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 const 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 #if 0 45 static char sccsid[] = "@(#)look.c 8.2 (Berkeley) 5/4/95"; 46 #endif 47 static const char rcsid[] = 48 "$FreeBSD$"; 49 #endif /* not lint */ 50 51 /* 52 * look -- find lines in a sorted list. 53 * 54 * The man page said that TABs and SPACEs participate in -d comparisons. 55 * In fact, they were ignored. This implements historic practice, not 56 * the manual page. 57 */ 58 59 #include <sys/types.h> 60 #include <sys/mman.h> 61 #include <sys/stat.h> 62 63 #include <ctype.h> 64 #include <err.h> 65 #include <errno.h> 66 #include <fcntl.h> 67 #include <limits.h> 68 #include <locale.h> 69 #include <stdio.h> 70 #include <stdlib.h> 71 #include <string.h> 72 #include <unistd.h> 73 74 #include "pathnames.h" 75 76 /* 77 * FOLD and DICT convert characters to a normal form for comparison, 78 * according to the user specified flags. 79 * 80 * DICT expects integers because it uses a non-character value to 81 * indicate a character which should not participate in comparisons. 82 */ 83 #define EQUAL 0 84 #define GREATER 1 85 #define LESS (-1) 86 #define NO_COMPARE (-2) 87 88 #define FOLD(c) (isupper(c) ? tolower(c) : (unsigned char) (c)) 89 #define DICT(c) (isalnum(c) ? (c) & 0xFF /* int */ : NO_COMPARE) 90 91 int dflag, fflag; 92 93 char *binary_search __P((unsigned char *, unsigned char *, unsigned char *)); 94 int compare __P((unsigned char *, unsigned char *, unsigned char *)); 95 char *linear_search __P((unsigned char *, unsigned char *, unsigned char *)); 96 int look __P((unsigned char *, unsigned char *, unsigned char *)); 97 void print_from __P((unsigned char *, unsigned char *, unsigned char *)); 98 99 static void usage __P((void)); 100 101 int 102 main(argc, argv) 103 int argc; 104 char *argv[]; 105 { 106 struct stat sb; 107 int ch, fd, termchar, match; 108 unsigned char *back, *file, *front, *string, *p; 109 110 (void) setlocale(LC_CTYPE, ""); 111 112 file = _PATH_WORDS; 113 termchar = '\0'; 114 while ((ch = getopt(argc, argv, "dft:")) != -1) 115 switch(ch) { 116 case 'd': 117 dflag = 1; 118 break; 119 case 'f': 120 fflag = 1; 121 break; 122 case 't': 123 termchar = *optarg; 124 break; 125 case '?': 126 default: 127 usage(); 128 } 129 argc -= optind; 130 argv += optind; 131 132 if (argc == 0) 133 usage(); 134 if (argc == 1) /* But set -df by default. */ 135 dflag = fflag = 1; 136 string = *argv++; 137 if (argc >= 2) 138 file = *argv++; 139 140 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL) 141 *++p = '\0'; 142 match = 1; 143 144 do { 145 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) 146 err(2, "%s", file); 147 if (sb.st_size > SIZE_T_MAX) 148 errx(2, "%s: %s", file, strerror(EFBIG)); 149 if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED) 150 err(2, "%s", file); 151 back = front + sb.st_size; 152 match *= (look(string, front, back)); 153 close(fd); 154 } while (argc-- > 2 && (file = *argv++)); 155 156 exit(match); 157 } 158 159 int 160 look(string, front, back) 161 unsigned char *string, *front, *back; 162 { 163 register int ch; 164 register unsigned char *readp, *writep; 165 166 /* Reformat string string to avoid doing it multiple times later. */ 167 for (readp = writep = string; ch = *readp++;) { 168 if (fflag) 169 ch = FOLD(ch); 170 if (dflag) 171 ch = DICT(ch); 172 if (ch != NO_COMPARE) 173 *(writep++) = ch; 174 } 175 *writep = '\0'; 176 177 front = binary_search(string, front, back); 178 front = linear_search(string, front, back); 179 180 if (front) 181 print_from(string, front, back); 182 return (front ? 0 : 1); 183 } 184 185 186 /* 187 * Binary search for "string" in memory between "front" and "back". 188 * 189 * This routine is expected to return a pointer to the start of a line at 190 * *or before* the first word matching "string". Relaxing the constraint 191 * this way simplifies the algorithm. 192 * 193 * Invariants: 194 * front points to the beginning of a line at or before the first 195 * matching string. 196 * 197 * back points to the beginning of a line at or after the first 198 * matching line. 199 * 200 * Base of the Invariants. 201 * front = NULL; 202 * back = EOF; 203 * 204 * Advancing the Invariants: 205 * 206 * p = first newline after halfway point from front to back. 207 * 208 * If the string at "p" is not greater than the string to match, 209 * p is the new front. Otherwise it is the new back. 210 * 211 * Termination: 212 * 213 * The definition of the routine allows it return at any point, 214 * since front is always at or before the line to print. 215 * 216 * In fact, it returns when the chosen "p" equals "back". This 217 * implies that there exists a string is least half as long as 218 * (back - front), which in turn implies that a linear search will 219 * be no more expensive than the cost of simply printing a string or two. 220 * 221 * Trying to continue with binary search at this point would be 222 * more trouble than it's worth. 223 */ 224 #define SKIP_PAST_NEWLINE(p, back) \ 225 while (p < back && *p++ != '\n'); 226 227 char * 228 binary_search(string, front, back) 229 register unsigned char *string, *front, *back; 230 { 231 register unsigned char *p; 232 233 p = front + (back - front) / 2; 234 SKIP_PAST_NEWLINE(p, back); 235 236 /* 237 * If the file changes underneath us, make sure we don't 238 * infinitely loop. 239 */ 240 while (p < back && back > front) { 241 if (compare(string, p, back) == GREATER) 242 front = p; 243 else 244 back = p; 245 p = front + (back - front) / 2; 246 SKIP_PAST_NEWLINE(p, back); 247 } 248 return (front); 249 } 250 251 /* 252 * Find the first line that starts with string, linearly searching from front 253 * to back. 254 * 255 * Return NULL for no such line. 256 * 257 * This routine assumes: 258 * 259 * o front points at the first character in a line. 260 * o front is before or at the first line to be printed. 261 */ 262 char * 263 linear_search(string, front, back) 264 unsigned char *string, *front, *back; 265 { 266 while (front < back) { 267 switch (compare(string, front, back)) { 268 case EQUAL: /* Found it. */ 269 return (front); 270 break; 271 case LESS: /* No such string. */ 272 return (NULL); 273 break; 274 case GREATER: /* Keep going. */ 275 break; 276 } 277 SKIP_PAST_NEWLINE(front, back); 278 } 279 return (NULL); 280 } 281 282 /* 283 * Print as many lines as match string, starting at front. 284 */ 285 void 286 print_from(string, front, back) 287 register unsigned char *string, *front, *back; 288 { 289 for (; front < back && compare(string, front, back) == EQUAL; ++front) { 290 for (; front < back && *front != '\n'; ++front) 291 if (putchar(*front) == EOF) 292 err(2, "stdout"); 293 if (putchar('\n') == EOF) 294 err(2, "stdout"); 295 } 296 } 297 298 /* 299 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with 300 * string2 (s1 ??? s2). 301 * 302 * o Matches up to len(s1) are EQUAL. 303 * o Matches up to len(s2) are GREATER. 304 * 305 * Compare understands about the -f and -d flags, and treats comparisons 306 * appropriately. 307 * 308 * The string "s1" is null terminated. The string s2 is '\n' terminated (or 309 * "back" terminated). 310 */ 311 int 312 compare(s1, s2, back) 313 register unsigned char *s1, *s2, *back; 314 { 315 register int ch; 316 317 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) { 318 ch = *s2; 319 if (fflag) 320 ch = FOLD(ch); 321 if (dflag) 322 ch = DICT(ch); 323 324 if (ch == NO_COMPARE) { 325 ++s2; /* Ignore character in comparison. */ 326 continue; 327 } 328 if (*s1 != ch) 329 return (*s1 < ch ? LESS : GREATER); 330 } 331 return (*s1 ? GREATER : EQUAL); 332 } 333 334 static void 335 usage() 336 { 337 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n"); 338 exit(2); 339 } 340