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