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WB_FCOPY.C
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1996-11-24
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/* +++Date last modified: 28-Jul-1996 */
/*
** by: Walter Bright via Usenet C newsgroup
**
** modified by: Bob Stout, Ray Gardner, and David Gersic
**
** 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):
*/
#include <stdlib.h>
#include <io.h>
#include <fcntl.h>
#include "snipfile.h"
#if !defined(__ZTC__) && !defined(__TURBOC__)
#include <sys\types.h>
#endif
#include <sys\stat.h>
int file_copy(char *from, char *to)
{
int fdfrom,fdto;
int bufsiz;
fdfrom = open(from,O_RDONLY|O_BINARY,0);
if (fdfrom < 0)
return Error_;
/* Open R/W by owner, R by everyone else */
fdto=open(to,O_BINARY|O_CREAT|O_TRUNC|O_RDWR,S_IREAD|S_IWRITE);
if (fdto >= 0)
{
if (Success_ == fdcopy(fdfrom, fdto))
{
close(fdto);
close(fdfrom);
return Success_;
}
else
{
close(fdto);
remove(to); /* delete any partial file */
}
}
close(fdfrom);
return Error_;
}
int fdcopy(int fdfrom, int fdto)
{
int bufsiz, retval = Error_;
/* 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 */
{
retval = Success_;
break;
}
if (n != write(fdto,buffer,(unsigned) n))
break;
}
free(buffer);
break;
}
}
return retval;
}