If the server provides a Content-Length header, use that to verify the
size of the downloaded file. This catches cases where the connection
terminates early, and gives the opportunity to retry. Without this, the
checksum will likely mismatch and fail without retry.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 tests/functional/qemu_test/asset.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tests/functional/qemu_test/asset.py b/tests/functional/qemu_test/asset.py
index 6a1c92ffbef..d34e8f5e2ad 100644
--- a/tests/functional/qemu_test/asset.py
+++ b/tests/functional/qemu_test/asset.py
@@ -124,6 +124,22 @@ def fetch(self):
                 with tmp_cache_file.open("xb") as dst:
                     with urllib.request.urlopen(self.url) as resp:
                         copyfileobj(resp, dst)
+                        length_hdr = resp.getheader("Content-Length")
+
+                # Verify downloaded file size against length metadata, if
+                # available. dst must be out of scope before testing st_size
+                # because # copyfileobj returns before all buffers are
+                # flushed to filesystem.
+                if length_hdr:
+                    length = int(length_hdr)
+                    if tmp_cache_file.stat().st_size != length:
+                        print("st_size %ld", tmp_cache_file.stat().st_size)
+                        self.log.error("Unable to download %s: "
+                                       "connection closed before "
+                                       "transfer complete",
+                                       self.url)
+                        tmp_cache_file.unlink()
+                        continue
                 break
             except FileExistsError:
                 self.log.debug("%s already exists, "
-- 
2.47.1

On 12/03/2025 06.17, Nicholas Piggin wrote:
> If the server provides a Content-Length header, use that to verify the
> size of the downloaded file. This catches cases where the connection
> terminates early, and gives the opportunity to retry. Without this, the
> checksum will likely mismatch and fail without retry.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   tests/functional/qemu_test/asset.py | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/tests/functional/qemu_test/asset.py b/tests/functional/qemu_test/asset.py
> index 6a1c92ffbef..d34e8f5e2ad 100644
> --- a/tests/functional/qemu_test/asset.py
> +++ b/tests/functional/qemu_test/asset.py
> @@ -124,6 +124,22 @@ def fetch(self):
>                   with tmp_cache_file.open("xb") as dst:
>                       with urllib.request.urlopen(self.url) as resp:
>                           copyfileobj(resp, dst)
> +                        length_hdr = resp.getheader("Content-Length")
> +
> +                # Verify downloaded file size against length metadata, if
> +                # available. dst must be out of scope before testing st_size
> +                # because # copyfileobj returns before all buffers are

remove the "#" after "because" ?

> +                # flushed to filesystem.

As far as I understood Python, that's the main reason for using "with" in 
cases like this here, so I'd maybe even rather scratch the last sentence
completely.

> +                if length_hdr:
> +                    length = int(length_hdr)
> +                    if tmp_cache_file.stat().st_size != length:
> +                        print("st_size %ld", tmp_cache_file.stat().st_size)

Debug left-over?

> +                        self.log.error("Unable to download %s: "
> +                                       "connection closed before "
> +                                       "transfer complete",
> +                                       self.url)

Maybe it would be good to include st_size and length in the log message instead?

> +                        tmp_cache_file.unlink()
> +                        continue
>                   break
>               except FileExistsError:
>                   self.log.debug("%s already exists, "

  Thomas