Sławek Rudnicki | 89f2bae | 2017-08-07 12:41:33 +0200 | [diff] [blame] | 1 | /* |
| 2 | FUSE: Filesystem in Userspace |
| 3 | Copyright (C) 2016 Nikolaus Rath <Nikolaus@rath.org> |
| 4 | (C) 2017 EditShare LLC <slawek.rudnicki@editshare.com> |
| 5 | |
| 6 | This program can be distributed under the terms of the GNU GPL. |
| 7 | See the file COPYING. |
| 8 | */ |
| 9 | |
| 10 | /** @file |
| 11 | * |
| 12 | * This example implements a file system with two files: |
| 13 | * * 'current-time', whose contents change dynamically: |
| 14 | * it always contains the current time (same as in |
| 15 | * notify_inval_inode.c). |
| 16 | * * 'growing', whose size changes dynamically, growing |
| 17 | * by 1 byte after each update. This aims to check |
| 18 | * if cached file metadata is also invalidated. |
| 19 | * |
| 20 | * ## Compilation ## |
| 21 | * |
Nikolaus Rath | fc83143 | 2017-08-24 14:23:13 +0200 | [diff] [blame] | 22 | * gcc -Wall @file `pkg-config fuse3 --cflags --libs` -o invalidate_path |
Sławek Rudnicki | 89f2bae | 2017-08-07 12:41:33 +0200 | [diff] [blame] | 23 | * |
| 24 | * ## Source code ## |
Nikolaus Rath | fc83143 | 2017-08-24 14:23:13 +0200 | [diff] [blame] | 25 | * \include @file |
Sławek Rudnicki | 89f2bae | 2017-08-07 12:41:33 +0200 | [diff] [blame] | 26 | */ |
| 27 | |
| 28 | #define FUSE_USE_VERSION 31 |
| 29 | |
Sławek Rudnicki | 89f2bae | 2017-08-07 12:41:33 +0200 | [diff] [blame] | 30 | #include <fuse.h> |
| 31 | #include <fuse_lowlevel.h> /* for fuse_cmdline_opts */ |
| 32 | |
| 33 | #include <stdio.h> |
| 34 | #include <stdlib.h> |
| 35 | #include <string.h> |
| 36 | #include <errno.h> |
| 37 | #include <fcntl.h> |
| 38 | #include <assert.h> |
| 39 | #include <stddef.h> |
| 40 | #include <unistd.h> |
| 41 | #include <pthread.h> |
| 42 | |
| 43 | /* We can't actually tell the kernel that there is no |
| 44 | timeout, so we just send a big value */ |
| 45 | #define NO_TIMEOUT 500000 |
| 46 | |
| 47 | #define MAX_STR_LEN 128 |
| 48 | #define TIME_FILE_NAME "current_time" |
| 49 | #define TIME_FILE_INO 2 |
| 50 | #define GROW_FILE_NAME "growing" |
| 51 | #define GROW_FILE_INO 3 |
| 52 | |
| 53 | static char time_file_contents[MAX_STR_LEN]; |
| 54 | static size_t grow_file_size; |
| 55 | |
| 56 | /* Command line parsing */ |
| 57 | struct options { |
| 58 | int no_notify; |
| 59 | int update_interval; |
| 60 | }; |
| 61 | static struct options options = { |
| 62 | .no_notify = 0, |
| 63 | .update_interval = 1, |
| 64 | }; |
| 65 | |
| 66 | #define OPTION(t, p) { t, offsetof(struct options, p), 1 } |
| 67 | static const struct fuse_opt option_spec[] = { |
| 68 | OPTION("--no-notify", no_notify), |
| 69 | OPTION("--update-interval=%d", update_interval), |
| 70 | FUSE_OPT_END |
| 71 | }; |
| 72 | |
| 73 | static void *xmp_init(struct fuse_conn_info *conn, struct fuse_config *cfg) |
| 74 | { |
| 75 | (void) conn; |
| 76 | cfg->entry_timeout = NO_TIMEOUT; |
| 77 | cfg->attr_timeout = NO_TIMEOUT; |
| 78 | cfg->negative_timeout = 0; |
| 79 | |
| 80 | return NULL; |
| 81 | } |
| 82 | |
| 83 | static int xmp_getattr(const char *path, |
| 84 | struct stat *stbuf, struct fuse_file_info* fi) { |
| 85 | (void) fi; |
| 86 | if (strcmp(path, "/") == 0) { |
| 87 | stbuf->st_ino = 1; |
| 88 | stbuf->st_mode = S_IFDIR | 0755; |
| 89 | stbuf->st_nlink = 1; |
| 90 | } else if (strcmp(path, "/" TIME_FILE_NAME) == 0) { |
| 91 | stbuf->st_ino = TIME_FILE_INO; |
| 92 | stbuf->st_mode = S_IFREG | 0444; |
| 93 | stbuf->st_nlink = 1; |
| 94 | stbuf->st_size = strlen(time_file_contents); |
| 95 | } else if (strcmp(path, "/" GROW_FILE_NAME) == 0) { |
| 96 | stbuf->st_ino = GROW_FILE_INO; |
| 97 | stbuf->st_mode = S_IFREG | 0444; |
| 98 | stbuf->st_nlink = 1; |
| 99 | stbuf->st_size = grow_file_size; |
| 100 | } else { |
| 101 | return -ENOENT; |
| 102 | } |
| 103 | |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | static int xmp_readdir(const char *path, void *buf, fuse_fill_dir_t filler, |
| 108 | off_t offset, struct fuse_file_info *fi, |
| 109 | enum fuse_readdir_flags flags) { |
| 110 | (void) fi; |
| 111 | (void) offset; |
| 112 | (void) flags; |
| 113 | if (strcmp(path, "/") != 0) { |
| 114 | return -ENOTDIR; |
| 115 | } else { |
| 116 | (void) filler; |
| 117 | (void) buf; |
| 118 | struct stat file_stat; |
| 119 | xmp_getattr("/" TIME_FILE_NAME, &file_stat, NULL); |
| 120 | filler(buf, TIME_FILE_NAME, &file_stat, 0, 0); |
| 121 | xmp_getattr("/" GROW_FILE_NAME, &file_stat, NULL); |
| 122 | filler(buf, GROW_FILE_NAME, &file_stat, 0, 0); |
| 123 | return 0; |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | static int xmp_open(const char *path, struct fuse_file_info *fi) { |
| 128 | (void) path; |
| 129 | /* Make cache persistent even if file is closed, |
| 130 | this makes it easier to see the effects */ |
| 131 | fi->keep_cache = 1; |
| 132 | return 0; |
| 133 | } |
| 134 | |
| 135 | static int xmp_read(const char *path, char *buf, size_t size, off_t offset, |
| 136 | struct fuse_file_info *fi) { |
| 137 | (void) fi; |
| 138 | (void) offset; |
| 139 | if (strcmp(path, "/" TIME_FILE_NAME) == 0) { |
| 140 | int file_length = strlen(time_file_contents); |
| 141 | int to_copy = offset + size <= file_length |
| 142 | ? size |
| 143 | : file_length - offset; |
| 144 | memcpy(buf, time_file_contents, to_copy); |
| 145 | return to_copy; |
| 146 | } else { |
| 147 | assert(strcmp(path, "/" GROW_FILE_NAME) == 0); |
| 148 | int to_copy = offset + size <= grow_file_size |
| 149 | ? size |
| 150 | : grow_file_size - offset; |
| 151 | memset(buf, 'x', to_copy); |
| 152 | return to_copy; |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | static struct fuse_operations xmp_oper = { |
| 157 | .init = xmp_init, |
| 158 | .getattr = xmp_getattr, |
| 159 | .readdir = xmp_readdir, |
| 160 | .open = xmp_open, |
| 161 | .read = xmp_read, |
| 162 | }; |
| 163 | |
| 164 | static void update_fs(void) { |
| 165 | static int count = 0; |
| 166 | struct tm *now; |
| 167 | time_t t; |
| 168 | t = time(NULL); |
| 169 | now = localtime(&t); |
| 170 | assert(now != NULL); |
| 171 | |
| 172 | int time_file_size = strftime(time_file_contents, MAX_STR_LEN, |
| 173 | "The current time is %H:%M:%S\n", now); |
| 174 | assert(time_file_size != 0); |
| 175 | |
| 176 | grow_file_size = count++; |
| 177 | } |
| 178 | |
| 179 | static int invalidate(struct fuse *fuse, const char *path) { |
| 180 | int status = fuse_invalidate_path(fuse, path); |
| 181 | if (status == -ENOENT) { |
| 182 | return 0; |
| 183 | } else { |
| 184 | return status; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | static void* update_fs_loop(void *data) { |
| 189 | struct fuse *fuse = (struct fuse*) data; |
| 190 | |
| 191 | while (1) { |
| 192 | update_fs(); |
| 193 | if (!options.no_notify) { |
| 194 | assert(invalidate(fuse, "/" TIME_FILE_NAME) == 0); |
| 195 | assert(invalidate(fuse, "/" GROW_FILE_NAME) == 0); |
| 196 | } |
| 197 | sleep(options.update_interval); |
| 198 | } |
| 199 | return NULL; |
| 200 | } |
| 201 | |
| 202 | static void show_help(const char *progname) |
| 203 | { |
| 204 | printf("usage: %s [options] <mountpoint>\n\n", progname); |
| 205 | printf("File-system specific options:\n" |
| 206 | " --update-interval=<secs> Update-rate of file system contents\n" |
| 207 | " --no-notify Disable kernel notifications\n" |
| 208 | "\n"); |
| 209 | } |
| 210 | |
| 211 | int main(int argc, char *argv[]) { |
| 212 | struct fuse_args args = FUSE_ARGS_INIT(argc, argv); |
| 213 | struct fuse *fuse; |
| 214 | struct fuse_cmdline_opts opts; |
| 215 | int res; |
| 216 | |
| 217 | /* Initialize the files */ |
| 218 | update_fs(); |
| 219 | |
| 220 | if (fuse_opt_parse(&args, &options, option_spec, NULL) == -1) |
| 221 | return 1; |
| 222 | |
| 223 | if (fuse_parse_cmdline(&args, &opts) != 0) |
| 224 | return 1; |
| 225 | |
| 226 | if (opts.show_version) { |
| 227 | printf("FUSE library version %s\n", fuse_pkgversion()); |
| 228 | fuse_lowlevel_version(); |
| 229 | res = 0; |
| 230 | goto out1; |
| 231 | } else if (opts.show_help) { |
| 232 | show_help(argv[0]); |
| 233 | fuse_cmdline_help(); |
| 234 | fuse_lib_help(&args); |
| 235 | res = 0; |
| 236 | goto out1; |
| 237 | } else if (!opts.mountpoint) { |
| 238 | fprintf(stderr, "error: no mountpoint specified\n"); |
| 239 | res = 1; |
| 240 | goto out1; |
| 241 | } |
| 242 | |
| 243 | fuse = fuse_new(&args, &xmp_oper, sizeof(xmp_oper), NULL); |
| 244 | if (fuse == NULL) { |
| 245 | res = 1; |
| 246 | goto out1; |
| 247 | } |
| 248 | |
| 249 | if (fuse_mount(fuse,opts.mountpoint) != 0) { |
| 250 | res = 1; |
| 251 | goto out2; |
| 252 | } |
| 253 | |
| 254 | if (fuse_daemonize(opts.foreground) != 0) { |
| 255 | res = 1; |
| 256 | goto out3; |
| 257 | } |
| 258 | |
| 259 | pthread_t updater; /* Start thread to update file contents */ |
| 260 | int ret = pthread_create(&updater, NULL, update_fs_loop, (void *) fuse); |
| 261 | if (ret != 0) { |
| 262 | fprintf(stderr, "pthread_create failed with %s\n", strerror(ret)); |
| 263 | return 1; |
| 264 | }; |
| 265 | |
| 266 | struct fuse_session *se = fuse_get_session(fuse); |
| 267 | if (fuse_set_signal_handlers(se) != 0) { |
| 268 | res = 1; |
| 269 | goto out3; |
| 270 | } |
| 271 | |
| 272 | if (opts.singlethread) |
| 273 | res = fuse_loop(fuse); |
| 274 | else |
| 275 | res = fuse_loop_mt(fuse, opts.clone_fd); |
| 276 | if (res) |
| 277 | res = 1; |
| 278 | |
| 279 | fuse_remove_signal_handlers(se); |
| 280 | out3: |
| 281 | fuse_unmount(fuse); |
| 282 | out2: |
| 283 | fuse_destroy(fuse); |
| 284 | out1: |
| 285 | free(opts.mountpoint); |
| 286 | fuse_opt_free_args(&args); |
| 287 | return res; |
| 288 | } |