#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <netdb.h>
#include <fcntl.h>

/*
 * Stolen from the LAM/MPI 6.2 distribution
 * http://www.lam-mpi.org/
 */

int
mreadv(int fd, struct iovec *iov, int iovcnt)
{
  int		nread;		/* # of bytes read */
  int		r;
  int		savelen;	/* save full length */
  void		*savebase;	/* save original base ptr */
  
  nread = 0;
  
  if (iovcnt > 0) {
    savelen = iov->iov_len;
    savebase = iov->iov_base;
  }
  
  do {
    r = readv(fd, iov, iovcnt);
    
    if (r < 0) {
      
      if (errno != EINTR) {
	iov->iov_len = savelen;
	iov->iov_base = (char*) savebase;
	return(-1);
      }
    } else if (r == 0) {	/* eof */
      iov->iov_len = savelen;
      iov->iov_base = (char*) savebase;
      
      while ((iovcnt > 0) && (iov->iov_len == 0)) {
	iov++;
	iovcnt--;
      }
      
      if (iovcnt > 0) {
	errno = 3;
      }
      
      return((int) nread);
    } else {
      nread += r;
      
      while (r > 0) {
	
	if (r >= iov->iov_len) {
	  r -= iov->iov_len;
	  iov->iov_len = savelen;
	  iov->iov_base = (char*) savebase;
	  iov++;
	  iovcnt--;
	  
	  if (iovcnt > 0) {
	    savelen = iov->iov_len;
	    savebase = iov->iov_base;
	  }
	} else {
	  iov->iov_len -= r;
	  iov->iov_base = (char *) iov->iov_base + r;
	  r = 0;
	}
      }
      
      while ((iovcnt > 0) && (iov->iov_len == 0)) {
	iov++;
	iovcnt--;
	if (iovcnt > 0) {
	  savelen = iov->iov_len;
	  savebase = iov->iov_base;
	}
      }
    }
  } while (iovcnt > 0);
  
  return((int) nread);
}


int
mwritev(int fd, struct iovec *iov, int iovcnt)
{
  int		nwritten;	/* # of bytes written */
  int		r;
  int		savelen;	/* save full length */
  void		*savebase;	/* save original base ptr */
  
  nwritten = 0;
  
  if (iovcnt > 0) {
    savelen = iov->iov_len;
    savebase = iov->iov_base;
  }
  
  do {
    r = writev(fd, iov, iovcnt);
    
    if (r < 0) {
      
      if (errno != EINTR) {
	iov->iov_len = savelen;
	iov->iov_base = (char *) savebase;
	return(-1);
      }
    } else if (r == 0) {	/* eof */
      iov->iov_len = savelen;
      iov->iov_base = (char*) savebase;
      
      while ((iovcnt > 0) && (iov->iov_len == 0)) {
	iov++;
	iovcnt--;
      }
      
      if (iovcnt > 0) {
	errno = 3;
      }
      
      return((int) nwritten);
    } else {
      nwritten += r;
      
      while (r > 0) {
	
	if (r >= iov->iov_len) {
	  r -= iov->iov_len;
	  iov->iov_len = savelen;
	  iov->iov_base = (char *)savebase;
	  iov++;
	  iovcnt--;
	  
	  if (iovcnt > 0) {
	    savelen = iov->iov_len;
	    savebase = iov->iov_base;
	  }
	} else {
	  iov->iov_len -= r;
	  iov->iov_base =
	    (char *) iov->iov_base + r;
	  r = 0;
	}
      }
      
      while ((iovcnt > 0) && (iov->iov_len == 0)) {
	iov++;
	iovcnt--;
	if (iovcnt > 0) {
	  savelen = iov->iov_len;
	  savebase = iov->iov_base;
	}
      }
    }
  } while (iovcnt > 0);
  
  return((int) nwritten);
}