shell_cmds-53.tar.gz

[apple/shell_cmds.git] / xargs / strnsubst.c

diff --git a/xargs/strnsubst.c b/xargs/strnsubst.c
new file mode 100644 (file)
index 0000000..fa8d933
--- /dev/null
+++ b/xargs/strnsubst.c
@@ -0,0 +1,99 @@
+/* $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>
+__RCSID("$FreeBSD: src/usr.bin/xargs/strnsubst.c,v 1.6 2002/06/22 12:58:42 jmallett Exp $");
+
+#include <err.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+void   strnsubst(char **, const char *, const char *, size_t);
+
+/*
+ * Replaces str with a string consisting of str with match replaced with
+ * replstr as many times as can be done before the constructed string is
+ * maxsize bytes large.  It does not free the string pointed to by str, it
+ * is up to the calling program to be sure that the original contents of
+ * str as well as the new contents are handled in an appropriate manner.
+ * If replstr is NULL, then that internally is changed to a nil-string, so
+ * that we can still pretend to do somewhat meaningful substitution.
+ * No value is returned.
+ */
+void
+strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
+{
+       char *s1, *s2, *this;
+
+       s1 = *str;
+       if (s1 == NULL)
+               return;
+       s2 = calloc(maxsize, 1);
+       if (s2 == NULL)
+               err(1, "calloc");
+
+       if (replstr == NULL)
+               replstr = "";
+
+       if (match == NULL || replstr == NULL || maxsize == strlen(s1)) {
+               strncpy(s2, s1, maxsize);
+               s2[maxsize - 1] = '\0';
+               goto done;
+       }
+
+       for (;;) {
+               this = strstr(s1, match);
+               if (this == NULL)
+                       break;
+               if ((strlen(s2) + ((uintptr_t)this - (uintptr_t)s1) +
+                   (strlen(replstr) - 1)) > maxsize && *replstr != '\0') {
+                       strncat(s2, s1, maxsize);
+                       s2[maxsize - 1] = '\0';
+                       goto done;
+               }
+               strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1);
+               strcat(s2, replstr);
+               s1 = this + strlen(match);
+       }
+       strcat(s2, s1);
+done:
+       *str = s2;
+       return;
+}
+
+#ifdef TEST
+#include <stdio.h>
+
+int 
+main(void)
+{
+       char *x, *y, *z, *za;
+
+       x = "{}%$";
+       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