alcove

/* Copyright (c) 2014-2022, Michael Santos <michael.santos@gmail.com>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "alcove.h"
#include "alcove_call.h"

#include "alcove_rlimit_constants.h"

/*
 * setrlimit(2)
 *
 */
ssize_t alcove_sys_setrlimit(alcove_state_t *ap, const char *arg, size_t len,
                             char *reply, size_t rlen) {
  int index = 0;
  int arity = 0;

  int resource = 0;
  char atom[MAXATOMLEN] = {0};
  unsigned long long cur = 0, max = 0;
  struct rlimit rlim = {0};
  int rv = 0;
  size_t nproc = 0;

  UNUSED(ap);

  /* resource */
  switch (alcove_decode_constant(arg, len, &index, &resource,
                                 alcove_rlimit_constants)) {
  case 0:
    break;
  case 1:
    return alcove_mk_error(reply, rlen, "enotsup");
  default:
    return -1;
  }

  /* {alcove_rlimit, rlim_cur, rlim_max} */
  if (alcove_decode_tuple_header(arg, len, &index, &arity) < 0 || arity != 3)
    return -1;

  /* 'alcove_rlimit' */
  if (alcove_decode_atom(arg, len, &index, atom) < 0 ||
      strcmp(atom, "alcove_rlimit") != 0)
    return -1;

  /* rlim_cur: soft limit */
  if (alcove_decode_ulonglong(arg, len, &index, &cur) < 0)
    return -1;

  /* rlim_max: hard limit */
  if (alcove_decode_ulonglong(arg, len, &index, &max) < 0)
    return -1;

  if (resource == RLIMIT_NOFILE) {
    /* Check:
     * * fd limit is not below an existing fd
     * * fd limit is large enough to hold existing processes
     */
    if (pid_foreach(ap, 0, &nproc, &cur, pid_not_equal, fdlimit_pid) < 0)
      return alcove_mk_errno(reply, rlen, EINVAL);

    if (ALCOVE_NFD(nproc) > cur)
      return alcove_mk_errno(reply, rlen, EINVAL);
  }

  rlim.rlim_cur = cur;
  rlim.rlim_max = max;

  rv = setrlimit(resource, &rlim);

  if (rv < 0)
    return alcove_mk_errno(reply, rlen, errno);

  /* lower maxchild if RLIMIT_NOFILE reduced */
  if (resource == RLIMIT_NOFILE) {
    int maxchild = ALCOVE_MAXCHILD(cur);
    if (ap->maxchild > maxchild)
      ap->maxchild = maxchild;
  }

  return alcove_mk_atom(reply, rlen, "ok");
}