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/*
Unix SMB/CIFS implementation.
Infrastructure for async requests
Copyright (C) Volker Lendecke 2008
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
/**
* @brief Print an async_req structure
* @param[in] mem_ctx The memory context for the result
* @param[in] req The request to be printed
* @retval Text representation of req
*
* This is a default print function for async requests. Implementations should
* override this with more specific information.
*
* This function should not be used by async API users, this is non-static
* only to allow implementations to easily provide default information in
* their specific functions.
*/
char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
{
return talloc_asprintf(mem_ctx, "async_req: state=%d, status=%s, "
"priv=%s", req->state, nt_errstr(req->status),
talloc_get_name(req->private_data));
}
/**
* @brief Create an async request
* @param[in] mem_ctx The memory context for the result
* @param[in] ev The event context this async request will be driven by
* @retval A new async request
*
* The new async request will be initialized in state ASYNC_REQ_IN_PROGRESS
*/
struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev)
{
struct async_req *result;
result = TALLOC_ZERO_P(mem_ctx, struct async_req);
if (result == NULL) {
return NULL;
}
result->state = ASYNC_REQ_IN_PROGRESS;
result->event_ctx = ev;
result->print = async_req_print;
return result;
}
/**
* @brief An async request has successfully finished
* @param[in] req The finished request
*
* async_req_done is to be used by implementors of async requests. When a
* request is successfully finished, this function calls the user's completion
* function.
*/
void async_req_done(struct async_req *req)
{
req->status = NT_STATUS_OK;
req->state = ASYNC_REQ_DONE;
if (req->async.fn != NULL) {
req->async.fn(req);
}
}
/**
* @brief An async request has seen an error
* @param[in] req The request with an error
* @param[in] status The error code
*
* async_req_done is to be used by implementors of async requests. When a
* request can not successfully completed, the implementation should call this
* function with the appropriate status code.
*/
void async_req_error(struct async_req *req, NTSTATUS status)
{
req->status = status;
req->state = ASYNC_REQ_ERROR;
if (req->async.fn != NULL) {
req->async.fn(req);
}
}
/**
* @brief Timed event callback
* @param[in] ev Event context
* @param[in] te The timed event
* @param[in] now current time
* @param[in] priv The async request to be finished
*/
static void async_trigger(struct event_context *ev, struct timed_event *te,
const struct timeval *now, void *priv)
{
struct async_req *req = talloc_get_type_abort(priv, struct async_req);
TALLOC_FREE(te);
if (NT_STATUS_IS_OK(req->status)) {
async_req_done(req);
}
else {
async_req_error(req, req->status);
}
}
/**
* @brief Finish a request before it started processing
* @param[in] req The finished request
* @param[in] status The success code
*
* An implementation of an async request might find that it can either finish
* the request without waiting for an external event, or it can't even start
* the engine. To present the illusion of a callback to the user of the API,
* the implementation can call this helper function which triggers an
* immediate timed event. This way the caller can use the same calling
* conventions, independent of whether the request was actually deferred.
*/
bool async_post_status(struct async_req *req, NTSTATUS status)
{
req->status = status;
if (event_add_timed(req->event_ctx, req, timeval_zero(),
"async_trigger",
async_trigger, req) == NULL) {
return false;
}
return true;
}
/**
* @brief Helper function for nomem check
* @param[in] p The pointer to be checked
* @param[in] req The request being processed
*
* Convenience helper to easily check alloc failure within a callback
* implementing the next step of an async request.
*
* Call pattern would be
* \code
* p = talloc(mem_ctx, bla);
* if (async_req_nomem(p, req)) {
* return;
* }
* \endcode
*/
bool async_req_nomem(const void *p, struct async_req *req)
{
if (p != NULL) {
return false;
}
async_req_error(req, NT_STATUS_NO_MEMORY);
return true;
}
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