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