glibc/sysdeps/unix/sysv/linux/prlimit.c

/* Copyright (C) 2010-2017 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 <errno.h>
#include <sys/resource.h>
#include <sys/syscall.h>


int
prlimit (__pid_t pid, enum __rlimit_resource resource,
	 const struct rlimit *new_rlimit, struct rlimit *old_rlimit)
{
  struct rlimit64 new_rlimit64_mem;
  struct rlimit64 *new_rlimit64 = NULL;
  struct rlimit64 old_rlimit64_mem;
  struct rlimit64 *old_rlimit64 = (old_rlimit != NULL
				   ? &old_rlimit64_mem : NULL);

  if (new_rlimit != NULL)
    {
      if (new_rlimit->rlim_cur == RLIM_INFINITY)
	new_rlimit64_mem.rlim_cur = RLIM64_INFINITY;
      else
	new_rlimit64_mem.rlim_cur = new_rlimit->rlim_cur;
      if (new_rlimit->rlim_max == RLIM_INFINITY)
	new_rlimit64_mem.rlim_max = RLIM64_INFINITY;
      else
	new_rlimit64_mem.rlim_max = new_rlimit->rlim_max;
      new_rlimit64 = &new_rlimit64_mem;
    }

  int res = INLINE_SYSCALL (prlimit64, 4, pid, resource, new_rlimit64,
			    old_rlimit64);

  if (res == 0 && old_rlimit != NULL)
    {
      /* The prlimit64 syscall is ill-designed for 32-bit machines.
	 We have to provide a 32-bit variant since otherwise the LFS
	 system would not work.  But what shall we do if the syscall
	 succeeds but the old values do not fit into a rlimit
	 structure?  We cannot return an error because the operation
	 itself worked.  Best is perhaps to return RLIM_INFINITY.  */
      old_rlimit->rlim_cur = old_rlimit64_mem.rlim_cur;
      if (old_rlimit->rlim_cur != old_rlimit64_mem.rlim_cur)
	{
	  if (new_rlimit == NULL)
	    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EOVERFLOW);
	  old_rlimit->rlim_cur = RLIM_INFINITY;
	}
      old_rlimit->rlim_max = old_rlimit64_mem.rlim_max;
      if (old_rlimit->rlim_max != old_rlimit64_mem.rlim_max)
	{
	  if (new_rlimit == NULL)
	    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EOVERFLOW);
	  old_rlimit->rlim_max = RLIM_INFINITY;
	}
    }

  return res;
}