jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2021, the SerenityOS developers.
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <LibTest/TestCase.h>
8#include <cstring>
9#include <sys/stat.h>
10#include <unistd.h>
11
12TEST_CASE(test_process_fd_readlink)
13{
14 // Make sure that stdin, stdout and stderr are actually symlinks that point somewhere interesting
15 // Sadly we can't assume that they all point to the same file.
16 struct stat stat_buf = {};
17 struct stat lstat_buf = {};
18 auto rc = stat("/proc/self/fd/0", &stat_buf);
19 EXPECT_EQ(rc, 0);
20 rc = lstat("/proc/self/fd/0", &lstat_buf);
21 EXPECT_EQ(rc, 0);
22 EXPECT_NE(0, memcmp(&stat_buf, &lstat_buf, sizeof(struct stat)));
23
24 stat_buf = {};
25 lstat_buf = {};
26 rc = stat("/proc/self/fd/1", &stat_buf);
27 EXPECT_EQ(rc, 0);
28 rc = lstat("/proc/self/fd/1", &lstat_buf);
29 EXPECT_EQ(rc, 0);
30 EXPECT_NE(0, memcmp(&stat_buf, &lstat_buf, sizeof(struct stat)));
31
32 stat_buf = {};
33 lstat_buf = {};
34 rc = stat("/proc/self/fd/2", &stat_buf);
35 EXPECT_EQ(rc, 0);
36 rc = lstat("/proc/self/fd/2", &lstat_buf);
37 EXPECT_EQ(rc, 0);
38 EXPECT_NE(0, memcmp(&stat_buf, &lstat_buf, sizeof(struct stat)));
39
40 // Create a new file descriptor that is a dup of 0 with various big values in order to reproduce issue #7820.
41 // We should get the same link value for each fd that was duplicated.
42 char expected_link[MAXPATHLEN];
43 char buf[MAXPATHLEN];
44
45 // Read the symlink for stdin, stdout and stderr
46 auto link_length = readlink("/proc/self/fd/0", expected_link, sizeof(expected_link));
47 expected_link[link_length] = '\0';
48
49 // 255 is the first broken file descriptor that was discovered and might be used by other software (e.g. bash)
50 auto new_fd = dup2(0, 255);
51 EXPECT_EQ(new_fd, 255);
52 link_length = readlink("/proc/self/fd/255", buf, sizeof(buf));
53 buf[link_length] = '\0';
54 EXPECT_EQ(0, strcmp(buf, expected_link));
55
56 // 215 is the last fd before we have to encode the fd using more than one byte (due to the offset by FI_MaxStaticFileIndex)
57 new_fd = dup2(0, 215);
58 EXPECT_EQ(new_fd, 215);
59 link_length = readlink("/proc/self/fd/215", buf, sizeof(buf));
60 buf[link_length] = '\0';
61 EXPECT_EQ(0, strcmp(buf, expected_link));
62
63 // 216 is the first fd that is encoded using more than one byte
64 new_fd = dup2(0, 216);
65 EXPECT_EQ(new_fd, 216);
66 link_length = readlink("/proc/self/fd/216", buf, sizeof(buf));
67 buf[link_length] = '\0';
68 EXPECT_EQ(0, strcmp(buf, expected_link));
69
70 // 1023 is the largest possible file descriptor
71 new_fd = dup2(0, 1023);
72 EXPECT_EQ(new_fd, 1023);
73 link_length = readlink("/proc/self/fd/1023", buf, sizeof(buf));
74 buf[link_length] = '\0';
75 EXPECT_EQ(0, strcmp(buf, expected_link));
76}