source4/ntvfs/posix/pvfs_wait.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    POSIX NTVFS backend - async request wait routines
   5
   6    Copyright (C) Andrew Tridgell 2004
   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 "lib/events/events.h"
  24 #include "../lib/util/dlinklist.h"
  25 #include "vfs_posix.h"
  26 #include "smbd/service_stream.h"
  27 #include "lib/messaging/irpc.h"
  28
  29 /* the context for a single wait instance */
  30 struct pvfs_wait {
  31         struct pvfs_wait *next, *prev;
  32         struct pvfs_state *pvfs;
  33         void (*handler)(void *, enum pvfs_wait_notice);
  34         void *private_data;
  35         int msg_type;
  36         struct imessaging_context *msg_ctx;
  37         struct tevent_context *ev;
  38         struct ntvfs_request *req;
  39         enum pvfs_wait_notice reason;
  40 };
  41
  42 /*
  43   called from the ntvfs layer when we have requested setup of an async
  44   call.  this ensures that async calls runs with the right state of
  45   previous ntvfs handlers in the chain (such as security context)
  46 */
  47 NTSTATUS pvfs_async_setup(struct ntvfs_module_context *ntvfs,
  48                           struct ntvfs_request *req, void *private_data)
  49 {
  50         struct pvfs_wait *pwait = talloc_get_type(private_data,
  51                                                   struct pvfs_wait);
  52         pwait->handler(pwait->private_data, pwait->reason);
  53         return NT_STATUS_OK;
  54 }
  55
  56 /*
  57   receive a completion message for a wait
  58 */
  59 static void pvfs_wait_dispatch(struct imessaging_context *msg,
  60                                void *private_data, uint32_t msg_type,
  61                                struct server_id src, DATA_BLOB *data)
  62 {
  63         struct pvfs_wait *pwait = talloc_get_type(private_data,
  64                                                   struct pvfs_wait);
  65         struct ntvfs_request *req;
  66         void *p = NULL;
  67
  68         /* we need to check that this one is for us. See
  69            imessaging_send_ptr() for the other side of this.
  70          */
  71         if (data->length == sizeof(void *)) {
  72                 void **pp;
  73                 pp = (void **)data->data;
  74                 p = *pp;
  75         }
  76         if (p == NULL || p != pwait->private_data) {
  77                 return;
  78         }
  79
  80         pwait->reason = PVFS_WAIT_EVENT;
  81
  82         /* the extra reference here is to ensure that the req
  83            structure is not destroyed when the async request reply is
  84            sent, which would cause problems with the other ntvfs
  85            modules above us */
  86         req = talloc_reference(msg, pwait->req);
  87         ntvfs_async_setup(pwait->req, pwait);
  88         talloc_unlink(msg, req);
  89 }
  90
  91
  92 /*
  93   receive a timeout on a message wait
  94 */
  95 static void pvfs_wait_timeout(struct tevent_context *ev,
  96                               struct tevent_timer *te, struct timeval t,
  97                               void *private_data)
  98 {
  99         struct pvfs_wait *pwait = talloc_get_type(private_data,
 100                                                   struct pvfs_wait);
 101         struct ntvfs_request *req = pwait->req;
 102
 103         pwait->reason = PVFS_WAIT_TIMEOUT;
 104
 105         req = talloc_reference(ev, req);
 106         if (req != NULL) {
 107                 ntvfs_async_setup(req, pwait);
 108                 talloc_unlink(ev, req);
 109         }
 110 }
 111
 112
 113 /*
 114   destroy a pending wait
 115  */
 116 static int pvfs_wait_destructor(struct pvfs_wait *pwait)
 117 {
 118         if (pwait->msg_type != -1) {
 119                 imessaging_deregister(pwait->msg_ctx, pwait->msg_type, pwait);
 120         }
 121         DLIST_REMOVE(pwait->pvfs->wait_list, pwait);
 122         return 0;
 123 }
 124
 125 /*
 126   setup a request to wait on a message of type msg_type, with a
 127   timeout (given as an expiry time)
 128
 129   the return value is a handle. To stop waiting talloc_free this
 130   handle.
 131
 132   if msg_type == -1 then no message is registered, and it is assumed
 133   that the caller handles any messaging setup needed
 134 */
 135 struct pvfs_wait *pvfs_wait_message(struct pvfs_state *pvfs,
 136                                     struct ntvfs_request *req,
 137                                     int msg_type,
 138                                     struct timeval end_time,
 139                                     void (*fn)(void *, enum pvfs_wait_notice),
 140                                     void *private_data)
 141 {
 142         struct pvfs_wait *pwait;
 143
 144         pwait = talloc(pvfs, struct pvfs_wait);
 145         if (pwait == NULL) {
 146                 return NULL;
 147         }
 148
 149         pwait->private_data = private_data;
 150         pwait->handler = fn;
 151         pwait->msg_ctx = pvfs->ntvfs->ctx->msg_ctx;
 152         pwait->ev = pvfs->ntvfs->ctx->event_ctx;
 153         pwait->msg_type = msg_type;
 154         pwait->req = talloc_reference(pwait, req);
 155         pwait->pvfs = pvfs;
 156
 157         if (!timeval_is_zero(&end_time)) {
 158                 /* setup a timer */
 159                 tevent_add_timer(pwait->ev, pwait, end_time, pvfs_wait_timeout, pwait);
 160         }
 161
 162         /* register with the messaging subsystem for this message
 163            type */
 164         if (msg_type != -1) {
 165                 imessaging_register(pwait->msg_ctx,
 166                                    pwait,
 167                                    msg_type,
 168                                    pvfs_wait_dispatch);
 169         }
 170
 171         /* tell the main smb server layer that we will be replying
 172            asynchronously */
 173         req->async_states->state |= NTVFS_ASYNC_STATE_ASYNC;
 174
 175         DLIST_ADD(pvfs->wait_list, pwait);
 176
 177         /* make sure we cleanup the timer and message handler */
 178         talloc_set_destructor(pwait, pvfs_wait_destructor);
 179
 180         return pwait;
 181 }
 182
 183
 184 /*
 185   cancel an outstanding async request
 186 */
 187 NTSTATUS pvfs_cancel(struct ntvfs_module_context *ntvfs, struct ntvfs_request *req)
 188 {
 189         struct pvfs_state *pvfs = talloc_get_type(ntvfs->private_data,
 190                                   struct pvfs_state);
 191         struct pvfs_wait *pwait;
 192
 193         for (pwait=pvfs->wait_list;pwait;pwait=pwait->next) {
 194                 if (pwait->req == req) {
 195                         /* trigger a cancel on the request */
 196                         pwait->reason = PVFS_WAIT_CANCEL;
 197                         ntvfs_async_setup(pwait->req, pwait);
 198                         return NT_STATUS_OK;
 199                 }
 200         }
 201
 202         return NT_STATUS_DOS(ERRDOS, ERRcancelviolation);
 203 }