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Diffstat (limited to 'text_cmds/look/look.c')
| -rw-r--r-- | text_cmds/look/look.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/text_cmds/look/look.c b/text_cmds/look/look.c new file mode 100644 index 0000000..4f146fa --- /dev/null +++ b/text_cmds/look/look.c @@ -0,0 +1,357 @@ +/*- + * 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. + */ + +#ifndef lint +static const char copyright[] = +"@(#) Copyright (c) 1991, 1993\n\ + The Regents of the University of California. All rights reserved.\n"; +#endif /* not lint */ + +#ifndef lint +#if 0 +static char sccsid[] = "@(#)look.c 8.2 (Berkeley) 5/4/95"; +#endif +#endif /* not lint */ +#include <sys/cdefs.h> +__FBSDID("$FreeBSD: src/usr.bin/look/look.c,v 1.18.10.2.4.1 2010/06/14 02:09:06 kensmith Exp $"); + +/* + * 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/types.h> +#include <sys/mman.h> +#include <sys/stat.h> + +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <locale.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <wchar.h> +#include <wctype.h> + +#include "pathnames.h" + +static char _path_words[] = _PATH_WORDS; + +#define EQUAL 0 +#define GREATER 1 +#define LESS (-1) + +int dflag, fflag; + +char *binary_search(wchar_t *, unsigned char *, unsigned char *); +int compare(wchar_t *, unsigned char *, unsigned char *); +char *linear_search(wchar_t *, unsigned char *, unsigned char *); +int look(wchar_t *, unsigned char *, unsigned char *); +wchar_t *prepkey(const char *, wchar_t); +void print_from(wchar_t *, unsigned char *, unsigned char *); + +static void usage(void); + +int +main(int argc, char *argv[]) +{ + struct stat sb; + int ch, fd, match; + wchar_t termchar; + unsigned char *back, *front; + unsigned const char *file; + wchar_t *key; + + (void) setlocale(LC_CTYPE, ""); + + file = _path_words; + termchar = L'\0'; + while ((ch = getopt(argc, argv, "dft:")) != -1) + switch(ch) { + case 'd': + dflag = 1; + break; + case 'f': + fflag = 1; + break; + case 't': + if (mbrtowc(&termchar, optarg, MB_LEN_MAX, NULL) != + strlen(optarg)) + errx(2, "invalid termination character"); + break; + case '?': + default: + usage(); + } + argc -= optind; + argv += optind; + +/* 4384130 */ +#ifdef __APPLE__ + if (argc <= 0) +#else + if (argc == 0) +#endif + usage(); + if (argc == 1) /* But set -df by default. */ + dflag = fflag = 1; + key = prepkey(*argv++, termchar); + if (argc >= 2) + file = *argv++; + + match = 1; + + do { + if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) + err(2, "%s", file); + if (sb.st_size > SIZE_T_MAX) + errx(2, "%s: %s", file, strerror(EFBIG)); + if (sb.st_size == 0) { + close(fd); + continue; + } + if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED) + err(2, "%s", file); + back = front + sb.st_size; + match *= (look(key, front, back)); + close(fd); + } while (argc-- > 2 && (file = *argv++)); + + exit(match); +} + +wchar_t * +prepkey(const char *string, wchar_t termchar) +{ + const char *readp; + wchar_t *key, *writep; + wchar_t ch; + size_t clen; + + /* + * Reformat search string and convert to wide character representation + * to avoid doing it multiple times later. + */ + if ((key = malloc(sizeof(wchar_t) * (strlen(string) + 1))) == NULL) + err(2, NULL); + readp = string; + writep = key; + while ((clen = mbrtowc(&ch, readp, MB_LEN_MAX, NULL)) != 0) { + if (clen == (size_t)-1 || clen == (size_t)-2) + errc(2, EILSEQ, NULL); + if (fflag) + ch = towlower(ch); + if (!dflag || iswalnum(ch)) + *writep++ = ch; + readp += clen; + } + *writep = L'\0'; + if (termchar != L'\0' && (writep = wcschr(key, termchar)) != NULL) + *++writep = L'\0'; + return (key); +} + +int +look(wchar_t *string, unsigned char *front, unsigned char *back) +{ + + front = binary_search(string, front, back); + front = linear_search(string, front, back); + + if (front) + print_from(string, front, back); + 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. + * + * Base of the Invariants. + * front = NULL; + * back = EOF; + * + * 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'); + +char * +binary_search(wchar_t *string, unsigned char *front, unsigned char *back) +{ + unsigned 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(string, 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. + */ +char * +linear_search(wchar_t *string, unsigned char *front, unsigned char *back) +{ + while (front < back) { + switch (compare(string, 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. + */ +void +print_from(wchar_t *string, unsigned char *front, unsigned char *back) +{ + for (; front < back && compare(string, front, back) == EQUAL; ++front) { + for (; front < back && *front != '\n'; ++front) + if (putchar(*front) == EOF) + err(2, "stdout"); + if (putchar('\n') == EOF) + err(2, "stdout"); + } +} + +/* + * Return LESS, GREATER, or EQUAL depending on how the string1 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 "s1" is null terminated. The string s2 is '\n' terminated (or + * "back" terminated). + */ +int +compare(wchar_t *s1, unsigned char *s2, unsigned char *back) +{ + wchar_t ch1, ch2; + size_t len2; + + for (; *s1 && s2 < back && *s2 != '\n'; ++s1, s2 += len2) { + ch1 = *s1; + len2 = mbrtowc(&ch2, s2, back - s2, NULL); + if (len2 == (size_t)-1 || len2 == (size_t)-2) { + ch2 = *s2; + len2 = 1; + } + if (fflag) + ch2 = towlower(ch2); + if (dflag && !iswalnum(ch2)) { + /* Ignore character in comparison. */ + --s1; + continue; + } + if (ch1 != ch2) + return (ch1 < ch2 ? LESS : GREATER); + } + return (*s1 ? GREATER : EQUAL); +} + +static void +usage(void) +{ + (void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n"); + exit(2); +} |