lib/sysfs: zero-terminate result of sysfs_blkdev_get_devchain()

sysfs_blkdev_get_devchain() does not zero-terminate its result, but the
caller expects a C-string.
Use ul_buffer_get_string() which includes a trailing zero-byte.

Now it's also valid for sz and bufsz to be equal.

See #3088.
Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>

diff --git a/lib/sysfs.c b/lib/sysfs.c
index e7294e6b1aa457552ba82bb84251ed38b93a3bb2..ac9c5c3bf324b5ec3e29ba8d07af96c400ec16b9 100644 (file)
--- a/lib/sysfs.c
+++ b/lib/sysfs.c
@@ -404,8 +404,8 @@ char *sysfs_blkdev_get_devchain(struct path_cxt *pc, char *buf, size_t bufsz)
        ul_buffer_append_string(&tmp, _PATH_SYS_DEVBLOCK "/");
        ul_buffer_append_data(&tmp, buf, ssz);
 
-       p = ul_buffer_get_data(&tmp, &sz, NULL);
-       if (p && sz < bufsz) {
+       p = ul_buffer_get_string(&tmp, &sz, NULL);
+       if (p && sz <= bufsz) {
                memcpy(buf, p, sz);
                res = buf;
        }