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 #endif /* not lint */ 48 #include <sys/cdefs.h> 49 __FBSDID("$FreeBSD$"); 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 static char _path_words[] = _PATH_WORDS; 77 78 /* 79 * FOLD and DICT convert characters to a normal form for comparison, 80 * according to the user specified flags. 81 * 82 * DICT expects integers because it uses a non-character value to 83 * indicate a character which should not participate in comparisons. 84 */ 85 #define EQUAL 0 86 #define GREATER 1 87 #define LESS (-1) 88 #define NO_COMPARE (-2) 89 90 #define FOLD(c) (isupper(c) ? tolower(c) : (unsigned char) (c)) 91 #define DICT(c) (isalnum(c) ? (c) & 0xFF /* int */ : NO_COMPARE) 92 93 int dflag, fflag; 94 95 char *binary_search(unsigned char *, unsigned char *, unsigned char *); 96 int compare(unsigned char *, unsigned char *, unsigned char *); 97 char *linear_search(unsigned char *, unsigned char *, unsigned char *); 98 int look(unsigned char *, unsigned char *, unsigned char *); 99 void print_from(unsigned char *, unsigned char *, unsigned char *); 100 101 static void usage(void); 102 103 int 104 main(int argc, char *argv[]) 105 { 106 struct stat sb; 107 int ch, fd, termchar, match; 108 unsigned char *back, *front, *string, *p; 109 unsigned const char *file; 110 111 (void) setlocale(LC_CTYPE, ""); 112 113 file = _path_words; 114 termchar = '\0'; 115 while ((ch = getopt(argc, argv, "dft:")) != -1) 116 switch(ch) { 117 case 'd': 118 dflag = 1; 119 break; 120 case 'f': 121 fflag = 1; 122 break; 123 case 't': 124 termchar = *optarg; 125 break; 126 case '?': 127 default: 128 usage(); 129 } 130 argc -= optind; 131 argv += optind; 132 133 if (argc == 0) 134 usage(); 135 if (argc == 1) /* But set -df by default. */ 136 dflag = fflag = 1; 137 string = *argv++; 138 if (argc >= 2) 139 file = *argv++; 140 141 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL) 142 *++p = '\0'; 143 match = 1; 144 145 do { 146 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) 147 err(2, "%s", file); 148 if (sb.st_size > SIZE_T_MAX) 149 errx(2, "%s: %s", file, strerror(EFBIG)); 150 if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED) 151 err(2, "%s", file); 152 back = front + sb.st_size; 153 match *= (look(string, front, back)); 154 close(fd); 155 } while (argc-- > 2 && (file = *argv++)); 156 157 exit(match); 158 } 159 160 int 161 look(unsigned char *string, unsigned char *front, unsigned char *back) 162 { 163 int ch; 164 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(unsigned char *string, unsigned char *front, unsigned char *back) 229 { 230 unsigned char *p; 231 232 p = front + (back - front) / 2; 233 SKIP_PAST_NEWLINE(p, back); 234 235 /* 236 * If the file changes underneath us, make sure we don't 237 * infinitely loop. 238 */ 239 while (p < back && back > front) { 240 if (compare(string, p, back) == GREATER) 241 front = p; 242 else 243 back = p; 244 p = front + (back - front) / 2; 245 SKIP_PAST_NEWLINE(p, back); 246 } 247 return (front); 248 } 249 250 /* 251 * Find the first line that starts with string, linearly searching from front 252 * to back. 253 * 254 * Return NULL for no such line. 255 * 256 * This routine assumes: 257 * 258 * o front points at the first character in a line. 259 * o front is before or at the first line to be printed. 260 */ 261 char * 262 linear_search(unsigned char *string, unsigned char *front, unsigned char *back) 263 { 264 while (front < back) { 265 switch (compare(string, front, back)) { 266 case EQUAL: /* Found it. */ 267 return (front); 268 break; 269 case LESS: /* No such string. */ 270 return (NULL); 271 break; 272 case GREATER: /* Keep going. */ 273 break; 274 } 275 SKIP_PAST_NEWLINE(front, back); 276 } 277 return (NULL); 278 } 279 280 /* 281 * Print as many lines as match string, starting at front. 282 */ 283 void 284 print_from(unsigned char *string, unsigned char *front, unsigned char *back) 285 { 286 for (; front < back && compare(string, front, back) == EQUAL; ++front) { 287 for (; front < back && *front != '\n'; ++front) 288 if (putchar(*front) == EOF) 289 err(2, "stdout"); 290 if (putchar('\n') == EOF) 291 err(2, "stdout"); 292 } 293 } 294 295 /* 296 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with 297 * string2 (s1 ??? s2). 298 * 299 * o Matches up to len(s1) are EQUAL. 300 * o Matches up to len(s2) are GREATER. 301 * 302 * Compare understands about the -f and -d flags, and treats comparisons 303 * appropriately. 304 * 305 * The string "s1" is null terminated. The string s2 is '\n' terminated (or 306 * "back" terminated). 307 */ 308 int 309 compare(unsigned char *s1, unsigned char *s2, unsigned char *back) 310 { 311 int ch; 312 313 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) { 314 ch = *s2; 315 if (fflag) 316 ch = FOLD(ch); 317 if (dflag) 318 ch = DICT(ch); 319 320 if (ch == NO_COMPARE) { 321 ++s2; /* Ignore character in comparison. */ 322 continue; 323 } 324 if (*s1 != ch) 325 return (*s1 < ch ? LESS : GREATER); 326 } 327 return (*s1 ? GREATER : EQUAL); 328 } 329 330 static void 331 usage(void) 332 { 333 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n"); 334 exit(2); 335 } 336