Re: [Libguestfs] [PATCH nbdkit v5 FINAL 14/19] data, memory: Implement extents.

These plugins are both based on the same sparse array structure which supports a simple implementation of extents. --- common/sparse/sparse.h | 7 +- common/sparse/sparse.c | 37 ++++++++++- plugins/data/data.c | 16 ++++- plugins/memory/memory.c | 16 ++++- README | 2 + tests/Makefile.am | 2 + tests/test-data-extents.sh | 131 +++++++++++++++++++++++++++++++++++++ 7 files changed, 207 insertions(+), 4 deletions(-) +int +sparse_array_extents (struct sparse_array *sa, + uint32_t count, uint64_t offset, + struct nbdkit_extents *extents) +{ + uint32_t n, type; + void *p; + + while (count > 0) { + p = lookup (sa, offset, false, &n, NULL); + if (n > count) + n = count;

+ + /* Work out the type of this extent. */ + if (p == NULL) + /* No backing page, so it's a hole. */ + type = NBDKIT_EXTENT_HOLE | NBDKIT_EXTENT_ZERO; + else { + if (is_zero (p, n)) + /* A backing page and it's all zero, it's a zero extent. */ + type = NBDKIT_EXTENT_ZERO; + else + /* Normal allocated data. */ + type = 0; + } + if (nbdkit_add_extent (extents, offset, n, type) == -1) + return -1; +