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