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