1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * James A. Woods. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #ifndef lint 12 static char copyright[] = 13 "@(#) Copyright (c) 1989, 1993\n\ 14 The Regents of the University of California. All rights reserved.\n"; 15 #endif /* not lint */ 16 17 #ifndef lint 18 static char sccsid[] = "@(#)locate.code.c 8.2 (Berkeley) 04/27/95"; 19 #endif /* not lint */ 20 21 /* 22 * PURPOSE: sorted list compressor (works with a modified 'find' 23 * to encode/decode a filename database) 24 * 25 * USAGE: bigram < list > bigrams 26 * process bigrams (see updatedb) > common_bigrams 27 * code common_bigrams < list > squozen_list 28 * 29 * METHOD: Uses 'front compression' (see ";login:", Volume 8, Number 1 30 * February/March 1983, p. 8). Output format is, per line, an 31 * offset differential count byte followed by a partially bigram- 32 * encoded ascii residue. A bigram is a two-character sequence, 33 * the first 128 most common of which are encoded in one byte. 34 * 35 * EXAMPLE: For simple front compression with no bigram encoding, 36 * if the input is... then the output is... 37 * 38 * /usr/src 0 /usr/src 39 * /usr/src/cmd/aardvark.c 8 /cmd/aardvark.c 40 * /usr/src/cmd/armadillo.c 14 armadillo.c 41 * /usr/tmp/zoo 5 tmp/zoo 42 * 43 * The codes are: 44 * 45 * 0-28 likeliest differential counts + offset to make nonnegative 46 * 30 switch code for out-of-range count to follow in next word 47 * 128-255 bigram codes (128 most common, as determined by 'updatedb') 48 * 32-127 single character (printable) ascii residue (ie, literal) 49 * 50 * SEE ALSO: updatedb.csh, bigram.c 51 * 52 * AUTHOR: James A. Woods, Informatics General Corp., 53 * NASA Ames Research Center, 10/82 54 */ 55 56 #include <sys/param.h> 57 #include <err.h> 58 #include <errno.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <stdio.h> 62 #include "locate.h" 63 64 #define BGBUFSIZE (NBG * 2) /* size of bigram buffer */ 65 66 char buf1[MAXPATHLEN] = " "; 67 char buf2[MAXPATHLEN]; 68 char bigrams[BGBUFSIZE + 1] = { 0 }; 69 70 int bgindex __P((char *)); 71 void usage __P((void)); 72 73 int 74 main(argc, argv) 75 int argc; 76 char *argv[]; 77 { 78 register char *cp, *oldpath, *path; 79 int ch, code, count, diffcount, oldcount; 80 FILE *fp; 81 82 while ((ch = getopt(argc, argv, "")) != EOF) 83 switch(ch) { 84 case '?': 85 default: 86 usage(); 87 } 88 argc -= optind; 89 argv += optind; 90 91 if (argc != 1) 92 usage(); 93 94 if ((fp = fopen(argv[0], "r")) == NULL) 95 err(1, "%s", argv[0]); 96 97 /* First copy bigram array to stdout. */ 98 (void)fgets(bigrams, BGBUFSIZE + 1, fp); 99 if (fwrite(bigrams, 1, BGBUFSIZE, stdout) != BGBUFSIZE) 100 err(1, "stdout"); 101 (void)fclose(fp); 102 103 oldpath = buf1; 104 path = buf2; 105 oldcount = 0; 106 while (fgets(path, sizeof(buf2), stdin) != NULL) { 107 /* Truncate newline. */ 108 cp = path + strlen(path) - 1; 109 if (cp > path && *cp == '\n') 110 *cp = '\0'; 111 112 /* Squelch characters that would botch the decoding. */ 113 for (cp = path; *cp != NULL; cp++) { 114 if ((u_char)*cp >= PARITY) 115 *cp &= PARITY-1; 116 if (*cp <= SWITCH) 117 *cp = '?'; 118 } 119 120 /* Skip longest common prefix. */ 121 for (cp = path; *cp == *oldpath; cp++, oldpath++) 122 if (*oldpath == NULL) 123 break; 124 count = cp - path; 125 diffcount = count - oldcount + OFFSET; 126 oldcount = count; 127 if (diffcount < 0 || diffcount > 2 * OFFSET) { 128 if (putchar(SWITCH) == EOF || 129 putw(diffcount, stdout) == EOF) 130 err(1, "stdout"); 131 } else 132 if (putchar(diffcount) == EOF) 133 err(1, "stdout"); 134 135 while (*cp != NULL) { 136 if (*(cp + 1) == NULL) { 137 if (putchar(*cp) == EOF) 138 err(1, "stdout"); 139 break; 140 } 141 if ((code = bgindex(cp)) < 0) { 142 if (putchar(*cp++) == EOF || 143 putchar(*cp++) == EOF) 144 err(1, "stdout"); 145 } else { 146 /* Found, so mark byte with parity bit. */ 147 if (putchar((code / 2) | PARITY) == EOF) 148 err(1, "stdout"); 149 cp += 2; 150 } 151 } 152 if (path == buf1) { /* swap pointers */ 153 path = buf2; 154 oldpath = buf1; 155 } else { 156 path = buf1; 157 oldpath = buf2; 158 } 159 } 160 /* Non-zero status if there were errors */ 161 if (fflush(stdout) != 0 || ferror(stdout)) 162 exit(1); 163 exit(0); 164 } 165 166 int 167 bgindex(bg) /* Return location of bg in bigrams or -1. */ 168 char *bg; 169 { 170 register char bg0, bg1, *p; 171 172 bg0 = bg[0]; 173 bg1 = bg[1]; 174 for (p = bigrams; *p != NULL; p++) 175 if (*p++ == bg0 && *p == bg1) 176 break; 177 return (*p == NULL ? -1 : --p - bigrams); 178 } 179 180 void 181 usage() 182 { 183 (void)fprintf(stderr, 184 "usage: locate.code common_bigrams < list > squozen_list\n"); 185 exit(1); 186 } 187