text_cmds/look/look.c

   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: src/usr.bin/look/look.c,v 1.18.10.2.4.1 2010/06/14 02:09:06 kensmith Exp $");
  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 <err.h>
  64 #include <errno.h>
  65 #include <fcntl.h>
  66 #include <limits.h>
  67 #include <locale.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72 #include <wchar.h>
  73 #include <wctype.h>
  74
  75 #include "pathnames.h"
  76
  77 static char _path_words[] = _PATH_WORDS;
  78
  79 #define EQUAL           0
  80 #define GREATER         1
  81 #define LESS            (-1)
  82
  83 int dflag, fflag;
  84
  85 char    *binary_search(wchar_t *, unsigned char *, unsigned char *);
  86 int      compare(wchar_t *, unsigned char *, unsigned char *);
  87 char    *linear_search(wchar_t *, unsigned char *, unsigned char *);
  88 int      look(wchar_t *, unsigned char *, unsigned char *);
  89 wchar_t *prepkey(const char *, wchar_t);
  90 void     print_from(wchar_t *, unsigned char *, unsigned char *);
  91
  92 static void usage(void);
  93
  94 int
  95 main(int argc, char *argv[])
  96 {
  97         struct stat sb;
  98         int ch, fd, match;
  99         wchar_t termchar;
 100         unsigned char *back, *front;
 101         unsigned const char *file;
 102         wchar_t *key;
 103
 104         (void) setlocale(LC_CTYPE, "");
 105
 106         file = _path_words;
 107         termchar = L'\0';
 108         while ((ch = getopt(argc, argv, "dft:")) != -1)
 109                 switch(ch) {
 110                 case 'd':
 111                         dflag = 1;
 112                         break;
 113                 case 'f':
 114                         fflag = 1;
 115                         break;
 116                 case 't':
 117                         if (mbrtowc(&termchar, optarg, MB_LEN_MAX, NULL) !=
 118                             strlen(optarg))
 119                                 errx(2, "invalid termination character");
 120                         break;
 121                 case '?':
 122                 default:
 123                         usage();
 124                 }
 125         argc -= optind;
 126         argv += optind;
 127
 128 /* 4384130 */
 129 #ifdef __APPLE__
 130         if (argc <= 0)
 131 #else
 132         if (argc == 0)
 133 #endif
 134                 usage();
 135         if (argc == 1)                  /* But set -df by default. */
 136                 dflag = fflag = 1;
 137         key = prepkey(*argv++, termchar);
 138         if (argc >= 2)
 139                 file = *argv++;
 140
 141         match = 1;
 142
 143         do {
 144                 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
 145                         err(2, "%s", file);
 146                 if (sb.st_size > SIZE_T_MAX)
 147                         errx(2, "%s: %s", file, strerror(EFBIG));
 148                 if (sb.st_size == 0) {
 149                         close(fd);
 150                         continue;
 151                 }
 152                 if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED)
 153                         err(2, "%s", file);
 154                 back = front + sb.st_size;
 155                 match *= (look(key, front, back));
 156                 close(fd);
 157         } while (argc-- > 2 && (file = *argv++));
 158
 159         exit(match);
 160 }
 161
 162 wchar_t *
 163 prepkey(const char *string, wchar_t termchar)
 164 {
 165         const char *readp;
 166         wchar_t *key, *writep;
 167         wchar_t ch;
 168         size_t clen;
 169
 170         /*
 171          * Reformat search string and convert to wide character representation
 172          * to avoid doing it multiple times later.
 173          */
 174         if ((key = malloc(sizeof(wchar_t) * (strlen(string) + 1))) == NULL)
 175                 err(2, NULL);
 176         readp = string;
 177         writep = key;
 178         while ((clen = mbrtowc(&ch, readp, MB_LEN_MAX, NULL)) != 0) {
 179                 if (clen == (size_t)-1 || clen == (size_t)-2)
 180                         errc(2, EILSEQ, NULL);
 181                 if (fflag)
 182                         ch = towlower(ch);
 183                 if (!dflag || iswalnum(ch))
 184                         *writep++ = ch;
 185                 readp += clen;
 186         }
 187         *writep = L'\0';
 188         if (termchar != L'\0' && (writep = wcschr(key, termchar)) != NULL)
 189                 *++writep = L'\0';
 190         return (key);
 191 }
 192
 193 int
 194 look(wchar_t *string, unsigned char *front, unsigned char *back)
 195 {
 196
 197         front = binary_search(string, front, back);
 198         front = linear_search(string, front, back);
 199
 200         if (front)
 201                 print_from(string, front, back);
 202         return (front ? 0 : 1);
 203 }
 204
 205
 206 /*
 207  * Binary search for "string" in memory between "front" and "back".
 208  *
 209  * This routine is expected to return a pointer to the start of a line at
 210  * *or before* the first word matching "string".  Relaxing the constraint
 211  * this way simplifies the algorithm.
 212  *
 213  * Invariants:
 214  *      front points to the beginning of a line at or before the first
 215  *      matching string.
 216  *
 217  *      back points to the beginning of a line at or after the first
 218  *      matching line.
 219  *
 220  * Base of the Invariants.
 221  *      front = NULL;
 222  *      back = EOF;
 223  *
 224  * Advancing the Invariants:
 225  *
 226  *      p = first newline after halfway point from front to back.
 227  *
 228  *      If the string at "p" is not greater than the string to match,
 229  *      p is the new front.  Otherwise it is the new back.
 230  *
 231  * Termination:
 232  *
 233  *      The definition of the routine allows it return at any point,
 234  *      since front is always at or before the line to print.
 235  *
 236  *      In fact, it returns when the chosen "p" equals "back".  This
 237  *      implies that there exists a string is least half as long as
 238  *      (back - front), which in turn implies that a linear search will
 239  *      be no more expensive than the cost of simply printing a string or two.
 240  *
 241  *      Trying to continue with binary search at this point would be
 242  *      more trouble than it's worth.
 243  */
 244 #define SKIP_PAST_NEWLINE(p, back) \
 245         while (p < back && *p++ != '\n');
 246
 247 char *
 248 binary_search(wchar_t *string, unsigned char *front, unsigned char *back)
 249 {
 250         unsigned char *p;
 251
 252         p = front + (back - front) / 2;
 253         SKIP_PAST_NEWLINE(p, back);
 254
 255         /*
 256          * If the file changes underneath us, make sure we don't
 257          * infinitely loop.
 258          */
 259         while (p < back && back > front) {
 260                 if (compare(string, p, back) == GREATER)
 261                         front = p;
 262                 else
 263                         back = p;
 264                 p = front + (back - front) / 2;
 265                 SKIP_PAST_NEWLINE(p, back);
 266         }
 267         return (front);
 268 }
 269
 270 /*
 271  * Find the first line that starts with string, linearly searching from front
 272  * to back.
 273  *
 274  * Return NULL for no such line.
 275  *
 276  * This routine assumes:
 277  *
 278  *      o front points at the first character in a line.
 279  *      o front is before or at the first line to be printed.
 280  */
 281 char *
 282 linear_search(wchar_t *string, unsigned char *front, unsigned char *back)
 283 {
 284         while (front < back) {
 285                 switch (compare(string, front, back)) {
 286                 case EQUAL:             /* Found it. */
 287                         return (front);
 288                 case LESS:              /* No such string. */
 289                         return (NULL);
 290                 case GREATER:           /* Keep going. */
 291                         break;
 292                 }
 293                 SKIP_PAST_NEWLINE(front, back);
 294         }
 295         return (NULL);
 296 }
 297
 298 /*
 299  * Print as many lines as match string, starting at front.
 300  */
 301 void
 302 print_from(wchar_t *string, unsigned char *front, unsigned char *back)
 303 {
 304         for (; front < back && compare(string, front, back) == EQUAL; ++front) {
 305                 for (; front < back && *front != '\n'; ++front)
 306                         if (putchar(*front) == EOF)
 307                                 err(2, "stdout");
 308                 if (putchar('\n') == EOF)
 309                         err(2, "stdout");
 310         }
 311 }
 312
 313 /*
 314  * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
 315  * string2 (s1 ??? s2).
 316  *
 317  *      o Matches up to len(s1) are EQUAL.
 318  *      o Matches up to len(s2) are GREATER.
 319  *
 320  * Compare understands about the -f and -d flags, and treats comparisons
 321  * appropriately.
 322  *
 323  * The string "s1" is null terminated.  The string s2 is '\n' terminated (or
 324  * "back" terminated).
 325  */
 326 int
 327 compare(wchar_t *s1, unsigned char *s2, unsigned char *back)
 328 {
 329         wchar_t ch1, ch2;
 330         size_t len2;
 331
 332         for (; *s1 && s2 < back && *s2 != '\n'; ++s1, s2 += len2) {
 333                 ch1 = *s1;
 334                 len2 = mbrtowc(&ch2, s2, back - s2, NULL);
 335                 if (len2 == (size_t)-1 || len2 == (size_t)-2) {
 336                         ch2 = *s2;
 337                         len2 = 1;
 338                 }
 339                 if (fflag)
 340                         ch2 = towlower(ch2);
 341                 if (dflag && !iswalnum(ch2)) {
 342                         /* Ignore character in comparison. */
 343                         --s1;
 344                         continue;
 345                 }
 346                 if (ch1 != ch2)
 347                         return (ch1 < ch2 ? LESS : GREATER);
 348         }
 349         return (*s1 ? GREATER : EQUAL);
 350 }
 351
 352 static void
 353 usage(void)
 354 {
 355         (void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n");
 356         exit(2);
 357 }