misc-utils/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  /* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
  38   * - added Native Language Support
  39   */
  40
  41 /*
  42  * look -- find lines in a sorted list.
  43  *
  44  * The man page said that TABs and SPACEs participate in -d comparisons.
  45  * In fact, they were ignored.  This implements historic practice, not
  46  * the manual page.
  47  */
  48
  49 #include <sys/types.h>
  50 #include <sys/mman.h>
  51 #include <sys/stat.h>
  52
  53 #include <limits.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <ctype.h>
  60 #include <getopt.h>
  61 #include <locale.h>
  62 #include "pathnames.h"
  63 #include "nls.h"
  64
  65 #define EQUAL           0
  66 #define GREATER         1
  67 #define LESS            (-1)
  68
  69 int dflag, fflag;
  70 /* uglified the source a bit with globals, so that we only need
  71    to allocate comparbuf once */
  72 int stringlen;
  73 char *string;
  74 char *comparbuf;
  75
  76 static char *binary_search (char *, char *);
  77 static int compare (char *, char *);
  78 static void err (const char *fmt, ...);
  79 static char *linear_search (char *, char *);
  80 static int look (char *, char *);
  81 static void print_from (char *, char *);
  82 static void usage (void);
  83
  84 int
  85 main(int argc, char *argv[])
  86 {
  87         struct stat sb;
  88         int ch, fd, termchar;
  89         char *back, *file, *front, *p;
  90
  91         setlocale(LC_ALL, "");
  92         bindtextdomain(PACKAGE, LOCALEDIR);
  93         textdomain(PACKAGE);
  94
  95         setlocale(LC_ALL, "");
  96
  97         file = _PATH_WORDS;
  98         termchar = '\0';
  99         string = NULL;          /* just for gcc */
 100
 101         while ((ch = getopt(argc, argv, "adft:")) != EOF)
 102                 switch(ch) {
 103                 case 'a':
 104                         file = _PATH_WORDS_ALT;
 105                         break;
 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         front = mmap(NULL, (size_t) sb.st_size, PROT_READ,
 141 #ifdef MAP_FILE
 142                      MAP_FILE |
 143 #endif
 144                      MAP_SHARED, fd, (off_t) 0);
 145         if
 146 #ifdef MAP_FAILED
 147            (front == MAP_FAILED)
 148 #else
 149            ((void *)(front) <= (void *)0)
 150 #endif
 151                 err("%s: %s", file, strerror(errno));
 152
 153 #if 0
 154         /* workaround for mmap problem (rmiller@duskglow.com) */
 155         if (front == (void *)0)
 156                 return 1;
 157 #endif
 158
 159         back = front + sb.st_size;
 160         return look(front, back);
 161 }
 162
 163 int
 164 look(char *front, char *back)
 165 {
 166         int ch;
 167         char *readp, *writep;
 168
 169         /* Reformat string string to avoid doing it multiple times later. */
 170         if (dflag) {
 171                 for (readp = writep = string; (ch = *readp++) != 0;) {
 172                         if (isalnum(ch))
 173                                 *(writep++) = ch;
 174                 }
 175                 *writep = '\0';
 176                 stringlen = writep - string;
 177         } else
 178                 stringlen = strlen(string);
 179
 180         comparbuf = malloc(stringlen+1);
 181         if (comparbuf == NULL)
 182                 err(_("Out of memory"));
 183
 184         front = binary_search(front, back);
 185         front = linear_search(front, back);
 186
 187         if (front)
 188                 print_from(front, back);
 189         return (front ? 0 : 1);
 190 }
 191
 192
 193 /*
 194  * Binary search for "string" in memory between "front" and "back".
 195  *
 196  * This routine is expected to return a pointer to the start of a line at
 197  * *or before* the first word matching "string".  Relaxing the constraint
 198  * this way simplifies the algorithm.
 199  *
 200  * Invariants:
 201  *      front points to the beginning of a line at or before the first
 202  *      matching string.
 203  *
 204  *      back points to the beginning of a line at or after the first
 205  *      matching line.
 206  *
 207  * Advancing the Invariants:
 208  *
 209  *      p = first newline after halfway point from front to back.
 210  *
 211  *      If the string at "p" is not greater than the string to match,
 212  *      p is the new front.  Otherwise it is the new back.
 213  *
 214  * Termination:
 215  *
 216  *      The definition of the routine allows it return at any point,
 217  *      since front is always at or before the line to print.
 218  *
 219  *      In fact, it returns when the chosen "p" equals "back".  This
 220  *      implies that there exists a string is least half as long as
 221  *      (back - front), which in turn implies that a linear search will
 222  *      be no more expensive than the cost of simply printing a string or two.
 223  *
 224  *      Trying to continue with binary search at this point would be
 225  *      more trouble than it's worth.
 226  */
 227 #define SKIP_PAST_NEWLINE(p, back) \
 228         while (p < back && *p++ != '\n');
 229
 230 char *
 231 binary_search(char *front, char *back)
 232 {
 233         char *p;
 234
 235         p = front + (back - front) / 2;
 236         SKIP_PAST_NEWLINE(p, back);
 237
 238         /*
 239          * If the file changes underneath us, make sure we don't
 240          * infinitely loop.
 241          */
 242         while (p < back && back > front) {
 243                 if (compare(p, back) == GREATER)
 244                         front = p;
 245                 else
 246                         back = p;
 247                 p = front + (back - front) / 2;
 248                 SKIP_PAST_NEWLINE(p, back);
 249         }
 250         return (front);
 251 }
 252
 253 /*
 254  * Find the first line that starts with string, linearly searching from front
 255  * to back.
 256  *
 257  * Return NULL for no such line.
 258  *
 259  * This routine assumes:
 260  *
 261  *      o front points at the first character in a line.
 262  *      o front is before or at the first line to be printed.
 263  */
 264 char *
 265 linear_search(char *front, char *back)
 266 {
 267         while (front < back) {
 268                 switch (compare(front, back)) {
 269                 case EQUAL:             /* Found it. */
 270                         return (front);
 271                         break;
 272                 case LESS:              /* No such string. */
 273                         return (NULL);
 274                         break;
 275                 case GREATER:           /* Keep going. */
 276                         break;
 277                 }
 278                 SKIP_PAST_NEWLINE(front, back);
 279         }
 280         return (NULL);
 281 }
 282
 283 /*
 284  * Print as many lines as match string, starting at front.
 285  */
 286 void
 287 print_from(char *front, char *back)
 288 {
 289         int eol;
 290
 291         while (front < back && compare(front, back) == EQUAL) {
 292                 if (compare(front, back) == EQUAL) {
 293                         eol = 0;
 294                         while (front < back && !eol) {
 295                                 if (putchar(*front) == EOF)
 296                                         err("stdout: %s", strerror(errno));
 297                                 if (*front++ == '\n')
 298                                         eol = 1;
 299                         }
 300                 } else
 301                         SKIP_PAST_NEWLINE(front, back);
 302         }
 303 }
 304
 305 /*
 306  * Return LESS, GREATER, or EQUAL depending on how  string  compares with
 307  * string2 (s1 ??? s2).
 308  *
 309  *      o Matches up to len(s1) are EQUAL.
 310  *      o Matches up to len(s2) are GREATER.
 311  *
 312  * Compare understands about the -f and -d flags, and treats comparisons
 313  * appropriately.
 314  *
 315  * The string "string" is null terminated.  The string "s2" is '\n' terminated
 316  * (or "s2end" terminated).
 317  *
 318  * We use strcasecmp etc, since it knows how to ignore case also
 319  * in other locales.
 320  */
 321 int
 322 compare(char *s2, char *s2end) {
 323         int i;
 324         char *p;
 325
 326         /* copy, ignoring things that should be ignored */
 327         p = comparbuf;
 328         i = stringlen;
 329         while(s2 < s2end && *s2 != '\n' && i--) {
 330                 if (!dflag || isalnum(*s2))
 331                         *p++ = *s2;
 332                 s2++;
 333         }
 334         *p = 0;
 335
 336         /* and compare */
 337         if (fflag)
 338                 i = strncasecmp(comparbuf, string, stringlen);
 339         else
 340                 i = strncmp(comparbuf, string, stringlen);
 341
 342         return ((i > 0) ? LESS : (i < 0) ? GREATER : EQUAL);
 343 }
 344
 345 static void
 346 usage()
 347 {
 348         (void)fprintf(stderr, _("usage: look [-dfa] [-t char] string [file]\n"));
 349         exit(2);
 350 }
 351
 352 #if __STDC__
 353 #include <stdarg.h>
 354 #else
 355 #include <varargs.h>
 356 #endif
 357
 358 void
 359 #if __STDC__
 360 err(const char *fmt, ...)
 361 #else
 362 err(fmt, va_alist)
 363         char *fmt;
 364         va_dcl
 365 #endif
 366 {
 367         va_list ap;
 368 #if __STDC__
 369         va_start(ap, fmt);
 370 #else
 371         va_start(ap);
 372 #endif
 373         (void)fprintf(stderr, "look: ");
 374         (void)vfprintf(stderr, fmt, ap);
 375         va_end(ap);
 376         (void)fprintf(stderr, "\n");
 377         exit(2);
 378         /* NOTREACHED */
 379 }