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