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