diff options
Diffstat (limited to 'doc/man3/ASYNC_WAIT_CTX_new.pod')
-rw-r--r-- | doc/man3/ASYNC_WAIT_CTX_new.pod | 73 |
1 files changed, 69 insertions, 4 deletions
diff --git a/doc/man3/ASYNC_WAIT_CTX_new.pod b/doc/man3/ASYNC_WAIT_CTX_new.pod index eeb2777a8b..9076be8171 100644 --- a/doc/man3/ASYNC_WAIT_CTX_new.pod +++ b/doc/man3/ASYNC_WAIT_CTX_new.pod @@ -4,13 +4,22 @@ ASYNC_WAIT_CTX_new, ASYNC_WAIT_CTX_free, ASYNC_WAIT_CTX_set_wait_fd, ASYNC_WAIT_CTX_get_fd, ASYNC_WAIT_CTX_get_all_fds, -ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd - functions to manage -waiting for asynchronous jobs to complete +ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd, +ASYNC_WAIT_CTX_set_callback, ASYNC_WAIT_CTX_get_callback, +ASYNC_WAIT_CTX_set_status, ASYNC_WAIT_CTX_get_status, ASYNC_callback_fn, +ASYNC_STATUS_UNSUPPORTED, ASYNC_STATUS_ERR, ASYNC_STATUS_OK, +ASYNC_STATUS_EAGAIN +- functions to manage waiting for asynchronous jobs to complete =head1 SYNOPSIS #include <openssl/async.h> + #define ASYNC_STATUS_UNSUPPORTED 0 + #define ASYNC_STATUS_ERR 1 + #define ASYNC_STATUS_OK 2 + #define ASYNC_STATUS_EAGAIN 3 + typedef int (*ASYNC_callback_fn)(void *arg); ASYNC_WAIT_CTX *ASYNC_WAIT_CTX_new(void); void ASYNC_WAIT_CTX_free(ASYNC_WAIT_CTX *ctx); int ASYNC_WAIT_CTX_set_wait_fd(ASYNC_WAIT_CTX *ctx, const void *key, @@ -26,6 +35,14 @@ waiting for asynchronous jobs to complete size_t *numaddfds, OSSL_ASYNC_FD *delfd, size_t *numdelfds); int ASYNC_WAIT_CTX_clear_fd(ASYNC_WAIT_CTX *ctx, const void *key); + int ASYNC_WAIT_CTX_set_callback(ASYNC_WAIT_CTX *ctx, + ASYNC_callback_fn callback, + void *callback_arg); + int ASYNC_WAIT_CTX_get_callback(ASYNC_WAIT_CTX *ctx, + ASYNC_callback_fn *callback, + void **callback_arg); + int ASYNC_WAIT_CTX_set_status(ASYNC_WAIT_CTX *ctx, int status); + int ASYNC_WAIT_CTX_get_status(ASYNC_WAIT_CTX *ctx); =head1 DESCRIPTION @@ -103,14 +120,58 @@ code that the job should be resumed by making the wait file descriptor "readable". Once resumed the engine should clear the wake signal on the wait file descriptor. +As well as a file descriptor, user code may also be notified via a callback. The +callback and data pointers are stored within the ASYNC_WAIT_CTX along with an +additional status field that can be used for the notification of retries from an +engine. This additional method can be used when the user thinks that a file +descriptor is too costly in terms of CPU cycles or in some context where a file +descriptor is not appropriate. + +ASYNC_WAIT_CTX_set_callback() sets the callback and the callback argument. The +callback will be called to notify user code when an engine completes a +cryptography operation. It is a requirement that the callback function is small +and non-blocking as it will be run in the context of a polling mechanism or an +interrupt. + +ASYNC_WAIT_CTX_get_callback() returns the callback set in the ASYNC_WAIT_CTX +structure. + +ASYNC_WAIT_CTX_set_status() allows an engine to set the current engine status. +The possible status values are the following: +ASYNC_STATUS_UNSUPPORTED: The engine does not support the callback mechanism. +This is the default value. The engine must call ASYNC_WAIT_CTX_set_status() to +set the status to some value other than ASYNC_STATUS_UNSUPPORTED if it intends +to enable the callback mechanism. +ASYNC_STATUS_ERR: The engine has a fatal problem with this request. The user +code should clean up this session. +ASYNC_STATUS_OK: The request has been successfully submitted. +ASYNC_STATUS_EAGAIN: The engine has some problem which will be recovered soon, +such as a buffer is full, so user code should resume the job. + +ASYNC_WAIT_CTX_get_status() allows user code to obtain the current status value. +If the status is any value other than ASYNC_STATUS_OK then the user code should +not expect to receive a callback from the engine even if one has been set. + +An example of the usage of the callback method might be the following. User +code would initiate cryptographic operations, and the engine code would dispatch +this operation to hardware, and if the dispatch is successful, then the engine +code would call ASYNC_pause_job() to return control to the user code. After +that, user code can perform other tasks. When the hardware completes the +operation, normally it is detected by a polling function or an interrupt, as the +user code set a callback by calling ASYNC_WAIT_CTX_set_callback() previously, +then the registered callback will be called. + =head1 RETURN VALUES ASYNC_WAIT_CTX_new() returns a pointer to the newly allocated ASYNC_WAIT_CTX or NULL on error. ASYNC_WAIT_CTX_set_wait_fd, ASYNC_WAIT_CTX_get_fd, ASYNC_WAIT_CTX_get_all_fds, -ASYNC_WAIT_CTX_get_changed_fds and ASYNC_WAIT_CTX_clear_fd all return 1 on -success or 0 on error. +ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd, +ASYNC_WAIT_CTX_set_callback, ASYNC_WAIT_CTX_get_callback and +ASYNC_WAIT_CTX_set_status all return 1 on success or 0 on error. +ASYNC_WAIT_CTX_get_status() returs the engine status. + =head1 NOTES @@ -132,6 +193,10 @@ ASYNC_WAIT_CTX_get_fd(), ASYNC_WAIT_CTX_get_all_fds(), ASYNC_WAIT_CTX_get_changed_fds() and ASYNC_WAIT_CTX_clear_fd() were added in OpenSSL 1.1.0. +ASYNC_WAIT_CTX_set_callback(), ASYNC_WAIT_CTX_get_callback(), +ASYNC_WAIT_CTX_set_status(), and ASYNC_WAIT_CTX_get_status() +were added in OpenSSL 3.0.0. + =head1 COPYRIGHT Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. |