Bug#925207: libsys-statistics-linux-perl: Sys::Statistics::Linux::DiskStats fails to parse /proc/diskstats for kernel >= v4.18

[Florian Schlichting]

Severity: important
thanks

On Thu, Mar 21, 2019 at 10:31:53AM +0100, Bryan Jurish wrote:
> According to https://www.kernel.org/doc/Documentation/iostats.txt, 4 new fields
> were added to /proc/diskstats for kernel version 4.18.  As a result, device
> names and the "old" attribute fields are misparsed by the (very narrow) regexes
> in Sys/Statistics/Linux/DiskStats.pm .  The attached patch appears to fix the
> problem.

The bug becomes visible when calling e.g.

$ perl -MData::Printer -MSys::Statistics::Linux::DiskStats -E'my $lxs = Sys::Statistics::Linux::DiskStats->new; $lxs->init; p $lxs->get;

The correct output will contain paragraphs like this:

    sda1    {
        major    8,
        minor    1,
        rdbyt    0.00,
        rdreq    0.00,
        ttbyt    0.00,
        ttreq    0.00,
        wrtbyt   0.00,
        wrtreq   0.00
    },

However on buster currently, output looks like this (notice the "device
name"):

    'sda1 3352 39 102172 153321'          {
        major    8,
        minor    1,
        rdbyt    0.00,
        rdreq    0.00,
        ttbyt    0.00,
        ttreq    0.00,
        wrtbyt   0.00,
        wrtreq   0.00
    },

The patch from Bryan Jurish (thanks!) correctly fixes this issue for the
buster kernel, however to prevent this from happening again I think the
device name regex should make sure to never match the field separator,
by using (\S+) instead of (.+?) for example.

Florian