libfuse: example/notify_inval_entry.c Source File

libfuse

notify_inval_entry.c
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1 /*
2 FUSE: Filesystem in Userspace
3 Copyright (C) 2016 Nikolaus Rath <Nikolaus@rath.org>
4
5 This program can be distributed under the terms of the GNU GPLv2.
6 See the file COPYING.
7 */
8
79 #define FUSE_USE_VERSION 34
80
81 #include <fuse_lowlevel.h>
82 #include <stdio.h>
83 #include <stdlib.h>
84 #include <string.h>
85 #include <errno.h>
86 #include <fcntl.h>
87 #include <assert.h>
88 #include <stddef.h>
89 #include <unistd.h>
90 #include <pthread.h>
91
92 #define MAX_STR_LEN 128
93 static char file_name[MAX_STR_LEN];
94 static fuse_ino_t file_ino = 2;
95 static int lookup_cnt = 0;
96
97 /* Command line parsing */
98 struct options {
99 int no_notify;
100 float timeout;
101 int update_interval;
102 int only_expire;
103 };
104 static struct options options = {
105 .timeout = 5,
106 .no_notify = 0,
107 .update_interval = 1,
108 .only_expire = 0,
109 };
110
111 #define OPTION(t, p) \
112 { t, offsetof(struct options, p), 1 }
113 static const struct fuse_opt option_spec[] = {
114 OPTION("--no-notify", no_notify),
115 OPTION("--update-interval=%d", update_interval),
116 OPTION("--timeout=%f", timeout),
117 OPTION("--only-expire", only_expire),
118 FUSE_OPT_END
119 };
120
121 static int tfs_stat(fuse_ino_t ino, struct stat *stbuf) {
122 stbuf->st_ino = ino;
123 if (ino == FUSE_ROOT_ID) {
124 stbuf->st_mode = S_IFDIR | 0755;
125 stbuf->st_nlink = 1;
126 }
127
128 else if (ino == file_ino) {
129 stbuf->st_mode = S_IFREG | 0000;
130 stbuf->st_nlink = 1;
131 stbuf->st_size = 0;
132 }
133
134 else
135 return -1;
136
137 return 0;
138 }
139
140 static void tfs_lookup(fuse_req_t req, fuse_ino_t parent,
141 const char *name) {
142 struct fuse_entry_param e;
143 memset(&e, 0, sizeof(e));
144
145 if (parent != FUSE_ROOT_ID)
146 goto err_out;
147 else if (strcmp(name, file_name) == 0) {
148 e.ino = file_ino;
149 lookup_cnt++;
150 } else
151 goto err_out;
152
153 e.attr_timeout = options.timeout;
154 e.entry_timeout = options.timeout;
155 if (tfs_stat(e.ino, &e.attr) != 0)
156 goto err_out;
157 fuse_reply_entry(req, &e);
158 return;
159
160 err_out:
161 fuse_reply_err(req, ENOENT);
162 }
163
164 static void tfs_forget (fuse_req_t req, fuse_ino_t ino,
165 uint64_t nlookup) {
166 (void) req;
167 if(ino == file_ino)
168 lookup_cnt -= nlookup;
169 else
170 assert(ino == FUSE_ROOT_ID);
171 fuse_reply_none(req);
172 }
173
174 static void tfs_getattr(fuse_req_t req, fuse_ino_t ino,
175 struct fuse_file_info *fi) {
176 struct stat stbuf;
177
178 (void) fi;
179
180 memset(&stbuf, 0, sizeof(stbuf));
181 if (tfs_stat(ino, &stbuf) != 0)
182 fuse_reply_err(req, ENOENT);
183 else
184 fuse_reply_attr(req, &stbuf, options.timeout);
185 }
186
187 struct dirbuf {
188 char *p;
189 size_t size;
190 };
191
192 static void dirbuf_add(fuse_req_t req, struct dirbuf *b, const char *name,
193 fuse_ino_t ino) {
194 struct stat stbuf;
195 size_t oldsize = b->size;
196 b->size += fuse_add_direntry(req, NULL, 0, name, NULL, 0);
197 b->p = (char *) realloc(b->p, b->size);
198 memset(&stbuf, 0, sizeof(stbuf));
199 stbuf.st_ino = ino;
200 fuse_add_direntry(req, b->p + oldsize, b->size - oldsize, name, &stbuf,
201 b->size);
202 }
203
204 #define min(x, y) ((x) < (y) ? (x) : (y))
205
206 static int reply_buf_limited(fuse_req_t req, const char *buf, size_t bufsize,
207 off_t off, size_t maxsize) {
208 if (off < bufsize)
209 return fuse_reply_buf(req, buf + off,
210 min(bufsize - off, maxsize));
211 else
212 return fuse_reply_buf(req, NULL, 0);
213 }
214
215 static void tfs_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
216 off_t off, struct fuse_file_info *fi) {
217 (void) fi;
218
219 if (ino != FUSE_ROOT_ID)
220 fuse_reply_err(req, ENOTDIR);
221 else {
222 struct dirbuf b;
223
224 memset(&b, 0, sizeof(b));
225 dirbuf_add(req, &b, file_name, file_ino);
226 reply_buf_limited(req, b.p, b.size, off, size);
227 free(b.p);
228 }
229 }
230
231 static const struct fuse_lowlevel_ops tfs_oper = {
232 .lookup = tfs_lookup,
233 .getattr = tfs_getattr,
234 .readdir = tfs_readdir,
235 .forget = tfs_forget,
236 };
237
238 static void update_fs(void) {
239 time_t t;
240 struct tm *now;
241 ssize_t ret;
242
243 t = time(NULL);
244 now = localtime(&t);
245 assert(now != NULL);
246
247 ret = strftime(file_name, MAX_STR_LEN,
248 "Time_is_%Hh_%Mm_%Ss", now);
249 assert(ret != 0);
250 }
251
252 static void* update_fs_loop(void *data) {
253 struct fuse_session *se = (struct fuse_session*) data;
254 char *old_name;
255
256 while(1) {
257 old_name = strdup(file_name);
258 update_fs();
259 if (!options.no_notify && lookup_cnt) {
260 if(options.only_expire) {
261 assert(fuse_lowlevel_notify_expire_entry
262 (se, FUSE_ROOT_ID, old_name, strlen(old_name), FUSE_LL_EXPIRE_ONLY) == 0);
263 } else {
264 assert(fuse_lowlevel_notify_inval_entry
265 (se, FUSE_ROOT_ID, old_name, strlen(old_name)) == 0);
266 }
267 }
268 free(old_name);
269 sleep(options.update_interval);
270 }
271 return NULL;
272 }
273
274 static void show_help(const char *progname)
275 {
276 printf("usage: %s [options] <mountpoint>\n\n", progname);
277 printf("File-system specific options:\n"
278 " --timeout=<secs> Timeout for kernel caches\n"
279 " --update-interval=<secs> Update-rate of file system contents\n"
280 " --no-notify Disable kernel notifications\n"
281 " --only-expire Expire entries instead of invalidating them\n"
282 "\n");
283 }
284
285 int main(int argc, char *argv[]) {
286 struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
287 struct fuse_session *se;
288 struct fuse_cmdline_opts opts;
289 struct fuse_loop_config config;
290 pthread_t updater;
291 int ret = -1;
292
293 if (fuse_opt_parse(&args, &options, option_spec, NULL) == -1)
294 return 1;
295
296 if (fuse_parse_cmdline(&args, &opts) != 0)
297 return 1;
298 if (opts.show_help) {
299 show_help(argv[0]);
300 fuse_cmdline_help();
301 fuse_lowlevel_help();
302 ret = 0;
303 goto err_out1;
304 } else if (opts.show_version) {
305 printf("FUSE library version %s\n", fuse_pkgversion());
306 fuse_lowlevel_version();
307 ret = 0;
308 goto err_out1;
309 }
310
311 /* Initial contents */
312 update_fs();
313
314 se = fuse_session_new(&args, &tfs_oper,
315 sizeof(tfs_oper), NULL);
316 if (se == NULL)
317 goto err_out1;
318
319 if (fuse_set_signal_handlers(se) != 0)
320 goto err_out2;
321
322 if (fuse_session_mount(se, opts.mountpoint) != 0)
323 goto err_out3;
324
325 fuse_daemonize(opts.foreground);
326
327 /* Start thread to update file contents */
328 ret = pthread_create(&updater, NULL, update_fs_loop, (void *)se);
329 if (ret != 0) {
330 fprintf(stderr, "pthread_create failed with %s\n",
331 strerror(ret));
332 goto err_out3;
333 }
334
335 /* Block until ctrl+c or fusermount -u */
336 if (opts.singlethread)
337 ret = fuse_session_loop(se);
338 else {
339 config.clone_fd = opts.clone_fd;
340 config.max_idle_threads = opts.max_idle_threads;
341 ret = fuse_session_loop_mt(se, &config);
342 }
343
344 fuse_session_unmount(se);
345 err_out3:
346 fuse_remove_signal_handlers(se);
347 err_out2:
348 fuse_session_destroy(se);
349 err_out1:
350 free(opts.mountpoint);
351 fuse_opt_free_args(&args);
352
353 return ret ? 1 : 0;
354 }
355
356
fuse_set_signal_handlers
int fuse_set_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:62
fuse_pkgversion
const char * fuse_pkgversion(void)
Definition: fuse.c:5113
fuse_remove_signal_handlers
void fuse_remove_signal_handlers(struct fuse_session *se)
Definition: fuse_signals.c:79
fuse_daemonize
int fuse_daemonize(int foreground)
Definition: helper.c:253
fuse_session_destroy
void fuse_session_destroy(struct fuse_session *se)
Definition: fuse_lowlevel.c:2763
FUSE_ROOT_ID
#define FUSE_ROOT_ID
Definition: fuse_lowlevel.h:43
fuse_reply_err
int fuse_reply_err(fuse_req_t req, int err)
Definition: fuse_lowlevel.c:319
fuse_reply_buf
int fuse_reply_buf(fuse_req_t req, const char *buf, size_t size)
Definition: fuse_lowlevel.c:483
fuse_req_t
struct fuse_req * fuse_req_t
Definition: fuse_lowlevel.h:49
fuse_session_loop
int fuse_session_loop(struct fuse_session *se)
Definition: fuse_loop.c:19
fuse_reply_entry
int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
Definition: fuse_lowlevel.c:412
fuse_session_unmount
void fuse_session_unmount(struct fuse_session *se)
Definition: fuse_lowlevel.c:3149
fuse_cmdline_help
void fuse_cmdline_help(void)
Definition: helper.c:130
fuse_reply_none
void fuse_reply_none(fuse_req_t req)
Definition: fuse_lowlevel.c:324
fuse_lowlevel_help
void fuse_lowlevel_help(void)
Definition: fuse_lowlevel.c:2753
fuse_session_new
struct fuse_session * fuse_session_new(struct fuse_args *args, const struct fuse_lowlevel_ops *op, size_t op_size, void *userdata)
Definition: fuse_lowlevel.c:2964
fuse_session_mount
int fuse_session_mount(struct fuse_session *se, const char *mountpoint)
Definition: fuse_lowlevel.c:3094
fuse_lowlevel_notify_expire_entry
int fuse_lowlevel_notify_expire_entry(struct fuse_session *se, fuse_ino_t parent, const char *name, size_t namelen, enum fuse_expire_flags flags)
Definition: fuse_lowlevel.c:2294
fuse_lowlevel_notify_inval_entry
int fuse_lowlevel_notify_inval_entry(struct fuse_session *se, fuse_ino_t parent, const char *name, size_t namelen)
Definition: fuse_lowlevel.c:2321
fuse_lowlevel_version
void fuse_lowlevel_version(void)
Definition: fuse_lowlevel.c:2746
fuse_ino_t
uint64_t fuse_ino_t
Definition: fuse_lowlevel.h:46
fuse_add_direntry
size_t fuse_add_direntry(fuse_req_t req, char *buf, size_t bufsize, const char *name, const struct stat *stbuf, off_t off)
Definition: fuse_lowlevel.c:274
fuse_reply_attr
int fuse_reply_attr(fuse_req_t req, const struct stat *attr, double attr_timeout)
Definition: fuse_lowlevel.c:444
fuse_opt_free_args
void fuse_opt_free_args(struct fuse_args *args)
Definition: fuse_opt.c:34
fuse_opt_parse
int fuse_opt_parse(struct fuse_args *args, void *data, const struct fuse_opt opts[], fuse_opt_proc_t proc)
Definition: fuse_opt.c:398
FUSE_ARGS_INIT
#define FUSE_ARGS_INIT(argc, argv)
Definition: fuse_opt.h:123
FUSE_OPT_END
#define FUSE_OPT_END
Definition: fuse_opt.h:104
fuse_args
Definition: fuse_opt.h:109
fuse_args::argc
int argc
Definition: fuse_opt.h:111
fuse_args::argv
char ** argv
Definition: fuse_opt.h:114
fuse_cmdline_opts
Definition: fuse_lowlevel.h:1935
fuse_entry_param
Definition: fuse_lowlevel.h:59
fuse_entry_param::ino
fuse_ino_t ino
Definition: fuse_lowlevel.h:67
fuse_file_info
Definition: fuse_common.h:50
fuse_loop_config
Definition: fuse_common.h:126
fuse_lowlevel_ops
Definition: fuse_lowlevel.h:200
fuse_lowlevel_ops::lookup
void(* lookup)(fuse_req_t req, fuse_ino_t parent, const char *name)
Definition: fuse_lowlevel.h:243
fuse_opt
Definition: fuse_opt.h:77