source/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
  26 #ifdef HAVE_INOTIFY
  27
  28 #if HAVE_SYS_INOTIFY_H
  29 #include <sys/inotify.h>
  30 #else
  31
  32 #ifdef HAVE_ASM_TYPES_H
  33 #include <asm/types.h>
  34 #endif
  35
  36 #ifndef HAVE_INOTIFY_INIT
  37
  38 #include <linux/inotify.h>
  39 #include <asm/unistd.h>
  40
  41
  42 /*
  43   glibc doesn't define these functions yet (as of March 2006)
  44 */
  45 static int inotify_init(void)
  46 {
  47         return syscall(__NR_inotify_init);
  48 }
  49
  50 static int inotify_add_watch(int fd, const char *path, __u32 mask)
  51 {
  52         return syscall(__NR_inotify_add_watch, fd, path, mask);
  53 }
  54
  55 static int inotify_rm_watch(int fd, int wd)
  56 {
  57         return syscall(__NR_inotify_rm_watch, fd, wd);
  58 }
  59 #else
  60
  61 #include <sys/inotify.h>
  62
  63 #endif
  64 #endif
  65
  66 /* older glibc headers don't have these defines either */
  67 #ifndef IN_ONLYDIR
  68 #define IN_ONLYDIR 0x01000000
  69 #endif
  70 #ifndef IN_MASK_ADD
  71 #define IN_MASK_ADD 0x20000000
  72 #endif
  73
  74 struct inotify_private {
  75         struct sys_notify_context *ctx;
  76         int fd;
  77         struct inotify_watch_context *watches;
  78 };
  79
  80 struct inotify_watch_context {
  81         struct inotify_watch_context *next, *prev;
  82         struct inotify_private *in;
  83         int wd;
  84         void (*callback)(struct sys_notify_context *ctx,
  85                          void *private_data,
  86                          struct notify_event *ev);
  87         void *private_data;
  88         uint32_t mask; /* the inotify mask */
  89         uint32_t filter; /* the windows completion filter */
  90         const char *path;
  91 };
  92
  93
  94 /*
  95   destroy the inotify private context
  96 */
  97 static int inotify_destructor(struct inotify_private *in)
  98 {
  99         close(in->fd);
 100         return 0;
 101 }
 102
 103
 104 /*
 105   see if a particular event from inotify really does match a requested
 106   notify event in SMB
 107 */
 108 static bool filter_match(struct inotify_watch_context *w,
 109                          struct inotify_event *e)
 110 {
 111         DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
 112                    e->mask, w->mask, w->filter));
 113
 114         if ((e->mask & w->mask) == 0) {
 115                 /* this happens because inotify_add_watch() coalesces watches on the same
 116                    path, oring their masks together */
 117                 return False;
 118         }
 119
 120         /* SMB separates the filters for files and directories */
 121         if (e->mask & IN_ISDIR) {
 122                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
 123                         return False;
 124                 }
 125         } else {
 126                 if ((e->mask & IN_ATTRIB) &&
 127                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
 128                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
 129                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
 130                                   FILE_NOTIFY_CHANGE_EA|
 131                                   FILE_NOTIFY_CHANGE_SECURITY))) {
 132                         return True;
 133                 }
 134                 if ((e->mask & IN_MODIFY) &&
 135                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 136                         return True;
 137                 }
 138                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
 139                         return False;
 140                 }
 141         }
 142
 143         return True;
 144 }
 145
 146
 147
 148 /*
 149   dispatch one inotify event
 150
 151   the cookies are used to correctly handle renames
 152 */
 153 static void inotify_dispatch(struct inotify_private *in,
 154                              struct inotify_event *e,
 155                              uint32_t prev_cookie,
 156                              struct inotify_event *e2)
 157 {
 158         struct inotify_watch_context *w, *next;
 159         struct notify_event ne;
 160
 161         DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
 162                    e->mask, e->len ? e->name : ""));
 163
 164         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 165         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 166                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 167                 return;
 168         }
 169
 170         /* map the inotify mask to a action. This gets complicated for
 171            renames */
 172         if (e->mask & IN_CREATE) {
 173                 ne.action = NOTIFY_ACTION_ADDED;
 174         } else if (e->mask & IN_DELETE) {
 175                 ne.action = NOTIFY_ACTION_REMOVED;
 176         } else if (e->mask & IN_MOVED_FROM) {
 177                 if (e2 != NULL && e2->cookie == e->cookie) {
 178                         ne.action = NOTIFY_ACTION_OLD_NAME;
 179                 } else {
 180                         ne.action = NOTIFY_ACTION_REMOVED;
 181                 }
 182         } else if (e->mask & IN_MOVED_TO) {
 183                 if (e->cookie == prev_cookie) {
 184                         ne.action = NOTIFY_ACTION_NEW_NAME;
 185                 } else {
 186                         ne.action = NOTIFY_ACTION_ADDED;
 187                 }
 188         } else {
 189                 ne.action = NOTIFY_ACTION_MODIFIED;
 190         }
 191         ne.path = e->name;
 192
 193         DEBUG(10, ("inotify_dispatch: ne.action = %d, ne.path = %s\n",
 194                    ne.action, ne.path));
 195
 196         /* find any watches that have this watch descriptor */
 197         for (w=in->watches;w;w=next) {
 198                 next = w->next;
 199                 if (w->wd == e->wd && filter_match(w, e)) {
 200                         w->callback(in->ctx, w->private_data, &ne);
 201                 }
 202         }
 203
 204         /* SMB expects a file rename to generate three events, two for
 205            the rename and the other for a modify of the
 206            destination. Strange! */
 207         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 208             (e->mask & IN_ISDIR) != 0) {
 209                 return;
 210         }
 211
 212         ne.action = NOTIFY_ACTION_MODIFIED;
 213         e->mask = IN_ATTRIB;
 214
 215         for (w=in->watches;w;w=next) {
 216                 next = w->next;
 217                 if (w->wd == e->wd && filter_match(w, e) &&
 218                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 219                         w->callback(in->ctx, w->private_data, &ne);
 220                 }
 221         }
 222 }
 223
 224 /*
 225   called when the kernel has some events for us
 226 */
 227 static void inotify_handler(struct event_context *ev, struct fd_event *fde,
 228                             uint16_t flags, void *private_data)
 229 {
 230         struct inotify_private *in = talloc_get_type(private_data,
 231                                                      struct inotify_private);
 232         int bufsize = 0;
 233         struct inotify_event *e0, *e;
 234         uint32_t prev_cookie=0;
 235
 236         /*
 237           we must use FIONREAD as we cannot predict the length of the
 238           filenames, and thus can't know how much to allocate
 239           otherwise
 240         */
 241         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 242             bufsize == 0) {
 243                 DEBUG(0,("No data on inotify fd?!\n"));
 244                 return;
 245         }
 246
 247         e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize);
 248         if (e == NULL) return;
 249
 250         if (sys_read(in->fd, e0, bufsize) != bufsize) {
 251                 DEBUG(0,("Failed to read all inotify data\n"));
 252                 talloc_free(e0);
 253                 return;
 254         }
 255
 256         /* we can get more than one event in the buffer */
 257         while (e && (bufsize >= sizeof(*e))) {
 258                 struct inotify_event *e2 = NULL;
 259                 bufsize -= e->len + sizeof(*e);
 260                 if (bufsize >= sizeof(*e)) {
 261                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 262                 }
 263                 inotify_dispatch(in, e, prev_cookie, e2);
 264                 prev_cookie = e->cookie;
 265                 e = e2;
 266         }
 267
 268         talloc_free(e0);
 269 }
 270
 271 /*
 272   setup the inotify handle - called the first time a watch is added on
 273   this context
 274 */
 275 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 276 {
 277         struct inotify_private *in;
 278
 279         if (!lp_parm_bool(-1, "notify", "inotify", True)) {
 280                 return NT_STATUS_INVALID_SYSTEM_SERVICE;
 281         }
 282
 283         in = talloc(ctx, struct inotify_private);
 284         NT_STATUS_HAVE_NO_MEMORY(in);
 285         in->fd = inotify_init();
 286         if (in->fd == -1) {
 287                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 288                 talloc_free(in);
 289                 return map_nt_error_from_unix(errno);
 290         }
 291         in->ctx = ctx;
 292         in->watches = NULL;
 293
 294         ctx->private_data = in;
 295         talloc_set_destructor(in, inotify_destructor);
 296
 297         /* add a event waiting for the inotify fd to be readable */
 298         event_add_fd(ctx->ev, in, in->fd, EVENT_FD_READ, inotify_handler, in);
 299
 300         return NT_STATUS_OK;
 301 }
 302
 303
 304 /*
 305   map from a change notify mask to a inotify mask. Remove any bits
 306   which we can handle
 307 */
 308 static const struct {
 309         uint32_t notify_mask;
 310         uint32_t inotify_mask;
 311 } inotify_mapping[] = {
 312         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 313         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 314         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 315         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 316         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 317         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 318         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 319 };
 320
 321 static uint32_t inotify_map(struct notify_entry *e)
 322 {
 323         int i;
 324         uint32_t out=0;
 325         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 326                 if (inotify_mapping[i].notify_mask & e->filter) {
 327                         out |= inotify_mapping[i].inotify_mask;
 328                         e->filter &= ~inotify_mapping[i].notify_mask;
 329                 }
 330         }
 331         return out;
 332 }
 333
 334 /*
 335   destroy a watch
 336 */
 337 static int watch_destructor(struct inotify_watch_context *w)
 338 {
 339         struct inotify_private *in = w->in;
 340         int wd = w->wd;
 341         DLIST_REMOVE(w->in->watches, w);
 342
 343         /* only rm the watch if its the last one with this wd */
 344         for (w=in->watches;w;w=w->next) {
 345                 if (w->wd == wd) break;
 346         }
 347         if (w == NULL) {
 348                 DEBUG(10, ("Deleting inotify watch %d\n", wd));
 349                 if (inotify_rm_watch(in->fd, wd) == -1) {
 350                         DEBUG(1, ("inotify_rm_watch returned %s\n",
 351                                   strerror(errno)));
 352                 }
 353
 354         }
 355         return 0;
 356 }
 357
 358
 359 /*
 360   add a watch. The watch is removed when the caller calls
 361   talloc_free() on *handle
 362 */
 363 NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 364                        struct notify_entry *e,
 365                        void (*callback)(struct sys_notify_context *ctx,
 366                                         void *private_data,
 367                                         struct notify_event *ev),
 368                        void *private_data,
 369                        void *handle_p)
 370 {
 371         struct inotify_private *in;
 372         int wd;
 373         uint32_t mask;
 374         struct inotify_watch_context *w;
 375         uint32_t filter = e->filter;
 376         void **handle = (void **)handle_p;
 377
 378         /* maybe setup the inotify fd */
 379         if (ctx->private_data == NULL) {
 380                 NTSTATUS status;
 381                 status = inotify_setup(ctx);
 382                 NT_STATUS_NOT_OK_RETURN(status);
 383         }
 384
 385         in = talloc_get_type(ctx->private_data, struct inotify_private);
 386
 387         mask = inotify_map(e);
 388         if (mask == 0) {
 389                 /* this filter can't be handled by inotify */
 390                 return NT_STATUS_INVALID_PARAMETER;
 391         }
 392
 393         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 394            watch descriptor for muliple watches on the same path */
 395         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 396
 397         /* get a new watch descriptor for this path */
 398         wd = inotify_add_watch(in->fd, e->path, mask);
 399         if (wd == -1) {
 400                 e->filter = filter;
 401                 DEBUG(1, ("inotify_add_watch returned %s\n", strerror(errno)));
 402                 return map_nt_error_from_unix(errno);
 403         }
 404
 405         DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
 406                    e->path, mask, wd));
 407
 408         w = talloc(in, struct inotify_watch_context);
 409         if (w == NULL) {
 410                 inotify_rm_watch(in->fd, wd);
 411                 e->filter = filter;
 412                 return NT_STATUS_NO_MEMORY;
 413         }
 414
 415         w->in = in;
 416         w->wd = wd;
 417         w->callback = callback;
 418         w->private_data = private_data;
 419         w->mask = mask;
 420         w->filter = filter;
 421         w->path = talloc_strdup(w, e->path);
 422         if (w->path == NULL) {
 423                 inotify_rm_watch(in->fd, wd);
 424                 e->filter = filter;
 425                 return NT_STATUS_NO_MEMORY;
 426         }
 427
 428         (*handle) = w;
 429
 430         DLIST_ADD(in->watches, w);
 431
 432         /* the caller frees the handle to stop watching */
 433         talloc_set_destructor(w, watch_destructor);
 434
 435         return NT_STATUS_OK;
 436 }
 437
 438 #endif