From: Michael A Cassaniti <michael@cassaniti.id.au>
Date: Wed, 17 Aug 2022 05:52:53 +0000 (+1000)
Subject: Use chunked reads when inserting partition
X-Git-Tag: v14~80
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=154f59f1797e98bac2de671435ba40081fa08a30;p=thirdparty%2Fmkosi.git

Use chunked reads when inserting partition
---

diff --git a/mkosi/__init__.py b/mkosi/__init__.py
index 9d0c8c424..f540f768f 100644
--- a/mkosi/__init__.py
+++ b/mkosi/__init__.py
@@ -3713,7 +3713,10 @@ def insert_partition(
             # Let's discard the partition block device first, to ensure the GPT partition table footer that
             # likely is stored in it is flushed out. After all we want to write with dd's sparse option.
             run(["blkdiscard", path])
-            path.write_bytes(blob.read())
+
+            # Without this the entire blob will be read into memory which could exceed system memory
+            with open(path, mode='wb') as path_fp:
+                os.sendfile(path_fp.fileno(), blob.fileno(), offset=0, count=blob_size)
 
     return part