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 <errno.h> 61 #include <fcntl.h> 62 #include <stdio.h> 63 #include <stdlib.h> 64 #include <string.h> 65 #include <ctype.h> 66 #include "pathnames.h" 67 68 /* 69 * FOLD and DICT convert characters to a normal form for comparison, 70 * according to the user specified flags. 71 * 72 * DICT expects integers because it uses a non-character value to 73 * indicate a character which should not participate in comparisons. 74 */ 75 #define EQUAL 0 76 #define GREATER 1 77 #define LESS (-1) 78 #define NO_COMPARE (-2) 79 80 #define FOLD(c) (isascii(c) && isupper(c) ? tolower(c) : (c)) 81 #define DICT(c) (isascii(c) && isalnum(c) ? (c) : NO_COMPARE) 82 83 int dflag, fflag; 84 85 char *binary_search __P((char *, char *, char *)); 86 int compare __P((char *, char *, char *)); 87 void err __P((const char *fmt, ...)); 88 char *linear_search __P((char *, char *, char *)); 89 int look __P((char *, char *, char *)); 90 void print_from __P((char *, char *, char *)); 91 92 static void usage __P((void)); 93 94 main(argc, argv) 95 int argc; 96 char *argv[]; 97 { 98 struct stat sb; 99 int ch, fd, termchar; 100 char *back, *file, *front, *string, *p; 101 102 file = _PATH_WORDS; 103 termchar = '\0'; 104 while ((ch = getopt(argc, argv, "dft:")) != EOF) 105 switch(ch) { 106 case 'd': 107 dflag = 1; 108 break; 109 case 'f': 110 fflag = 1; 111 break; 112 case 't': 113 termchar = *optarg; 114 break; 115 case '?': 116 default: 117 usage(); 118 } 119 argc -= optind; 120 argv += optind; 121 122 switch (argc) { 123 case 2: /* Don't set -df for user. */ 124 string = *argv++; 125 file = *argv; 126 break; 127 case 1: /* But set -df by default. */ 128 dflag = fflag = 1; 129 string = *argv; 130 break; 131 default: 132 usage(); 133 } 134 135 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL) 136 *++p = '\0'; 137 138 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) 139 err("%s: %s", file, strerror(errno)); 140 if (sb.st_size > SIZE_T_MAX) 141 err("%s: %s", file, strerror(EFBIG)); 142 if ((front = mmap(NULL, 143 (size_t)sb.st_size, PROT_READ, 0, fd, (off_t)0)) == NULL) 144 err("%s: %s", file, strerror(errno)); 145 back = front + sb.st_size; 146 exit(look(string, front, back)); 147 } 148 149 look(string, front, back) 150 char *string, *front, *back; 151 { 152 register int ch; 153 register char *readp, *writep; 154 155 /* Reformat string string to avoid doing it multiple times later. */ 156 for (readp = writep = string; ch = *readp++;) { 157 if (fflag) 158 ch = FOLD(ch); 159 if (dflag) 160 ch = DICT(ch); 161 if (ch != NO_COMPARE) 162 *(writep++) = ch; 163 } 164 *writep = '\0'; 165 166 front = binary_search(string, front, back); 167 front = linear_search(string, front, back); 168 169 if (front) 170 print_from(string, front, back); 171 return (front ? 0 : 1); 172 } 173 174 175 /* 176 * Binary search for "string" in memory between "front" and "back". 177 * 178 * This routine is expected to return a pointer to the start of a line at 179 * *or before* the first word matching "string". Relaxing the constraint 180 * this way simplifies the algorithm. 181 * 182 * Invariants: 183 * front points to the beginning of a line at or before the first 184 * matching string. 185 * 186 * back points to the beginning of a line at or after the first 187 * matching line. 188 * 189 * Base of the Invariants. 190 * front = NULL; 191 * back = EOF; 192 * 193 * Advancing the Invariants: 194 * 195 * p = first newline after halfway point from front to back. 196 * 197 * If the string at "p" is not greater than the string to match, 198 * p is the new front. Otherwise it is the new back. 199 * 200 * Termination: 201 * 202 * The definition of the routine allows it return at any point, 203 * since front is always at or before the line to print. 204 * 205 * In fact, it returns when the chosen "p" equals "back". This 206 * implies that there exists a string is least half as long as 207 * (back - front), which in turn implies that a linear search will 208 * be no more expensive than the cost of simply printing a string or two. 209 * 210 * Trying to continue with binary search at this point would be 211 * more trouble than it's worth. 212 */ 213 #define SKIP_PAST_NEWLINE(p, back) \ 214 while (p < back && *p++ != '\n'); 215 216 char * 217 binary_search(string, front, back) 218 register char *string, *front, *back; 219 { 220 register char *p; 221 222 p = front + (back - front) / 2; 223 SKIP_PAST_NEWLINE(p, back); 224 225 /* 226 * If the file changes underneath us, make sure we don't 227 * infinitely loop. 228 */ 229 while (p < back && back > front) { 230 if (compare(string, p, back) == GREATER) 231 front = p; 232 else 233 back = p; 234 p = front + (back - front) / 2; 235 SKIP_PAST_NEWLINE(p, back); 236 } 237 return (front); 238 } 239 240 /* 241 * Find the first line that starts with string, linearly searching from front 242 * to back. 243 * 244 * Return NULL for no such line. 245 * 246 * This routine assumes: 247 * 248 * o front points at the first character in a line. 249 * o front is before or at the first line to be printed. 250 */ 251 char * 252 linear_search(string, front, back) 253 char *string, *front, *back; 254 { 255 while (front < back) { 256 switch (compare(string, front, back)) { 257 case EQUAL: /* Found it. */ 258 return (front); 259 break; 260 case LESS: /* No such string. */ 261 return (NULL); 262 break; 263 case GREATER: /* Keep going. */ 264 break; 265 } 266 SKIP_PAST_NEWLINE(front, back); 267 } 268 return (NULL); 269 } 270 271 /* 272 * Print as many lines as match string, starting at front. 273 */ 274 void 275 print_from(string, front, back) 276 register char *string, *front, *back; 277 { 278 for (; front < back && compare(string, front, back) == EQUAL; ++front) { 279 for (; front < back && *front != '\n'; ++front) 280 if (putchar(*front) == EOF) 281 err("stdout: %s", strerror(errno)); 282 if (putchar('\n') == EOF) 283 err("stdout: %s", strerror(errno)); 284 } 285 } 286 287 /* 288 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with 289 * string2 (s1 ??? s2). 290 * 291 * o Matches up to len(s1) are EQUAL. 292 * o Matches up to len(s2) are GREATER. 293 * 294 * Compare understands about the -f and -d flags, and treats comparisons 295 * appropriately. 296 * 297 * The string "s1" is null terminated. The string s2 is '\n' terminated (or 298 * "back" terminated). 299 */ 300 int 301 compare(s1, s2, back) 302 register char *s1, *s2, *back; 303 { 304 register int ch; 305 306 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) { 307 ch = *s2; 308 if (fflag) 309 ch = FOLD(ch); 310 if (dflag) 311 ch = DICT(ch); 312 313 if (ch == NO_COMPARE) { 314 ++s2; /* Ignore character in comparison. */ 315 continue; 316 } 317 if (*s1 != ch) 318 return (*s1 < ch ? LESS : GREATER); 319 } 320 return (*s1 ? GREATER : EQUAL); 321 } 322 323 static void 324 usage() 325 { 326 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file]\n"); 327 exit(2); 328 } 329 330 #if __STDC__ 331 #include <stdarg.h> 332 #else 333 #include <varargs.h> 334 #endif 335 336 void 337 #if __STDC__ 338 err(const char *fmt, ...) 339 #else 340 err(fmt, va_alist) 341 char *fmt; 342 va_dcl 343 #endif 344 { 345 va_list ap; 346 #if __STDC__ 347 va_start(ap, fmt); 348 #else 349 va_start(ap); 350 #endif 351 (void)fprintf(stderr, "look: "); 352 (void)vfprintf(stderr, fmt, ap); 353 va_end(ap); 354 (void)fprintf(stderr, "\n"); 355 exit(2); 356 /* NOTREACHED */ 357 } 358