feat: create sparse images

Instead of allocating the whole image on the disk, only allocate the parts that actually contain data. This reduces the required disk space to store or create images. Changelog: Title Ticket: None Signed-off-by: Yannis Gerlach <[email protected]>
mendersoftware · Nov 21, 2024 · add822b · add822b
1 parent 94f9c1f
commit add822b
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/modules/disk.sh b/modules/disk.sh
@@ -60,7 +60,7 @@ disk_get_part_nums() {
 #  $3 - size (in 512 blocks)
 #  $4 - path to output file
 disk_extract_part() {
-    run_and_log_cmd "dd if=$1 of=$4 skip=${2}b bs=1M count=${3}b status=none iflag=count_bytes,skip_bytes"
+    run_and_log_cmd "dd if=$1 of=$4 skip=${2}b bs=1M count=${3}b status=none conv=sparse iflag=count_bytes,skip_bytes"
 }
 
 # Convert MiB to number of 512 sectors
@@ -98,7 +98,7 @@ disk_align_sectors() {
 # $2 - destination file
 # $3 - offset in number of 512 sectors
 disk_write_at_offset() {
-    run_and_log_cmd "dd if=${1} of=${2} seek=${3} conv=notrunc status=none"
+    run_and_log_cmd "dd if=${1} of=${2} seek=${3} bs=512 conv=notrunc,sparse status=none"
 }
 
 # Create file system image from directory content