/* $OpenBSD: atomicio.c,v 1.30 2019/01/24 02:42:23 dtucker Exp $ */

/*

 * Copyright (c) 2006 Damien Miller. All rights reserved.

 * Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.

 * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "includes.h"

#include <sys/uio.h>

#include <errno.h>

#include <poll.h>

#include <string.h>

#include <unistd.h>

#include <limits.h>

#include "atomicio.h"

/*

 * ensure all of data on socket comes through. f==read || f==vwrite

 */

size_t

atomicio6(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n,

    int (*cb)(void *, size_t), void *cb_arg)

{

  char *s = _s;

  size_t pos = 0;

  ssize_t res;

  struct pollfd pfd;

  pfd.fd = fd;

#ifndef BROKEN_READ_COMPARISON

  pfd.events = f == read ? POLLIN : POLLOUT;

#else

  pfd.events = POLLIN|POLLOUT;

#endif

  while (n > pos) {

    res = (f) (fd, s + pos, n - pos);

    switch (res) {

    case -1:

      if (errno == EINTR) {

        /* possible SIGALARM, update callback */

        if (cb != NULL && cb(cb_arg, 0) == -1) {

          errno = EINTR;

          return pos;

        }

        continue;

      } else if (errno == EAGAIN || errno == EWOULDBLOCK) {

        (void)poll(&pfd, 1, -1);

        continue;

      }

      return 0;

    case 0:

      errno = EPIPE;

      return pos;

    default:

      pos += (size_t)res;

      if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {

        errno = EINTR;

        return pos;

      }

    }

  }

  return pos;

}

size_t

atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)

{

  return atomicio6(f, fd, _s, n, NULL, NULL);

}

/*

 * ensure all of data on socket comes through. f==readv || f==writev

 */

size_t

atomiciov6(ssize_t (*f) (int, const struct iovec *, int), int fd,

    const struct iovec *_iov, int iovcnt,

    int (*cb)(void *, size_t), void *cb_arg)

{

  size_t pos = 0, rem;

  ssize_t res;

  struct iovec iov_array[IOV_MAX], *iov = iov_array;

  struct pollfd pfd;

  if (iovcnt < 0 || iovcnt > IOV_MAX) {

    errno = EINVAL;

    return 0;

  }

  /* Make a copy of the iov array because we may modify it below */

  memcpy(iov, _iov, (size_t)iovcnt * sizeof(*_iov));

  pfd.fd = fd;

#ifndef BROKEN_READV_COMPARISON

  pfd.events = f == readv ? POLLIN : POLLOUT;

#else

  pfd.events = POLLIN|POLLOUT;

#endif

  for (; iovcnt > 0 && iov[0].iov_len > 0;) {

    res = (f) (fd, iov, iovcnt);

    switch (res) {

    case -1:

      if (errno == EINTR) {

        /* possible SIGALARM, update callback */

        if (cb != NULL && cb(cb_arg, 0) == -1) {

          errno = EINTR;

          return pos;

        }

        continue;

      } else if (errno == EAGAIN || errno == EWOULDBLOCK) {

        (void)poll(&pfd, 1, -1);

        continue;

      }

      return 0;

    case 0:

      errno = EPIPE;

      return pos;

    default:

      rem = (size_t)res;

      pos += rem;

      /* skip completed iov entries */

      while (iovcnt > 0 && rem >= iov[0].iov_len) {

        rem -= iov[0].iov_len;

        iov++;

        iovcnt--;

      }

      /* This shouldn't happen... */

      if (rem > 0 && (iovcnt <= 0 || rem > iov[0].iov_len)) {

        errno = EFAULT;

        return 0;

      }

      if (iovcnt == 0)

        break;

      /* update pointer in partially complete iov */

      iov[0].iov_base = ((char *)iov[0].iov_base) + rem;

      iov[0].iov_len -= rem;

    }

    if (cb != NULL && cb(cb_arg, (size_t)res) == -1) {

      errno = EINTR;

      return pos;

    }

  }

  return pos;

}

size_t

atomiciov(ssize_t (*f) (int, const struct iovec *, int), int fd,

    const struct iovec *_iov, int iovcnt)

{

  return atomiciov6(f, fd, _iov, iovcnt, NULL, NULL);

}