]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
87b2d440 DH |
2 | /* |
3 | * memfd test file-system | |
4 | * This file uses FUSE to create a dummy file-system with only one file /memfd. | |
5 | * This file is read-only and takes 1s per read. | |
6 | * | |
7 | * This file-system is used by the memfd test-cases to force the kernel to pin | |
8 | * pages during reads(). Due to the 1s delay of this file-system, this is a | |
9 | * nice way to test race-conditions against get_user_pages() in the kernel. | |
10 | * | |
11 | * We use direct_io==1 to force the kernel to use direct-IO for this | |
12 | * file-system. | |
13 | */ | |
14 | ||
15 | #define FUSE_USE_VERSION 26 | |
16 | ||
17 | #include <fuse.h> | |
18 | #include <stdio.h> | |
19 | #include <string.h> | |
20 | #include <errno.h> | |
21 | #include <fcntl.h> | |
22 | #include <unistd.h> | |
23 | ||
24 | static const char memfd_content[] = "memfd-example-content"; | |
25 | static const char memfd_path[] = "/memfd"; | |
26 | ||
27 | static int memfd_getattr(const char *path, struct stat *st) | |
28 | { | |
29 | memset(st, 0, sizeof(*st)); | |
30 | ||
31 | if (!strcmp(path, "/")) { | |
32 | st->st_mode = S_IFDIR | 0755; | |
33 | st->st_nlink = 2; | |
34 | } else if (!strcmp(path, memfd_path)) { | |
35 | st->st_mode = S_IFREG | 0444; | |
36 | st->st_nlink = 1; | |
37 | st->st_size = strlen(memfd_content); | |
38 | } else { | |
39 | return -ENOENT; | |
40 | } | |
41 | ||
42 | return 0; | |
43 | } | |
44 | ||
45 | static int memfd_readdir(const char *path, | |
46 | void *buf, | |
47 | fuse_fill_dir_t filler, | |
48 | off_t offset, | |
49 | struct fuse_file_info *fi) | |
50 | { | |
51 | if (strcmp(path, "/")) | |
52 | return -ENOENT; | |
53 | ||
54 | filler(buf, ".", NULL, 0); | |
55 | filler(buf, "..", NULL, 0); | |
56 | filler(buf, memfd_path + 1, NULL, 0); | |
57 | ||
58 | return 0; | |
59 | } | |
60 | ||
61 | static int memfd_open(const char *path, struct fuse_file_info *fi) | |
62 | { | |
63 | if (strcmp(path, memfd_path)) | |
64 | return -ENOENT; | |
65 | ||
66 | if ((fi->flags & 3) != O_RDONLY) | |
67 | return -EACCES; | |
68 | ||
69 | /* force direct-IO */ | |
70 | fi->direct_io = 1; | |
71 | ||
72 | return 0; | |
73 | } | |
74 | ||
75 | static int memfd_read(const char *path, | |
76 | char *buf, | |
77 | size_t size, | |
78 | off_t offset, | |
79 | struct fuse_file_info *fi) | |
80 | { | |
81 | size_t len; | |
82 | ||
83 | if (strcmp(path, memfd_path) != 0) | |
84 | return -ENOENT; | |
85 | ||
86 | sleep(1); | |
87 | ||
88 | len = strlen(memfd_content); | |
89 | if (offset < len) { | |
90 | if (offset + size > len) | |
91 | size = len - offset; | |
92 | ||
93 | memcpy(buf, memfd_content + offset, size); | |
94 | } else { | |
95 | size = 0; | |
96 | } | |
97 | ||
98 | return size; | |
99 | } | |
100 | ||
101 | static struct fuse_operations memfd_ops = { | |
102 | .getattr = memfd_getattr, | |
103 | .readdir = memfd_readdir, | |
104 | .open = memfd_open, | |
105 | .read = memfd_read, | |
106 | }; | |
107 | ||
108 | int main(int argc, char *argv[]) | |
109 | { | |
110 | return fuse_main(argc, argv, &memfd_ops, NULL); | |
111 | } |