source3/smbd/notify_inotify.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2006
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21   notify implementation using inotify
  22 */
  23
  24 #include "includes.h"
  25 #include "../librpc/gen_ndr/notify.h"
  26 #include "smbd/smbd.h"
  27 #include "lib/sys_rw_data.h"
  28
  29 #ifdef HAVE_INOTIFY
  30
  31 #include <sys/inotify.h>
  32
  33 /* glibc < 2.5 headers don't have these defines */
  34 #ifndef IN_ONLYDIR
  35 #define IN_ONLYDIR 0x01000000
  36 #endif
  37 #ifndef IN_MASK_ADD
  38 #define IN_MASK_ADD 0x20000000
  39 #endif
  40
  41 struct inotify_private {
  42         struct sys_notify_context *ctx;
  43         int fd;
  44         struct inotify_watch_context *watches;
  45 };
  46
  47 struct inotify_watch_context {
  48         struct inotify_watch_context *next, *prev;
  49         struct inotify_private *in;
  50         int wd;
  51         void (*callback)(struct sys_notify_context *ctx,
  52                          void *private_data,
  53                          struct notify_event *ev);
  54         void *private_data;
  55         uint32_t mask; /* the inotify mask */
  56         uint32_t filter; /* the windows completion filter */
  57         const char *path;
  58 };
  59
  60
  61 /*
  62   destroy the inotify private context
  63 */
  64 static int inotify_destructor(struct inotify_private *in)
  65 {
  66         close(in->fd);
  67         return 0;
  68 }
  69
  70
  71 /*
  72   see if a particular event from inotify really does match a requested
  73   notify event in SMB
  74 */
  75 static bool filter_match(struct inotify_watch_context *w,
  76                          struct inotify_event *e)
  77 {
  78         DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
  79                    e->mask, w->mask, w->filter));
  80
  81         if ((e->mask & w->mask) == 0) {
  82                 /* this happens because inotify_add_watch() coalesces watches on the same
  83                    path, oring their masks together */
  84                 return False;
  85         }
  86
  87         /* SMB separates the filters for files and directories */
  88         if (e->mask & IN_ISDIR) {
  89                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
  90                         return False;
  91                 }
  92         } else {
  93                 if ((e->mask & IN_ATTRIB) &&
  94                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
  95                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
  96                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
  97                                   FILE_NOTIFY_CHANGE_EA|
  98                                   FILE_NOTIFY_CHANGE_SECURITY))) {
  99                         return True;
 100                 }
 101                 if ((e->mask & IN_MODIFY) &&
 102                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 103                         return True;
 104                 }
 105                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
 106                         return False;
 107                 }
 108         }
 109
 110         return True;
 111 }
 112
 113
 114
 115 /*
 116   dispatch one inotify event
 117
 118   the cookies are used to correctly handle renames
 119 */
 120 static void inotify_dispatch(struct inotify_private *in,
 121                              struct inotify_event *e,
 122                              int prev_wd,
 123                              uint32_t prev_cookie,
 124                              struct inotify_event *e2)
 125 {
 126         struct inotify_watch_context *w, *next;
 127         struct notify_event ne;
 128
 129         DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
 130                    e->mask, e->len ? e->name : ""));
 131
 132         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 133         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 134                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 135                 return;
 136         }
 137
 138         /* map the inotify mask to a action. This gets complicated for
 139            renames */
 140         if (e->mask & IN_CREATE) {
 141                 ne.action = NOTIFY_ACTION_ADDED;
 142         } else if (e->mask & IN_DELETE) {
 143                 ne.action = NOTIFY_ACTION_REMOVED;
 144         } else if (e->mask & IN_MOVED_FROM) {
 145                 if (e2 != NULL && e2->cookie == e->cookie &&
 146                     e2->wd == e->wd) {
 147                         ne.action = NOTIFY_ACTION_OLD_NAME;
 148                 } else {
 149                         ne.action = NOTIFY_ACTION_REMOVED;
 150                 }
 151         } else if (e->mask & IN_MOVED_TO) {
 152                 if ((e->cookie == prev_cookie) && (e->wd == prev_wd)) {
 153                         ne.action = NOTIFY_ACTION_NEW_NAME;
 154                 } else {
 155                         ne.action = NOTIFY_ACTION_ADDED;
 156                 }
 157         } else {
 158                 ne.action = NOTIFY_ACTION_MODIFIED;
 159         }
 160         ne.path = e->name;
 161
 162         DEBUG(10, ("inotify_dispatch: ne.action = %d, ne.path = %s\n",
 163                    ne.action, ne.path));
 164
 165         /* find any watches that have this watch descriptor */
 166         for (w=in->watches;w;w=next) {
 167                 next = w->next;
 168                 if (w->wd == e->wd && filter_match(w, e)) {
 169                         w->callback(in->ctx, w->private_data, &ne);
 170                 }
 171         }
 172
 173         /* SMB expects a file rename to generate three events, two for
 174            the rename and the other for a modify of the
 175            destination. Strange! */
 176         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 177             (e->mask & IN_ISDIR) != 0) {
 178                 return;
 179         }
 180
 181         ne.action = NOTIFY_ACTION_MODIFIED;
 182         e->mask = IN_ATTRIB;
 183
 184         for (w=in->watches;w;w=next) {
 185                 next = w->next;
 186                 if (w->wd == e->wd && filter_match(w, e) &&
 187                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 188                         w->callback(in->ctx, w->private_data, &ne);
 189                 }
 190         }
 191 }
 192
 193 /*
 194   called when the kernel has some events for us
 195 */
 196 static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,
 197                             uint16_t flags, void *private_data)
 198 {
 199         struct inotify_private *in = talloc_get_type(private_data,
 200                                                      struct inotify_private);
 201         int bufsize = 0;
 202         struct inotify_event *e0, *e;
 203         uint32_t prev_cookie=0;
 204         int prev_wd = -1;
 205         ssize_t ret;
 206
 207         /*
 208           we must use FIONREAD as we cannot predict the length of the
 209           filenames, and thus can't know how much to allocate
 210           otherwise
 211         */
 212         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 213             bufsize == 0) {
 214                 DEBUG(0,("No data on inotify fd?!\n"));
 215                 TALLOC_FREE(fde);
 216                 return;
 217         }
 218
 219         e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize + 1);
 220         if (e == NULL) return;
 221         ((uint8_t *)e)[bufsize] = '\0';
 222
 223         ret = read_data(in->fd, e0, bufsize);
 224         if (ret != bufsize) {
 225                 DEBUG(0, ("Failed to read all inotify data - %s\n",
 226                           strerror(errno)));
 227                 talloc_free(e0);
 228                 /* the inotify fd will now be out of sync,
 229                  * can't keep reading data off it */
 230                 TALLOC_FREE(fde);
 231                 return;
 232         }
 233
 234         /* we can get more than one event in the buffer */
 235         while (e && (bufsize >= sizeof(*e))) {
 236                 struct inotify_event *e2 = NULL;
 237                 bufsize -= e->len + sizeof(*e);
 238                 if (bufsize >= sizeof(*e)) {
 239                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 240                 }
 241                 inotify_dispatch(in, e, prev_wd, prev_cookie, e2);
 242                 prev_wd = e->wd;
 243                 prev_cookie = e->cookie;
 244                 e = e2;
 245         }
 246
 247         talloc_free(e0);
 248 }
 249
 250 /*
 251   setup the inotify handle - called the first time a watch is added on
 252   this context
 253 */
 254 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 255 {
 256         struct inotify_private *in;
 257
 258         if (!lp_parm_bool(-1, "notify", "inotify", True)) {
 259                 return NT_STATUS_INVALID_SYSTEM_SERVICE;
 260         }
 261
 262         in = talloc(ctx, struct inotify_private);
 263         NT_STATUS_HAVE_NO_MEMORY(in);
 264         in->fd = inotify_init();
 265         if (in->fd == -1) {
 266                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 267                 talloc_free(in);
 268                 return map_nt_error_from_unix(errno);
 269         }
 270         in->ctx = ctx;
 271         in->watches = NULL;
 272
 273         ctx->private_data = in;
 274         talloc_set_destructor(in, inotify_destructor);
 275
 276         /* add a event waiting for the inotify fd to be readable */
 277         tevent_add_fd(ctx->ev, in, in->fd, TEVENT_FD_READ, inotify_handler, in);
 278
 279         return NT_STATUS_OK;
 280 }
 281
 282
 283 /*
 284   map from a change notify mask to a inotify mask. Remove any bits
 285   which we can handle
 286 */
 287 static const struct {
 288         uint32_t notify_mask;
 289         uint32_t inotify_mask;
 290 } inotify_mapping[] = {
 291         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 292         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 293         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 294         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 295         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 296         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 297         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 298 };
 299
 300 static uint32_t inotify_map(uint32_t *filter)
 301 {
 302         int i;
 303         uint32_t out=0;
 304         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 305                 if (inotify_mapping[i].notify_mask & *filter) {
 306                         out |= inotify_mapping[i].inotify_mask;
 307                         *filter &= ~inotify_mapping[i].notify_mask;
 308                 }
 309         }
 310         return out;
 311 }
 312
 313 /*
 314   destroy a watch
 315 */
 316 static int watch_destructor(struct inotify_watch_context *w)
 317 {
 318         struct inotify_private *in = w->in;
 319         int wd = w->wd;
 320         DLIST_REMOVE(w->in->watches, w);
 321
 322         /* only rm the watch if its the last one with this wd */
 323         for (w=in->watches;w;w=w->next) {
 324                 if (w->wd == wd) break;
 325         }
 326         if (w == NULL) {
 327                 DEBUG(10, ("Deleting inotify watch %d\n", wd));
 328                 if (inotify_rm_watch(in->fd, wd) == -1) {
 329                         DEBUG(1, ("inotify_rm_watch returned %s\n",
 330                                   strerror(errno)));
 331                 }
 332
 333         }
 334         return 0;
 335 }
 336
 337
 338 /*
 339   add a watch. The watch is removed when the caller calls
 340   talloc_free() on *handle
 341 */
 342 NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 343                        const char *path,
 344                        uint32_t *filter,
 345                        uint32_t *subdir_filter,
 346                        void (*callback)(struct sys_notify_context *ctx,
 347                                         void *private_data,
 348                                         struct notify_event *ev),
 349                        void *private_data,
 350                        void *handle_p)
 351 {
 352         struct inotify_private *in;
 353         int wd;
 354         uint32_t mask;
 355         struct inotify_watch_context *w;
 356         uint32_t orig_filter = *filter;
 357         void **handle = (void **)handle_p;
 358
 359         /* maybe setup the inotify fd */
 360         if (ctx->private_data == NULL) {
 361                 NTSTATUS status;
 362                 status = inotify_setup(ctx);
 363                 NT_STATUS_NOT_OK_RETURN(status);
 364         }
 365
 366         in = talloc_get_type(ctx->private_data, struct inotify_private);
 367
 368         mask = inotify_map(filter);
 369         if (mask == 0) {
 370                 /* this filter can't be handled by inotify */
 371                 return NT_STATUS_INVALID_PARAMETER;
 372         }
 373
 374         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 375            watch descriptor for multiple watches on the same path */
 376         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 377
 378         /* get a new watch descriptor for this path */
 379         wd = inotify_add_watch(in->fd, path, mask);
 380         if (wd == -1) {
 381                 *filter = orig_filter;
 382                 DEBUG(1, ("inotify_add_watch returned %s\n", strerror(errno)));
 383                 return map_nt_error_from_unix(errno);
 384         }
 385
 386         DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
 387                    path, mask, wd));
 388
 389         w = talloc(in, struct inotify_watch_context);
 390         if (w == NULL) {
 391                 inotify_rm_watch(in->fd, wd);
 392                 *filter = orig_filter;
 393                 return NT_STATUS_NO_MEMORY;
 394         }
 395
 396         w->in = in;
 397         w->wd = wd;
 398         w->callback = callback;
 399         w->private_data = private_data;
 400         w->mask = mask;
 401         w->filter = orig_filter;
 402         w->path = talloc_strdup(w, path);
 403         if (w->path == NULL) {
 404                 inotify_rm_watch(in->fd, wd);
 405                 *filter = orig_filter;
 406                 TALLOC_FREE(w);
 407                 return NT_STATUS_NO_MEMORY;
 408         }
 409
 410         (*handle) = w;
 411
 412         DLIST_ADD(in->watches, w);
 413
 414         /* the caller frees the handle to stop watching */
 415         talloc_set_destructor(w, watch_destructor);
 416
 417         return NT_STATUS_OK;
 418 }
 419
 420 #endif