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+/*-
+ * Copyright (c) 1991, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * David Hitz of Auspex Systems, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+ /* 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
+ * - added Native Language Support
+ */
+
+/*
+ * look -- find lines in a sorted list.
+ *
+ * The man page said that TABs and SPACEs participate in -d comparisons.
+ * In fact, they were ignored. This implements historic practice, not
+ * the manual page.
+ */
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <string.h>
+#include <ctype.h>
+#include <getopt.h>
+
+#include "nls.h"
+#include "xalloc.h"
+#include "pathnames.h"
+#include "closestream.h"
+
+#define EQUAL 0
+#define GREATER 1
+#define LESS (-1)
+
+static int dflag, fflag;
+/* uglified the source a bit with globals, so that we only need
+ to allocate comparbuf once */
+static int stringlen;
+static char *string;
+static char *comparbuf;
+
+static char *binary_search (char *, char *);
+static int compare (char *, char *);
+static char *linear_search (char *, char *);
+static int look (char *, char *);
+static void print_from (char *, char *);
+static void __attribute__((__noreturn__)) usage(void);
+
+int
+main(int argc, char *argv[])
+{
+ struct stat sb;
+ int ch, fd, termchar;
+ char *back, *file, *front, *p;
+
+ static const struct option longopts[] = {
+ {"alternative", no_argument, NULL, 'a'},
+ {"alphanum", no_argument, NULL, 'd'},
+ {"ignore-case", no_argument, NULL, 'f'},
+ {"terminate", required_argument, NULL, 't'},
+ {"version", no_argument, NULL, 'V'},
+ {"help", no_argument, NULL, 'h'},
+ {NULL, 0, NULL, 0}
+ };
+
+ setlocale(LC_ALL, "");
+ bindtextdomain(PACKAGE, LOCALEDIR);
+ textdomain(PACKAGE);
+ close_stdout_atexit();
+
+ if ((file = getenv("WORDLIST")) && !access(file, R_OK))
+ /* use the WORDLIST */;
+ else
+ file = _PATH_WORDS;
+
+ termchar = '\0';
+ string = NULL; /* just for gcc */
+
+ while ((ch = getopt_long(argc, argv, "adft:Vh", longopts, NULL)) != -1)
+ switch(ch) {
+ case 'a':
+ file = _PATH_WORDS_ALT;
+ break;
+ case 'd':
+ dflag = 1;
+ break;
+ case 'f':
+ fflag = 1;
+ break;
+ case 't':
+ termchar = *optarg;
+ break;
+ case 'V':
+ print_version(EXIT_SUCCESS);
+ case 'h':
+ usage();
+ default:
+ errtryhelp(EXIT_FAILURE);
+ }
+ argc -= optind;
+ argv += optind;
+
+ switch (argc) {
+ case 2: /* Don't set -df for user. */
+ string = *argv++;
+ file = *argv;
+ break;
+ case 1: /* But set -df by default. */
+ dflag = fflag = 1;
+ string = *argv;
+ break;
+ default:
+ warnx(_("bad usage"));
+ errtryhelp(EXIT_FAILURE);
+ }
+
+ if (termchar != '\0' && (p = strchr(string, termchar)) != NULL)
+ *++p = '\0';
+
+ if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
+ err(EXIT_FAILURE, "%s", file);
+ front = mmap(NULL, (size_t) sb.st_size, PROT_READ,
+ MAP_SHARED, fd, (off_t) 0);
+ if
+#ifdef MAP_FAILED
+ (front == MAP_FAILED)
+#else
+ ((void *)(front) <= (void *)0)
+#endif
+ err(EXIT_FAILURE, "%s", file);
+ back = front + sb.st_size;
+ return look(front, back);
+}
+
+static int
+look(char *front, char *back)
+{
+ int ch;
+ char *readp, *writep;
+
+ /* Reformat string to avoid doing it multiple times later. */
+ if (dflag) {
+ for (readp = writep = string; (ch = *readp++) != 0;) {
+ if (isalnum(ch) || isblank(ch))
+ *(writep++) = ch;
+ }
+ *writep = '\0';
+ stringlen = writep - string;
+ } else
+ stringlen = strlen(string);
+
+ comparbuf = xmalloc(stringlen+1);
+
+ front = binary_search(front, back);
+ front = linear_search(front, back);
+
+ if (front)
+ print_from(front, back);
+
+ free(comparbuf);
+
+ return (front ? 0 : 1);
+}
+
+
+/*
+ * Binary search for "string" in memory between "front" and "back".
+ *
+ * This routine is expected to return a pointer to the start of a line at
+ * *or before* the first word matching "string". Relaxing the constraint
+ * this way simplifies the algorithm.
+ *
+ * Invariants:
+ * front points to the beginning of a line at or before the first
+ * matching string.
+ *
+ * back points to the beginning of a line at or after the first
+ * matching line.
+ *
+ * Advancing the Invariants:
+ *
+ * p = first newline after halfway point from front to back.
+ *
+ * If the string at "p" is not greater than the string to match,
+ * p is the new front. Otherwise it is the new back.
+ *
+ * Termination:
+ *
+ * The definition of the routine allows it return at any point,
+ * since front is always at or before the line to print.
+ *
+ * In fact, it returns when the chosen "p" equals "back". This
+ * implies that there exists a string is least half as long as
+ * (back - front), which in turn implies that a linear search will
+ * be no more expensive than the cost of simply printing a string or two.
+ *
+ * Trying to continue with binary search at this point would be
+ * more trouble than it's worth.
+ */
+#define SKIP_PAST_NEWLINE(p, back) \
+ while (p < back && *p++ != '\n')
+
+static char *
+binary_search(char *front, char *back)
+{
+ char *p;
+
+ p = front + (back - front) / 2;
+ SKIP_PAST_NEWLINE(p, back);
+
+ /*
+ * If the file changes underneath us, make sure we don't
+ * infinitely loop.
+ */
+ while (p < back && back > front) {
+ if (compare(p, back) == GREATER)
+ front = p;
+ else
+ back = p;
+ p = front + (back - front) / 2;
+ SKIP_PAST_NEWLINE(p, back);
+ }
+ return (front);
+}
+
+/*
+ * Find the first line that starts with string, linearly searching from front
+ * to back.
+ *
+ * Return NULL for no such line.
+ *
+ * This routine assumes:
+ *
+ * o front points at the first character in a line.
+ * o front is before or at the first line to be printed.
+ */
+static char *
+linear_search(char *front, char *back)
+{
+ while (front < back) {
+ switch (compare(front, back)) {
+ case EQUAL: /* Found it. */
+ return (front);
+ case LESS: /* No such string. */
+ return (NULL);
+ case GREATER: /* Keep going. */
+ break;
+ }
+ SKIP_PAST_NEWLINE(front, back);
+ }
+ return (NULL);
+}
+
+/*
+ * Print as many lines as match string, starting at front.
+ */
+static void
+print_from(char *front, char *back)
+{
+ int eol;
+
+ while (front < back && compare(front, back) == EQUAL) {
+ if (compare(front, back) == EQUAL) {
+ eol = 0;
+ while (front < back && !eol) {
+ if (putchar(*front) == EOF)
+ err(EXIT_FAILURE, "stdout");
+ if (*front++ == '\n')
+ eol = 1;
+ }
+ } else
+ SKIP_PAST_NEWLINE(front, back);
+ }
+}
+
+/*
+ * Return LESS, GREATER, or EQUAL depending on how string compares with
+ * string2 (s1 ??? s2).
+ *
+ * o Matches up to len(s1) are EQUAL.
+ * o Matches up to len(s2) are GREATER.
+ *
+ * Compare understands about the -f and -d flags, and treats comparisons
+ * appropriately.
+ *
+ * The string "string" is null terminated. The string "s2" is '\n' terminated
+ * (or "s2end" terminated).
+ *
+ * We use strcasecmp etc, since it knows how to ignore case also
+ * in other locales.
+ */
+static int
+compare(char *s2, char *s2end) {
+ int i;
+ char *p;
+
+ /* copy, ignoring things that should be ignored */
+ p = comparbuf;
+ i = stringlen;
+ while(s2 < s2end && *s2 != '\n' && i) {
+ if (!dflag || isalnum(*s2) || isblank(*s2))
+ {
+ *p++ = *s2;
+ i--;
+ }
+ s2++;
+ }
+ *p = 0;
+
+ /* and compare */
+ if (fflag)
+ i = strncasecmp(comparbuf, string, stringlen);
+ else
+ i = strncmp(comparbuf, string, stringlen);
+
+ return ((i > 0) ? LESS : (i < 0) ? GREATER : EQUAL);
+}
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+ FILE *out = stdout;
+ fputs(USAGE_HEADER, out);
+ fprintf(out, _(" %s [options] <string> [<file>...]\n"), program_invocation_short_name);
+
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_("Display lines beginning with a specified string.\n"), out);
+
+ fputs(USAGE_OPTIONS, out);
+ fputs(_(" -a, --alternative use the alternative dictionary\n"), out);
+ fputs(_(" -d, --alphanum compare only blanks and alphanumeric characters\n"), out);
+ fputs(_(" -f, --ignore-case ignore case differences when comparing\n"), out);
+ fputs(_(" -t, --terminate <char> define the string-termination character\n"), out);
+
+ fputs(USAGE_SEPARATOR, out);
+ printf(USAGE_HELP_OPTIONS(26));
+ printf(USAGE_MAN_TAIL("look(1)"));
+
+ exit(EXIT_SUCCESS);
+}
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