source4/ntvfs/posix/pvfs_notify.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    POSIX NTVFS backend - notify
   5
   6    Copyright (C) Andrew Tridgell 2006
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "vfs_posix.h"
  24 #include "lib/messaging/irpc.h"
  25 #include "messaging/messaging.h"
  26 #include "../lib/util/dlinklist.h"
  27 #include "lib/events/events.h"
  28
  29 /* pending notifies buffer, hung off struct pvfs_file for open directories
  30    that have used change notify */
  31 struct pvfs_notify_buffer {
  32         struct pvfs_file *f;
  33         uint32_t num_changes;
  34         struct notify_changes *changes;
  35         uint32_t max_buffer_size;
  36         uint32_t current_buffer_size;
  37         bool overflowed;
  38
  39         /* a list of requests waiting for events on this handle */
  40         struct notify_pending {
  41                 struct notify_pending *next, *prev;
  42                 struct ntvfs_request *req;
  43                 union smb_notify *info;
  44         } *pending;
  45 };
  46
  47 /*
  48   send a notify on the next event run.
  49 */
  50 static void pvfs_notify_send_next(struct tevent_context *ev, struct tevent_timer *te,
  51                                   struct timeval t, void *ptr)
  52 {
  53         struct ntvfs_request *req = talloc_get_type(ptr, struct ntvfs_request);
  54         req->async_states->send_fn(req);
  55 }
  56
  57
  58 /*
  59   send a reply to a pending notify request
  60 */
  61 static void pvfs_notify_send(struct pvfs_notify_buffer *notify_buffer,
  62                              NTSTATUS status, bool immediate)
  63 {
  64         struct notify_pending *pending = notify_buffer->pending;
  65         struct ntvfs_request *req;
  66         union smb_notify *info;
  67
  68         if (notify_buffer->current_buffer_size > notify_buffer->max_buffer_size &&
  69             notify_buffer->num_changes != 0) {
  70                 /* on buffer overflow return no changes and destroys the notify buffer */
  71                 notify_buffer->num_changes = 0;
  72                 while (notify_buffer->pending) {
  73                         pvfs_notify_send(notify_buffer, NT_STATUS_OK, immediate);
  74                 }
  75                 notify_buffer->overflowed = true;
  76                 return;
  77         }
  78
  79         /* see if there is anyone waiting */
  80         if (notify_buffer->pending == NULL) {
  81                 return;
  82         }
  83
  84         DLIST_REMOVE(notify_buffer->pending, pending);
  85
  86         req = pending->req;
  87         info = pending->info;
  88
  89         info->nttrans.out.num_changes = notify_buffer->num_changes;
  90         info->nttrans.out.changes = talloc_steal(req, notify_buffer->changes);
  91         notify_buffer->num_changes = 0;
  92         notify_buffer->overflowed = false;
  93         notify_buffer->changes = NULL;
  94         notify_buffer->current_buffer_size = 0;
  95
  96         talloc_free(pending);
  97
  98         if (info->nttrans.out.num_changes != 0) {
  99                 status = NT_STATUS_OK;
 100         }
 101
 102         req->async_states->status = status;
 103
 104         if (immediate) {
 105                 req->async_states->send_fn(req);
 106                 return;
 107         }
 108
 109         /* we can't call pvfs_notify_send() directly here, as that
 110            would free the request, and the ntvfs modules above us
 111            could use it, so call it on the next event */
 112         event_add_timed(req->ctx->event_ctx,
 113                         req, timeval_zero(), pvfs_notify_send_next, req);
 114 }
 115
 116 /*
 117   destroy a notify buffer. Called when the handle is closed
 118  */
 119 static int pvfs_notify_destructor(struct pvfs_notify_buffer *n)
 120 {
 121         notify_remove(n->f->pvfs->notify_context, n);
 122         n->f->notify_buffer = NULL;
 123         pvfs_notify_send(n, NT_STATUS_OK, true);
 124         return 0;
 125 }
 126
 127
 128 /*
 129   called when a async notify event comes in
 130 */
 131 static void pvfs_notify_callback(void *private_data, const struct notify_event *ev)
 132 {
 133         struct pvfs_notify_buffer *n = talloc_get_type(private_data, struct pvfs_notify_buffer);
 134         size_t len;
 135         struct notify_changes *n2;
 136         char *new_path;
 137
 138         if (n->overflowed) {
 139                 return;
 140         }
 141
 142         n2 = talloc_realloc(n, n->changes, struct notify_changes, n->num_changes+1);
 143         if (n2 == NULL) {
 144                 /* nothing much we can do for this */
 145                 return;
 146         }
 147         n->changes = n2;
 148
 149         new_path = talloc_strdup(n->changes, ev->path);
 150         if (new_path == NULL) {
 151                 return;
 152         }
 153         string_replace(new_path, '/', '\\');
 154
 155         n->changes[n->num_changes].action = ev->action;
 156         n->changes[n->num_changes].name.s = new_path;
 157         n->num_changes++;
 158
 159         /*
 160           work out how much room this will take in the buffer
 161         */
 162         len = 12 + strlen_m(ev->path)*2;
 163         if (len & 3) {
 164                 len += 4 - (len & 3);
 165         }
 166         n->current_buffer_size += len;
 167
 168         /* send what we have, unless its the first part of a rename */
 169         if (ev->action != NOTIFY_ACTION_OLD_NAME) {
 170                 pvfs_notify_send(n, NT_STATUS_OK, true);
 171         }
 172 }
 173
 174 /*
 175   setup a notify buffer on a directory handle
 176 */
 177 static NTSTATUS pvfs_notify_setup(struct pvfs_state *pvfs, struct pvfs_file *f,
 178                                   uint32_t buffer_size, uint32_t filter, bool recursive)
 179 {
 180         NTSTATUS status;
 181         struct notify_entry e;
 182
 183         f->notify_buffer = talloc_zero(f, struct pvfs_notify_buffer);
 184         NT_STATUS_HAVE_NO_MEMORY(f->notify_buffer);
 185
 186         f->notify_buffer->max_buffer_size = buffer_size;
 187         f->notify_buffer->f = f;
 188
 189         e.filter    = filter;
 190         e.path      = f->handle->name->full_name;
 191         if (recursive) {
 192                 e.subdir_filter = filter;
 193         } else {
 194                 e.subdir_filter = 0;
 195         }
 196
 197         status = notify_add(pvfs->notify_context, &e,
 198                             pvfs_notify_callback, f->notify_buffer);
 199         NT_STATUS_NOT_OK_RETURN(status);
 200
 201         talloc_set_destructor(f->notify_buffer, pvfs_notify_destructor);
 202
 203         return NT_STATUS_OK;
 204 }
 205
 206 /*
 207   called from the pvfs_wait code when either an event has come in, or
 208   the notify request has been cancelled
 209 */
 210 static void pvfs_notify_end(void *private_data, enum pvfs_wait_notice reason)
 211 {
 212         struct pvfs_notify_buffer *notify_buffer = talloc_get_type(private_data,
 213                                                                    struct pvfs_notify_buffer);
 214         if (reason == PVFS_WAIT_CANCEL) {
 215                 pvfs_notify_send(notify_buffer, NT_STATUS_CANCELLED, false);
 216         } else {
 217                 pvfs_notify_send(notify_buffer, NT_STATUS_OK, true);
 218         }
 219 }
 220
 221 /* change notify request - always async. This request blocks until the
 222    event buffer is non-empty */
 223 NTSTATUS pvfs_notify(struct ntvfs_module_context *ntvfs,
 224                      struct ntvfs_request *req,
 225                      union smb_notify *info)
 226 {
 227         struct pvfs_state *pvfs = talloc_get_type(ntvfs->private_data,
 228                                                   struct pvfs_state);
 229         struct pvfs_file *f;
 230         NTSTATUS status;
 231         struct notify_pending *pending;
 232
 233         if (info->nttrans.level != RAW_NOTIFY_NTTRANS) {
 234                 return ntvfs_map_notify(ntvfs, req, info);
 235         }
 236
 237         f = pvfs_find_fd(pvfs, req, info->nttrans.in.file.ntvfs);
 238         if (!f) {
 239                 return NT_STATUS_INVALID_HANDLE;
 240         }
 241
 242         /* this request doesn't make sense unless its async */
 243         if (!(req->async_states->state & NTVFS_ASYNC_STATE_MAY_ASYNC)) {
 244                 return NT_STATUS_INVALID_PARAMETER;
 245         }
 246
 247         /* its only valid for directories */
 248         if (f->handle->fd != -1) {
 249                 return NT_STATUS_INVALID_PARAMETER;
 250         }
 251
 252         /* if the handle doesn't currently have a notify buffer then
 253            create one */
 254         if (f->notify_buffer == NULL) {
 255                 status = pvfs_notify_setup(pvfs, f,
 256                                            info->nttrans.in.buffer_size,
 257                                            info->nttrans.in.completion_filter,
 258                                            info->nttrans.in.recursive);
 259                 NT_STATUS_NOT_OK_RETURN(status);
 260         }
 261
 262         /* we update the max_buffer_size on each call, but we do not
 263            update the recursive flag or filter */
 264         f->notify_buffer->max_buffer_size = info->nttrans.in.buffer_size;
 265
 266         pending = talloc(f->notify_buffer, struct notify_pending);
 267         NT_STATUS_HAVE_NO_MEMORY(pending);
 268
 269         pending->req = talloc_reference(pending, req);
 270         NT_STATUS_HAVE_NO_MEMORY(pending->req);
 271         pending->info = info;
 272
 273         DLIST_ADD_END(f->notify_buffer->pending, pending, struct notify_pending *);
 274
 275         /* if the buffer is empty then start waiting */
 276         if (f->notify_buffer->num_changes == 0 &&
 277             !f->notify_buffer->overflowed) {
 278                 struct pvfs_wait *wait_handle;
 279                 wait_handle = pvfs_wait_message(pvfs, req, -1,
 280                                                 timeval_zero(),
 281                                                 pvfs_notify_end,
 282                                                 f->notify_buffer);
 283                 NT_STATUS_HAVE_NO_MEMORY(wait_handle);
 284                 talloc_steal(req, wait_handle);
 285                 return NT_STATUS_OK;
 286         }
 287
 288         req->async_states->state |= NTVFS_ASYNC_STATE_ASYNC;
 289         pvfs_notify_send(f->notify_buffer, NT_STATUS_OK, false);
 290
 291         return NT_STATUS_OK;
 292 }