systemd-journald drops all bytes after '\0'

[evverx]

I'm sorry for not being specific. I will have to update the description so that it won't cause confusion like #6838 (comment).

$ printf '<13>Sep 15 15:07:58 HOST: null\0here' | nc -w1 -u -U /run/systemd/journal/dev-log

$ journalctl -t HOST -o verbose
...
    MESSAGE=null

From #1460

Of course, this will make the patch more complicated, as this means we have to patch much further down to ensure we always keep the ptr+length bit intact.

[poettering]

Fix waiting in #6838.

[poettering]

Since ec20fe5 we will no consider '\n', '\0' as well as line size limits and EOF all as fully equivalent EOL markers. This means the command proposed will now cleanly result in multiple log lines generated. Here's an example:

$ printf 'ab\0cd\nef' | systemd-cat --identifier drop-after-zero
$ journalctl -n 3
-- Logs begin at Thu 2016-08-18 23:09:37 CEST, end at Thu 2018-05-24 13:21:25 CEST. --
Mai 24 13:21:25 sigma drop-after-zero[51513]: ab
Mai 24 13:21:25 sigma drop-after-zero[51513]: cd
Mai 24 13:21:25 sigma drop-after-zero[51513]: ef

I am pretty sure this new behaviour makes a ton of sense, and no data is lost. In fact the structure log message contains enough information to even reconstruct whether the line was broken due to \n, \0, line limit or EOF through the _LINE_BREAK= property:

-- Logs begin at Thu 2016-08-18 23:09:37 CEST, end at Thu 2018-05-24 13:22:41 CEST. --
Thu 2018-05-24 13:22:41.713886 CEST [s=65e4e3725e08482e859073adf7e3ab40;i=559c3;b=47906844deef4cbe971b732ad7db2129;m=364e98d427;t=56cf1dea346de;x=179b7582b4966cdb]
    _UID=1000
    _GID=1000
    _SELINUX_CONTEXT=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
    _MACHINE_ID=c455a9847b7b47cb8a6d206e1a8d04c0
    _HOSTNAME=sigma
    _CAP_EFFECTIVE=0
    _TRANSPORT=stdout
    PRIORITY=6
    _BOOT_ID=47906844deef4cbe971b732ad7db2129
    SYSLOG_IDENTIFIER=drop-after-zero
    _LINE_BREAK=nul
    MESSAGE=ab
    _COMM=cat
    _STREAM_ID=91bb4a4b07c248cd98d8ef74f29f6219
    _PID=51541
Thu 2018-05-24 13:22:41.713886 CEST [s=65e4e3725e08482e859073adf7e3ab40;i=559c4;b=47906844deef4cbe971b732ad7db2129;m=364e98d427;t=56cf1dea346de;x=76f0cb041ca50029]
    _UID=1000
    _GID=1000
    _SELINUX_CONTEXT=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
    _MACHINE_ID=c455a9847b7b47cb8a6d206e1a8d04c0
    _HOSTNAME=sigma
    _CAP_EFFECTIVE=0
    _TRANSPORT=stdout
    PRIORITY=6
    _BOOT_ID=47906844deef4cbe971b732ad7db2129
    SYSLOG_IDENTIFIER=drop-after-zero
    _COMM=cat
    MESSAGE=cd
    _STREAM_ID=91bb4a4b07c248cd98d8ef74f29f6219
    _PID=51541
Thu 2018-05-24 13:22:41.727466 CEST [s=65e4e3725e08482e859073adf7e3ab40;i=559c5;b=47906844deef4cbe971b732ad7db2129;m=364e990933;t=56cf1dea37bea;x=baf41e133020694f]
    _UID=1000
    _GID=1000
    _SELINUX_CONTEXT=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
    _MACHINE_ID=c455a9847b7b47cb8a6d206e1a8d04c0
    _HOSTNAME=sigma
    _CAP_EFFECTIVE=0
    _TRANSPORT=stdout
    PRIORITY=6
    _BOOT_ID=47906844deef4cbe971b732ad7db2129
    _LINE_BREAK=eof
    SYSLOG_IDENTIFIER=drop-after-zero
    _COMM=cat
    MESSAGE=ef
    _STREAM_ID=91bb4a4b07c248cd98d8ef74f29f6219
    _PID=51541

[evverx]

It's not fixed. That's why I wrote in the description that I should update it and we discussed it in #6838 (comment).