[Libguestfs] [libnbd PATCH] info: Try harder to report contents from nbd-server
nbd-server 3.25 blindly reports a size of 0 for NBD_OPT_INFO,
regardless of whether it is exporting a block device or regular file.
While that will likely be fixed for the next nbd-server release, we
can at least rely on the accurate size after NBD_OPT_GO to report
contents more accurately. A more invasive patch would be to
unconditionally try NBD_OPT_GO if NBD_OPT_INFO reports a size of 0.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
info/show.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/info/show.c b/info/show.c
index ac483f34..a3a57ef0 100644
--- a/info/show.c
+++ b/info/show.c
@@ -355,10 +355,20 @@ get_content (struct nbd_handle *nbd, int64_t size)
if (!probe_content)
return NULL;
- if (nbd_aio_is_negotiating (nbd) &&
- nbd_opt_go (nbd) == -1) {
- fprintf (stderr, "%s: %s\n", progname, nbd_get_error ());
- exit (EXIT_FAILURE);
+ if (nbd_aio_is_negotiating (nbd)) {
+ if (nbd_opt_go (nbd) == -1) {
+ fprintf (stderr, "%s: %s\n", progname, nbd_get_error ());
+ exit (EXIT_FAILURE);
+ }
+ /* nbd-server 3.25 only reports accurate size to NBD_OPT_GO and 0
+ * to NBD_OPT_INFO; this hack won't fix what we report for size,
+ * but improves what we report for contents.
+ */
+ if (size == 0) {
+ size = nbd_get_size (nbd);
+ if (size == -1)
+ size = 0;
+ }
}
/* Write the first part of the NBD export to a temporary file. */
--
2.43.2