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
  27 #ifdef HAVE_INOTIFY
  28
  29 #if HAVE_SYS_INOTIFY_H
  30 #include <sys/inotify.h>
  31 #else
  32
  33 #ifdef HAVE_ASM_TYPES_H
  34 #include <asm/types.h>
  35 #endif
  36
  37 #ifndef HAVE_INOTIFY_INIT
  38
  39 #include <linux/inotify.h>
  40 #include <asm/unistd.h>
  41
  42
  43 /*
  44   glibc doesn't define these functions yet (as of March 2006)
  45 */
  46 static int inotify_init(void)
  47 {
  48         return syscall(__NR_inotify_init);
  49 }
  50
  51 static int inotify_add_watch(int fd, const char *path, __u32 mask)
  52 {
  53         return syscall(__NR_inotify_add_watch, fd, path, mask);
  54 }
  55
  56 static int inotify_rm_watch(int fd, int wd)
  57 {
  58         return syscall(__NR_inotify_rm_watch, fd, wd);
  59 }
  60 #else
  61
  62 #include <sys/inotify.h>
  63
  64 #endif
  65 #endif
  66
  67 /* older glibc headers don't have these defines either */
  68 #ifndef IN_ONLYDIR
  69 #define IN_ONLYDIR 0x01000000
  70 #endif
  71 #ifndef IN_MASK_ADD
  72 #define IN_MASK_ADD 0x20000000
  73 #endif
  74
  75 struct inotify_private {
  76         struct sys_notify_context *ctx;
  77         int fd;
  78         struct inotify_watch_context *watches;
  79 };
  80
  81 struct inotify_watch_context {
  82         struct inotify_watch_context *next, *prev;
  83         struct inotify_private *in;
  84         int wd;
  85         void (*callback)(struct sys_notify_context *ctx,
  86                          void *private_data,
  87                          struct notify_event *ev);
  88         void *private_data;
  89         uint32_t mask; /* the inotify mask */
  90         uint32_t filter; /* the windows completion filter */
  91         const char *path;
  92 };
  93
  94
  95 /*
  96   destroy the inotify private context
  97 */
  98 static int inotify_destructor(struct inotify_private *in)
  99 {
 100         close(in->fd);
 101         return 0;
 102 }
 103
 104
 105 /*
 106   see if a particular event from inotify really does match a requested
 107   notify event in SMB
 108 */
 109 static bool filter_match(struct inotify_watch_context *w,
 110                          struct inotify_event *e)
 111 {
 112         DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
 113                    e->mask, w->mask, w->filter));
 114
 115         if ((e->mask & w->mask) == 0) {
 116                 /* this happens because inotify_add_watch() coalesces watches on the same
 117                    path, oring their masks together */
 118                 return False;
 119         }
 120
 121         /* SMB separates the filters for files and directories */
 122         if (e->mask & IN_ISDIR) {
 123                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
 124                         return False;
 125                 }
 126         } else {
 127                 if ((e->mask & IN_ATTRIB) &&
 128                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
 129                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
 130                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
 131                                   FILE_NOTIFY_CHANGE_EA|
 132                                   FILE_NOTIFY_CHANGE_SECURITY))) {
 133                         return True;
 134                 }
 135                 if ((e->mask & IN_MODIFY) &&
 136                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 137                         return True;
 138                 }
 139                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
 140                         return False;
 141                 }
 142         }
 143
 144         return True;
 145 }
 146
 147
 148
 149 /*
 150   dispatch one inotify event
 151
 152   the cookies are used to correctly handle renames
 153 */
 154 static void inotify_dispatch(struct inotify_private *in,
 155                              struct inotify_event *e,
 156                              uint32_t prev_cookie,
 157                              struct inotify_event *e2)
 158 {
 159         struct inotify_watch_context *w, *next;
 160         struct notify_event ne;
 161
 162         DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
 163                    e->mask, e->len ? e->name : ""));
 164
 165         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 166         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 167                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 168                 return;
 169         }
 170
 171         /* map the inotify mask to a action. This gets complicated for
 172            renames */
 173         if (e->mask & IN_CREATE) {
 174                 ne.action = NOTIFY_ACTION_ADDED;
 175         } else if (e->mask & IN_DELETE) {
 176                 ne.action = NOTIFY_ACTION_REMOVED;
 177         } else if (e->mask & IN_MOVED_FROM) {
 178                 if (e2 != NULL && e2->cookie == e->cookie) {
 179                         ne.action = NOTIFY_ACTION_OLD_NAME;
 180                 } else {
 181                         ne.action = NOTIFY_ACTION_REMOVED;
 182                 }
 183         } else if (e->mask & IN_MOVED_TO) {
 184                 if (e->cookie == prev_cookie) {
 185                         ne.action = NOTIFY_ACTION_NEW_NAME;
 186                 } else {
 187                         ne.action = NOTIFY_ACTION_ADDED;
 188                 }
 189         } else {
 190                 ne.action = NOTIFY_ACTION_MODIFIED;
 191         }
 192         ne.path = e->name;
 193
 194         DEBUG(10, ("inotify_dispatch: ne.action = %d, ne.path = %s\n",
 195                    ne.action, ne.path));
 196
 197         /* find any watches that have this watch descriptor */
 198         for (w=in->watches;w;w=next) {
 199                 next = w->next;
 200                 if (w->wd == e->wd && filter_match(w, e)) {
 201                         w->callback(in->ctx, w->private_data, &ne);
 202                 }
 203         }
 204
 205         /* SMB expects a file rename to generate three events, two for
 206            the rename and the other for a modify of the
 207            destination. Strange! */
 208         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 209             (e->mask & IN_ISDIR) != 0) {
 210                 return;
 211         }
 212
 213         ne.action = NOTIFY_ACTION_MODIFIED;
 214         e->mask = IN_ATTRIB;
 215
 216         for (w=in->watches;w;w=next) {
 217                 next = w->next;
 218                 if (w->wd == e->wd && filter_match(w, e) &&
 219                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 220                         w->callback(in->ctx, w->private_data, &ne);
 221                 }
 222         }
 223 }
 224
 225 /*
 226   called when the kernel has some events for us
 227 */
 228 static void inotify_handler(struct event_context *ev, struct fd_event *fde,
 229                             uint16_t flags, void *private_data)
 230 {
 231         struct inotify_private *in = talloc_get_type(private_data,
 232                                                      struct inotify_private);
 233         int bufsize = 0;
 234         struct inotify_event *e0, *e;
 235         uint32_t prev_cookie=0;
 236         NTSTATUS status;
 237
 238         /*
 239           we must use FIONREAD as we cannot predict the length of the
 240           filenames, and thus can't know how much to allocate
 241           otherwise
 242         */
 243         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 244             bufsize == 0) {
 245                 DEBUG(0,("No data on inotify fd?!\n"));
 246                 TALLOC_FREE(fde);
 247                 return;
 248         }
 249
 250         e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize + 1);
 251         if (e == NULL) return;
 252         ((uint8_t *)e)[bufsize] = '\0';
 253
 254         status = read_data(in->fd, (char *)e0, bufsize);
 255         if (!NT_STATUS_IS_OK(status)) {
 256                 DEBUG(0,("Failed to read all inotify data - %s\n",
 257                         nt_errstr(status)));
 258                 talloc_free(e0);
 259                 /* the inotify fd will now be out of sync,
 260                  * can't keep reading data off it */
 261                 TALLOC_FREE(fde);
 262                 return;
 263         }
 264
 265         /* we can get more than one event in the buffer */
 266         while (e && (bufsize >= sizeof(*e))) {
 267                 struct inotify_event *e2 = NULL;
 268                 bufsize -= e->len + sizeof(*e);
 269                 if (bufsize >= sizeof(*e)) {
 270                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 271                 }
 272                 inotify_dispatch(in, e, prev_cookie, e2);
 273                 prev_cookie = e->cookie;
 274                 e = e2;
 275         }
 276
 277         talloc_free(e0);
 278 }
 279
 280 /*
 281   setup the inotify handle - called the first time a watch is added on
 282   this context
 283 */
 284 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 285 {
 286         struct inotify_private *in;
 287
 288         if (!lp_parm_bool(-1, "notify", "inotify", True)) {
 289                 return NT_STATUS_INVALID_SYSTEM_SERVICE;
 290         }
 291
 292         in = talloc(ctx, struct inotify_private);
 293         NT_STATUS_HAVE_NO_MEMORY(in);
 294         in->fd = inotify_init();
 295         if (in->fd == -1) {
 296                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 297                 talloc_free(in);
 298                 return map_nt_error_from_unix(errno);
 299         }
 300         in->ctx = ctx;
 301         in->watches = NULL;
 302
 303         ctx->private_data = in;
 304         talloc_set_destructor(in, inotify_destructor);
 305
 306         /* add a event waiting for the inotify fd to be readable */
 307         event_add_fd(ctx->ev, in, in->fd, EVENT_FD_READ, inotify_handler, in);
 308
 309         return NT_STATUS_OK;
 310 }
 311
 312
 313 /*
 314   map from a change notify mask to a inotify mask. Remove any bits
 315   which we can handle
 316 */
 317 static const struct {
 318         uint32_t notify_mask;
 319         uint32_t inotify_mask;
 320 } inotify_mapping[] = {
 321         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 322         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 323         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 324         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 325         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 326         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 327         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 328 };
 329
 330 static uint32_t inotify_map(struct notify_entry *e)
 331 {
 332         int i;
 333         uint32_t out=0;
 334         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 335                 if (inotify_mapping[i].notify_mask & e->filter) {
 336                         out |= inotify_mapping[i].inotify_mask;
 337                         e->filter &= ~inotify_mapping[i].notify_mask;
 338                 }
 339         }
 340         return out;
 341 }
 342
 343 /*
 344   destroy a watch
 345 */
 346 static int watch_destructor(struct inotify_watch_context *w)
 347 {
 348         struct inotify_private *in = w->in;
 349         int wd = w->wd;
 350         DLIST_REMOVE(w->in->watches, w);
 351
 352         /* only rm the watch if its the last one with this wd */
 353         for (w=in->watches;w;w=w->next) {
 354                 if (w->wd == wd) break;
 355         }
 356         if (w == NULL) {
 357                 DEBUG(10, ("Deleting inotify watch %d\n", wd));
 358                 if (inotify_rm_watch(in->fd, wd) == -1) {
 359                         DEBUG(1, ("inotify_rm_watch returned %s\n",
 360                                   strerror(errno)));
 361                 }
 362
 363         }
 364         return 0;
 365 }
 366
 367
 368 /*
 369   add a watch. The watch is removed when the caller calls
 370   talloc_free() on *handle
 371 */
 372 NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 373                        struct notify_entry *e,
 374                        void (*callback)(struct sys_notify_context *ctx,
 375                                         void *private_data,
 376                                         struct notify_event *ev),
 377                        void *private_data,
 378                        void *handle_p)
 379 {
 380         struct inotify_private *in;
 381         int wd;
 382         uint32_t mask;
 383         struct inotify_watch_context *w;
 384         uint32_t filter = e->filter;
 385         void **handle = (void **)handle_p;
 386
 387         /* maybe setup the inotify fd */
 388         if (ctx->private_data == NULL) {
 389                 NTSTATUS status;
 390                 status = inotify_setup(ctx);
 391                 NT_STATUS_NOT_OK_RETURN(status);
 392         }
 393
 394         in = talloc_get_type(ctx->private_data, struct inotify_private);
 395
 396         mask = inotify_map(e);
 397         if (mask == 0) {
 398                 /* this filter can't be handled by inotify */
 399                 return NT_STATUS_INVALID_PARAMETER;
 400         }
 401
 402         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 403            watch descriptor for muliple watches on the same path */
 404         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 405
 406         /* get a new watch descriptor for this path */
 407         wd = inotify_add_watch(in->fd, e->path, mask);
 408         if (wd == -1) {
 409                 e->filter = filter;
 410                 DEBUG(1, ("inotify_add_watch returned %s\n", strerror(errno)));
 411                 return map_nt_error_from_unix(errno);
 412         }
 413
 414         DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
 415                    e->path, mask, wd));
 416
 417         w = talloc(in, struct inotify_watch_context);
 418         if (w == NULL) {
 419                 inotify_rm_watch(in->fd, wd);
 420                 e->filter = filter;
 421                 return NT_STATUS_NO_MEMORY;
 422         }
 423
 424         w->in = in;
 425         w->wd = wd;
 426         w->callback = callback;
 427         w->private_data = private_data;
 428         w->mask = mask;
 429         w->filter = filter;
 430         w->path = talloc_strdup(w, e->path);
 431         if (w->path == NULL) {
 432                 inotify_rm_watch(in->fd, wd);
 433                 e->filter = filter;
 434                 return NT_STATUS_NO_MEMORY;
 435         }
 436
 437         (*handle) = w;
 438
 439         DLIST_ADD(in->watches, w);
 440
 441         /* the caller frees the handle to stop watching */
 442         talloc_set_destructor(w, watch_destructor);
 443
 444         return NT_STATUS_OK;
 445 }
 446
 447 #endif