/*

 * Unix SMB/CIFS implementation.

 * Samba system utilities

 * Copyright (C) Andrew Tridgell 1992-1998

 * Copyright (C) Jeremy Allison  1998-2005

 * Copyright (C) Timur Bakeyev        2005

 * Copyright (C) Bjoern Jacke    2006-2007

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#include "replace.h"

#include "system/filesys.h"

#include "lib/util/sys_rw.h"

#include <assert.h>

bool sys_valid_io_range(off_t offset, size_t length)

{

  uint64_t last_byte_ofs;

  if (offset < 0) {

    return false;

  }

  if (offset > INT64_MAX) {

    return false;

  }

  if (length > UINT32_MAX) {

    return false;

  }

  last_byte_ofs = (uint64_t)offset + (uint64_t)length;

  if (last_byte_ofs > INT64_MAX) {

    return false;

  }

  return true;

}

bool sys_io_ranges_overlap(size_t c1, off_t o1,

         size_t c2, off_t o2)

{

  if (c1 == 0 || c2 == 0) {

    return false;

  }

  if (o2 < o1) {

    /*

     *          o1

     *          |····c1····|

     *  o2

     *  |····c2···| ?

     */

    return (o2 + c2 > o1);

  } else {

    /*

     *  o1

     *  |····c1···|

     *          o2

     *          |····c2····| ?

     */

    return (o1 + c1 > o2);

  }

}

off_t sys_block_align_truncate(off_t len, off_t align)

{

  assert(align > 1);

  assert(((align - 1) & align) == 0);

  return len & (~align + 1);

}

off_t sys_block_align(off_t len, off_t align)

{

  assert(align > 1);

  assert(((align - 1) & align) == 0);

  return (len + (align - 1)) & ~(align - 1);

}

/*******************************************************************

A read wrapper that will deal with EINTR/EWOULDBLOCK

********************************************************************/

ssize_t sys_read(int fd, void *buf, size_t count)

{

  ssize_t ret;

  do {

    ret = read(fd, buf, count);

  } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||

             errno == EWOULDBLOCK));

  return ret;

}

/**

 * read wrapper, void variant:

 * This is intended to be used as a void variant of

 * read in situations where the caller wants to ignore

 * the result. Hence not checking for EAGAIN|EWOULDBLOCK.

 */

void sys_read_v(int fd, void *buf, size_t count)

{

  ssize_t ret;

  do {

    ret = read(fd, buf, count);

  } while (ret == -1 && errno == EINTR);

}

/*******************************************************************

A write wrapper that will deal with EINTR/EWOULDBLOCK.

********************************************************************/

ssize_t sys_write(int fd, const void *buf, size_t count)

{

  ssize_t ret;

  do {

    ret = write(fd, buf, count);

  } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||

             errno == EWOULDBLOCK));

  return ret;

}

/**

 * write wrapper to deal with EINTR and friends.

 * void-variant that ignores the number of bytes written.

 * This is intended to be used as a void variant of

 * write in situations where the caller wants to ignore

 * the result. Hence not checking for EAGAIN|EWOULDBLOCK.

 */

void sys_write_v(int fd, const void *buf, size_t count)

{

  ssize_t ret;

  do {

    ret = write(fd, buf, count);

  } while (ret == -1 && errno == EINTR);

}

/*******************************************************************

A writev wrapper that will deal with EINTR.

********************************************************************/

ssize_t sys_writev(int fd, const struct iovec *iov, int iovcnt)

{

  ssize_t ret;

  do {

    ret = writev(fd, iov, iovcnt);

  } while (ret == -1 && (errno == EINTR || errno == EAGAIN ||

             errno == EWOULDBLOCK));

  return ret;

}

/*******************************************************************

A pread wrapper that will deal with EINTR

********************************************************************/

ssize_t sys_pread(int fd, void *buf, size_t count, off_t off)

{

  ssize_t ret;

  do {

    ret = pread(fd, buf, count, off);

  } while (ret == -1 && errno == EINTR);

  return ret;

}

/*******************************************************************

 A pread wrapper that will deal with EINTR and never return a short

 read unless pread returns zero meaning EOF.

********************************************************************/

ssize_t sys_pread_full(int fd, void *buf, size_t count, off_t off)

{

  ssize_t total_read = 0;

  uint8_t *curr_buf = (uint8_t *)buf;

  size_t curr_count = count;

  off_t curr_off = off;

  bool ok;

  ok = sys_valid_io_range(off, count);

  if (!ok) {

    errno = EINVAL;

    return -1;

  }

  while (curr_count != 0) {

    ssize_t ret = sys_pread(fd,

          curr_buf,

          curr_count,

          curr_off);

    if (ret == -1) {

      return -1;

    }

    if (ret == 0) {

      /* EOF */

      break;

    }

    if (ret > curr_count) {

      errno = EIO;

      return -1;

    }

    curr_buf += ret;

    curr_count -= ret;

    curr_off += ret;

    total_read += ret;

  }

  return total_read;

}

/*******************************************************************

A write wrapper that will deal with EINTR

********************************************************************/

ssize_t sys_pwrite(int fd, const void *buf, size_t count, off_t off)

{

  ssize_t ret;

  do {

    ret = pwrite(fd, buf, count, off);

  } while (ret == -1 && errno == EINTR);

  return ret;

}

/*******************************************************************

 A pwrite wrapper that will deal with EINTR and never allow a short

 write unless the file system returns an error.

********************************************************************/

ssize_t sys_pwrite_full(int fd, const void *buf, size_t count, off_t off)

{

  ssize_t total_written = 0;

  const uint8_t *curr_buf = (const uint8_t *)buf;

  size_t curr_count = count;

  off_t curr_off = off;

  bool ok;

  ok = sys_valid_io_range(off, count);

  if (!ok) {

    errno = EINVAL;

    return -1;

  }

  while (curr_count != 0) {

    ssize_t ret = sys_pwrite(fd,

           curr_buf,

           curr_count,

           curr_off);

    if (ret == -1) {

      return -1;

    }

    if (ret == 0) {

      /* Ensure we can never spin. */

      errno = ENOSPC;

      return -1;

    }

    if (ret > curr_count) {

      errno = EIO;

      return -1;

    }

    curr_buf += ret;

    curr_count -= ret;

    curr_off += ret;

    total_written += ret;

  }

  return total_written;

}

/*******************************************************************

 A write wrapper that will deal with EINTR and never allow a short

 write unless the file system returns an error.

********************************************************************/

ssize_t sys_write_full(int fd, const void *buf, size_t count)

{

  ssize_t total_written = 0;

  const uint8_t *curr_buf = (const uint8_t *)buf;

  size_t curr_count = count;

  while (curr_count != 0) {

    ssize_t ret = sys_write(fd,

          curr_buf,

          curr_count);

    if (ret == -1) {

      return -1;

    }

    if (ret == 0) {

      /* Ensure we can never spin. */

      errno = ENOSPC;

      return -1;

    }

    if (ret > curr_count) {

      errno = EIO;

      return -1;

    }

    curr_buf += ret;

    curr_count -= ret;

    total_written += ret;

  }

  return total_written;

}