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//
// iovec.c
//
// Scatter/gather utility routines
//
// Copyright (C) 2002 Michael Ringgaard. 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.  
// 3. Neither the name of the project nor the names of its contributors
//    may be used to endorse or promote products derived from this software
//    without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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 <os/krnl.h>

int check_iovec(struct iovec *iov, int iovlen, int modify) {
  if (iov) {
    if (iovlen < 0) return -EINVAL;
    if (!mem_access(iov, iovlen * sizeof(struct iovec), PT_USER_READ)) return -EFAULT;
    while (iovlen > 0) {
      if (iov->iov_len < 0) return -EINVAL;
      if (iov->iov_base) {
        if (!mem_access(iov->iov_base, iov->iov_len, modify ? PT_USER_WRITE : PT_USER_READ)) return -EFAULT;
      } else if (iov->iov_len != 0) {
        return -EFAULT;
      }

      iov++;
      iovlen--;
    }
  } else {
    if (iovlen != 0) return -EFAULT;
  }

  return 0;
}

size_t get_iovec_size(struct iovec *iov, int iovlen) {
  size_t size = 0;

  while (iovlen > 0) {
    size += iov->iov_len;
    iov++;
    iovlen--;
  }

  return size;
}

struct iovec *dup_iovec(struct iovec *iov, int iovlen) {
  struct iovec *newiov;

  newiov = (struct iovec *) kmalloc(iovlen * sizeof(struct iovec));
  if (!newiov) return NULL;
  memcpy(newiov, iov, iovlen * sizeof(struct iovec));

  return newiov;
}

int read_iovec(struct iovec *iov, int iovlen, char *buf, size_t count) {
  size_t read = 0;
  size_t len;

  while (count > 0 && iovlen > 0) {
    if (iov->iov_len > 0) {
      len = iov->iov_len;
      if (count < iov->iov_len) len = count;

      memcpy(buf, iov->iov_base, len);
      read += len;

      (char *) iov->iov_base += len;
      iov->iov_len -= len;

      buf += len;
      count -= len;
    }

    iov++;
    iovlen--;
  }

  return read;
}

int write_iovec(struct iovec *iov, int iovlen, char *buf, size_t count) {
  size_t written = 0;
  size_t len;

  while (count > 0 && iovlen > 0) {
    if (iov->iov_len > 0) {
      len = iov->iov_len;
      if (count < iov->iov_len) len = count;

      memcpy(iov->iov_base, buf, len);
      written += len;

      (char *) iov->iov_base += len;
      iov->iov_len -= len;

      buf += len;
      count -= len;
    }

    iov++;
    iovlen--;
  }

  return written;
}