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Annotation of src/usr.bin/xargs/strnsubst.c, Revision 1.1

1.1     ! millert     1: /*     $OpenBSD$       */
        !             2: /*     $FreeBSD: strnsubst.c,v 1.6 2002/06/22 12:58:42 jmallett Exp $  */
        !             3:
        !             4: /*
        !             5:  * Copyright (c) 2002 J. Mallett.  All rights reserved.
        !             6:  * You may do whatever you want with this file as long as
        !             7:  * the above copyright and this notice remain intact, along
        !             8:  * with the following statement:
        !             9:  *     For the man who taught me vi, and who got too old, too young.
        !            10:  */
        !            11:
        !            12: #ifndef lint
        !            13: static const char rcsid[] = "$OpenBSD$";
        !            14: #endif /* not lint */
        !            15:
        !            16: #include <err.h>
        !            17: #include <stdio.h>
        !            18: #include <stdlib.h>
        !            19: #include <string.h>
        !            20: #include <unistd.h>
        !            21:
        !            22: void   strnsubst(char **, const char *, const char *, size_t);
        !            23:
        !            24: /*
        !            25:  * Replaces str with a string consisting of str with match replaced with
        !            26:  * replstr as many times as can be done before the constructed string is
        !            27:  * maxsize bytes large.  It does not free the string pointed to by str, it
        !            28:  * is up to the calling program to be sure that the original contents of
        !            29:  * str as well as the new contents are handled in an appropriate manner.
        !            30:  * If replstr is NULL, then that internally is changed to a nil-string, so
        !            31:  * that we can still pretend to do somewhat meaningful substitution.
        !            32:  * No value is returned.
        !            33:  */
        !            34: void
        !            35: strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
        !            36: {
        !            37:        char *s1, *s2, *this;
        !            38:        size_t matchlen, repllen, s2len, n;
        !            39:
        !            40:        if ((s1 = *str) == NULL)
        !            41:                return;
        !            42:        if ((s2 = malloc(maxsize)) == NULL)
        !            43:                err(1, NULL);
        !            44:
        !            45:        if (replstr == NULL)
        !            46:                replstr = "";
        !            47:
        !            48:        if (match == NULL || *match == '\0' || strlen(s1) >= maxsize) {
        !            49:                strlcpy(s2, s1, maxsize);
        !            50:                goto done;
        !            51:        }
        !            52:
        !            53:        *s2 = '\0';
        !            54:        s2len = 0;
        !            55:        matchlen = strlen(match);
        !            56:        repllen = strlen(replstr);
        !            57:        for (;;) {
        !            58:                if ((this = strstr(s1, match)) == NULL)
        !            59:                        break;
        !            60:                n = snprintf(s2 + s2len, maxsize - s2len, "%.*s%s",
        !            61:                    (int)(this - s1), s1, replstr);
        !            62:                if (n + s2len + strlen(this + matchlen) >= maxsize)
        !            63:                        break;                  /* out of room */
        !            64:                s2len += n;
        !            65:                s1 = this + matchlen;
        !            66:        }
        !            67:        strlcpy(s2 + s2len, s1, maxsize - s2len);
        !            68: done:
        !            69:        *str = s2;
        !            70:        return;
        !            71: }
        !            72:
        !            73: #ifdef TEST
        !            74: #include <stdio.h>
        !            75:
        !            76: int
        !            77: main(void)
        !            78: {
        !            79:        char *x, *y, *z, *za;
        !            80:
        !            81:        x = "{}%$";
        !            82:        strnsubst(&x, "%$", "{} enpury!", 255);
        !            83:        y = x;
        !            84:        strnsubst(&y, "}{}", "ybir", 255);
        !            85:        z = y;
        !            86:        strnsubst(&z, "{", "v ", 255);
        !            87:        za = z;
        !            88:        strnsubst(&z, NULL, za, 255);
        !            89:        if (strcmp(z, "v ybir enpury!") == 0)
        !            90:                printf("strnsubst() seems to work!\n");
        !            91:        else
        !            92:                printf("strnsubst() is broken.\n");
        !            93:        printf("%s\n", z);
        !            94:        free(x);
        !            95:        free(y);
        !            96:        free(z);
        !            97:        free(za);
        !            98:        return 0;
        !            99: }
        !           100: #endif