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 #include <sys/inotify.h>
  33
  34 /* glibc < 2.5 headers don't have these defines */
  35 #ifndef IN_ONLYDIR
  36 #define IN_ONLYDIR 0x01000000
  37 #endif
  38 #ifndef IN_MASK_ADD
  39 #define IN_MASK_ADD 0x20000000
  40 #endif
  41
  42 struct inotify_private {
  43         struct sys_notify_context *ctx;
  44         int fd;
  45         struct inotify_watch_context *watches;
  46 };
  47
  48 struct inotify_watch_context {
  49         struct inotify_watch_context *next, *prev;
  50         struct inotify_private *in;
  51         int wd;
  52         sys_notify_callback_t callback;
  53         void *private_data;
  54         uint32_t mask; /* the inotify mask */
  55         uint32_t filter; /* the windows completion filter */
  56         const char *path;
  57 };
  58
  59
  60 /*
  61   see if a particular event from inotify really does match a requested
  62   notify event in SMB
  63 */
  64 static bool filter_match(struct inotify_watch_context *w,
  65                          struct inotify_event *e)
  66 {
  67         if ((e->mask & w->mask) == 0) {
  68                 /* this happens because inotify_add_watch() coalesces watches on the same
  69                    path, oring their masks together */
  70                 return false;
  71         }
  72
  73         /* SMB separates the filters for files and directories */
  74         if (e->mask & IN_ISDIR) {
  75                 if ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) == 0) {
  76                         return false;
  77                 }
  78         } else {
  79                 if ((e->mask & IN_ATTRIB) &&
  80                     (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
  81                                   FILE_NOTIFY_CHANGE_LAST_WRITE|
  82                                   FILE_NOTIFY_CHANGE_LAST_ACCESS|
  83                                   FILE_NOTIFY_CHANGE_EA|
  84                                   FILE_NOTIFY_CHANGE_SECURITY))) {
  85                         return true;
  86                 }
  87                 if ((e->mask & IN_MODIFY) &&
  88                     (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
  89                         return true;
  90                 }
  91                 if ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) == 0) {
  92                         return false;
  93                 }
  94         }
  95
  96         return true;
  97 }
  98
  99
 100
 101 /*
 102   dispatch one inotify event
 103
 104   the cookies are used to correctly handle renames
 105 */
 106 static void inotify_dispatch(struct inotify_private *in,
 107                              struct inotify_event *e,
 108                              uint32_t prev_cookie,
 109                              struct inotify_event *e2)
 110 {
 111         struct inotify_watch_context *w, *next;
 112         struct notify_event ne;
 113
 114         /* ignore extraneous events, such as unmount and IN_IGNORED events */
 115         if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
 116                         IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
 117                 return;
 118         }
 119
 120         /* map the inotify mask to a action. This gets complicated for
 121            renames */
 122         if (e->mask & IN_CREATE) {
 123                 ne.action = NOTIFY_ACTION_ADDED;
 124         } else if (e->mask & IN_DELETE) {
 125                 ne.action = NOTIFY_ACTION_REMOVED;
 126         } else if (e->mask & IN_MOVED_FROM) {
 127                 if (e2 != NULL && e2->cookie == e->cookie) {
 128                         ne.action = NOTIFY_ACTION_OLD_NAME;
 129                 } else {
 130                         ne.action = NOTIFY_ACTION_REMOVED;
 131                 }
 132         } else if (e->mask & IN_MOVED_TO) {
 133                 if (e->cookie == prev_cookie) {
 134                         ne.action = NOTIFY_ACTION_NEW_NAME;
 135                 } else {
 136                         ne.action = NOTIFY_ACTION_ADDED;
 137                 }
 138         } else {
 139                 ne.action = NOTIFY_ACTION_MODIFIED;
 140         }
 141         ne.path = e->name;
 142
 143         /* find any watches that have this watch descriptor */
 144         for (w=in->watches;w;w=next) {
 145                 next = w->next;
 146                 if (w->wd == e->wd && filter_match(w, e)) {
 147                         w->callback(in->ctx, w->private_data, &ne);
 148                 }
 149         }
 150
 151         /* SMB expects a file rename to generate three events, two for
 152            the rename and the other for a modify of the
 153            destination. Strange! */
 154         if (ne.action != NOTIFY_ACTION_NEW_NAME ||
 155             (e->mask & IN_ISDIR) != 0) {
 156                 return;
 157         }
 158
 159         ne.action = NOTIFY_ACTION_MODIFIED;
 160         e->mask = IN_ATTRIB;
 161
 162         for (w=in->watches;w;w=next) {
 163                 next = w->next;
 164                 if (w->wd == e->wd && filter_match(w, e) &&
 165                     !(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
 166                         w->callback(in->ctx, w->private_data, &ne);
 167                 }
 168         }
 169 }
 170
 171 /*
 172   called when the kernel has some events for us
 173 */
 174 static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,
 175                             uint16_t flags, void *private_data)
 176 {
 177         struct inotify_private *in = talloc_get_type(private_data,
 178                                                      struct inotify_private);
 179         int bufsize = 0;
 180         struct inotify_event *e0, *e;
 181         uint32_t prev_cookie=0;
 182
 183         /*
 184           we must use FIONREAD as we cannot predict the length of the
 185           filenames, and thus can't know how much to allocate
 186           otherwise
 187         */
 188         if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
 189             bufsize == 0) {
 190                 DEBUG(0,("No data on inotify fd?!\n"));
 191                 return;
 192         }
 193
 194         e0 = e = talloc_size(in, bufsize);
 195         if (e == NULL) return;
 196
 197         if (read(in->fd, e0, bufsize) != bufsize) {
 198                 DEBUG(0,("Failed to read all inotify data\n"));
 199                 talloc_free(e0);
 200                 return;
 201         }
 202
 203         /* we can get more than one event in the buffer */
 204         while (bufsize >= sizeof(*e)) {
 205                 struct inotify_event *e2 = NULL;
 206                 bufsize -= e->len + sizeof(*e);
 207                 if (bufsize >= sizeof(*e)) {
 208                         e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
 209                 }
 210                 inotify_dispatch(in, e, prev_cookie, e2);
 211                 prev_cookie = e->cookie;
 212                 e = e2;
 213         }
 214
 215         talloc_free(e0);
 216 }
 217
 218 /*
 219   setup the inotify handle - called the first time a watch is added on
 220   this context
 221 */
 222 static NTSTATUS inotify_setup(struct sys_notify_context *ctx)
 223 {
 224         struct inotify_private *in;
 225         struct tevent_fd *fde;
 226
 227         in = talloc(ctx, struct inotify_private);
 228         NT_STATUS_HAVE_NO_MEMORY(in);
 229
 230         in->fd = inotify_init();
 231         if (in->fd == -1) {
 232                 DEBUG(0,("Failed to init inotify - %s\n", strerror(errno)));
 233                 talloc_free(in);
 234                 return map_nt_error_from_unix_common(errno);
 235         }
 236         in->ctx = ctx;
 237         in->watches = NULL;
 238
 239         ctx->private_data = in;
 240
 241         /* add a event waiting for the inotify fd to be readable */
 242         fde = tevent_add_fd(ctx->ev, in, in->fd,
 243                            TEVENT_FD_READ, inotify_handler, in);
 244         if (!fde) {
 245                 if (errno == 0) {
 246                         errno = ENOMEM;
 247                 }
 248                 DEBUG(0,("Failed to tevent_add_fd() - %s\n", strerror(errno)));
 249                 talloc_free(in);
 250                 return map_nt_error_from_unix_common(errno);
 251         }
 252
 253         tevent_fd_set_auto_close(fde);
 254
 255         return NT_STATUS_OK;
 256 }
 257
 258
 259 /*
 260   map from a change notify mask to a inotify mask. Remove any bits
 261   which we can handle
 262 */
 263 static const struct {
 264         uint32_t notify_mask;
 265         uint32_t inotify_mask;
 266 } inotify_mapping[] = {
 267         {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 268         {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
 269         {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
 270         {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},
 271         {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
 272         {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},
 273         {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}
 274 };
 275
 276 static uint32_t inotify_map(struct notify_entry *e)
 277 {
 278         int i;
 279         uint32_t out=0;
 280         for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
 281                 if (inotify_mapping[i].notify_mask & e->filter) {
 282                         out |= inotify_mapping[i].inotify_mask;
 283                         e->filter &= ~inotify_mapping[i].notify_mask;
 284                 }
 285         }
 286         return out;
 287 }
 288
 289 /*
 290   destroy a watch
 291 */
 292 static int watch_destructor(struct inotify_watch_context *w)
 293 {
 294         struct inotify_private *in = w->in;
 295         int wd = w->wd;
 296         DLIST_REMOVE(w->in->watches, w);
 297
 298         /* only rm the watch if its the last one with this wd */
 299         for (w=in->watches;w;w=w->next) {
 300                 if (w->wd == wd) break;
 301         }
 302         if (w == NULL) {
 303                 inotify_rm_watch(in->fd, wd);
 304         }
 305         return 0;
 306 }
 307
 308
 309 /*
 310   add a watch. The watch is removed when the caller calls
 311   talloc_free() on *handle
 312 */
 313 static NTSTATUS inotify_watch(struct sys_notify_context *ctx,
 314                               struct notify_entry *e,
 315                               sys_notify_callback_t callback,
 316                               void *private_data,
 317                               void *handle_p)
 318 {
 319         struct inotify_private *in;
 320         int wd;
 321         uint32_t mask;
 322         struct inotify_watch_context *w;
 323         uint32_t filter = e->filter;
 324         void **handle = (void **)handle_p;
 325
 326         /* maybe setup the inotify fd */
 327         if (ctx->private_data == NULL) {
 328                 NTSTATUS status;
 329                 status = inotify_setup(ctx);
 330                 NT_STATUS_NOT_OK_RETURN(status);
 331         }
 332
 333         in = talloc_get_type(ctx->private_data, struct inotify_private);
 334
 335         mask = inotify_map(e);
 336         if (mask == 0) {
 337                 /* this filter can't be handled by inotify */
 338                 return NT_STATUS_INVALID_PARAMETER;
 339         }
 340
 341         /* using IN_MASK_ADD allows us to cope with inotify() returning the same
 342            watch descriptor for muliple watches on the same path */
 343         mask |= (IN_MASK_ADD | IN_ONLYDIR);
 344
 345         /* get a new watch descriptor for this path */
 346         wd = inotify_add_watch(in->fd, e->path, mask);
 347         if (wd == -1) {
 348                 e->filter = filter;
 349                 return map_nt_error_from_unix_common(errno);
 350         }
 351
 352         w = talloc(in, struct inotify_watch_context);
 353         if (w == NULL) {
 354                 inotify_rm_watch(in->fd, wd);
 355                 e->filter = filter;
 356                 return NT_STATUS_NO_MEMORY;
 357         }
 358
 359         w->in = in;
 360         w->wd = wd;
 361         w->callback = callback;
 362         w->private_data = private_data;
 363         w->mask = mask;
 364         w->filter = filter;
 365         w->path = talloc_strdup(w, e->path);
 366         if (w->path == NULL) {
 367                 inotify_rm_watch(in->fd, wd);
 368                 e->filter = filter;
 369                 return NT_STATUS_NO_MEMORY;
 370         }
 371
 372         (*handle) = w;
 373
 374         DLIST_ADD(in->watches, w);
 375
 376         /* the caller frees the handle to stop watching */
 377         talloc_set_destructor(w, watch_destructor);
 378
 379         return NT_STATUS_OK;
 380 }
 381
 382
 383 static struct sys_notify_backend inotify = {
 384         .name = "inotify",
 385         .notify_watch = inotify_watch
 386 };
 387
 388 /*
 389   initialialise the inotify module
 390  */
 391 NTSTATUS sys_notify_inotify_init(void)
 392 {
 393         /* register ourselves as a system inotify module */
 394         return sys_notify_register(&inotify);
 395 }