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 Miśkiewicz <misiek@pld.ORG.PL>
  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/mman.h>
  50 #include <sys/stat.h>
  51 #include <errno.h>
  52 #include <fcntl.h>
  53 #include <stdio.h>
  54 #include <stdlib.h>
  55 #include <stddef.h>
  56 #include <string.h>
  57 #include <ctype.h>
  58 #include <getopt.h>
  59
  60 #include "nls.h"
  61 #include "xalloc.h"
  62 #include "pathnames.h"
  63 #include "closestream.h"
  64
  65 #define EQUAL           0
  66 #define GREATER         1
  67 #define LESS            (-1)
  68
  69 static int dflag, fflag;
  70 /* uglified the source a bit with globals, so that we only need
  71    to allocate comparbuf once */
  72 static int stringlen;
  73 static char *string;
  74 static char *comparbuf;
  75
  76 static char *binary_search (char *, char *);
  77 static int compare (char *, char *);
  78 static char *linear_search (char *, char *);
  79 static int look (char *, char *);
  80 static void print_from (char *, char *);
  81 static void __attribute__((__noreturn__)) usage(void);
  82
  83 int
  84 main(int argc, char *argv[])
  85 {
  86         struct stat sb;
  87         int ch, fd, termchar;
  88         char *back, *file, *front, *p;
  89
  90         static const struct option longopts[] = {
  91                 {"alternative", no_argument, NULL, 'a'},
  92                 {"alphanum", no_argument, NULL, 'd'},
  93                 {"ignore-case", no_argument, NULL, 'f'},
  94                 {"terminate", required_argument, NULL, 't'},
  95                 {"version", no_argument, NULL, 'V'},
  96                 {"help", no_argument, NULL, 'h'},
  97                 {NULL, 0, NULL, 0}
  98         };
  99
 100         setlocale(LC_ALL, "");
 101         bindtextdomain(PACKAGE, LOCALEDIR);
 102         textdomain(PACKAGE);
 103         close_stdout_atexit();
 104
 105         if ((file = getenv("WORDLIST")) && !access(file, R_OK))
 106                 /* use the WORDLIST */;
 107         else
 108                 file = _PATH_WORDS;
 109
 110         termchar = '\0';
 111         string = NULL;          /* just for gcc */
 112
 113         while ((ch = getopt_long(argc, argv, "adft:Vh", longopts, NULL)) != -1)
 114                 switch(ch) {
 115                 case 'a':
 116                         file = _PATH_WORDS_ALT;
 117                         break;
 118                 case 'd':
 119                         dflag = 1;
 120                         break;
 121                 case 'f':
 122                         fflag = 1;
 123                         break;
 124                 case 't':
 125                         termchar = *optarg;
 126                         break;
 127                 case 'V':
 128                         print_version(EXIT_SUCCESS);
 129                 case 'h':
 130                         usage();
 131                 default:
 132                         errtryhelp(EXIT_FAILURE);
 133                 }
 134         argc -= optind;
 135         argv += optind;
 136
 137         switch (argc) {
 138         case 2:                         /* Don't set -df for user. */
 139                 string = *argv++;
 140                 file = *argv;
 141                 break;
 142         case 1:                         /* But set -df by default. */
 143                 dflag = fflag = 1;
 144                 string = *argv;
 145                 break;
 146         default:
 147                 warnx(_("bad usage"));
 148                 errtryhelp(EXIT_FAILURE);
 149         }
 150
 151         if (termchar != '\0' && (p = strchr(string, termchar)) != NULL)
 152                 *++p = '\0';
 153
 154         if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
 155                 err(EXIT_FAILURE, "%s", file);
 156         front = mmap(NULL, (size_t) sb.st_size, PROT_READ,
 157                      MAP_SHARED, fd, (off_t) 0);
 158         if
 159 #ifdef MAP_FAILED
 160                 (front == MAP_FAILED)
 161 #else
 162                 ((void *)(front) <= (void *)0)
 163 #endif
 164                         err(EXIT_FAILURE, "%s", file);
 165         back = front + sb.st_size;
 166         return look(front, back);
 167 }
 168
 169 static int
 170 look(char *front, char *back)
 171 {
 172         int ch;
 173         char *readp, *writep;
 174
 175         /* Reformat string to avoid doing it multiple times later. */
 176         if (dflag) {
 177                 for (readp = writep = string; (ch = *readp++) != 0;) {
 178                         if (isalnum(ch) || isblank(ch))
 179                                 *(writep++) = ch;
 180                 }
 181                 *writep = '\0';
 182                 stringlen = writep - string;
 183         } else
 184                 stringlen = strlen(string);
 185
 186         comparbuf = xmalloc(stringlen+1);
 187
 188         front = binary_search(front, back);
 189         front = linear_search(front, back);
 190
 191         if (front)
 192                 print_from(front, back);
 193
 194         free(comparbuf);
 195
 196         return (front ? 0 : 1);
 197 }
 198
 199
 200 /*
 201  * Binary search for "string" in memory between "front" and "back".
 202  *
 203  * This routine is expected to return a pointer to the start of a line at
 204  * *or before* the first word matching "string".  Relaxing the constraint
 205  * this way simplifies the algorithm.
 206  *
 207  * Invariants:
 208  *      front points to the beginning of a line at or before the first
 209  *      matching string.
 210  *
 211  *      back points to the beginning of a line at or after the first
 212  *      matching line.
 213  *
 214  * Advancing the Invariants:
 215  *
 216  *      p = first newline after halfway point from front to back.
 217  *
 218  *      If the string at "p" is not greater than the string to match,
 219  *      p is the new front.  Otherwise it is the new back.
 220  *
 221  * Termination:
 222  *
 223  *      The definition of the routine allows it return at any point,
 224  *      since front is always at or before the line to print.
 225  *
 226  *      In fact, it returns when the chosen "p" equals "back".  This
 227  *      implies that there exists a string is least half as long as
 228  *      (back - front), which in turn implies that a linear search will
 229  *      be no more expensive than the cost of simply printing a string or two.
 230  *
 231  *      Trying to continue with binary search at this point would be
 232  *      more trouble than it's worth.
 233  */
 234 #define SKIP_PAST_NEWLINE(p, back) \
 235         while (p < back && *p++ != '\n')
 236
 237 static char *
 238 binary_search(char *front, char *back)
 239 {
 240         char *p;
 241
 242         p = front + (back - front) / 2;
 243         SKIP_PAST_NEWLINE(p, back);
 244
 245         /*
 246          * If the file changes underneath us, make sure we don't
 247          * infinitely loop.
 248          */
 249         while (p < back && back > front) {
 250                 if (compare(p, back) == GREATER)
 251                         front = p;
 252                 else
 253                         back = p;
 254                 p = front + (back - front) / 2;
 255                 SKIP_PAST_NEWLINE(p, back);
 256         }
 257         return (front);
 258 }
 259
 260 /*
 261  * Find the first line that starts with string, linearly searching from front
 262  * to back.
 263  *
 264  * Return NULL for no such line.
 265  *
 266  * This routine assumes:
 267  *
 268  *      o front points at the first character in a line.
 269  *      o front is before or at the first line to be printed.
 270  */
 271 static char *
 272 linear_search(char *front, char *back)
 273 {
 274         while (front < back) {
 275                 switch (compare(front, back)) {
 276                 case EQUAL:             /* Found it. */
 277                         return (front);
 278                 case LESS:              /* No such string. */
 279                         return (NULL);
 280                 case GREATER:           /* Keep going. */
 281                         break;
 282                 }
 283                 SKIP_PAST_NEWLINE(front, back);
 284         }
 285         return (NULL);
 286 }
 287
 288 /*
 289  * Print as many lines as match string, starting at front.
 290  */
 291 static void
 292 print_from(char *front, char *back)
 293 {
 294         int eol;
 295
 296         while (front < back && compare(front, back) == EQUAL) {
 297                 if (compare(front, back) == EQUAL) {
 298                         eol = 0;
 299                         while (front < back && !eol) {
 300                                 if (putchar(*front) == EOF)
 301                                         err(EXIT_FAILURE, "stdout");
 302                                 if (*front++ == '\n')
 303                                         eol = 1;
 304                         }
 305                 } else
 306                         SKIP_PAST_NEWLINE(front, back);
 307         }
 308 }
 309
 310 /*
 311  * Return LESS, GREATER, or EQUAL depending on how  string  compares with
 312  * string2 (s1 ??? s2).
 313  *
 314  *      o Matches up to len(s1) are EQUAL.
 315  *      o Matches up to len(s2) are GREATER.
 316  *
 317  * Compare understands about the -f and -d flags, and treats comparisons
 318  * appropriately.
 319  *
 320  * The string "string" is null terminated.  The string "s2" is '\n' terminated
 321  * (or "s2end" terminated).
 322  *
 323  * We use strcasecmp etc, since it knows how to ignore case also
 324  * in other locales.
 325  */
 326 static int
 327 compare(char *s2, char *s2end) {
 328         int i;
 329         char *p;
 330
 331         /* copy, ignoring things that should be ignored */
 332         p = comparbuf;
 333         i = stringlen;
 334         while(s2 < s2end && *s2 != '\n' && i) {
 335                 if (!dflag || isalnum(*s2) || isblank(*s2))
 336                 {
 337                         *p++ = *s2;
 338                         i--;
 339                 }
 340                 s2++;
 341         }
 342         *p = 0;
 343
 344         /* and compare */
 345         if (fflag)
 346                 i = strncasecmp(comparbuf, string, stringlen);
 347         else
 348                 i = strncmp(comparbuf, string, stringlen);
 349
 350         return ((i > 0) ? LESS : (i < 0) ? GREATER : EQUAL);
 351 }
 352
 353 static void __attribute__((__noreturn__)) usage(void)
 354 {
 355         FILE *out = stdout;
 356         fputs(USAGE_HEADER, out);
 357         fprintf(out, _(" %s [options] <string> [<file>...]\n"), program_invocation_short_name);
 358
 359         fputs(USAGE_SEPARATOR, out);
 360         fputs(_("Display lines beginning with a specified string.\n"), out);
 361
 362         fputs(USAGE_OPTIONS, out);
 363         fputs(_(" -a, --alternative        use the alternative dictionary\n"), out);
 364         fputs(_(" -d, --alphanum           compare only blanks and alphanumeric characters\n"), out);
 365         fputs(_(" -f, --ignore-case        ignore case differences when comparing\n"), out);
 366         fputs(_(" -t, --terminate <char>   define the string-termination character\n"), out);
 367
 368         fputs(USAGE_SEPARATOR, out);
 369         fprintf(out, USAGE_HELP_OPTIONS(26));
 370         fprintf(out, USAGE_MAN_TAIL("look(1)"));
 371
 372         exit(EXIT_SUCCESS);
 373 }