remove buffer-overrun risk in readlink call

readlink does not write a nul character to the end of the
string it returns. Therefore ask for one fewer character
than the buffer size so there's always room for an extra \0.

Signed-off-by: Mathias Nyman <mathias.nyman@nokia.com>
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Martin Pitt <martin.pitt@ubuntu.com>

udev/udev-node.c

@@ -163,7 +163,7 @@ static int node_symlink(struct udev *udev, const char *node, const char *slink)
 			int len;
 
 			dbg(udev, "found existing symlink '%s'\n", slink);
-			len = readlink(slink, buf, sizeof(buf));
+			len = readlink(slink, buf, sizeof(buf) - 1);
 			if (len > 0) {
 				buf[len] = '\0';
 				if (strcmp(target, buf) == 0) {