Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 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 |
Chetan Pant | 61f3c91 | 2020-10-23 12:44:24 +0000 | [diff] [blame] | 9 | * version 2.1 of the License, or (at your option) any later version. |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 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; |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 32 | QemuMutex lock; /* protects dirs & idmap */ |
| 33 | GHashTable *dirs; /* dirname => QFileMonitorDir */ |
| 34 | GHashTable *idmap; /* inotify ID => dirname */ |
| 35 | }; |
| 36 | |
| 37 | |
| 38 | typedef struct { |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 39 | int64_t id; /* watch ID */ |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 40 | char *filename; /* optional filter */ |
| 41 | QFileMonitorHandler cb; |
| 42 | void *opaque; |
| 43 | } QFileMonitorWatch; |
| 44 | |
| 45 | |
| 46 | typedef struct { |
| 47 | char *path; |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 48 | int inotify_id; /* inotify ID */ |
| 49 | int next_file_id; /* file ID counter */ |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 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) { |
| 84 | struct inotify_event *ev = |
| 85 | (struct inotify_event *)(buf + used); |
| 86 | const char *name = ev->len ? ev->name : ""; |
| 87 | QFileMonitorDir *dir = g_hash_table_lookup(mon->idmap, |
| 88 | GINT_TO_POINTER(ev->wd)); |
| 89 | uint32_t iev = ev->mask & |
| 90 | (IN_CREATE | IN_MODIFY | IN_DELETE | IN_IGNORED | |
| 91 | IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB); |
| 92 | int qev; |
| 93 | gsize i; |
| 94 | |
| 95 | used += sizeof(struct inotify_event) + ev->len; |
| 96 | |
| 97 | if (!dir) { |
| 98 | continue; |
| 99 | } |
| 100 | |
| 101 | /* |
| 102 | * During a rename operation, the old name gets |
| 103 | * IN_MOVED_FROM and the new name gets IN_MOVED_TO. |
| 104 | * To simplify life for callers, we turn these into |
| 105 | * DELETED and CREATED events |
| 106 | */ |
| 107 | switch (iev) { |
| 108 | case IN_CREATE: |
| 109 | case IN_MOVED_TO: |
| 110 | qev = QFILE_MONITOR_EVENT_CREATED; |
| 111 | break; |
| 112 | case IN_MODIFY: |
| 113 | qev = QFILE_MONITOR_EVENT_MODIFIED; |
| 114 | break; |
| 115 | case IN_DELETE: |
| 116 | case IN_MOVED_FROM: |
| 117 | qev = QFILE_MONITOR_EVENT_DELETED; |
| 118 | break; |
| 119 | case IN_ATTRIB: |
| 120 | qev = QFILE_MONITOR_EVENT_ATTRIBUTES; |
| 121 | break; |
| 122 | case IN_IGNORED: |
| 123 | qev = QFILE_MONITOR_EVENT_IGNORED; |
| 124 | break; |
| 125 | default: |
| 126 | g_assert_not_reached(); |
| 127 | } |
| 128 | |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 129 | trace_qemu_file_monitor_event(mon, dir->path, name, ev->mask, |
| 130 | dir->inotify_id); |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 131 | for (i = 0; i < dir->watches->len; i++) { |
| 132 | QFileMonitorWatch *watch = &g_array_index(dir->watches, |
| 133 | QFileMonitorWatch, |
| 134 | i); |
| 135 | |
| 136 | if (watch->filename == NULL || |
| 137 | (name && g_str_equal(watch->filename, name))) { |
| 138 | trace_qemu_file_monitor_dispatch(mon, dir->path, name, |
| 139 | qev, watch->cb, |
| 140 | watch->opaque, watch->id); |
| 141 | watch->cb(watch->id, qev, name, watch->opaque); |
| 142 | } |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | cleanup: |
| 147 | qemu_mutex_unlock(&mon->lock); |
| 148 | } |
| 149 | |
| 150 | |
| 151 | static void |
| 152 | qemu_file_monitor_dir_free(void *data) |
| 153 | { |
| 154 | QFileMonitorDir *dir = data; |
| 155 | gsize i; |
| 156 | |
| 157 | for (i = 0; i < dir->watches->len; i++) { |
| 158 | QFileMonitorWatch *watch = &g_array_index(dir->watches, |
| 159 | QFileMonitorWatch, i); |
| 160 | g_free(watch->filename); |
| 161 | } |
| 162 | g_array_unref(dir->watches); |
| 163 | g_free(dir->path); |
| 164 | g_free(dir); |
| 165 | } |
| 166 | |
| 167 | |
| 168 | QFileMonitor * |
| 169 | qemu_file_monitor_new(Error **errp) |
| 170 | { |
| 171 | int fd; |
| 172 | QFileMonitor *mon; |
| 173 | |
| 174 | fd = inotify_init1(IN_NONBLOCK); |
| 175 | if (fd < 0) { |
| 176 | error_setg_errno(errp, errno, |
| 177 | "Unable to initialize inotify"); |
| 178 | return NULL; |
| 179 | } |
| 180 | |
| 181 | mon = g_new0(QFileMonitor, 1); |
| 182 | qemu_mutex_init(&mon->lock); |
| 183 | mon->fd = fd; |
| 184 | |
| 185 | mon->dirs = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, |
| 186 | qemu_file_monitor_dir_free); |
| 187 | mon->idmap = g_hash_table_new(g_direct_hash, g_direct_equal); |
| 188 | |
| 189 | trace_qemu_file_monitor_new(mon, mon->fd); |
| 190 | |
| 191 | return mon; |
| 192 | } |
| 193 | |
| 194 | static gboolean |
| 195 | qemu_file_monitor_free_idle(void *opaque) |
| 196 | { |
| 197 | QFileMonitor *mon = opaque; |
| 198 | |
| 199 | if (!mon) { |
| 200 | return G_SOURCE_REMOVE; |
| 201 | } |
| 202 | |
| 203 | qemu_mutex_lock(&mon->lock); |
| 204 | |
| 205 | g_hash_table_unref(mon->idmap); |
| 206 | g_hash_table_unref(mon->dirs); |
| 207 | |
| 208 | qemu_mutex_unlock(&mon->lock); |
| 209 | |
| 210 | qemu_mutex_destroy(&mon->lock); |
| 211 | g_free(mon); |
| 212 | |
| 213 | return G_SOURCE_REMOVE; |
| 214 | } |
| 215 | |
| 216 | void |
| 217 | qemu_file_monitor_free(QFileMonitor *mon) |
| 218 | { |
| 219 | if (!mon) { |
| 220 | return; |
| 221 | } |
| 222 | |
| 223 | qemu_mutex_lock(&mon->lock); |
| 224 | if (mon->fd != -1) { |
| 225 | qemu_set_fd_handler(mon->fd, NULL, NULL, NULL); |
| 226 | close(mon->fd); |
| 227 | mon->fd = -1; |
| 228 | } |
| 229 | qemu_mutex_unlock(&mon->lock); |
| 230 | |
| 231 | /* |
| 232 | * Can't free it yet, because another thread |
| 233 | * may be running event loop, so the inotify |
| 234 | * callback might be pending. Using an idle |
| 235 | * source ensures we'll only free after the |
| 236 | * pending callback is done |
| 237 | */ |
| 238 | g_idle_add((GSourceFunc)qemu_file_monitor_free_idle, mon); |
| 239 | } |
| 240 | |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 241 | int64_t |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 242 | qemu_file_monitor_add_watch(QFileMonitor *mon, |
| 243 | const char *dirpath, |
| 244 | const char *filename, |
| 245 | QFileMonitorHandler cb, |
| 246 | void *opaque, |
| 247 | Error **errp) |
| 248 | { |
| 249 | QFileMonitorDir *dir; |
| 250 | QFileMonitorWatch watch; |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 251 | int64_t ret = -1; |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 252 | |
| 253 | qemu_mutex_lock(&mon->lock); |
| 254 | dir = g_hash_table_lookup(mon->dirs, dirpath); |
| 255 | if (!dir) { |
| 256 | int rv = inotify_add_watch(mon->fd, dirpath, |
| 257 | IN_CREATE | IN_DELETE | IN_MODIFY | |
| 258 | IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB); |
| 259 | |
| 260 | if (rv < 0) { |
| 261 | error_setg_errno(errp, errno, "Unable to watch '%s'", dirpath); |
| 262 | goto cleanup; |
| 263 | } |
| 264 | |
| 265 | trace_qemu_file_monitor_enable_watch(mon, dirpath, rv); |
| 266 | |
| 267 | dir = g_new0(QFileMonitorDir, 1); |
| 268 | dir->path = g_strdup(dirpath); |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 269 | dir->inotify_id = rv; |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 270 | dir->watches = g_array_new(FALSE, TRUE, sizeof(QFileMonitorWatch)); |
| 271 | |
| 272 | g_hash_table_insert(mon->dirs, dir->path, dir); |
| 273 | g_hash_table_insert(mon->idmap, GINT_TO_POINTER(rv), dir); |
| 274 | |
| 275 | if (g_hash_table_size(mon->dirs) == 1) { |
| 276 | qemu_set_fd_handler(mon->fd, qemu_file_monitor_watch, NULL, mon); |
| 277 | } |
| 278 | } |
| 279 | |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 280 | watch.id = (((int64_t)dir->inotify_id) << 32) | dir->next_file_id++; |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 281 | watch.filename = g_strdup(filename); |
| 282 | watch.cb = cb; |
| 283 | watch.opaque = opaque; |
| 284 | |
| 285 | g_array_append_val(dir->watches, watch); |
| 286 | |
| 287 | trace_qemu_file_monitor_add_watch(mon, dirpath, |
| 288 | filename ? filename : "<none>", |
| 289 | cb, opaque, watch.id); |
| 290 | |
| 291 | ret = watch.id; |
| 292 | |
| 293 | cleanup: |
| 294 | qemu_mutex_unlock(&mon->lock); |
| 295 | return ret; |
| 296 | } |
| 297 | |
| 298 | |
| 299 | void qemu_file_monitor_remove_watch(QFileMonitor *mon, |
| 300 | const char *dirpath, |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 301 | int64_t id) |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 302 | { |
| 303 | QFileMonitorDir *dir; |
| 304 | gsize i; |
| 305 | |
| 306 | qemu_mutex_lock(&mon->lock); |
| 307 | |
| 308 | trace_qemu_file_monitor_remove_watch(mon, dirpath, id); |
| 309 | |
| 310 | dir = g_hash_table_lookup(mon->dirs, dirpath); |
| 311 | if (!dir) { |
| 312 | goto cleanup; |
| 313 | } |
| 314 | |
| 315 | for (i = 0; i < dir->watches->len; i++) { |
| 316 | QFileMonitorWatch *watch = &g_array_index(dir->watches, |
| 317 | QFileMonitorWatch, i); |
| 318 | if (watch->id == id) { |
| 319 | g_free(watch->filename); |
| 320 | g_array_remove_index(dir->watches, i); |
| 321 | break; |
| 322 | } |
| 323 | } |
| 324 | |
| 325 | if (dir->watches->len == 0) { |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 326 | inotify_rm_watch(mon->fd, dir->inotify_id); |
| 327 | trace_qemu_file_monitor_disable_watch(mon, dir->path, dir->inotify_id); |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 328 | |
Daniel P. Berrangé | b4682a6 | 2019-03-19 15:47:47 +0000 | [diff] [blame] | 329 | g_hash_table_remove(mon->idmap, GINT_TO_POINTER(dir->inotify_id)); |
Daniel P. Berrangé | 90e33df | 2018-06-08 17:24:57 +0100 | [diff] [blame] | 330 | g_hash_table_remove(mon->dirs, dir->path); |
| 331 | |
| 332 | if (g_hash_table_size(mon->dirs) == 0) { |
| 333 | qemu_set_fd_handler(mon->fd, NULL, NULL, NULL); |
| 334 | } |
| 335 | } |
| 336 | |
| 337 | cleanup: |
| 338 | qemu_mutex_unlock(&mon->lock); |
| 339 | } |