look.c

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/*      look 1.3 - Find lines in a sorted list.         Author: Kees J. Bot
 */
#define nil 0
#include <sys/types.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

char DEFAULT[] = "/usr/lib/dict/words";

char *string, *wordlist= DEFAULT;

#define MAXLEN  1024    /* Maximum word length. */

int dflg= 0, fflg= 0;

void nonascii(char *what)
{
        fprintf(stderr, "look: %s contains non-ASCII characters.\n", what);
        exit(1);
}

int compare(char *prefix, char *word)
{
        char *p= prefix, *w= word;
        int cp, cw;

        do {
                do {
                        if ((cp= *p++) == 0) return 0;
                        if (!isascii(cp)) nonascii("prefix string");
                } while (dflg && !isspace(cp) && !isalnum(cp));

                if (dflg) {
                        if (isspace(cp)) {
                                while (isspace(*p)) p++;
                                cp= ' ';
                        }
                }
                if (fflg && isupper(cp)) cp= tolower(cp);

                do {
                        if ((cw= *w++) == 0) return 1;
                        if (!isascii(cw)) nonascii(wordlist);
                } while (dflg && !isspace(cw) && !isalnum(cw));

                if (dflg) {
                        if (isspace(cw)) {
                                while (isspace(*w)) w++;
                                cw= ' ';
                        }
                }
                if (fflg && isupper(cw)) cw= tolower(cw);
        } while (cp == cw);

        return cp - cw;
}

char *readword(FILE *f)
{
        static char word[MAXLEN + 2];
        int n;

        if (fgets(word, sizeof(word), f) == nil) {
                if (ferror(f)) {
                        fprintf(stderr, "look: read error on %s",
                                wordlist);
                        exit(1);
                }
                return nil;
        }

        n= strlen(word);

        if (word[n-1] != '\n') {
                fprintf(stderr, "look: word from %s is too long\n", wordlist);
                exit(1);
        }
        word[n-1] = 0;

        return word;
}

void look(void)
{
        off_t low, mid, high;
        FILE *f;
        char *word;
        int c;

        if ((f= fopen(wordlist, "r")) == nil) {
                fprintf(stderr, "look: Can't open %s\n", wordlist);
                exit(1);
        }

        low= 0;

        fseek(f, (off_t) 0, 2);

        high= ftell(f);

        while (low <= high) {
                mid= (low + high) / 2;

                fseek(f, mid, 0);

                if (mid != 0) readword(f);

                if ((word= readword(f)) == nil)
                        c= -1;
                else
                        c= compare(string, word);

                if (c <= 0) high= mid - 1; else low= mid + 1;
        }
        fseek(f, low, 0);
        if (low != 0) readword(f);

        c=0;
        while (c >= 0 && (word= readword(f)) != nil) {
                c= compare(string, word);

                if (c == 0) puts(word);
        }
}

int main(int argc, char **argv)
{
        if (argc == 2) dflg= fflg= 1;

        while (argc > 1 && argv[1][0] == '-') {
                char *p= argv[1] + 1;

                while (*p != 0) {
                        switch (*p++) {
                        case 'd':       dflg= 1; break;
                        case 'f':       fflg= 1; break;
                        default:
                                fprintf(stderr, "look: Bad flag: %c\n", p[-1]);
                                exit(1);
                        }
                }
                argc--;
                argv++;
        }
        if (argc == 3)
                wordlist= argv[2];
        else
        if (argc != 2) {
                fprintf(stderr, "Usage: look [-df] string [file]\n");
                exit(1);
        }
        string= argv[1];
        look();
        exit(0);
}
/* Kees J. Bot 24-5-89. */

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