RE: START_REPLICATION silently truncates an overlong LSN component

Dear Fujii-san,

Thanks for pushing the first half!

> + if (fscanf(lfp,
> + "CHECKPOINT LOCATION: %" CppAsString2(MAXPG_LSNLEN) "s%c", lsn,
> + &ch) != 2 ||
> + ch != '\n' ||
> + !pg_parse_lsn(lsn, checkPointLoc))
>
> This seems to accept malformed LSN fields such as:
>
> CHECKPOINT LOCATION: 0/123<NUL>junk
>
> Here, <NUL> represents an actual NUL byte. fscanf("%17s") reads past it,
> but pg_parse_lsn() sees only 0/123. The old code rejected this because %c
> read the NUL instead of a newline. START WAL LOCATION seems to
> have the same issue.

Right, it should be rejected. One my primitive fix idea is to directly specify the
acceptable strings, like [0-9A-Fa-f/]. PSA the patch.
I also attached the test code to check invalid strings can be rejected, see 0002.
I'm not intended to be pushed.

Best regards,
Hayato Kuroda
FUJITSU LIMITED