Re: [Libguestfs] [PATCH] WIP: ddrescue mapfile filter
On Fri, May 01, 2020 at 07:14:32PM +0200, François Revol wrote:
This allows to overlay bad sectors according to the mapfile generated
by
ddrescue, to then see where sectors are used using fsck and trying to
copy files around.
Signed-off-by: François Revol <revol(a)free.fr>
...
+nbdkit_ddrescue_filter_la_LDFLAGS = \
+ -module -avoid-version -shared \
We recently added $(SHARED_LDFLAGS) to the end of this line.
Compare filters/ip/Makefile.am to your file.
diff --git a/filters/ddrescue/ddrescue.c
b/filters/ddrescue/ddrescue.c
new file mode 100644
index 00000000..a0e49e3c
--- /dev/null
+++ b/filters/ddrescue/ddrescue.c
@@ -0,0 +1,218 @@
+/* nbdkit
+ * Copyright (C) 2018-2020 Red Hat Inc.
In several files and the man page you're assigning copyright over
to Red Hat, but it's probably better to copyright them to yourself
and/or your organisation.
+struct range {
+ int64_t start;
+ int64_t end;
+ int64_t size;
+ char status;
+};
+
+struct mapfile {
+ int ranges_count;
+ struct range *ranges;
+};
+static struct mapfile map = { 0, NULL };
There are actually two generic types in common/ which might help here.
There's a vector type for building lists:
https://github.com/libguestfs/nbdkit/blob/master/common/utils/vector.h
Example usage:
https://github.com/libguestfs/nbdkit/blob/master/plugins/split/split.c
And there's a regions type (built on top of vector) for building
contiguous ranges covering a disk, which has a fast look-up method:
https://github.com/libguestfs/nbdkit/blob/master/common/regions/regions.h
Of course it's optional to use these but they will probably simplify
your code.
+
+
+static void
+ddrescue_load (void)
+{
+}
Double blank line before this function, but also this function is
empty so you don't need to include it (even though there is an .unload
function - .unload will still be called even if .load is missing).
+/* We need this because otherwise the layer below can_write is
called
+ * and that might return true (eg. if the plugin has a pwrite method
+ * at all), resulting in writes being passed through to the layer
+ * below. This is possibly a bug in nbdkit.
+ */
I think this is working as intended, not a bug. However it's good to
comment on why the can_write function is needed.
[...]
+=back
+
+=head1 VERSION
+
+C<nbdkit-ddrescue-filter> first appeared in nbdkit 1.21.
It'll be 1.22 (next stable version after 1.20).
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-file-plugin(1)>,
+L<nbdkit-filter(3)>,
+L<ddrescue(1)>,
+L<https://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html>.
+
+=head1 AUTHORS
+
+François Revol
+
+Richard W.M. Jones
I guess the author is only you!
+=head1 COPYRIGHT
+
+Copyright (C) 2020 Red Hat Inc.
See note about copyright above.
It generally looks fine to me.
Rich.
--
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