/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et 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/calls/calls.h"
#include "libc/calls/createfileflags.internal.h"
#include "libc/calls/internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/errno.h"
#include "libc/intrin/fds.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/weaken.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/zipos.internal.h"
#include "libc/sock/internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"

// Implements dup(), dup2(), dup3(), and F_DUPFD for Windows.
static textwindows int sys_dup_nt_impl(int oldfd, int newfd, int flags,
                                       int start) {
  int64_t rc, handle;
  unassert(!(flags & ~O_CLOEXEC));

  __fds_lock();

  if (!__isfdopen(oldfd) || newfd < -1) {
    __fds_unlock();
    return ebadf();
  }

  // allocate a new file descriptor
  if (newfd == -1) {
    if ((newfd = __reservefd_unlocked(start)) == -1) {
      __fds_unlock();
      return -1;
    }
  } else {
    if (__ensurefds_unlocked(newfd) == -1) {
      __fds_unlock();
      return -1;
    }
    if (g_fds.p[newfd].kind) {
      sys_close_nt(newfd, newfd);
    }
  }

  if (__isfdkind(oldfd, kFdZip)) {
    handle = (intptr_t)_weaken(__zipos_keep)(
        (struct ZiposHandle *)(intptr_t)g_fds.p[oldfd].handle);
    rc = newfd;
  } else {
    if (DuplicateHandle(GetCurrentProcess(), g_fds.p[oldfd].handle,
                        GetCurrentProcess(), &handle, 0, true,
                        kNtDuplicateSameAccess)) {
      rc = newfd;
    } else {
      rc = __winerr();
      __releasefd(newfd);
      __fds_unlock();
      return rc;
    }
  }

  g_fds.p[newfd] = g_fds.p[oldfd];
  g_fds.p[newfd].handle = handle;
  __cursor_ref(g_fds.p[newfd].cursor);
  if (flags & _O_CLOEXEC) {
    g_fds.p[newfd].flags |= _O_CLOEXEC;
  } else {
    g_fds.p[newfd].flags &= ~_O_CLOEXEC;
  }
  __fds_unlock();
  return rc;
}

textwindows int sys_dup_nt(int oldfd, int newfd, int flags, int start) {
  int rc;
  BLOCK_SIGNALS;
  rc = sys_dup_nt_impl(oldfd, newfd, flags, start);
  ALLOW_SIGNALS;
  return rc;
}
