_fail(buf);
90	}
91	for (u = UINT_MAX - 1024; u != 0; u++) {
92		snprintf(buf, sizeof(buf), "/proc/self/fd/%u", u);
93		test_lookup_fail(buf);
94	}
95
96
97}
98
99int main(void)
100{
101	struct dirent *de;
102	unsigned int fd, target_fd;
103
104	if (unshare(CLONE_FILES) == -1)
105		return 1;
106
107	/* Wipe fdtable. */
108	do {
109		DIR *d;
110
111		d = opendir("/proc/self/fd");
112		if (!d)
113			return 1;
114
115		de = xreaddir(d);
116		assert(de->d_type == DT_DIR);
117		assert(streq(de->d_name, "."));
118
119		de = xreaddir(d);
120		assert(de->d_type == DT_DIR);
121		assert(streq(de->d_name, ".."));
122next:
123		de = xreaddir(d);
124		if (de) {
125			unsigned long long fd_ull;
126			unsigned int fd;
127			char *end;
128
129			assert(de->d_type == DT_LNK);
130
131			fd_ull = xstrtoull(de->d_name, &end);
132			assert(*end == '\0');
133			assert(fd_ull == (unsigned int)fd_ull);
134
135			fd = fd_ull;
136			if (fd == dirfd(d))
137				goto next;
138			close(fd);
139		}
140
141		closedir(d);
142	} while (de);
143
144	/* Now fdtable is clean. */
145
146	fd = open("/", O_PATH|O_DIRECTORY);
147	assert(fd == 0);
148	test_lookup(fd);
149	close(fd);
150
151	/* Clean again! */
152
153	fd = open("/", O_PATH|O_DIRECTORY);
154	assert(fd == 0);
155	/* Default RLIMIT_NOFILE-1 */
156	target_fd = 1023;
157	while (target_fd > 0) {
158		if (dup2(fd, target_fd) == target_fd)
159			break;
160		target_fd /= 2;
161	}
162	assert(target_fd > 0);
163	close(fd);
164	test_lookup(target_fd);
165	close(target_fd);
166
167	return 0;
168}
169