NetBSD/usr.bin/locate/code/locate.code.c

166 lines
5.4 KiB
C

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* James A. Woods.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)locate.code.c 4.8 (Berkeley) 6/1/90";
#endif /* not lint */
/*
* PURPOSE: sorted list compressor (works with a modified 'find'
* to encode/decode a filename database)
*
* USAGE: bigram < list > bigrams
* process bigrams (see updatedb) > common_bigrams
* code common_bigrams < list > squozen_list
*
* METHOD: Uses 'front compression' (see ";login:", Volume 8, Number 1
* February/March 1983, p. 8 ). Output format is, per line, an
* offset differential count byte followed by a partially bigram-
* encoded ascii residue. A bigram is a two-character sequence,
* the first 128 most common of which are encoded in one byte.
*
* EXAMPLE: For simple front compression with no bigram encoding,
* if the input is... then the output is...
*
* /usr/src 0 /usr/src
* /usr/src/cmd/aardvark.c 8 /cmd/aardvark.c
* /usr/src/cmd/armadillo.c 14 armadillo.c
* /usr/tmp/zoo 5 tmp/zoo
*
* The codes are:
*
* 0-28 likeliest differential counts + offset to make nonnegative
* 30 switch code for out-of-range count to follow in next word
* 128-255 bigram codes (128 most common, as determined by 'updatedb')
* 32-127 single character (printable) ascii residue (ie, literal)
*
* SEE ALSO: updatedb.csh, bigram.c, find.c
*
* AUTHOR: James A. Woods, Informatics General Corp.,
* NASA Ames Research Center, 10/82
*/
#include <sys/param.h>
#include <stdio.h>
#include "locate.h"
#define BGBUFSIZE (NBG * 2) /* size of bigram buffer */
char buf1[MAXPATHLEN] = " ";
char buf2[MAXPATHLEN];
char bigrams[BGBUFSIZE + 1] = { 0 };
main ( argc, argv )
int argc; char *argv[];
{
register char *cp, *oldpath = buf1, *path = buf2;
int code, count, diffcount, oldcount = 0;
FILE *fp;
if ((fp = fopen(argv[1], "r")) == NULL) {
printf("Usage: code common_bigrams < list > squozen_list\n");
exit(1);
}
/* first copy bigram array to stdout */
fgets ( bigrams, BGBUFSIZE + 1, fp );
fwrite ( bigrams, 1, BGBUFSIZE, stdout );
fclose( fp );
while ( fgets ( path, sizeof(buf2), stdin ) != NULL ) {
/* truncate newline */
cp = path + strlen(path) - 1;
if (cp > path && *cp == '\n')
*cp = '\0';
/* squelch characters that would botch the decoding */
for ( cp = path; *cp != NULL; cp++ ) {
if ( (unsigned char)*cp >= PARITY )
*cp &= PARITY-1;
else if ( *cp <= SWITCH )
*cp = '?';
}
/* skip longest common prefix */
for ( cp = path; *cp == *oldpath; cp++, oldpath++ )
if ( *oldpath == NULL )
break;
count = cp - path;
diffcount = count - oldcount + OFFSET;
oldcount = count;
if ( diffcount < 0 || diffcount > 2*OFFSET ) {
putc ( SWITCH, stdout );
putw ( diffcount, stdout );
}
else
putc ( diffcount, stdout );
while ( *cp != NULL ) {
if ( *(cp + 1) == NULL ) {
putchar ( *cp );
break;
}
if ( (code = bgindex ( cp )) < 0 ) {
putchar ( *cp++ );
putchar ( *cp++ );
}
else { /* found, so mark byte with parity bit */
putchar ( (code / 2) | PARITY );
cp += 2;
}
}
if ( path == buf1 ) /* swap pointers */
path = buf2, oldpath = buf1;
else
path = buf1, oldpath = buf2;
}
}
bgindex ( bg ) /* return location of bg in bigrams or -1 */
char *bg;
{
register char *p;
register char bg0 = bg[0], bg1 = bg[1];
for ( p = bigrams; *p != NULL; p++ )
if ( *p++ == bg0 && *p == bg1 )
break;
return ( *p == NULL ? -1 : --p - bigrams );
}