/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ 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 "libc/assert.h"
#include "libc/bits/weaken.h"
#include "libc/calls/internal.h"
#include "libc/mem/mem.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"

int __ensurefds(int fd) {
  size_t n;
  struct Fd *p;
  if (fd < g_fds.n) return fd;
  if (weaken(malloc)) {
    n = MAX(fd + 1, g_fds.n + (g_fds.n << 1));
    if ((p = weaken(malloc)(n * sizeof(*p)))) {
      memcpy(p, g_fds.p, g_fds.n * sizeof(*p));
      memset(p + g_fds.n, 0, (n - g_fds.n) * sizeof(*p));
      if (g_fds.p != g_fds.__init_p && weaken(free)) {
        weaken(free)(g_fds.p);
      }
      g_fds.p = p;
      g_fds.n = n;
      return fd;
    } else {
      return enomem();
    }
  } else {
    return emfile();
  }
}