/* 
** by: Walter Bright via Usenet C newsgroup
**
** modified by: Bob Stout based on a recommendation by Ray Gardner
**
** modified by: David Gersic to deal with binary files
**
** There is no point in going to asm to get high speed file copies. Since it
** is inherently disk-bound, there is no sense (unless tiny code size is
** the goal). Here's a C version that you'll find is as fast as any asm code
** for files larger than a few bytes (the trick is to use large disk buffers):
**
** To compile file_copy(), define Afilecopy=1 on the command line
** To compile file_append(), define Afileappe=1 on the command line
*/

#include <stdlib.h>
#include <io.h>
#include <fcntl.h>

#if !defined(__ZTC__) && !defined(__TURBOC__)
 #include <sys\types.h>
#endif

#include <sys\stat.h>

#if Afilecopy
 int file_copy(char *from, char *to)
#else
 int file_append(char *from, char *to)
#endif
{
      int fdfrom,fdto;
      int bufsiz;

      fdfrom = open(from,O_RDONLY|O_BINARY,0);
      if (fdfrom < 0)
            return 1;
#if Afileappe

      /* Open R/W by owner, R by everyone else        */

      fdto=open(to,O_BINARY|O_CREAT|O_APPEND|O_RDWR,S_IREAD|S_IWRITE);
      if (fdto < 0)
            goto err;
#else
      fdto=open(to,O_BINARY|O_CREAT|O_TRUNC|O_RDWR,S_IREAD|S_IWRITE);
      if (fdto < 0)
            goto err;
#endif

      /* Use the largest buffer we can get    */

      for (bufsiz = 0x4000; bufsiz >= 128; bufsiz >>= 1)
      {
            register char *buffer;

            buffer = (char *) malloc(bufsiz);
            if (buffer)
            {
                  while (1)
                  {
                        register int n;

                        n = read(fdfrom,buffer,bufsiz);
                        if (n == -1)                /* if error             */
                              break;
                        if (n == 0)                 /* if end of file       */
                        {
                              free(buffer);
                              close(fdto);
                              close(fdfrom);
                              return 0;             /* success              */
                        }
                        if (n != write(fdto,buffer,(unsigned) n))
                              break;
                  }
                  free(buffer);
                  break;
            }
      }
err2: close(fdto);
      remove(to);                               /* delete any partial file  */
err:  close(fdfrom);
      return 1;
}