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90e33dfe DB |
1 | /* |
2 | * QEMU file monitor Linux inotify impl | |
3 | * | |
4 | * Copyright (c) 2018 Red Hat, Inc. | |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; either | |
61f3c91a | 9 | * version 2.1 of the License, or (at your option) any later version. |
90e33dfe DB |
10 | * |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, see <http://www.gnu.org/licenses/>. | |
18 | * | |
19 | */ | |
20 | ||
21 | #include "qemu/osdep.h" | |
22 | #include "qemu/filemonitor.h" | |
23 | #include "qemu/main-loop.h" | |
24 | #include "qemu/error-report.h" | |
25 | #include "qapi/error.h" | |
26 | #include "trace.h" | |
27 | ||
28 | #include <sys/inotify.h> | |
29 | ||
30 | struct QFileMonitor { | |
31 | int fd; | |
90e33dfe DB |
32 | QemuMutex lock; /* protects dirs & idmap */ |
33 | GHashTable *dirs; /* dirname => QFileMonitorDir */ | |
34 | GHashTable *idmap; /* inotify ID => dirname */ | |
35 | }; | |
36 | ||
37 | ||
38 | typedef struct { | |
b4682a63 | 39 | int64_t id; /* watch ID */ |
90e33dfe DB |
40 | char *filename; /* optional filter */ |
41 | QFileMonitorHandler cb; | |
42 | void *opaque; | |
43 | } QFileMonitorWatch; | |
44 | ||
45 | ||
46 | typedef struct { | |
47 | char *path; | |
b4682a63 DB |
48 | int inotify_id; /* inotify ID */ |
49 | int next_file_id; /* file ID counter */ | |
90e33dfe DB |
50 | GArray *watches; /* QFileMonitorWatch elements */ |
51 | } QFileMonitorDir; | |
52 | ||
53 | ||
54 | static void qemu_file_monitor_watch(void *arg) | |
55 | { | |
56 | QFileMonitor *mon = arg; | |
57 | char buf[4096] | |
58 | __attribute__ ((aligned(__alignof__(struct inotify_event)))); | |
59 | int used = 0; | |
60 | int len; | |
61 | ||
62 | qemu_mutex_lock(&mon->lock); | |
63 | ||
64 | if (mon->fd == -1) { | |
65 | qemu_mutex_unlock(&mon->lock); | |
66 | return; | |
67 | } | |
68 | ||
69 | len = read(mon->fd, buf, sizeof(buf)); | |
70 | ||
71 | if (len < 0) { | |
72 | if (errno != EAGAIN) { | |
73 | error_report("Failure monitoring inotify FD '%s'," | |
74 | "disabling events", strerror(errno)); | |
75 | goto cleanup; | |
76 | } | |
77 | ||
78 | /* no more events right now */ | |
79 | goto cleanup; | |
80 | } | |
81 | ||
82 | /* Loop over all events in the buffer */ | |
83 | while (used < len) { | |
2e12dd40 VSO |
84 | const char *name; |
85 | QFileMonitorDir *dir; | |
86 | uint32_t iev; | |
90e33dfe DB |
87 | int qev; |
88 | gsize i; | |
2e12dd40 VSO |
89 | struct inotify_event *ev = (struct inotify_event *)(buf + used); |
90 | ||
91 | /* | |
92 | * We trust the kenel to provide valid buffer with complete event | |
93 | * records. | |
94 | */ | |
95 | assert(len - used >= sizeof(struct inotify_event)); | |
96 | assert(len - used - sizeof(struct inotify_event) >= ev->len); | |
97 | ||
98 | name = ev->len ? ev->name : ""; | |
99 | dir = g_hash_table_lookup(mon->idmap, GINT_TO_POINTER(ev->wd)); | |
100 | iev = ev->mask & | |
101 | (IN_CREATE | IN_MODIFY | IN_DELETE | IN_IGNORED | | |
102 | IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB); | |
90e33dfe DB |
103 | |
104 | used += sizeof(struct inotify_event) + ev->len; | |
105 | ||
106 | if (!dir) { | |
107 | continue; | |
108 | } | |
109 | ||
110 | /* | |
111 | * During a rename operation, the old name gets | |
112 | * IN_MOVED_FROM and the new name gets IN_MOVED_TO. | |
113 | * To simplify life for callers, we turn these into | |
114 | * DELETED and CREATED events | |
115 | */ | |
116 | switch (iev) { | |
117 | case IN_CREATE: | |
118 | case IN_MOVED_TO: | |
119 | qev = QFILE_MONITOR_EVENT_CREATED; | |
120 | break; | |
121 | case IN_MODIFY: | |
122 | qev = QFILE_MONITOR_EVENT_MODIFIED; | |
123 | break; | |
124 | case IN_DELETE: | |
125 | case IN_MOVED_FROM: | |
126 | qev = QFILE_MONITOR_EVENT_DELETED; | |
127 | break; | |
128 | case IN_ATTRIB: | |
129 | qev = QFILE_MONITOR_EVENT_ATTRIBUTES; | |
130 | break; | |
131 | case IN_IGNORED: | |
132 | qev = QFILE_MONITOR_EVENT_IGNORED; | |
133 | break; | |
134 | default: | |
135 | g_assert_not_reached(); | |
136 | } | |
137 | ||
b4682a63 DB |
138 | trace_qemu_file_monitor_event(mon, dir->path, name, ev->mask, |
139 | dir->inotify_id); | |
90e33dfe DB |
140 | for (i = 0; i < dir->watches->len; i++) { |
141 | QFileMonitorWatch *watch = &g_array_index(dir->watches, | |
142 | QFileMonitorWatch, | |
143 | i); | |
144 | ||
145 | if (watch->filename == NULL || | |
146 | (name && g_str_equal(watch->filename, name))) { | |
147 | trace_qemu_file_monitor_dispatch(mon, dir->path, name, | |
148 | qev, watch->cb, | |
149 | watch->opaque, watch->id); | |
150 | watch->cb(watch->id, qev, name, watch->opaque); | |
151 | } | |
152 | } | |
153 | } | |
154 | ||
155 | cleanup: | |
156 | qemu_mutex_unlock(&mon->lock); | |
157 | } | |
158 | ||
159 | ||
160 | static void | |
161 | qemu_file_monitor_dir_free(void *data) | |
162 | { | |
163 | QFileMonitorDir *dir = data; | |
164 | gsize i; | |
165 | ||
166 | for (i = 0; i < dir->watches->len; i++) { | |
167 | QFileMonitorWatch *watch = &g_array_index(dir->watches, | |
168 | QFileMonitorWatch, i); | |
169 | g_free(watch->filename); | |
170 | } | |
171 | g_array_unref(dir->watches); | |
172 | g_free(dir->path); | |
173 | g_free(dir); | |
174 | } | |
175 | ||
176 | ||
177 | QFileMonitor * | |
178 | qemu_file_monitor_new(Error **errp) | |
179 | { | |
180 | int fd; | |
181 | QFileMonitor *mon; | |
182 | ||
183 | fd = inotify_init1(IN_NONBLOCK); | |
184 | if (fd < 0) { | |
185 | error_setg_errno(errp, errno, | |
186 | "Unable to initialize inotify"); | |
187 | return NULL; | |
188 | } | |
189 | ||
190 | mon = g_new0(QFileMonitor, 1); | |
191 | qemu_mutex_init(&mon->lock); | |
192 | mon->fd = fd; | |
193 | ||
194 | mon->dirs = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, | |
195 | qemu_file_monitor_dir_free); | |
196 | mon->idmap = g_hash_table_new(g_direct_hash, g_direct_equal); | |
197 | ||
198 | trace_qemu_file_monitor_new(mon, mon->fd); | |
199 | ||
200 | return mon; | |
201 | } | |
202 | ||
203 | static gboolean | |
204 | qemu_file_monitor_free_idle(void *opaque) | |
205 | { | |
206 | QFileMonitor *mon = opaque; | |
207 | ||
208 | if (!mon) { | |
209 | return G_SOURCE_REMOVE; | |
210 | } | |
211 | ||
212 | qemu_mutex_lock(&mon->lock); | |
213 | ||
214 | g_hash_table_unref(mon->idmap); | |
215 | g_hash_table_unref(mon->dirs); | |
216 | ||
217 | qemu_mutex_unlock(&mon->lock); | |
218 | ||
219 | qemu_mutex_destroy(&mon->lock); | |
220 | g_free(mon); | |
221 | ||
222 | return G_SOURCE_REMOVE; | |
223 | } | |
224 | ||
225 | void | |
226 | qemu_file_monitor_free(QFileMonitor *mon) | |
227 | { | |
228 | if (!mon) { | |
229 | return; | |
230 | } | |
231 | ||
232 | qemu_mutex_lock(&mon->lock); | |
233 | if (mon->fd != -1) { | |
234 | qemu_set_fd_handler(mon->fd, NULL, NULL, NULL); | |
235 | close(mon->fd); | |
236 | mon->fd = -1; | |
237 | } | |
238 | qemu_mutex_unlock(&mon->lock); | |
239 | ||
240 | /* | |
241 | * Can't free it yet, because another thread | |
242 | * may be running event loop, so the inotify | |
243 | * callback might be pending. Using an idle | |
244 | * source ensures we'll only free after the | |
245 | * pending callback is done | |
246 | */ | |
247 | g_idle_add((GSourceFunc)qemu_file_monitor_free_idle, mon); | |
248 | } | |
249 | ||
b4682a63 | 250 | int64_t |
90e33dfe DB |
251 | qemu_file_monitor_add_watch(QFileMonitor *mon, |
252 | const char *dirpath, | |
253 | const char *filename, | |
254 | QFileMonitorHandler cb, | |
255 | void *opaque, | |
256 | Error **errp) | |
257 | { | |
258 | QFileMonitorDir *dir; | |
259 | QFileMonitorWatch watch; | |
b4682a63 | 260 | int64_t ret = -1; |
90e33dfe DB |
261 | |
262 | qemu_mutex_lock(&mon->lock); | |
263 | dir = g_hash_table_lookup(mon->dirs, dirpath); | |
264 | if (!dir) { | |
265 | int rv = inotify_add_watch(mon->fd, dirpath, | |
266 | IN_CREATE | IN_DELETE | IN_MODIFY | | |
267 | IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB); | |
268 | ||
269 | if (rv < 0) { | |
270 | error_setg_errno(errp, errno, "Unable to watch '%s'", dirpath); | |
271 | goto cleanup; | |
272 | } | |
273 | ||
274 | trace_qemu_file_monitor_enable_watch(mon, dirpath, rv); | |
275 | ||
276 | dir = g_new0(QFileMonitorDir, 1); | |
277 | dir->path = g_strdup(dirpath); | |
b4682a63 | 278 | dir->inotify_id = rv; |
90e33dfe DB |
279 | dir->watches = g_array_new(FALSE, TRUE, sizeof(QFileMonitorWatch)); |
280 | ||
281 | g_hash_table_insert(mon->dirs, dir->path, dir); | |
282 | g_hash_table_insert(mon->idmap, GINT_TO_POINTER(rv), dir); | |
283 | ||
284 | if (g_hash_table_size(mon->dirs) == 1) { | |
285 | qemu_set_fd_handler(mon->fd, qemu_file_monitor_watch, NULL, mon); | |
286 | } | |
287 | } | |
288 | ||
b4682a63 | 289 | watch.id = (((int64_t)dir->inotify_id) << 32) | dir->next_file_id++; |
90e33dfe DB |
290 | watch.filename = g_strdup(filename); |
291 | watch.cb = cb; | |
292 | watch.opaque = opaque; | |
293 | ||
294 | g_array_append_val(dir->watches, watch); | |
295 | ||
296 | trace_qemu_file_monitor_add_watch(mon, dirpath, | |
297 | filename ? filename : "<none>", | |
298 | cb, opaque, watch.id); | |
299 | ||
300 | ret = watch.id; | |
301 | ||
302 | cleanup: | |
303 | qemu_mutex_unlock(&mon->lock); | |
304 | return ret; | |
305 | } | |
306 | ||
307 | ||
308 | void qemu_file_monitor_remove_watch(QFileMonitor *mon, | |
309 | const char *dirpath, | |
b4682a63 | 310 | int64_t id) |
90e33dfe DB |
311 | { |
312 | QFileMonitorDir *dir; | |
313 | gsize i; | |
314 | ||
315 | qemu_mutex_lock(&mon->lock); | |
316 | ||
317 | trace_qemu_file_monitor_remove_watch(mon, dirpath, id); | |
318 | ||
319 | dir = g_hash_table_lookup(mon->dirs, dirpath); | |
320 | if (!dir) { | |
321 | goto cleanup; | |
322 | } | |
323 | ||
324 | for (i = 0; i < dir->watches->len; i++) { | |
325 | QFileMonitorWatch *watch = &g_array_index(dir->watches, | |
326 | QFileMonitorWatch, i); | |
327 | if (watch->id == id) { | |
328 | g_free(watch->filename); | |
329 | g_array_remove_index(dir->watches, i); | |
330 | break; | |
331 | } | |
332 | } | |
333 | ||
334 | if (dir->watches->len == 0) { | |
b4682a63 DB |
335 | inotify_rm_watch(mon->fd, dir->inotify_id); |
336 | trace_qemu_file_monitor_disable_watch(mon, dir->path, dir->inotify_id); | |
90e33dfe | 337 | |
b4682a63 | 338 | g_hash_table_remove(mon->idmap, GINT_TO_POINTER(dir->inotify_id)); |
90e33dfe DB |
339 | g_hash_table_remove(mon->dirs, dir->path); |
340 | ||
341 | if (g_hash_table_size(mon->dirs) == 0) { | |
342 | qemu_set_fd_handler(mon->fd, NULL, NULL, NULL); | |
343 | } | |
344 | } | |
345 | ||
346 | cleanup: | |
347 | qemu_mutex_unlock(&mon->lock); | |
348 | } |