source4/ntvfs/sysdep/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 "system/filesys.h"
  26 #include <tevent.h>
  27 #include "ntvfs/sysdep/sys_notify.h"
  28 #include "../lib/util/dlinklist.h"
  29 #include "libcli/raw/smb.h"
  30 #include "param/param.h"
  31
  32 #if HAVE_SYS_INOTIFY_H
  33 #include <sys/inotify.h>
  34 #else
  35 /* for older glibc varients - we can remove this eventually */
  36 #include <linux/inotify.h>
  37 #include <asm/unistd.h>
  38
  39 #ifndef HAVE_INOTIFY_INIT
  40 /*
  41   glibc doesn't define these functions yet (as of March 2006)
  42 */
  43 static int inotify_init(void)
  44 {
  45         return syscall(__NR_inotify_init);
  46 }
  47
  48 static int inotify_add_watch(int fd, const char *path, __u32 mask)
  49 {
  50         return syscall(__NR_inotify_add_watch, fd, path, mask);
  51 }
  52
  53 static int inotify_rm_watch(int fd, int wd)
  54 {
  55         return syscall(__NR_inotify_rm_watch, fd, wd);
  56 }
  57 #endif
  58 #endif
  59
  60
  61 /* older glibc headers don't have these defines either */
  62 #ifndef IN_ONLYDIR
  63 #define IN_ONLYDIR 0x01000000
  64 #endif
  65 #ifndef IN_MASK_ADD
  66 #define IN_MASK_ADD 0x20000000
  67 #endif
  68
  69 struct inotify_private {
  70         struct sys_notify_context *ctx;
  71         int fd;
  72         struct inotify_watch_context *watches;
  73 };
  74
  75 struct inotify_watch_context {
  76         struct inotify_watch_context *next, *prev;
  77         struct inotify_private *in;
  78         int wd;
  79         sys_notify_callback_t callback;
  80         void *private_data;
  81         uint32_t mask; /* the inotify mask */
  82         uint32_t filter; /* the windows completion filter */
  83         const char *path;
  84 };
  85
  86
  87 /*
  88   see if a particular event from inotify really does match a requested
  89   notify event in SMB
  90 */
  91 static bool filter_match(struct inotify_watch_context *w,
  92                          struct inotify_event *e)
  93 {
  94         if ((e->mask & w->mask) == 0) {
  95                 /* this happens because inotify_add_watch() coalesces watches on the same
  96                    path, oring their masks together */
  97                 return false;
  98         }
  99
 100         /* SMB separates the filters for files and directories */
 101         if (e->mask & IN_ISDIR) {
 102                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
 103                         return false;
 104                 }
 105         } else {
 106                 if ((e->mask & IN_ATTRIB) &&
 107                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
 108                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
 109                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
 110                                   FILE_NOTIFY_CHANGE_EA|
 111                                   FILE_NOTIFY_CHANGE_SECURITY))) {
 112                         return true;
 113                 }
 114                 if ((e->mask & IN_MODIFY) &&
 115                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
 116                         return true;
 117                 }
 118                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
 119                         return false;
 120                 }
 121         }
 122
 123         return true;
 124 }
 125
 126
 127
 128 /*
 129   dispatch one inotify event
 130
 131   the cookies are used to correctly handle renames
 132 */
 133 static void inotify_dispatch(struct inotify_private *in,
 134                              struct inotify_event *e,
 135                              uint32_t prev_cookie,
 136                              struct inotify_event *e2)
 137 {
 138         struct inotify_watch_context *w, *next;
 139         struct notify_event ne;
 140
 141         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 142         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 143                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 144                 return;
 145         }
 146
 147         /* map the inotify mask to a action. This gets complicated for
 148            renames */
 149         if (e->mask & IN_CREATE) {
 150                 ne.action = NOTIFY_ACTION_ADDED;
 151         } else if (e->mask & IN_DELETE) {
 152                 ne.action = NOTIFY_ACTION_REMOVED;
 153         } else if (e->mask & IN_MOVED_FROM) {
 154                 if (e2 != NULL && e2->cookie == e->cookie) {
 155                         ne.action = NOTIFY_ACTION_OLD_NAME;
 156                 } else {
 157                         ne.action = NOTIFY_ACTION_REMOVED;
 158                 }
 159         } else if (e->mask & IN_MOVED_TO) {
 160                 if (e->cookie == prev_cookie) {
 161                         ne.action = NOTIFY_ACTION_NEW_NAME;
 162                 } else {
 163                         ne.action = NOTIFY_ACTION_ADDED;
 164                 }
 165         } else {
 166                 ne.action = NOTIFY_ACTION_MODIFIED;
 167         }
 168         ne.path = e->name;
 169
 170         /* find any watches that have this watch descriptor */
 171         for (w=in->watches;w;w=next) {
 172                 next = w->next;
 173                 if (w->wd == e->wd && filter_match(w, e)) {
 174                         w->callback(in->ctx, w->private_data, &ne);
 175                 }
 176         }
 177
 178         /* SMB expects a file rename to generate three events, two for
 179            the rename and the other for a modify of the
 180            destination. Strange! */
 181         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 182             (e->mask & IN_ISDIR) != 0) {
 183                 return;
 184         }
 185
 186         ne.action = NOTIFY_ACTION_MODIFIED;
 187         e->mask = IN_ATTRIB;
 188
 189         for (w=in->watches;w;w=next) {
 190                 next = w->next;
 191                 if (w->wd == e->wd && filter_match(w, e) &&
 192                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 193                         w->callback(in->ctx, w->private_data, &ne);
 194                 }
 195         }
 196 }
 197
 198 /*
 199   called when the kernel has some events for us
 200 */
 201 static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,
 202                             uint16_t flags, void *private_data)
 203 {
 204         struct inotify_private *in = talloc_get_type(private_data,
 205                                                      struct inotify_private);
 206         int bufsize = 0;
 207         struct inotify_event *e0, *e;
 208         uint32_t prev_cookie=0;
 209
 210         /*
 211           we must use FIONREAD as we cannot predict the length of the
 212           filenames, and thus can't know how much to allocate
 213           otherwise
 214         */
 215         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 216             bufsize == 0) {
 217                 DEBUG(0,("No data on inotify fd?!\n"));
 218                 return;
 219         }
 220
 221         e0 = e = talloc_size(in, bufsize);
 222         if (e == NULL) return;
 223
 224         if (read(in->fd, e0, bufsize) != bufsize) {
 225                 DEBUG(0,("Failed to read all inotify data\n"));
 226                 talloc_free(e0);
 227                 return;
 228         }
 229
 230         /* we can get more than one event in the buffer */
 231         while (bufsize >= sizeof(*e)) {
 232                 struct inotify_event *e2 = NULL;
 233                 bufsize -= e->len + sizeof(*e);
 234                 if (bufsize >= sizeof(*e)) {
 235                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 236                 }
 237                 inotify_dispatch(in, e, prev_cookie, e2);
 238                 prev_cookie = e->cookie;
 239                 e = e2;
 240         }
 241
 242         talloc_free(e0);
 243 }
 244
 245 /*
 246   setup the inotify handle - called the first time a watch is added on
 247   this context
 248 */
 249 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 250 {
 251         struct inotify_private *in;
 252         struct tevent_fd *fde;
 253
 254         in = talloc(ctx, struct inotify_private);
 255         NT_STATUS_HAVE_NO_MEMORY(in);
 256
 257         in->fd = inotify_init();
 258         if (in->fd == -1) {
 259                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 260                 talloc_free(in);
 261                 return map_nt_error_from_unix_common(errno);
 262         }
 263         in->ctx = ctx;
 264         in->watches = NULL;
 265
 266         ctx->private_data = in;
 267
 268         /* add a event waiting for the inotify fd to be readable */
 269         fde = tevent_add_fd(ctx->ev, in, in->fd,
 270                            TEVENT_FD_READ, inotify_handler, in);
 271         if (!fde) {
 272                 if (errno == 0) {
 273                         errno = ENOMEM;
 274                 }
 275                 DEBUG(0,("Failed to tevent_add_fd() - %s\n", strerror(errno)));
 276                 talloc_free(in);
 277                 return map_nt_error_from_unix_common(errno);
 278         }
 279
 280         tevent_fd_set_auto_close(fde);
 281
 282         return NT_STATUS_OK;
 283 }
 284
 285
 286 /*
 287   map from a change notify mask to a inotify mask. Remove any bits
 288   which we can handle
 289 */
 290 static const struct {
 291         uint32_t notify_mask;
 292         uint32_t inotify_mask;
 293 } inotify_mapping[] = {
 294         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 295         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 296         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 297         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 298         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 299         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 300         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 301 };
 302
 303 static uint32_t inotify_map(struct notify_entry *e)
 304 {
 305         int i;
 306         uint32_t out=0;
 307         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 308                 if (inotify_mapping[i].notify_mask & e->filter) {
 309                         out |= inotify_mapping[i].inotify_mask;
 310                         e->filter &= ~inotify_mapping[i].notify_mask;
 311                 }
 312         }
 313         return out;
 314 }
 315
 316 /*
 317   destroy a watch
 318 */
 319 static int watch_destructor(struct inotify_watch_context *w)
 320 {
 321         struct inotify_private *in = w->in;
 322         int wd = w->wd;
 323         DLIST_REMOVE(w->in->watches, w);
 324
 325         /* only rm the watch if its the last one with this wd */
 326         for (w=in->watches;w;w=w->next) {
 327                 if (w->wd == wd) break;
 328         }
 329         if (w == NULL) {
 330                 inotify_rm_watch(in->fd, wd);
 331         }
 332         return 0;
 333 }
 334
 335
 336 /*
 337   add a watch. The watch is removed when the caller calls
 338   talloc_free() on *handle
 339 */
 340 static NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 341                               struct notify_entry *e,
 342                               sys_notify_callback_t callback,
 343                               void *private_data,
 344                               void *handle_p)
 345 {
 346         struct inotify_private *in;
 347         int wd;
 348         uint32_t mask;
 349         struct inotify_watch_context *w;
 350         uint32_t filter = e->filter;
 351         void **handle = (void **)handle_p;
 352
 353         /* maybe setup the inotify fd */
 354         if (ctx->private_data == NULL) {
 355                 NTSTATUS status;
 356                 status = inotify_setup(ctx);
 357                 NT_STATUS_NOT_OK_RETURN(status);
 358         }
 359
 360         in = talloc_get_type(ctx->private_data, struct inotify_private);
 361
 362         mask = inotify_map(e);
 363         if (mask == 0) {
 364                 /* this filter can't be handled by inotify */
 365                 return NT_STATUS_INVALID_PARAMETER;
 366         }
 367
 368         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 369            watch descriptor for muliple watches on the same path */
 370         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 371
 372         /* get a new watch descriptor for this path */
 373         wd = inotify_add_watch(in->fd, e->path, mask);
 374         if (wd == -1) {
 375                 e->filter = filter;
 376                 return map_nt_error_from_unix_common(errno);
 377         }
 378
 379         w = talloc(in, struct inotify_watch_context);
 380         if (w == NULL) {
 381                 inotify_rm_watch(in->fd, wd);
 382                 e->filter = filter;
 383                 return NT_STATUS_NO_MEMORY;
 384         }
 385
 386         w->in = in;
 387         w->wd = wd;
 388         w->callback = callback;
 389         w->private_data = private_data;
 390         w->mask = mask;
 391         w->filter = filter;
 392         w->path = talloc_strdup(w, e->path);
 393         if (w->path == NULL) {
 394                 inotify_rm_watch(in->fd, wd);
 395                 e->filter = filter;
 396                 return NT_STATUS_NO_MEMORY;
 397         }
 398
 399         (*handle) = w;
 400
 401         DLIST_ADD(in->watches, w);
 402
 403         /* the caller frees the handle to stop watching */
 404         talloc_set_destructor(w, watch_destructor);
 405
 406         return NT_STATUS_OK;
 407 }
 408
 409
 410 static struct sys_notify_backend inotify = {
 411         .name = "inotify",
 412         .notify_watch = inotify_watch
 413 };
 414
 415 /*
 416   initialialise the inotify module
 417  */
 418 NTSTATUS sys_notify_inotify_init(void)
 419 {
 420         /* register ourselves as a system inotify module */
 421         return sys_notify_register(&inotify);
 422 }