Re: [Libguestfs] [PATCH nbdkit] server: Implement extents/can_extents calls for plugins and filters.

This pair of calls allows plugins to describe which extents in the virtual disk are allocated, holes or zeroes. ---

+ int nbdkit_extents_foreach_range ( + const struct nbdkit_extents_map *extents_map, + uint64_t range_offset, uint64_t range_length, + int (*fn) (uint64_t offset, uint64_t length, + uint32_t type, void *opaque), + void *opaque); + +Iterate over the extents in ascending order, calling C<fn> for each. +C<fn> should return 0 on success or -1 on failure. If a call to C<fn> +fails then C<nbdkit_extents_foreach*> also fails immediately. + +The C<nbdkit_extents_foreach_range> variant only iterates over extents +overlapping C<[range_offset...range_offset+range_length-1]>. + +C<nbdkit_extents_foreach*> returns C<0> on success or C<-1> on failure. +However it does not call C<nbdkit_error> or C<nbdkit_set_error> - it +is expected that C<fn> will call those functions on failure.

+++ b/server/extents.c @@ -0,0 +1,71 @@ +/* nbdkit

+#if 0 +int nbdkit_extents_foreach (const struct nbdkit_extents_map *, + int (*fn) (uint64_t offset, uint64_t length, + uint32_t type, void *opaque), + void *opaque); +int nbdkit_extents_foreach_range (const struct nbdkit_extents_map *, + uint64_t range_offset, uint64_t range_length, + int (*fn) (uint64_t offset, uint64_t length,

+ uint32_t type, void *opaque), + void *opaque);