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