[meta-oe][RESEND PATCH v2 1/2] image_types_sparse: Pad source image to block size

Sean Anderson <sean.anderson@...>

If the source image's size is not aligned to the sparse image's block
size, then conversion will fail with

img2simg: libsparse/sparse.cpp:133: int write_all_blocks(sparse_file*, output_file*): Assertion `pad >= 0' failed.

This is a bug in img2simg, but an easy way to work around it is to pad
the source image ourselves. The default block size of 4096 matches
img2simg's default block size.

Signed-off-by: Sean Anderson <sean.anderson@...>

Changes in v2:
- New

meta-oe/classes/image_types_sparse.bbclass | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/meta-oe/classes/image_types_sparse.bbclass b/meta-oe/classes/image_types_sparse.bbclass
index 4263593a8d..355a3dafc2 100644
--- a/meta-oe/classes/image_types_sparse.bbclass
+++ b/meta-oe/classes/image_types_sparse.bbclass
@@ -1,8 +1,16 @@
inherit image_types

+# This sets the granularity of the sparse image conversion. Chunk sizes will be
+# specified in units of this value. Setting this value smaller than the
+# underlying image's block size will not result in any further space saving.
+# However, there is no loss in correctness if this value is larger or smaller
+# than optimal. This value should be a power of two.
-CONVERSION_CMD:sparse = " \
- img2simg "${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}" \
- "${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.${type}.sparse" \
+CONVERSION_CMD:sparse() {
+ truncate --no-create --size=%${SPARSE_BLOCK_SIZE} "$INPUT"
+ img2simg "$INPUT" "$INPUT.sparse" ${SPARSE_BLOCK_SIZE}
CONVERSION_DEPENDS_sparse = "android-tools-native"

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