[Libguestfs] [PATCH nbdkit 5/9] offset: Implement mapping of extents.

Allows you to safely use nbdkit-offset-filter on top of a plugin supporting extents. --- filters/offset/offset.c | 43 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/filters/offset/offset.c b/filters/offset/offset.c index 058571d..4e3f74d 100644 --- a/filters/offset/offset.c +++ b/filters/offset/offset.c @@ -37,6 +37,7 @@ #include <stdlib.h> #include <stdint.h> #include <string.h> +#include <assert.h> #include <nbdkit-filter.h> @@ -132,6 +133,47 @@ offset_zero (struct nbdkit_next_ops *next_ops, void *nxdata, return next_ops->zero (nxdata, count, offs + offset, flags, err); } +/* Extents. */ +static int +subtract_offset (uint64_t offs, uint64_t length, uint32_t type, + void *vp) +{ + struct nbdkit_extents_map *extents_map = vp; + + assert (offs >= offset); + offs -= offset; + return nbdkit_extent_add (extents_map, offs, length, type); +} + +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_map *extents_map, + int *err) +{ + struct nbdkit_extents_map *map2; + + map2 = nbdkit_extents_new (); + if (map2 == NULL) + return -1; + if (next_ops->extents (nxdata, count, offs + offset, + flags, map2, err) == -1) { + nbdkit_extents_free (map2); + return -1; + } + + /* Transform offsets in map2, return result in extents_map. */ + if (nbdkit_extents_foreach (map2, subtract_offset, extents_map, + NBDKIT_EXTENTS_FOREACH_FLAG_RANGE, + offset, range) == -1) { + nbdkit_extents_free (map2); + return -1; + } + nbdkit_extents_free (map2); + + return 0; +} + static struct nbdkit_filter filter = { .name = "offset", .longname = "nbdkit offset filter", @@ -144,6 +186,7 @@ static struct nbdkit_filter filter = { .pwrite = offset_pwrite, .trim = offset_trim, .zero = offset_zero, + .extents = offset_extents, }; NBDKIT_REGISTER_FILTER(filter) -- 2.20.1