On Wed, Feb 03, 2021 at 06:32:33PM -0300, Joao Morais wrote:
>
> Hello William, here[1] is some context. I implemented a parsing of the reload
> command sent to the master cli, leave it running for a while and got an index
> out of bounds (in my code) this week.
>
> I'm using this lay out to parse the reload output:
>
> // 1 3 4 6
> 8 8
> //
> 0.......|.......6.......|.......2.......|.......8.......|.......4.......|.......0.......|.......8
> //
> // #<PID> <type> <relative PID> <reloads> <uptime>
> <version>
> // 1 master 0 2
> 0d00h01m28s 2.2.3-0e58a34
> // # workers
> // 3 worker 1 0
> 0d00h00m00s 2.2.3-0e58a34
> // # old workers
> // 2 worker [was: 1] 1
> 0d00h00m28s 2.2.3-0e58a34
> // # programs
> //
>
> Apparently I found a line that: starting char isn't '#', have 32 chars or
> more, have less than 48 chars. Is that even possible?
I had a quick look at the code producing this output and it writes
full lines at once, but the second one is a string which is mostly a
constant ("worker", "master"), or taken from a structure for old
programs. So I'm seeing two possibilities:
- either your parser received an incomplete line due to network buffering
and decided to parse it before getting the trailing "\n"; this is a
pretty common issue in line-oriented parsers ported to consume data
from other processes ;
- or the process memory was corrupted so that an old program's "child->id"
contained some crap and a "\n", which would have resulted in printing
the PID, this crappy string, and the rest of the line on a second separate
line.
The last point seems pretty possible given that your outdated version is
affected by 123 known bugs, 2 of which could cause memory corruption.
> How would you expand the lay out above, so I can improve my parser and my
> tests? Thanks!
Please read the chunk_appendf() statements in cli_io_handler_show_proc(),
they're pretty explicit and you'll get the exact output format for various
types of dumps. But that's basically what's documented above, it's just
that it may help you to figure some constants there (or that some fields
are unsigned for example).
Cheers,
Willy
