Re: [Libguestfs] [PATCH nbdkit 4/8] offset: Implement mapping of extents.
On 3/20/19 5:11 PM, Richard W.M. Jones wrote:
Allows you to safely use nbdkit-offset-filter on top of a plugin
supporting extents.
---
filters/offset/offset.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
If we don't change our minds on the interface in patch 1, then this
looks correct.
+/* Extents. */
+static int
+offset_extents (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offs, uint32_t flags,
+ struct nbdkit_extents *extents, int *err)
+{
+ size_t i;
+ struct nbdkit_extents *extents2;
+ struct nbdkit_extent e;
+
+ extents2 = nbdkit_extents_new (offs + offset);
+ if (extents2 == NULL) {
+ *err = errno;
+ return -1;
+ }
Ouch - nbdkit_extents_new() returns NULL for 'start >= INT64_MAX'
without setting errno. Of course, that failure path should be
unreachable here, but if you are going to assign *err based on errno,
then we have to make sure patch 1 guarantees sane errno settings on all
failure paths.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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