when the 'max-ixfr-ratio' option was added, journal transaction
headers were revised to include a count of RR's in each transaction.
this made it impossible to read old journal files after an upgrade.
this branch restores the ability to read version 1 transaction
headers. when rolling forward, printing journal contents, if
the wrong transaction header format is found, we can switch.
when dns_journal_rollforward() detects a version 1 transaction
header, it returns DNS_R_RECOVERABLE. this triggers zone_postload()
to force a rewrite of the journal file in the new format, and
also to schedule a dump of the zone database with minimal delay.
journal repair is done by dns_journal_compact(), which rewrites
the entire journal, ignoring 'max-journal-size'. journal size is
corrected later.
newly created journal files now have "BIND LOG V9.2" in their headers
instead of "BIND LOG V9". files with the new version string cannot be
read using the old transaction header format. note that this means
newly created journal files will be rejected by older versions of named.
named-journalprint now takes a "-x" option, causing it to print
transaction header information before each delta, including its
format version.
(cherry picked from commit ee19966326)
Evan Hunt
47a274e9f1