/* Generic GNU/Linux target using traditional ptrace register access.

   Copyright (C) 1988-2020 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "linux-nat-trad.h"

#include "nat/gdb_ptrace.h"
#include "inf-ptrace.h"
#include "gdbarch.h"

/* Fetch register REGNUM from the inferior.  */

void
linux_nat_trad_target::fetch_register (struct regcache *regcache, int regnum)
{
  struct gdbarch *gdbarch = regcache->arch ();
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR addr;
  gdb_byte *buf;
  size_t size;
  pid_t pid;
  int i;

  /* This isn't really an address, but ptrace thinks of it as one.  */
  addr = register_u_offset (gdbarch, regnum, 0);
  if (addr == (CORE_ADDR)-1
      || gdbarch_cannot_fetch_register (gdbarch, regnum))
    {
      regcache->raw_supply (regnum, NULL);
      return;
    }

  pid = get_ptrace_pid (regcache->ptid ());

  size = register_size (gdbarch, regnum);
  buf = (gdb_byte *) alloca (size);

  /* Read the register contents from the inferior a chunk at a time.  */
  for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
    {
      size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
      PTRACE_TYPE_RET val;

      errno = 0;
      val = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, 0);
      if (errno != 0)
	error (_("Couldn't read register %s (#%d): %s."),
	       gdbarch_register_name (gdbarch, regnum),
	       regnum, safe_strerror (errno));
      store_unsigned_integer (buf + i, chunk, byte_order, val);

      addr += sizeof (PTRACE_TYPE_RET);
    }
  regcache->raw_supply (regnum, buf);
}

/* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
   for all registers.  */

void
linux_nat_trad_target::fetch_registers (struct regcache *regcache, int regnum)
{
  if (regnum == -1)
    for (regnum = 0;
	 regnum < gdbarch_num_regs (regcache->arch ());
	 regnum++)
      fetch_register (regcache, regnum);
  else
    fetch_register (regcache, regnum);
}

/* Store register REGNUM into the inferior.  */

void
linux_nat_trad_target::store_register (const struct regcache *regcache,
				       int regnum)
{
  struct gdbarch *gdbarch = regcache->arch ();
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR addr;
  size_t size;
  gdb_byte *buf;
  pid_t pid;
  int i;

  /* This isn't really an address, but ptrace thinks of it as one.  */
  addr = register_u_offset (gdbarch, regnum, 1);
  if (addr == (CORE_ADDR)-1
      || gdbarch_cannot_store_register (gdbarch, regnum))
    return;

  pid = get_ptrace_pid (regcache->ptid ());

  size = register_size (gdbarch, regnum);
  buf = (gdb_byte *) alloca (size);

  /* Write the register contents into the inferior a chunk at a time.  */
  regcache->raw_collect (regnum, buf);
  for (i = 0; i < size; i += sizeof (PTRACE_TYPE_RET))
    {
      size_t chunk = std::min (sizeof (PTRACE_TYPE_RET), size - i);
      PTRACE_TYPE_RET val;

      val = extract_unsigned_integer (buf + i, chunk, byte_order);
      errno = 0;
      ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) (uintptr_t) addr, val);
      if (errno != 0)
	error (_("Couldn't write register %s (#%d): %s."),
	       gdbarch_register_name (gdbarch, regnum),
	       regnum, safe_strerror (errno));

      addr += sizeof (PTRACE_TYPE_RET);
    }
}

/* Store register REGNUM back into the inferior.  If REGNUM is -1, do
   this for all registers.  */

void
linux_nat_trad_target::store_registers (struct regcache *regcache, int regnum)
{
  if (regnum == -1)
    for (regnum = 0;
	 regnum < gdbarch_num_regs (regcache->arch ());
	 regnum++)
      store_register (regcache, regnum);
  else
    store_register (regcache, regnum);
}