1 files changed, 45 insertions, 0 deletions
diff --git a/9bind.c b/9bind.c
new file mode 100644
index 0000000..620d092
--- /dev/null
+++ b/9bind.c
@@ -0,0 +1,45 @@
+/* © 2008 sqweek <sqweek@gmail.com>
+ * See COPYING for details.
+ */
+#include <err.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+#include <sys/mount.h>
+
+int
+main(int argc, char **argv)
+{
+	char *old = NULL, *new = NULL;
+	struct stat stbuf;
+
+	while (*++argv) {
+		if (!old) {
+			old = *argv;
+		} else if (!new) {
+			new = *argv;
+		} else {
+			errx(1, "%s: too many arguments", *argv);
+		}
+	}
+
+	if (!old || !new) {
+		errx(1, "usage: 9bind old new");
+	}
+
+	/* Make sure mount exists, is writable, and not sticky */
+	if (stat(new, &stbuf) || access(new, W_OK)) {
+		err(1, "%s", new);
+	}
+	if (stbuf.st_mode & S_ISVTX) {
+		errx(1, "%s: refusing to bind over sticky directory", new);
+	}
+
+	if (mount(old, new, NULL, MS_BIND, NULL)) {
+		err(1, "mount");
+	}
+
+	return 0;
+}