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author | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 12:33:43 +0000 |
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committer | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 12:33:43 +0000 |
commit | f9ab90d9d6d02989a075d0f0074496d5b1045e4b (patch) | |
tree | add7e996bac5289cdc55e6935750c352505560a9 /usr.bin/look/look.c | |
parent | be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da (diff) | |
download | FreeBSD-src-f9ab90d9d6d02989a075d0f0074496d5b1045e4b.zip FreeBSD-src-f9ab90d9d6d02989a075d0f0074496d5b1045e4b.tar.gz |
BSD 4.4 Lite Usr.bin Sources
Diffstat (limited to 'usr.bin/look/look.c')
-rw-r--r-- | usr.bin/look/look.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/usr.bin/look/look.c b/usr.bin/look/look.c new file mode 100644 index 0000000..87db927 --- /dev/null +++ b/usr.bin/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 char copyright[] = +"@(#) Copyright (c) 1991, 1993\n\ + The Regents of the University of California. All rights reserved.\n"; +#endif /* not lint */ + +#ifndef lint +static char sccsid[] = "@(#)look.c 8.1 (Berkeley) 6/14/93"; +#endif /* not lint */ + +/* + * 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 <limits.h> +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <ctype.h> +#include "pathnames.h" + +/* + * FOLD and DICT convert characters to a normal form for comparison, + * according to the user specified flags. + * + * DICT expects integers because it uses a non-character value to + * indicate a character which should not participate in comparisons. + */ +#define EQUAL 0 +#define GREATER 1 +#define LESS (-1) +#define NO_COMPARE (-2) + +#define FOLD(c) (isascii(c) && isupper(c) ? tolower(c) : (c)) +#define DICT(c) (isascii(c) && isalnum(c) ? (c) : NO_COMPARE) + +int dflag, fflag; + +char *binary_search __P((char *, char *, char *)); +int compare __P((char *, char *, char *)); +void err __P((const char *fmt, ...)); +char *linear_search __P((char *, char *, char *)); +int look __P((char *, char *, char *)); +void print_from __P((char *, char *, char *)); + +static void usage __P((void)); + +main(argc, argv) + int argc; + char *argv[]; +{ + struct stat sb; + int ch, fd, termchar; + char *back, *file, *front, *string, *p; + + file = _PATH_WORDS; + termchar = '\0'; + while ((ch = getopt(argc, argv, "dft:")) != EOF) + switch(ch) { + case 'd': + dflag = 1; + break; + case 'f': + fflag = 1; + break; + case 't': + termchar = *optarg; + break; + case '?': + default: + usage(); + } + 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: + usage(); + } + + if (termchar != '\0' && (p = strchr(string, termchar)) != NULL) + *++p = '\0'; + + if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb)) + err("%s: %s", file, strerror(errno)); + if (sb.st_size > SIZE_T_MAX) + err("%s: %s", file, strerror(EFBIG)); + if ((front = mmap(NULL, + (size_t)sb.st_size, PROT_READ, 0, fd, (off_t)0)) == NULL) + err("%s: %s", file, strerror(errno)); + back = front + sb.st_size; + exit(look(string, front, back)); +} + +look(string, front, back) + char *string, *front, *back; +{ + register int ch; + register char *readp, *writep; + + /* Reformat string string to avoid doing it multiple times later. */ + for (readp = writep = string; ch = *readp++;) { + if (fflag) + ch = FOLD(ch); + if (dflag) + ch = DICT(ch); + if (ch != NO_COMPARE) + *(writep++) = ch; + } + *writep = '\0'; + + 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(string, front, back) + register char *string, *front, *back; +{ + register 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(string, front, back) + char *string, *front, *back; +{ + while (front < back) { + switch (compare(string, front, back)) { + case EQUAL: /* Found it. */ + return (front); + break; + case LESS: /* No such string. */ + return (NULL); + break; + 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(string, front, back) + register char *string, *front, *back; +{ + for (; front < back && compare(string, front, back) == EQUAL; ++front) { + for (; front < back && *front != '\n'; ++front) + if (putchar(*front) == EOF) + err("stdout: %s", strerror(errno)); + if (putchar('\n') == EOF) + err("stdout: %s", strerror(errno)); + } +} + +/* + * 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(s1, s2, back) + register char *s1, *s2, *back; +{ + register int ch; + + for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) { + ch = *s2; + if (fflag) + ch = FOLD(ch); + if (dflag) + ch = DICT(ch); + + if (ch == NO_COMPARE) { + ++s2; /* Ignore character in comparison. */ + continue; + } + if (*s1 != ch) + return (*s1 < ch ? LESS : GREATER); + } + return (*s1 ? GREATER : EQUAL); +} + +static void +usage() +{ + (void)fprintf(stderr, "usage: look [-df] [-t char] string [file]\n"); + exit(2); +} + +#if __STDC__ +#include <stdarg.h> +#else +#include <varargs.h> +#endif + +void +#if __STDC__ +err(const char *fmt, ...) +#else +err(fmt, va_alist) + char *fmt; + va_dcl +#endif +{ + va_list ap; +#if __STDC__ + va_start(ap, fmt); +#else + va_start(ap); +#endif + (void)fprintf(stderr, "look: "); + (void)vfprintf(stderr, fmt, ap); + va_end(ap); + (void)fprintf(stderr, "\n"); + exit(2); + /* NOTREACHED */ +} |