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/* 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
* 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 ();
}