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         bool ok;
  79
  80         DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
  81                    e->mask, w->mask, w->filter));
  82
  83         if ((e->mask & w->mask) == 0) {
  84                 /* this happens because inotify_add_watch() coalesces watches on the same
  85                    path, oring their masks together */
  86                 return False;
  87         }
  88
  89         /* SMB separates the filters for files and directories */
  90         if (e->mask & IN_ISDIR) {
  91                 ok = ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) != 0);
  92                 return ok;
  93         }
  94
  95         if ((e->mask & IN_ATTRIB) &&
  96             (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
  97                           FILE_NOTIFY_CHANGE_LAST_WRITE|
  98                           FILE_NOTIFY_CHANGE_LAST_ACCESS|
  99                           FILE_NOTIFY_CHANGE_EA|
 100                           FILE_NOTIFY_CHANGE_SECURITY))) {
 101                 return True;
 102         }
 103         if ((e->mask & IN_MODIFY) &&
 104             (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 105                 return True;
 106         }
 107
 108         ok = ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) != 0);
 109         return ok;
 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                              int prev_wd,
 122                              uint32_t prev_cookie,
 123                              struct inotify_event *e2)
 124 {
 125         struct inotify_watch_context *w, *next;
 126         struct notify_event ne;
 127
 128         DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
 129                    e->mask, e->len ? e->name : ""));
 130
 131         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 132         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 133                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 134                 return;
 135         }
 136
 137         /* map the inotify mask to a action. This gets complicated for
 138            renames */
 139         if (e->mask & IN_CREATE) {
 140                 ne.action = NOTIFY_ACTION_ADDED;
 141         } else if (e->mask & IN_DELETE) {
 142                 ne.action = NOTIFY_ACTION_REMOVED;
 143         } else if (e->mask & IN_MOVED_FROM) {
 144                 if (e2 != NULL && e2->cookie == e->cookie &&
 145                     e2->wd == e->wd) {
 146                         ne.action = NOTIFY_ACTION_OLD_NAME;
 147                 } else {
 148                         ne.action = NOTIFY_ACTION_REMOVED;
 149                 }
 150         } else if (e->mask & IN_MOVED_TO) {
 151                 if ((e->cookie == prev_cookie) && (e->wd == prev_wd)) {
 152                         ne.action = NOTIFY_ACTION_NEW_NAME;
 153                 } else {
 154                         ne.action = NOTIFY_ACTION_ADDED;
 155                 }
 156         } else {
 157                 ne.action = NOTIFY_ACTION_MODIFIED;
 158         }
 159         ne.path = e->name;
 160
 161         DEBUG(10, ("inotify_dispatch: ne.action = %d, ne.path = %s\n",
 162                    ne.action, ne.path));
 163
 164         /* find any watches that have this watch descriptor */
 165         for (w=in->watches;w;w=next) {
 166                 next = w->next;
 167                 if (w->wd == e->wd && filter_match(w, e)) {
 168                         w->callback(in->ctx, w->private_data, &ne);
 169                 }
 170         }
 171
 172         /* SMB expects a file rename to generate three events, two for
 173            the rename and the other for a modify of the
 174            destination. Strange! */
 175         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 176             (e->mask & IN_ISDIR) != 0) {
 177                 return;
 178         }
 179
 180         ne.action = NOTIFY_ACTION_MODIFIED;
 181         e->mask = IN_ATTRIB;
 182
 183         for (w=in->watches;w;w=next) {
 184                 next = w->next;
 185                 if (w->wd == e->wd && filter_match(w, e) &&
 186                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 187                         w->callback(in->ctx, w->private_data, &ne);
 188                 }
 189         }
 190 }
 191
 192 /*
 193   called when the kernel has some events for us
 194 */
 195 static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,
 196                             uint16_t flags, void *private_data)
 197 {
 198         struct inotify_private *in = talloc_get_type(private_data,
 199                                                      struct inotify_private);
 200         int bufsize = 0;
 201         struct inotify_event *e0, *e;
 202         uint32_t prev_cookie=0;
 203         int prev_wd = -1;
 204         ssize_t ret;
 205
 206         /*
 207           we must use FIONREAD as we cannot predict the length of the
 208           filenames, and thus can't know how much to allocate
 209           otherwise
 210         */
 211         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 212             bufsize == 0) {
 213                 DEBUG(0,("No data on inotify fd?!\n"));
 214                 TALLOC_FREE(fde);
 215                 return;
 216         }
 217
 218         e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize + 1);
 219         if (e == NULL) return;
 220         ((uint8_t *)e)[bufsize] = '\0';
 221
 222         ret = read_data(in->fd, e0, bufsize);
 223         if (ret != bufsize) {
 224                 DEBUG(0, ("Failed to read all inotify data - %s\n",
 225                           strerror(errno)));
 226                 talloc_free(e0);
 227                 /* the inotify fd will now be out of sync,
 228                  * can't keep reading data off it */
 229                 TALLOC_FREE(fde);
 230                 return;
 231         }
 232
 233         /* we can get more than one event in the buffer */
 234         while (e && (bufsize >= sizeof(*e))) {
 235                 struct inotify_event *e2 = NULL;
 236                 bufsize -= e->len + sizeof(*e);
 237                 if (bufsize >= sizeof(*e)) {
 238                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 239                 }
 240                 inotify_dispatch(in, e, prev_wd, prev_cookie, e2);
 241                 prev_wd = e->wd;
 242                 prev_cookie = e->cookie;
 243                 e = e2;
 244         }
 245
 246         talloc_free(e0);
 247 }
 248
 249 /*
 250   setup the inotify handle - called the first time a watch is added on
 251   this context
 252 */
 253 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 254 {
 255         struct inotify_private *in;
 256         struct tevent_fd *fde;
 257
 258         in = talloc(ctx, struct inotify_private);
 259         NT_STATUS_HAVE_NO_MEMORY(in);
 260         in->fd = inotify_init();
 261         if (in->fd == -1) {
 262                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 263                 talloc_free(in);
 264                 return map_nt_error_from_unix(errno);
 265         }
 266         in->ctx = ctx;
 267         in->watches = NULL;
 268
 269         ctx->private_data = in;
 270         talloc_set_destructor(in, inotify_destructor);
 271
 272         /* add a event waiting for the inotify fd to be readable */
 273         fde = tevent_add_fd(ctx->ev, in, in->fd, TEVENT_FD_READ,
 274                             inotify_handler, in);
 275         if (fde == NULL) {
 276                 ctx->private_data = NULL;
 277                 TALLOC_FREE(in);
 278                 return NT_STATUS_NO_MEMORY;
 279         }
 280
 281         return NT_STATUS_OK;
 282 }
 283
 284
 285 /*
 286   map from a change notify mask to a inotify mask. Remove any bits
 287   which we can handle
 288 */
 289 static const struct {
 290         uint32_t notify_mask;
 291         uint32_t inotify_mask;
 292 } inotify_mapping[] = {
 293         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 294         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 295         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 296         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 297         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 298         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 299         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 300 };
 301
 302 static uint32_t inotify_map(uint32_t *filter)
 303 {
 304         int i;
 305         uint32_t out=0;
 306         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 307                 if (inotify_mapping[i].notify_mask & *filter) {
 308                         out |= inotify_mapping[i].inotify_mask;
 309                         *filter &= ~inotify_mapping[i].notify_mask;
 310                 }
 311         }
 312         return out;
 313 }
 314
 315 /*
 316   destroy a watch
 317 */
 318 static int watch_destructor(struct inotify_watch_context *w)
 319 {
 320         struct inotify_private *in = w->in;
 321         int wd = w->wd;
 322         DLIST_REMOVE(w->in->watches, w);
 323
 324         /* only rm the watch if its the last one with this wd */
 325         for (w=in->watches;w;w=w->next) {
 326                 if (w->wd == wd) break;
 327         }
 328         if (w == NULL) {
 329                 DEBUG(10, ("Deleting inotify watch %d\n", wd));
 330                 if (inotify_rm_watch(in->fd, wd) == -1) {
 331                         DEBUG(1, ("inotify_rm_watch returned %s\n",
 332                                   strerror(errno)));
 333                 }
 334
 335         }
 336         return 0;
 337 }
 338
 339
 340 /*
 341   add a watch. The watch is removed when the caller calls
 342   talloc_free() on *handle
 343 */
 344 NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 345                        const char *path,
 346                        uint32_t *filter,
 347                        uint32_t *subdir_filter,
 348                        void (*callback)(struct sys_notify_context *ctx,
 349                                         void *private_data,
 350                                         struct notify_event *ev),
 351                        void *private_data,
 352                        void *handle_p)
 353 {
 354         struct inotify_private *in;
 355         int wd;
 356         uint32_t mask;
 357         struct inotify_watch_context *w;
 358         uint32_t orig_filter = *filter;
 359         void **handle = (void **)handle_p;
 360
 361         /* maybe setup the inotify fd */
 362         if (ctx->private_data == NULL) {
 363                 NTSTATUS status;
 364                 status = inotify_setup(ctx);
 365                 NT_STATUS_NOT_OK_RETURN(status);
 366         }
 367
 368         in = talloc_get_type(ctx->private_data, struct inotify_private);
 369
 370         mask = inotify_map(filter);
 371         if (mask == 0) {
 372                 /* this filter can't be handled by inotify */
 373                 return NT_STATUS_INVALID_PARAMETER;
 374         }
 375
 376         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 377            watch descriptor for multiple watches on the same path */
 378         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 379
 380         /* get a new watch descriptor for this path */
 381         wd = inotify_add_watch(in->fd, path, mask);
 382         if (wd == -1) {
 383                 *filter = orig_filter;
 384                 DEBUG(1, ("inotify_add_watch returned %s\n", strerror(errno)));
 385                 return map_nt_error_from_unix(errno);
 386         }
 387
 388         DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
 389                    path, mask, wd));
 390
 391         w = talloc(in, struct inotify_watch_context);
 392         if (w == NULL) {
 393                 inotify_rm_watch(in->fd, wd);
 394                 *filter = orig_filter;
 395                 return NT_STATUS_NO_MEMORY;
 396         }
 397
 398         w->in = in;
 399         w->wd = wd;
 400         w->callback = callback;
 401         w->private_data = private_data;
 402         w->mask = mask;
 403         w->filter = orig_filter;
 404         w->path = talloc_strdup(w, path);
 405         if (w->path == NULL) {
 406                 inotify_rm_watch(in->fd, wd);
 407                 *filter = orig_filter;
 408                 TALLOC_FREE(w);
 409                 return NT_STATUS_NO_MEMORY;
 410         }
 411
 412         (*handle) = w;
 413
 414         DLIST_ADD(in->watches, w);
 415
 416         /* the caller frees the handle to stop watching */
 417         talloc_set_destructor(w, watch_destructor);
 418
 419         return NT_STATUS_OK;
 420 }
 421
 422 #endif