/* syscall-clamp.c - Syscall clamp related stuff

 * Copyright (C) 2016, 2017 g10 Code GmbH

 *

 * This file is part of Libgpg-error.

 *

 * Libgpg-error is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * Libgpg-error 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not, see <https://www.gnu.org/licenses/>.

 * SPDX-License-Identifier: LGPL-2.1+

 */

#include <config.h>

#include "gpgrt-int.h"

/*

 * Functions called before and after blocking syscalls.

 * gpgrt_set_syscall_clamp is used to set them.

 */

static void (*pre_syscall_func)(void);

static void (*post_syscall_func)(void);

/*

 * Register the syscall clamp.  These two functions are called

 * immediately before and after a possible blocking system call.  This

 * should be used before any I/O happens.  The function is commonly

 * used with the nPth library:

 *

 *    gpgrt_set_syscall_clamp (npth_unprotect, npth_protect);

 *

 * These functions may not modify ERRNO.

 *

 * Setting the clamp is not thread-safe and should thus be done as

 * early as possible.

 */

void

_gpgrt_set_syscall_clamp (void (*pre)(void), void (*post)(void))

{

  pre_syscall_func = pre;

  post_syscall_func = post;

}

/*

 * Return the current sycall clamp functions.  This can be used by

 * other libraries which have blocking functions.

 */

void

_gpgrt_get_syscall_clamp (void (**r_pre)(void), void (**r_post)(void))

{

  *r_pre  = pre_syscall_func;

  *r_post = post_syscall_func;

}

/* Call this function before a blocking system or libc call.  */

void

_gpgrt_pre_syscall (void)

{

  if (pre_syscall_func)

    pre_syscall_func ();

}

/* Call this function after a blocking system or libc call.  */

void

_gpgrt_post_syscall (void)

{

  if (post_syscall_func)

    post_syscall_func ();

}