/* prmcix.c: MUTATOR CONTEXT (POSIX)
 *
 * $Id$
 * Copyright (c) 2016-2020 Ravenbrook Limited.  See end of file for license.
 *
 * .purpose: Implement the mutator context module. <design/prmc>.
 *
 *
 * ASSUMPTIONS
 *
 * .context.regroots: The root registers are assumed to be recorded in
 * the context at pointer-aligned boundaries.
 */

#include "mpm.h"

#if !defined(MPS_OS_FR) && !defined(MPS_OS_LI) && !defined(MPS_OS_CY)
#error "prmcix.c is specific to MPS_OS_FR, MPS_OS_LI, or MPS_OS_CY"
#endif

#include "prmcix.h"

SRCID(prmcix, "$Id$");


Bool MutatorContextCheck(MutatorContext context)
{
  CHECKS(MutatorContext, context);
  CHECKL(NONNEGATIVE(context->var));
  CHECKL(context->var < MutatorContextLIMIT);
  CHECKL((context->var == MutatorContextTHREAD) == (context->info == NULL));
  CHECKL(context->ucontext != NULL);
  return TRUE;
}


void MutatorContextInitFault(MutatorContext context, siginfo_t *info,
                             ucontext_t *ucontext)
{
  AVER(context != NULL);
  AVER(info != NULL);
  AVER(ucontext != NULL);

  context->var = MutatorContextFAULT;
  context->info = info;
  context->ucontext = ucontext;
  context->sig = MutatorContextSig;

  AVERT(MutatorContext, context);
}


void MutatorContextInitThread(MutatorContext context, ucontext_t *ucontext)
{
  AVER(context != NULL);
  AVER(ucontext != NULL);

  context->var = MutatorContextTHREAD;
  context->info = NULL;
  context->ucontext = ucontext;
  context->sig = MutatorContextSig;

  AVERT(MutatorContext, context);
}


Res MutatorContextScan(ScanState ss, MutatorContext context,
                       mps_area_scan_t scan_area, void *closure)
{
  mcontext_t *mc;
  Res res;

  /* This scans the root registers (.context.regroots).  It also
     unnecessarily scans the rest of the context.  The optimisation
     to scan only relevant parts would be machine dependent. */
  mc = &context->ucontext->uc_mcontext;
  res = TraceScanArea(ss,
                      (Word *)mc,
                      (Word *)((char *)mc + sizeof(*mc)),
                      scan_area, closure);
  return res;
}


/* C. COPYRIGHT AND LICENSE
 *
 * Copyright (C) 2016-2020 Ravenbrook Limited <https://www.ravenbrook.com/>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */