read data correctly

abbbi · Feb 5, 2025 · a703133 · a703133
1 parent 912daac
commit a703133
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Showing 2 changed files with 6 additions and 4 deletions.
diff --git a/libvirtnbdbackup/qemu/util.py b/libvirtnbdbackup/qemu/util.py
@@ -195,12 +195,10 @@ def startNbdkitProcess(
             f"{args.listen_port}",
             "-e",
             f"{self.exportName}",
-            "--filter=blocksize",
             "--filter=cow",
             "-v",
             "python",
             f"{nbdkitModule}",
-            f"maxlen={args.blocksize}",
             f"blockmap={blockMap}",
             f"disk={fullImage}",
             f"debug={debug}",

diff --git a/virtnbd-nbdkit-plugin b/virtnbd-nbdkit-plugin
@@ -148,6 +148,7 @@ def pread(h, buf, offset, flags):
 
     log(f"Processing block: {block}")
 
+    # where to read in the stream file
     fileOffset = block["offset"] - block["originalOffset"] + offset
 
     dataFile = block["file"]
@@ -182,13 +183,16 @@ def pread(h, buf, offset, flags):
                 None,
             )
             if not next_block:
-                raise RuntimeError("Unable to find next block")
+                raise RuntimeError("Unable to locate next block")
 
             log(f"Found next block: {next_block}")
 
             if next_block["data"]:
                 log(f"Read {remaining} data size from next block.")
-                data += os.pread(h, remaining, next_block["offset"])
+                fileOffset = (
+                    next_block["offset"] - next_block["originalOffset"] + offset
+                )
+                data += os.pread(h, remaining, fileOffset)
                 remaining -= remaining
             else:
                 log(f"Next block contains zeroes, return {remaining} zeroes")