source: MondoRescue/branches/2.2.9/mindi-busybox/shell/match.c@ 3320

/*
 * ##/%% variable matching code ripped out of ash shell for code sharing
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
 * was re-ported from NetBSD and debianized.
 */
#ifdef STANDALONE
# include <stdbool.h>
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# include <unistd.h>
# define FAST_FUNC /* nothing */
# define PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN /* nothing */
# define POP_SAVED_FUNCTION_VISIBILITY /* nothing */
#else
# include "libbb.h"
#endif
#include <fnmatch.h>
#include "match.h"

char* FAST_FUNC scan_and_match(char *string, const char *pattern, unsigned flags)
{
    char *loc;
    char *end;
    unsigned len = strlen(string);
    int early_exit;

    /* We can stop the scan early only if the string part
     * we are matching against is shrinking, and the pattern has
     * an unquoted "star" at the corresponding end. There are two cases.
     * Case 1:
     * "qwerty" does not match against pattern "*zy",
     * no point in trying to match "werty", "erty" etc:
     */
    early_exit = (flags == (SCAN_MOVE_FROM_LEFT + SCAN_MATCH_RIGHT_HALF) && pattern[0] == '*');

    if (flags & SCAN_MOVE_FROM_LEFT) {
        loc = string;
        end = string + len + 1;
    } else {
        loc = string + len;
        end = string - 1;
        if (flags == (SCAN_MOVE_FROM_RIGHT + SCAN_MATCH_LEFT_HALF)) {
            /* Case 2:
             * "qwerty" does not match against pattern "qz*",
             * no point in trying to match "qwert", "qwer" etc:
             */
            const char *p = pattern + strlen(pattern);
            if (--p >= pattern && *p == '*') {
                early_exit = 1;
                while (--p >= pattern && *p == '\\')
                    early_exit ^= 1;
            }
        }
    }

    while (loc != end) {
        char c;
        int r;

        c = *loc;
        if (flags & SCAN_MATCH_LEFT_HALF) {
            *loc = '\0';
            r = fnmatch(pattern, string, 0);
            *loc = c;
        } else {
            r = fnmatch(pattern, loc, 0);
        }
        if (r == 0) /* match found */
            return loc;
        if (early_exit) {
#ifdef STANDALONE
            printf("(early exit) ");
#endif
            break;
        }

        if (flags & SCAN_MOVE_FROM_LEFT) {
            loc++;
        } else {
            loc--;
        }
    }
    return NULL;
}

#ifdef STANDALONE
int main(int argc, char *argv[])
{
    char *string;
    char *op;
    char *pattern;
    char *loc;

    setvbuf(stdout, NULL, _IONBF, 0);

    if (!argv[1]) {
        puts(
            "Usage: match <test> [test...]\n\n"
            "Where a <test> is the form: <string><op><match>\n"
            "This is to test the shell ${var#val} expression type.\n\n"
            "e.g. `match 'abc#a*'` -> bc"
        );
        return 1;
    }

    while (*++argv) {
        size_t off;
        unsigned scan_flags;

        string = *argv;
        off = strcspn(string, "#%");
        if (!off) {
            printf("invalid format\n");
            continue;
        }
        op = string + off;
        scan_flags = pick_scan(op[0], op[1]);

        printf("'%s': flags:%x, ", string, scan_flags);
        pattern = op + 1;
        if (op[0] == op[1])
            pattern++;
        op[0] = '\0';

        loc = scan_and_match(string, pattern, scan_flags);

        if (scan_flags & SCAN_MATCH_LEFT_HALF) {
            printf("'%s'\n", loc);
        } else {
            if (loc)
                *loc = '\0';
            printf("'%s'\n", string);
        }
    }

    return 0;
}
#endif