/*-*- 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/calls/strace.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/calls/syscall_support-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"

#define F_DUP2FD         10
#define F_DUP2FD_CLOEXEC 18

int32_t sys_dup3(int32_t oldfd, int32_t newfd, int flags) {
  static bool once;
  static bool demodernize;
  int olderr, how, fd;
  if (!once) {
    olderr = errno;
    fd = __sys_dup3(oldfd, newfd, flags);
    if (fd == -1 && errno == ENOSYS) {
      STRACE("demodernizing %s() due to %s", "dup3", "RHEL5:CVE-2010-3301");
      demodernize = true;
      once = true;
      errno = olderr;
    } else {
      once = true;
      return fd;
    }
  } else if (!demodernize) {
    return __sys_dup3(oldfd, newfd, flags);
  }
  if (oldfd == newfd) return einval();
  if (flags & ~O_CLOEXEC) return einval();
  if (IsFreebsd()) {
    how = flags & O_CLOEXEC ? F_DUP2FD_CLOEXEC : F_DUP2FD;
    return __sys_fcntl(oldfd, how, newfd);
  } else {
    return __fixupnewfd(sys_dup2(oldfd, newfd), flags);
  }
}