I've spent some more time on this. I've tcpdump'ed the connection whilst doing the download (via both HTTP & FTP).
In the last data packet, the last byte that is missing on the filesystem is in the packet, but the packet has the urgent bit set with the urgent pointer the same as the length of the packet. I'm not sure but this might cause the client app to discard part of the packet? Unclear. Also I've build Qemu 4.2.1 on MacOS X/Big Sur - I'm seeing the same issue on FreeBSD/amd64. This bug might be related: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237441 ** Bug watch added: bugs.freebsd.org/bugzilla/ #237441 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237441 -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1914117 Title: Short files returned via FTP on Qemu with various architectures and OSes Status in QEMU: New Bug description: Qemu 5.2 on Mac OS X Big Sur. I originally thought that it might be caused by the home-brew version of Qemu, but this evening I have removed the brew edition and compiled from scratch (using Ninja & Xcode compiler). Still getting the same problem,. On the following architectures: arm64, amd64 and sometimes i386 running NetBSD host OS; i386 running OpenBSD host OS: I have seen a consistent problem with FTP returning short files. The file will be a couple of bytes too short. I do not believe this is a problem with the OS. Downloading the perl source code from CPAN does not work properly, nor does downloading bind from isc. I've tried this on different architectures as above. (Qemu 4.2 on Ubuntu/x86_64 with NetBSD/i386 seems to function fine. My gut feel is there is something not right on the Mac OS version of Qemu or a bug in 5.2 - obviously in the network layer somewhere. If you have anything you want me to try, please let me know - happy to help get a resolution.) To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1914117/+subscriptions
