1 files changed, 109 insertions, 0 deletions
diff --git a/usr.bin/xargs/strnsubst.c b/usr.bin/xargs/strnsubst.c
new file mode 100644
index 0000000..33366b6
--- /dev/null
+++ b/usr.bin/xargs/strnsubst.c
@@ -0,0 +1,109 @@
+/* $xMach: strnsubst.c,v 1.3 2002/02/23 02:10:24 jmallett Exp $ */
+
+/*
+ * Copyright (c) 2002 J. Mallett.  All rights reserved.
+ * You may do whatever you want with this file as long as
+ * the above copyright and this notice remain intact, along
+ * with the following statement:
+ * 	For the man who taught me vi, and who got too old, too young.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <err.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+void	strnsubst(char **, const char *, const char *, size_t);
+
+/*
+ * Replaces str with a string consisting of str with match replaced with
+ * replstr as many times as can be done before the constructed string is
+ * maxsize bytes large.  It does not free the string pointed to by str, it
+ * is up to the calling program to be sure that the original contents of
+ * str as well as the new contents are handled in an appropriate manner.
+ * If replstr is NULL, then that internally is changed to a nil-string, so
+ * that we can still pretend to do somewhat meaningful substitution.
+ * No value is returned.
+ */
+void
+strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
+{
+	char *s1, *s2, *this;
+
+	s1 = *str;
+	if (s1 == NULL)
+		return;
+	/*
+	 * If maxsize is 0 then set it to to the length of s1, because we have
+	 * to duplicate s1.  XXX we maybe should double-check whether the match
+	 * appears in s1.  If it doesn't, then we also have to set the length
+	 * to the length of s1, to avoid modifying the argument.  It may make
+	 * sense to check if maxsize is <= strlen(s1), because in that case we
+	 * want to return the unmodified string, too.
+	 */
+	if (maxsize == 0) {
+		match = NULL;
+		maxsize = strlen(s1) + 1;
+	}
+	s2 = calloc(maxsize, 1);
+	if (s2 == NULL)
+		err(1, "calloc");
+
+	if (replstr == NULL)
+		replstr = "";
+
+	if (match == NULL || replstr == NULL || maxsize == strlen(s1)) {
+		strlcpy(s2, s1, maxsize);
+		goto done;
+	}
+
+	for (;;) {
+		this = strstr(s1, match);
+		if (this == NULL)
+			break;
+		if ((strlen(s2) + strlen(s1) + strlen(replstr) -
+		    strlen(match) + 1) > maxsize) {
+			strlcat(s2, s1, maxsize);
+			goto done;
+		}
+		strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1);
+		strcat(s2, replstr);
+		s1 = this + strlen(match);
+	}
+	strcat(s2, s1);
+done:
+	*str = s2;
+	return;
+}
+
+#ifdef TEST
+#include <stdio.h>
+
+int 
+main(void)
+{
+	char *x, *y, *z, *za;
+
+	x = "{}%$";
+	strnsubst(&x, "%$", "{} enpury!", 255);
+	y = x;
+	strnsubst(&y, "}{}", "ybir", 255);
+	z = y;
+	strnsubst(&z, "{", "v ", 255);
+	za = z;
+	strnsubst(&z, NULL, za, 255);
+	if (strcmp(z, "v ybir enpury!") == 0)
+		printf("strnsubst() seems to work!\n");
+	else
+		printf("strnsubst() is broken.\n");
+	printf("%s\n", z);
+	free(x);
+	free(y);
+	free(z);
+	free(za);
+	return 0;
+}
+#endif