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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 /*
  22   notify implementation using inotify
  23 */
  24
  25 #include "includes.h"
  26
  27 #ifdef HAVE_INOTIFY
  28
  29 #ifdef HAVE_ASM_TYPES_H
  30 #include <asm/types.h>
  31 #endif
  32
  33 #include <linux/inotify.h>
  34 #include <asm/unistd.h>
  35
  36 #ifndef HAVE_INOTIFY_INIT
  37 /*
  38   glibc doesn't define these functions yet (as of March 2006)
  39 */
  40 static int inotify_init(void)
  41 {
  42         return syscall(__NR_inotify_init);
  43 }
  44
  45 static int inotify_add_watch(int fd, const char *path, __u32 mask)
  46 {
  47         return syscall(__NR_inotify_add_watch, fd, path, mask);
  48 }
  49
  50 static int inotify_rm_watch(int fd, int wd)
  51 {
  52         return syscall(__NR_inotify_rm_watch, fd, wd);
  53 }
  54 #endif
  55
  56
  57 /* older glibc headers don't have these defines either */
  58 #ifndef IN_ONLYDIR
  59 #define IN_ONLYDIR 0x01000000
  60 #endif
  61 #ifndef IN_MASK_ADD
  62 #define IN_MASK_ADD 0x20000000
  63 #endif
  64
  65 struct inotify_private {
  66         struct sys_notify_context *ctx;
  67         int fd;
  68         struct inotify_watch_context *watches;
  69 };
  70
  71 struct inotify_watch_context {
  72         struct inotify_watch_context *next, *prev;
  73         struct inotify_private *in;
  74         int wd;
  75         void (*callback)(struct sys_notify_context *ctx,
  76                          void *private_data,
  77                          struct notify_event *ev);
  78         void *private_data;
  79         uint32_t mask; /* the inotify mask */
  80         uint32_t filter; /* the windows completion filter */
  81         const char *path;
  82 };
  83
  84
  85 /*
  86   destroy the inotify private context
  87 */
  88 static int inotify_destructor(struct inotify_private *in)
  89 {
  90         close(in->fd);
  91         return 0;
  92 }
  93
  94
  95 /*
  96   see if a particular event from inotify really does match a requested
  97   notify event in SMB
  98 */
  99 static BOOL filter_match(struct inotify_watch_context *w,
 100                          struct inotify_event *e)
 101 {
 102         DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
 103                    e->mask, w->mask, w->filter));
 104
 105         if ((e->mask & w->mask) == 0) {
 106                 /* this happens because inotify_add_watch() coalesces watches on the same
 107                    path, oring their masks together */
 108                 return False;
 109         }
 110
 111         /* SMB separates the filters for files and directories */
 112         if (e->mask & IN_ISDIR) {
 113                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
 114                         return False;
 115                 }
 116         } else {
 117                 if ((e->mask & IN_ATTRIB) &&
 118                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
 119                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
 120                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
 121                                   FILE_NOTIFY_CHANGE_EA|
 122                                   FILE_NOTIFY_CHANGE_SECURITY))) {
 123                         return True;
 124                 }
 125                 if ((e->mask & IN_MODIFY) &&
 126                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 127                         return True;
 128                 }
 129                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
 130                         return False;
 131                 }
 132         }
 133
 134         return True;
 135 }
 136
 137
 138
 139 /*
 140   dispatch one inotify event
 141
 142   the cookies are used to correctly handle renames
 143 */
 144 static void inotify_dispatch(struct inotify_private *in,
 145                              struct inotify_event *e,
 146                              uint32_t prev_cookie,
 147                              struct inotify_event *e2)
 148 {
 149         struct inotify_watch_context *w, *next;
 150         struct notify_event ne;
 151
 152         DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
 153                    e->mask, e->len ? e->name : ""));
 154
 155         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 156         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 157                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 158                 return;
 159         }
 160
 161         /* map the inotify mask to a action. This gets complicated for
 162            renames */
 163         if (e->mask & IN_CREATE) {
 164                 ne.action = NOTIFY_ACTION_ADDED;
 165         } else if (e->mask & IN_DELETE) {
 166                 ne.action = NOTIFY_ACTION_REMOVED;
 167         } else if (e->mask & IN_MOVED_FROM) {
 168                 if (e2 != NULL && e2->cookie == e->cookie) {
 169                         ne.action = NOTIFY_ACTION_OLD_NAME;
 170                 } else {
 171                         ne.action = NOTIFY_ACTION_REMOVED;
 172                 }
 173         } else if (e->mask & IN_MOVED_TO) {
 174                 if (e->cookie == prev_cookie) {
 175                         ne.action = NOTIFY_ACTION_NEW_NAME;
 176                 } else {
 177                         ne.action = NOTIFY_ACTION_ADDED;
 178                 }
 179         } else {
 180                 ne.action = NOTIFY_ACTION_MODIFIED;
 181         }
 182         ne.path = e->name;
 183
 184         DEBUG(10, ("inotify_dispatch: ne.action = %d, ne.path = %s\n",
 185                    ne.action, ne.path));
 186
 187         /* find any watches that have this watch descriptor */
 188         for (w=in->watches;w;w=next) {
 189                 next = w->next;
 190                 if (w->wd == e->wd && filter_match(w, e)) {
 191                         w->callback(in->ctx, w->private_data, &ne);
 192                 }
 193         }
 194
 195         /* SMB expects a file rename to generate three events, two for
 196            the rename and the other for a modify of the
 197            destination. Strange! */
 198         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 199             (e->mask & IN_ISDIR) != 0) {
 200                 return;
 201         }
 202
 203         ne.action = NOTIFY_ACTION_MODIFIED;
 204         e->mask = IN_ATTRIB;
 205
 206         for (w=in->watches;w;w=next) {
 207                 next = w->next;
 208                 if (w->wd == e->wd && filter_match(w, e) &&
 209                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 210                         w->callback(in->ctx, w->private_data, &ne);
 211                 }
 212         }
 213 }
 214
 215 /*
 216   called when the kernel has some events for us
 217 */
 218 static void inotify_handler(struct event_context *ev, struct fd_event *fde,
 219                             uint16_t flags, void *private_data)
 220 {
 221         struct inotify_private *in = talloc_get_type(private_data,
 222                                                      struct inotify_private);
 223         int bufsize = 0;
 224         struct inotify_event *e0, *e;
 225         uint32_t prev_cookie=0;
 226
 227         /*
 228           we must use FIONREAD as we cannot predict the length of the
 229           filenames, and thus can't know how much to allocate
 230           otherwise
 231         */
 232         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 233             bufsize == 0) {
 234                 DEBUG(0,("No data on inotify fd?!\n"));
 235                 return;
 236         }
 237
 238         e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize);
 239         if (e == NULL) return;
 240
 241         if (read(in->fd, e0, bufsize) != bufsize) {
 242                 DEBUG(0,("Failed to read all inotify data\n"));
 243                 talloc_free(e0);
 244                 return;
 245         }
 246
 247         /* we can get more than one event in the buffer */
 248         while (bufsize >= sizeof(*e)) {
 249                 struct inotify_event *e2 = NULL;
 250                 bufsize -= e->len + sizeof(*e);
 251                 if (bufsize >= sizeof(*e)) {
 252                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 253                 }
 254                 inotify_dispatch(in, e, prev_cookie, e2);
 255                 prev_cookie = e->cookie;
 256                 e = e2;
 257         }
 258
 259         talloc_free(e0);
 260 }
 261
 262 /*
 263   setup the inotify handle - called the first time a watch is added on
 264   this context
 265 */
 266 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 267 {
 268         struct inotify_private *in;
 269
 270         if (!lp_parm_bool(-1, "notify", "inotify", True)) {
 271                 return NT_STATUS_INVALID_SYSTEM_SERVICE;
 272         }
 273
 274         in = talloc(ctx, struct inotify_private);
 275         NT_STATUS_HAVE_NO_MEMORY(in);
 276         in->fd = inotify_init();
 277         if (in->fd == -1) {
 278                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 279                 talloc_free(in);
 280                 return map_nt_error_from_unix(errno);
 281         }
 282         in->ctx = ctx;
 283         in->watches = NULL;
 284
 285         ctx->private_data = in;
 286         talloc_set_destructor(in, inotify_destructor);
 287
 288         /* add a event waiting for the inotify fd to be readable */
 289         event_add_fd(ctx->ev, in, in->fd, EVENT_FD_READ, inotify_handler, in);
 290
 291         return NT_STATUS_OK;
 292 }
 293
 294
 295 /*
 296   map from a change notify mask to a inotify mask. Remove any bits
 297   which we can handle
 298 */
 299 static const struct {
 300         uint32_t notify_mask;
 301         uint32_t inotify_mask;
 302 } inotify_mapping[] = {
 303         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 304         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 305         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 306         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 307         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 308         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 309         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 310 };
 311
 312 static uint32_t inotify_map(struct notify_entry *e)
 313 {
 314         int i;
 315         uint32_t out=0;
 316         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 317                 if (inotify_mapping[i].notify_mask & e->filter) {
 318                         out |= inotify_mapping[i].inotify_mask;
 319                         e->filter &= ~inotify_mapping[i].notify_mask;
 320                 }
 321         }
 322         return out;
 323 }
 324
 325 /*
 326   destroy a watch
 327 */
 328 static int watch_destructor(struct inotify_watch_context *w)
 329 {
 330         struct inotify_private *in = w->in;
 331         int wd = w->wd;
 332         DLIST_REMOVE(w->in->watches, w);
 333
 334         /* only rm the watch if its the last one with this wd */
 335         for (w=in->watches;w;w=w->next) {
 336                 if (w->wd == wd) break;
 337         }
 338         if (w == NULL) {
 339                 DEBUG(10, ("Deleting inotify watch %d\n", wd));
 340                 if (inotify_rm_watch(in->fd, wd) == -1) {
 341                         DEBUG(1, ("inotify_rm_watch returned %s\n",
 342                                   strerror(errno)));
 343                 }
 344
 345         }
 346         return 0;
 347 }
 348
 349
 350 /*
 351   add a watch. The watch is removed when the caller calls
 352   talloc_free() on *handle
 353 */
 354 NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 355                        struct notify_entry *e,
 356                        void (*callback)(struct sys_notify_context *ctx,
 357                                         void *private_data,
 358                                         struct notify_event *ev),
 359                        void *private_data,
 360                        void *handle_p)
 361 {
 362         struct inotify_private *in;
 363         int wd;
 364         uint32_t mask;
 365         struct inotify_watch_context *w;
 366         uint32_t filter = e->filter;
 367         void **handle = (void **)handle_p;
 368
 369         /* maybe setup the inotify fd */
 370         if (ctx->private_data == NULL) {
 371                 NTSTATUS status;
 372                 status = inotify_setup(ctx);
 373                 NT_STATUS_NOT_OK_RETURN(status);
 374         }
 375
 376         in = talloc_get_type(ctx->private_data, struct inotify_private);
 377
 378         mask = inotify_map(e);
 379         if (mask == 0) {
 380                 /* this filter can't be handled by inotify */
 381                 return NT_STATUS_INVALID_PARAMETER;
 382         }
 383
 384         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 385            watch descriptor for muliple watches on the same path */
 386         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 387
 388         /* get a new watch descriptor for this path */
 389         wd = inotify_add_watch(in->fd, e->path, mask);
 390         if (wd == -1) {
 391                 e->filter = filter;
 392                 DEBUG(1, ("inotify_add_watch returned %s\n", strerror(errno)));
 393                 return map_nt_error_from_unix(errno);
 394         }
 395
 396         DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
 397                    e->path, mask, wd));
 398
 399         w = talloc(in, struct inotify_watch_context);
 400         if (w == NULL) {
 401                 inotify_rm_watch(in->fd, wd);
 402                 e->filter = filter;
 403                 return NT_STATUS_NO_MEMORY;
 404         }
 405
 406         w->in = in;
 407         w->wd = wd;
 408         w->callback = callback;
 409         w->private_data = private_data;
 410         w->mask = mask;
 411         w->filter = filter;
 412         w->path = talloc_strdup(w, e->path);
 413         if (w->path == NULL) {
 414                 inotify_rm_watch(in->fd, wd);
 415                 e->filter = filter;
 416                 return NT_STATUS_NO_MEMORY;
 417         }
 418
 419         (*handle) = w;
 420
 421         DLIST_ADD(in->watches, w);
 422
 423         /* the caller frees the handle to stop watching */
 424         talloc_set_destructor(w, watch_destructor);
 425
 426         return NT_STATUS_OK;
 427 }
 428
 429 #endif