Test for `NFT_MSG_MAX` fails on my Linux machine

[tbu-]

RUNNING ALL TESTS
bad ucontext_t size: rust: 936 (0x3a8) != c 968 (0x3c8)
bad NFT_MSG_MAX value at byte 0: rust: 22 (0x16) != c 25 (0x19)

glibc 0.28
Linux 4.18.6.arch1
Arch Linux

NFT_MSG_MAX, from /usr/include/linux/netfilter/nf_tables.h:

enum nf_tables_msg_types {
        NFT_MSG_NEWTABLE,
        NFT_MSG_GETTABLE,
        NFT_MSG_DELTABLE,
        NFT_MSG_NEWCHAIN,
        NFT_MSG_GETCHAIN,
        NFT_MSG_DELCHAIN,
        NFT_MSG_NEWRULE,
        NFT_MSG_GETRULE,
        NFT_MSG_DELRULE,
        NFT_MSG_NEWSET,
        NFT_MSG_GETSET,
        NFT_MSG_DELSET,
        NFT_MSG_NEWSETELEM,
        NFT_MSG_GETSETELEM,
        NFT_MSG_DELSETELEM,
        NFT_MSG_NEWGEN,
        NFT_MSG_GETGEN,
        NFT_MSG_TRACE,
        NFT_MSG_NEWOBJ,
        NFT_MSG_GETOBJ,
        NFT_MSG_DELOBJ,
        NFT_MSG_GETOBJ_RESET,
        NFT_MSG_NEWFLOWTABLE,
        NFT_MSG_GETFLOWTABLE,
        NFT_MSG_DELFLOWTABLE,
        NFT_MSG_MAX,
};

It seems like

        NFT_MSG_NEWFLOWTABLE,
        NFT_MSG_GETFLOWTABLE,
        NFT_MSG_DELFLOWTABLE,

were added and thus NFT_MSG_MAX increased. Linux doesn't consider this a breaking change. I'd assume that more messages might be added in the future, so just adjusting the constant in libc as a breaking change doesn't seem to be useful.

[gnzlbg]

This is expected, the values of constants change across different kernel versions, and libc contains static values of constants.

[pusateri]

Same issue on Ubuntu 18.10 cosmic

$ uname -a
Linux virt 4.18.0-13-generic #14-Ubuntu SMP Wed Dec 5 09:04:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

PASSED 58 tests
     Running /home/pusateri/Projects/libc/target/debug/deps/main-b7d3c13f1915adf3
RUNNING ALL TESTS
bad ucontext_t size: rust: 936 (0x3a8) != c 968 (0x3c8)
bad NFT_MSG_MAX value at byte 0: rust: 22 (0x16) != c 25 (0x19)

[gnzlbg]

As mentioned, this is expected behavior, that version of Linux is not supported by libc.

The path forward here is to upgrade the version of Linux that libc supports on CI, and then update the constants to match that version.

[gnzlbg]

Fixed on master.

[tbu-]

Fixed by 4497a78.