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/*
This file is part of GNUnet.
(C) 2011, 2012 Christian Grothoff
GNUnet 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, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file include/gnunet_helper_lib.h
* @brief API for dealing with (SUID) helper processes that communicate via
* GNUNET_MessageHeaders on stdin/stdout
* @author Philipp Toelke
* @author Christian Grothoff
*/
#ifndef GNUNET_HELPER_LIB_H
#define GNUNET_HELPER_LIB_H
#include "gnunet_scheduler_lib.h"
#include "gnunet_server_lib.h"
/**
* The handle to a helper process.
*/
struct GNUNET_HELPER_Handle;
/**
* Callback that will be called when the helper process dies. This is not called
* when the helper process is stoped using GNUNET_HELPER_stop()
*
* @param cls the closure from GNUNET_HELPER_start()
*/
typedef void (*GNUNET_HELPER_ExceptionCallback) (void *cls);
/**
* Starts a helper and begins reading from it. The helper process is
* restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
* or when the exp_cb callback is not NULL.
*
* @param with_control_pipe does the helper support the use of a control pipe for signalling?
* @param binary_name name of the binary to run
* @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
* argument must not be modified by the client for
* the lifetime of the helper handle)
* @param cb function to call if we get messages from the helper
* @param exp_cb the exception callback to call. Set this to NULL if the helper
* process has to be restarted automatically when it dies/crashes
* @param cb_cls closure for the above callbacks
* @return the new Handle, NULL on error
*/
struct GNUNET_HELPER_Handle *
GNUNET_HELPER_start (int with_control_pipe,
const char *binary_name,
char *const binary_argv[],
GNUNET_SERVER_MessageTokenizerCallback cb,
GNUNET_HELPER_ExceptionCallback exp_cb,
void *cb_cls);
/**
* Sends termination signal to the helper process. The helper process is not
* reaped; call GNUNET_HELPER_wait() for reaping the dead helper process.
*
* @param h the helper handle
* @param soft_kill if GNUNET_YES, signals termination by closing the helper's
* stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
* @return GNUNET_OK on success; GNUNET_SYSERR on error
*/
int
GNUNET_HELPER_kill (struct GNUNET_HELPER_Handle *h, int soft_kill);
/**
* Reap the helper process. This call is blocking(!). The helper process
* should either be sent a termination signal before or should be dead before
* calling this function
*
* @param h the helper handle
* @return GNUNET_OK on success; GNUNET_SYSERR on error
*/
int
GNUNET_HELPER_wait (struct GNUNET_HELPER_Handle *h);
/**
* Free's the resources occupied by the helper handle
*
* @param h the helper handle to free
*/
void
GNUNET_HELPER_destroy (struct GNUNET_HELPER_Handle *h);
/**
* Kills the helper, closes the pipe, frees the handle and calls wait() on the
* helper process
*
* @param h handle to helper to stop
* @param soft_kill if GNUNET_YES, signals termination by closing the helper's
* stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
*/
void
GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h, int soft_kill);
/**
* Continuation function.
*
* @param cls closure
* @param result GNUNET_OK on success,
* GNUNET_NO if helper process died
* GNUNET_SYSERR during GNUNET_HELPER_stop
*/
typedef void (*GNUNET_HELPER_Continuation)(void *cls,
int result);
/**
* Handle to cancel 'send'
*/
struct GNUNET_HELPER_SendHandle;
/**
* Send an message to the helper.
*
* @param h helper to send message to
* @param msg message to send
* @param can_drop can the message be dropped if there is already one in the queue?
* @param cont continuation to run once the message is out
* @param cont_cls closure for 'cont'
* @return NULL if the message was dropped,
* otherwise handle to cancel *cont* (actual transmission may
* not be abortable)
*/
struct GNUNET_HELPER_SendHandle *
GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
const struct GNUNET_MessageHeader *msg,
int can_drop,
GNUNET_HELPER_Continuation cont,
void *cont_cls);
/**
* Cancel a 'send' operation. If possible, transmitting the
* message is also aborted, but at least 'cont' won't be
* called.
*
* @param sh operation to cancel
*/
void
GNUNET_HELPER_send_cancel (struct GNUNET_HELPER_SendHandle *sh);
#endif /* end of include guard: GNUNET_HELPER_LIB_H */
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