1 /*- 2 * Copyright (c) 1991, 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 * David Hitz of Auspex Systems, Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #ifndef lint 38 static char copyright[] = 39 "@(#) Copyright (c) 1991, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41 #endif /* not lint */ 42 43 #ifndef lint 44 static char sccsid[] = "@(#)look.c 8.1 (Berkeley) 6/14/93"; 45 #endif /* not lint */ 46 47 /* 48 * look -- find lines in a sorted list. 49 * 50 * The man page said that TABs and SPACEs participate in -d comparisons. 51 * In fact, they were ignored. This implements historic practice, not 52 * the manual page. 53 */ 54 55 #include <sys/types.h> 56 #include <sys/mman.h> 57 #include <sys/stat.h> 58 59 #include <limits.h> 60 #include <locale.h> 61 #include <errno.h> 62 #include <fcntl.h> 63 #include <stdio.h> 64 #include <stdlib.h> 65 #include <string.h> 66 #include <ctype.h> 67 #include "pathnames.h" 68 69 /* 70 * FOLD and DICT convert characters to a normal form for comparison, 71 * according to the user specified flags. 72 * 73 * DICT expects integers because it uses a non-character value to 74 * indicate a character which should not participate in comparisons. 75 */ 76 #define EQUAL 0 77 #define GREATER 1 78 #define LESS (-1) 79 #define NO_COMPARE (-2) 80 81 #define FOLD(c) (isupper(c) ? tolower(c) : (unsigned char) (c)) 82 #define DICT(c) (isalnum(c) ? (c) & 0xFF /* int */ : NO_COMPARE) 83 84 int dflag, fflag; 85 86 char *binary_search __P((unsigned char *, unsigned char *, unsigned char *)); 87 int compare __P((unsigned char *, unsigned char *, unsigned char *)); 88 void err __P((const char *fmt, ...)); 89 char *linear_search __P((unsigned char *, unsigned char *, unsigned char *)); 90 int look __P((unsigned char *, unsigned char *, unsigned char *)); 91 void print_from __P((unsigned char *, unsigned char *, unsigned char *)); 92 93 static void usage __P((void)); 94 95 main(argc, argv) 96 int argc; 97 char *argv[]; 98 { 99 struct stat sb; 100 int ch, fd, termchar; 101 unsigned char *back, *file, *front, *string, *p; 102 103 (void) setlocale(LC_CTYPE, ""); 104 105 file = _PATH_WORDS; 106 termchar = '\0'; 107 while ((ch = getopt(argc, argv, "dft:")) != EOF) 108 switch(ch) { 109 case 'd': 110 dflag = 1; 111 break; 112 case 'f': 113 fflag = 1; 114 break; 115 case 't': 116 termchar = *optarg; 117 break; 118 case '?': 119 default: 120 usage(); 121 } 122 argc -= optind; 123 argv += optind; 124 125 switch (argc) { 126 case 2: /* Don't set -df for user. */ 127 string = *argv++; 128 file = *argv; 129 break; 130 case 1: /* But set -df by default. */ 131 dflag = fflag = 1; 132 string = *argv; 133 break; 134 default: 135 usage(); 136 } 137 138 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL) 139 *++p = '\0'; 140 141 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) 142 err("%s: %s", file, strerror(errno)); 143 if (sb.st_size > SIZE_T_MAX) 144 err("%s: %s", file, strerror(EFBIG)); 145 if ((front = mmap(NULL, 146 (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED) 147 err("%s: %s", file, strerror(errno)); 148 back = front + sb.st_size; 149 exit(look(string, front, back)); 150 } 151 152 look(string, front, back) 153 unsigned char *string, *front, *back; 154 { 155 register int ch; 156 register unsigned char *readp, *writep; 157 158 /* Reformat string string to avoid doing it multiple times later. */ 159 for (readp = writep = string; ch = *readp++;) { 160 if (fflag) 161 ch = FOLD(ch); 162 if (dflag) 163 ch = DICT(ch); 164 if (ch != NO_COMPARE) 165 *(writep++) = ch; 166 } 167 *writep = '\0'; 168 169 front = binary_search(string, front, back); 170 front = linear_search(string, front, back); 171 172 if (front) 173 print_from(string, front, back); 174 return (front ? 0 : 1); 175 } 176 177 178 /* 179 * Binary search for "string" in memory between "front" and "back". 180 * 181 * This routine is expected to return a pointer to the start of a line at 182 * *or before* the first word matching "string". Relaxing the constraint 183 * this way simplifies the algorithm. 184 * 185 * Invariants: 186 * front points to the beginning of a line at or before the first 187 * matching string. 188 * 189 * back points to the beginning of a line at or after the first 190 * matching line. 191 * 192 * Base of the Invariants. 193 * front = NULL; 194 * back = EOF; 195 * 196 * Advancing the Invariants: 197 * 198 * p = first newline after halfway point from front to back. 199 * 200 * If the string at "p" is not greater than the string to match, 201 * p is the new front. Otherwise it is the new back. 202 * 203 * Termination: 204 * 205 * The definition of the routine allows it return at any point, 206 * since front is always at or before the line to print. 207 * 208 * In fact, it returns when the chosen "p" equals "back". This 209 * implies that there exists a string is least half as long as 210 * (back - front), which in turn implies that a linear search will 211 * be no more expensive than the cost of simply printing a string or two. 212 * 213 * Trying to continue with binary search at this point would be 214 * more trouble than it's worth. 215 */ 216 #define SKIP_PAST_NEWLINE(p, back) \ 217 while (p < back && *p++ != '\n'); 218 219 char * 220 binary_search(string, front, back) 221 register unsigned char *string, *front, *back; 222 { 223 register unsigned char *p; 224 225 p = front + (back - front) / 2; 226 SKIP_PAST_NEWLINE(p, back); 227 228 /* 229 * If the file changes underneath us, make sure we don't 230 * infinitely loop. 231 */ 232 while (p < back && back > front) { 233 if (compare(string, p, back) == GREATER) 234 front = p; 235 else 236 back = p; 237 p = front + (back - front) / 2; 238 SKIP_PAST_NEWLINE(p, back); 239 } 240 return (front); 241 } 242 243 /* 244 * Find the first line that starts with string, linearly searching from front 245 * to back. 246 * 247 * Return NULL for no such line. 248 * 249 * This routine assumes: 250 * 251 * o front points at the first character in a line. 252 * o front is before or at the first line to be printed. 253 */ 254 char * 255 linear_search(string, front, back) 256 unsigned char *string, *front, *back; 257 { 258 while (front < back) { 259 switch (compare(string, front, back)) { 260 case EQUAL: /* Found it. */ 261 return (front); 262 break; 263 case LESS: /* No such string. */ 264 return (NULL); 265 break; 266 case GREATER: /* Keep going. */ 267 break; 268 } 269 SKIP_PAST_NEWLINE(front, back); 270 } 271 return (NULL); 272 } 273 274 /* 275 * Print as many lines as match string, starting at front. 276 */ 277 void 278 print_from(string, front, back) 279 register unsigned char *string, *front, *back; 280 { 281 for (; front < back && compare(string, front, back) == EQUAL; ++front) { 282 for (; front < back && *front != '\n'; ++front) 283 if (putchar(*front) == EOF) 284 err("stdout: %s", strerror(errno)); 285 if (putchar('\n') == EOF) 286 err("stdout: %s", strerror(errno)); 287 } 288 } 289 290 /* 291 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with 292 * string2 (s1 ??? s2). 293 * 294 * o Matches up to len(s1) are EQUAL. 295 * o Matches up to len(s2) are GREATER. 296 * 297 * Compare understands about the -f and -d flags, and treats comparisons 298 * appropriately. 299 * 300 * The string "s1" is null terminated. The string s2 is '\n' terminated (or 301 * "back" terminated). 302 */ 303 int 304 compare(s1, s2, back) 305 register unsigned char *s1, *s2, *back; 306 { 307 register int ch; 308 309 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) { 310 ch = *s2; 311 if (fflag) 312 ch = FOLD(ch); 313 if (dflag) 314 ch = DICT(ch); 315 316 if (ch == NO_COMPARE) { 317 ++s2; /* Ignore character in comparison. */ 318 continue; 319 } 320 if (*s1 != ch) 321 return (*s1 < ch ? LESS : GREATER); 322 } 323 return (*s1 ? GREATER : EQUAL); 324 } 325 326 static void 327 usage() 328 { 329 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file]\n"); 330 exit(2); 331 } 332 333 #if __STDC__ 334 #include <stdarg.h> 335 #else 336 #include <varargs.h> 337 #endif 338 339 void 340 #if __STDC__ 341 err(const char *fmt, ...) 342 #else 343 err(fmt, va_alist) 344 char *fmt; 345 va_dcl 346 #endif 347 { 348 va_list ap; 349 #if __STDC__ 350 va_start(ap, fmt); 351 #else 352 va_start(ap); 353 #endif 354 (void)fprintf(stderr, "look: "); 355 (void)vfprintf(stderr, fmt, ap); 356 va_end(ap); 357 (void)fprintf(stderr, "\n"); 358 exit(2); 359 /* NOTREACHED */ 360 } 361