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Commit	Line	Data
	1	/* $xMach: strnsubst.c,v 1.3 2002/02/23 02:10:24 jmallett Exp $ */
	2
	3	/*
	4	* Copyright (c) 2002 J. Mallett. All rights reserved.
	5	* You may do whatever you want with this file as long as
	6	* the above copyright and this notice remain intact, along
	7	* with the following statement:
	8	* For the man who taught me vi, and who got too old, too young.
	9	*/
	10
	11	#include <sys/cdefs.h>
	12	__FBSDID("$FreeBSD: src/usr.bin/xargs/strnsubst.c,v 1.7 2004/10/18 15:40:47 cperciva Exp $");
	13
	14	#include <err.h>
	15	#include <stdlib.h>
	16	#include <string.h>
	17	#include <unistd.h>
	18
	19	void strnsubst(char *, const char , const char *, size_t);
	20
	21	/*
	22	* Replaces str with a string consisting of str with match replaced with
	23	* replstr as many times as can be done before the constructed string is
	24	* maxsize bytes large. It does not free the string pointed to by str, it
	25	* is up to the calling program to be sure that the original contents of
	26	* str as well as the new contents are handled in an appropriate manner.
	27	* If replstr is NULL, then that internally is changed to a nil-string, so
	28	* that we can still pretend to do somewhat meaningful substitution.
	29	* No value is returned.
	30	*/
	31	void
	32	strnsubst(char *str, const char match, const char *replstr, size_t maxsize)
	33	{
	34	char s1, s2, *this;
	35
	36	s1 = *str;
	37	if (s1 == NULL)
	38	return;
	39	s2 = calloc(maxsize, 1);
	40	if (s2 == NULL)
	41	err(1, "calloc");
	42
	43	if (replstr == NULL)
	44	replstr = "";
	45
	46	if (match == NULL \|\| replstr == NULL \|\| maxsize == strlen(s1)) {
	47	strlcpy(s2, s1, maxsize);
	48	goto done;
	49	}
	50
	51	for (;;) {
	52	this = strstr(s1, match);
	53	if (this == NULL)
	54	break;
	55	if ((strlen(s2) + strlen(s1) + strlen(replstr) -
	56	strlen(match) + 1) > maxsize) {
	57	strlcat(s2, s1, maxsize);
	58	goto done;
	59	}
	60	strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1);
	61	strcat(s2, replstr);
	62	s1 = this + strlen(match);
	63	}
	64	strcat(s2, s1);
	65	done:
	66	*str = s2;
	67	return;
	68	}
	69
	70	#ifdef TEST
	71	#include <stdio.h>
	72
	73	int
	74	main(void)
	75	{
	76	char x, y, z, za;
	77
	78	x = "{}%$";
	79	strnsubst(&x, "%$", "{} enpury!", 255);
	80	y = x;
	81	strnsubst(&y, "}{}", "ybir", 255);
	82	z = y;
	83	strnsubst(&z, "{", "v ", 255);
	84	za = z;
	85	strnsubst(&z, NULL, za, 255);
	86	if (strcmp(z, "v ybir enpury!") == 0)
	87	printf("strnsubst() seems to work!\n");
	88	else
	89	printf("strnsubst() is broken.\n");
	90	printf("%s\n", z);
	91	free(x);
	92	free(y);
	93	free(z);
	94	free(za);
	95	return 0;
	96	}
	97	#endif