Add a convenience function for building nmount iov arrays.

sbin/mount/getmntopts.c

@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/stat.h>
+#include <sys/uio.h>
 
 #include <err.h>
 #include <errno.h>
@@ -138,3 +139,26 @@ checkpath(path, resolved)
 	} else
 		errx(EX_USAGE, "%s: %s", resolved, strerror(errno));
 }
+
+void
+build_iovec(struct iovec **iov, int *iovlen, const char *name, void *val, int len)
+{
+	int i;
+
+	if (iovlen < 0)
+		return;
+	i = *iovlen;
+	*iov = realloc(*iov, sizeof **iov * (i + 2));
+	if (*iov == NULL) {
+		*iovlen = -1;
+		return;
+	}
+	(*iov)[i].iov_base = strdup(name);
+	(*iov)[i].iov_len = strlen(name) + 1;
+	i++;
+	(*iov)[i].iov_base = val;
+	if (len < 0)
+		len = strlen(val) + 1;
+	(*iov)[i].iov_len = len;
+	*iovlen = ++i;
+}

sbin/mount/mntopts.h

@@ -92,3 +92,4 @@ void getmntopts(const char *, const struct mntopt *, int *, int *);
 void rmslashes(char *, char *);
 void checkpath(const char *, char resolved_path[]);
 extern int getmnt_silent;
+void build_iovec(struct iovec **iov, int *iovlen, const char *name, void *val, int len);