mirror of
https://github.com/openssl/openssl.git
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202 lines
7.0 KiB
Plaintext
202 lines
7.0 KiB
Plaintext
=pod
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=head1 NAME
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OSSL_EVENT_QUEUE, OSSL_EVENT, OSSL_EVENT_SUBSCRIPTION, ossl_event_callback_fn,
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ossl_event_queue_add, ossl_event_queue_add_new, ossl_event_free,
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ossl_event_get_type, ossl_event_get_priority, ossl_event_get_when,
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ossl_event_get0_payload,
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ossl_event_queue_new, ossl_event_queue_free,
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ossl_event_queue_schedule, ossl_event_queue_delete,
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ossl_event_time_until, ossl_event_queue_time_until_next,
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ossl_event_queue_postpone_until,
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ossl_event_queue_get1_next_event
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- event and timer queue
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=head1 SYNOPSIS
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#include "internal/event_queue.h"
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typedef OSSL_EVENT;
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typedef OSSL_EVENT_QUEUE;
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typedef OSSL_EVENT_SUBSCRIPTION;
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typedef int ossl_event_callback_fn(OSSL_EVENT *event, void *callback_data);
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OSSL_EVENT_QUEUE *ossl_event_queue_new(void);
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void ossl_event_queue_free(OSSL_EVENT_QUEUE *queue);
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int ossl_event_queue_add(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event,
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uint32_t type, uint32_t priority,
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OSSL_TIME when, void *ctx,
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void *payload, size_t payload_size);
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OSSL_EVENT *ossl_event_queue_add_new(OSSL_EVENT_QUEUE *queue,
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uint32_t type, uint32_t priority,
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OSSL_TIME when, void *ctx,
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void *payload, size_t payload_size);
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void ossl_event_free(OSSL_EVENT *event);
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uint32_t ossl_event_get_type(const OSSL_EVENT *event);
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uint32_t ossl_event_get_priority(const OSSL_EVENT *event);
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OSSL_TIME ossl_event_get_when(const OSSL_EVENT *event);
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void *ossl_event_get0_payload(const OSSL_EVENT *event, size_t *length);
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int ossl_event_queue_schedule(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event);
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int ossl_event_queue_delete(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event);
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OSSL_TIME ossl_event_time_until(OSSL_EVENT *event);
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OSSL_TIME ossl_event_queue_time_until_next(const OSSL_EVENT_QUEUE *queue);
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int ossl_event_queue_postpone_until(OSSL_EVENT_QUEUE *queue,
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OSSL_EVENT *event,
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OSSL_TIME when);
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int ossl_event_queue_get1_next_event(OSSL_EVENT_QUEUE *queue,
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OSSL_EVENT **event);
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=head1 DESCRIPTION
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These functions implement an event queue.
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=head2 Event
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An event is a small structure, B<OSSL_EVENT>, carrying information:
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=over 4
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=item type
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A mandatory event type, which is a simple numeric identity, the
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meaning of which is not known by the event functionality itself.
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=item priority
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A mandatory nonnegative integral quantity. The lower the priority the earlier
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the event will be processed.
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=item when
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An optional time indicating when the event could be triggered. Events are
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guaranteed to not trigger before their time.
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=item context
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A reference to user supplied contextual information. The event queue passes
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this to callbacks and never dereferences the pointer.
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=item payload, payload_size
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A reference to some event specific data of a specified length.
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=back
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The event itself is designed for a single synchronous thread, i.e. cannot be
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shared by multiple threads. The diverse objects it refers to may, however,
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be shared by multiple threads, at the discretion of the functions in the
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method structure.
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Once populated, the event type, the references to event context, and the
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reference to the destructor function are considered immutable, up until the
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event structure is destroyed.
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The reference to the auxiliary identifying material or to the payload,
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however, are considered mutable. Any event handler may "steal" them and
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replace the reference to them in the event structure with NULL. Stealing
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must be done with much care.
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Events may be embedded in another structure or as a static variable.
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Events may also be dynamically allocated.
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B<ossl_event_queue_add> initialises/reinitialises a static event object
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with the specified parameters and adds it to the event queue I<queue>.
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The event object I<event> has it's fields set to the passed parameters.
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B<ossl_event_queue_add_new> allocates a new timer event on the heap
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and initialises and adds it as per B<ossl_event_queue_add>. A pointer to the
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new event is returned on success and NULL is returned on error.
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B<ossl_event_free> frees an allocated event returned by B<ossl_event_new>.
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Does nothing if passed a pointer to a static event object which was initialised
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using B<ossl_event_set>.
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B<ossl_event_time_until> returns the time until I<event> would
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trigger. The event need not be part of an event queue.
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B<ossl_event_queue_postpone_until> reschedules the I<event>, which must
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be scheduled as part of timer event queue I<queue>, so that it will activate
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at time I<when>.
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B<ossl_event_get_type> returns the type of the I<event>.
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B<ossl_event_get_priority> returns the priority of the I<event>.
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B<ossl_event_get_when> returns the triggering time of the I<event>.
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B<ossl_event_get0_payload> returns the payload for the I<event>, the length
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of the payload is stored in I<length>.
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=head2 Event queue
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B<OSSL_EVENT_QUEUE> is an opaque structure that defines a timer based
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event queue. Event queue objects can only be dynamically allocated.
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B<ossl_event_queue_new> returns a newly allocated event queue object.
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B<ossl_event_queue_free> frees a event queue object returned by
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B<ossl_event_queue_new>.
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B<ossl_event_queue_schedule> adds the specified I<event> to the timer
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event queue I<queue>. The I<event> must not already be contained by any
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timer event queue including I<queue>.
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B<ossl_event_queue_delete> removes the specified I<event> from the
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timer event queue I<queue>. The event must have previously been added
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to I<queue> using the B<ossl_event_queue_schedule> call and must not yet
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have triggered.
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B<ossl_event_queue_time_until_next> returns the time until the next
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event in the timer event queue I<queue> is scheduled to trigger.
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B<ossl_event_queue_get1_next_event> gets the next event to process.
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The event is removed from the event queue and, if dynamically allocated,
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must be freed by the caller. A NULL event is returned if there is no event
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to process.
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=head1 RETURN VALUES
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B<ossl_event_queue_new> returns a new timer queue or NULL on failure.
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B<ossl_event_new> returns a new event or NULL on failure.
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B<ossl_event_get_type>, B<ossl_event_get_priority> and
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B<ossl_event_get_when> return the corresponding event field.
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B<ossl_event_get0_payload> returns a pointer to the event's payload.
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B<ossl_event_queue_add>, B<ossl_event_queue_remove>,
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B<ossl_event_queue_postpone_until> and
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B<ossl_event_queue_get1_next_event> return 1 on success and 0 on failure.
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B<ossl_event_time_until> and B<ossl_event_queue_time_until_next>
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return a time until the next event or B<OSSL_TIME_INFINITY> if there is no
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next event.
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=head1 SEE ALSO
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L<OSSL_TIME(3)>
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=head1 HISTORY
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This functionality was added to OpenSSL 3.2.
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=head1 COPYRIGHT
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Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use this
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file except in compliance with the License. You can obtain a copy in the file
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LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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