[openwrt/openwrt] build: fix generation of large .vdi images

[LEDE Commits]

chunkeey pushed a commit to openwrt/openwrt.git, branch openwrt-23.05:
https://git.openwrt.org/4ab8abfbf7b1e4aa006507e220a4f2db17421845

commit 4ab8abfbf7b1e4aa006507e220a4f2db17421845
Author: Adones Pitogo <pitogo.adones at gmail.com>
AuthorDate: Tue Jul 11 13:31:50 2023 +0800

    build: fix generation of large .vdi images
    
    Instead of loading the whole image into the memory when generating the
    sha256 sum, we load the file in chunks and update the hash incrementally
    to avoid MemoryError in python. Also remove a stray empty line.
    
    Fixes: #13056
    Signed-off-by: Adones Pitogo <pitogo.adones at gmail.com>
    (mention empty line removal, adds Fixes from PR)
    Signed-off-by: Christian Lamparter <chunkeey at gmail.com>
    (cherry picked from commit bdb4b78210cfb6bc8a6cda62fc990dd45ec3054c)
---
 scripts/json_add_image_info.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/scripts/json_add_image_info.py b/scripts/json_add_image_info.py
index 0c441b9334..aded743bcc 100755
--- a/scripts/json_add_image_info.py
+++ b/scripts/json_add_image_info.py
@@ -13,7 +13,6 @@ if len(argv) != 2:
 json_path = Path(argv[1])
 file_path = Path(getenv("FILE_DIR")) / getenv("FILE_NAME")
 
-
 if not file_path.is_file():
     print("Skip JSON creation for non existing file", file_path)
     exit(0)
@@ -37,7 +36,14 @@ def get_titles():
 
 
 device_id = getenv("DEVICE_ID")
-hash_file = hashlib.sha256(file_path.read_bytes()).hexdigest()
+
+sha256_hash = hashlib.sha256()
+with open(str(file_path),"rb") as f:
+    # Read and update hash string value in blocks of 4K
+    for byte_block in iter(lambda: f.read(4096),b""):
+        sha256_hash.update(byte_block)
+
+hash_file = sha256_hash.hexdigest()
 
 if file_path.with_suffix(file_path.suffix + ".sha256sum").exists():
     hash_unsigned = (