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/* Convenience function to catch expected signals during an operation.
Copyright (C) 1996-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C Library 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <hurd/signal.h>
#include <hurd/sigpreempt.h>
#include <string.h>
#include <assert.h>
error_t
hurd_catch_signal (sigset_t sigset,
unsigned long int first, unsigned long int last,
error_t (*operate) (struct hurd_signal_preemptor *),
sighandler_t handler)
{
/* We need to restore the signal mask, because otherwise the
signal-handling code will have blocked the caught signal and for
instance calling hurd_catch_signal again would then dump core. */
sigjmp_buf buf;
void throw (int signo, long int sigcode, struct sigcontext *scp)
{ siglongjmp (buf, scp->sc_error ?: EGRATUITOUS); }
struct hurd_signal_preemptor preemptor =
{
sigset, first, last,
NULL, handler == SIG_ERR ? (sighandler_t) &throw : handler,
};
struct hurd_sigstate *const ss = _hurd_self_sigstate ();
error_t error;
if (handler != SIG_ERR)
/* Not our handler; don't bother saving state. */
error = 0;
else
/* This returns again with nonzero value when we preempt a signal. */
error = sigsetjmp (buf, 1);
if (error == 0)
{
/* Install a signal preemptor for the thread. */
__spin_lock (&ss->lock);
preemptor.next = ss->preemptors;
ss->preemptors = &preemptor;
__spin_unlock (&ss->lock);
/* Try the operation that might crash. */
(*operate) (&preemptor);
}
/* Either FUNCTION completed happily and ERROR is still zero, or it hit
an expected signal and `throw' made setjmp return the signal error
code in ERROR. Now we can remove the preemptor and return. */
__spin_lock (&ss->lock);
assert (ss->preemptors == &preemptor);
ss->preemptors = preemptor.next;
__spin_unlock (&ss->lock);
return error;
}
error_t
hurd_safe_memset (void *dest, int byte, size_t nbytes)
{
error_t operate (struct hurd_signal_preemptor *preemptor)
{
memset (dest, byte, nbytes);
return 0;
}
return hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),
(vm_address_t) dest, (vm_address_t) dest + nbytes,
&operate, SIG_ERR);
}
error_t
hurd_safe_copyout (void *dest, const void *src, size_t nbytes)
{
error_t operate (struct hurd_signal_preemptor *preemptor)
{
memcpy (dest, src, nbytes);
return 0;
}
return hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),
(vm_address_t) dest, (vm_address_t) dest + nbytes,
&operate, SIG_ERR);
}
error_t
hurd_safe_copyin (void *dest, const void *src, size_t nbytes)
{
error_t operate (struct hurd_signal_preemptor *preemptor)
{
memcpy (dest, src, nbytes);
return 0;
}
return hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),
(vm_address_t) src, (vm_address_t) src + nbytes,
&operate, SIG_ERR);
}
error_t
hurd_safe_memmove (void *dest, const void *src, size_t nbytes)
{
jmp_buf buf;
void throw (int signo, long int sigcode, struct sigcontext *scp)
{ longjmp (buf, scp->sc_error ?: EGRATUITOUS); }
struct hurd_signal_preemptor src_preemptor =
{
sigmask (SIGBUS) | sigmask (SIGSEGV),
(vm_address_t) src, (vm_address_t) src + nbytes,
NULL, (sighandler_t) &throw,
};
struct hurd_signal_preemptor dest_preemptor =
{
sigmask (SIGBUS) | sigmask (SIGSEGV),
(vm_address_t) dest, (vm_address_t) dest + nbytes,
NULL, (sighandler_t) &throw,
&src_preemptor
};
struct hurd_sigstate *const ss = _hurd_self_sigstate ();
error_t error;
/* This returns again with nonzero value when we preempt a signal. */
error = setjmp (buf);
if (error == 0)
{
/* Install a signal preemptor for the thread. */
__spin_lock (&ss->lock);
src_preemptor.next = ss->preemptors;
ss->preemptors = &dest_preemptor;
__spin_unlock (&ss->lock);
/* Do the copy; it might fault. */
memmove (dest, src, nbytes);
}
/* Either memmove completed happily and ERROR is still zero, or it hit
an expected signal and `throw' made setjmp return the signal error
code in ERROR. Now we can remove the preemptor and return. */
__spin_lock (&ss->lock);
assert (ss->preemptors == &dest_preemptor);
ss->preemptors = src_preemptor.next;
__spin_unlock (&ss->lock);
return error;
}
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