/* readn.c - From Jon C. Snader: Effective TCP/IP Programming
 *           Addison-Wesley 2000
 *           For better understanding, read the excellent Snader book.
 */

#include "etcp.h"

/* readn - read exactly len bytes from socket fd into buffer bp */
/*         It returns the number of characters actually read    */
/*         if successful, -1 in case of error.                  */
/*         The buffer is assumed to be of size at least len, and*/
/*         the data read is left as is, without '\0'.           */
int readn( SOCKET fd, char *bp, size_t len)
{
  int cnt;
  int rc;
  
  cnt = len;
  while ( cnt > 0 )
    {
      rc = recv( fd, bp, cnt, 0 );

      if ( rc < 0 )		/* read error? */
	{
	  if ( errno == EINTR )	/* interrupted? */
	    continue;		/* restart the read */
	  return -1;		/* return error */
	}
      if ( rc == 0 )		/* EOF? */
	return len - cnt;	/* return short count */
      bp += rc;
      cnt -= rc;
    }
  return len;
}