HardenedBSD/usr.sbin/sup/lib/filecopy.c
Peter Wemm d14071a4b3 Import the unmodified version of the sup that we are using.
The heritage of this version is not clear.  It appears to be NetBSD
derived from some time ago.
1995-12-26 04:54:48 +00:00

66 lines
2.5 KiB
C

/*
* Copyright (c) 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the rights
* to redistribute these changes.
*/
/* filecopy -- copy a file from here to there
*
* Usage: i = filecopy (here,there);
* int i, here, there;
*
* Filecopy performs a fast copy of the file "here" to the
* file "there". Here and there are both file descriptors of
* open files; here is open for input, and there for output.
* Filecopy returns 0 if all is OK; -1 on error.
*
* I have performed some tests for possible improvements to filecopy.
* Using a buffer size of 10240 provides about a 1.5 times speedup
* over 512 for a file of about 200,000 bytes. Of course, other
* buffer sized should also work; this is a rather arbitrary choice.
* I have also tried inserting special startup code to attempt
* to align either the input or the output file to lie on a
* physical (512-byte) block boundary prior to the big loop,
* but this presents only a small (about 5% speedup, so I've
* canned that code. The simple thing seems to be good enough.
*
* HISTORY
* 20-Nov-79 Steven Shafer (sas) at Carnegie-Mellon University
* Rewritten for VAX; same as "filcopy" on PDP-11. Bigger buffer
* size (20 physical blocks) seems to be a big win; aligning things
* on block boundaries seems to be a negligible improvement at
* considerable cost in complexity.
*
*/
#define BUFFERSIZE 10240
int filecopy (here,there)
int here,there;
{
register int kount;
char buffer[BUFFERSIZE];
kount = 0;
while (kount == 0 && (kount=read(here,buffer,BUFFERSIZE)) > 0)
kount -= write (there,buffer,kount);
return (kount ? -1 : 0);
}