mirrors/git
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

reftable: prevent 'update_index' changes after adding records

Browse Source 
The function `reftable_writer_set_limits()` allows updating the
'min_update_index' and 'max_update_index' of a reftable writer. These
values are written to both the writer's header and footer.

Since the header is written during the first block write, any subsequent
changes to the update index would create a mismatch between the header
and footer values. The footer would contain the newer values while the
header retained the original ones.

To protect against this bug, prevent callers from updating these values
after any record is written. To do this, modify the function to return
an error whenever the limits are modified after any record adds. Check
for record adds within `reftable_writer_set_limits()` by checking the
`last_key` and `next` variable. The former is updated after each record
added, but is reset at certain points. The latter is set after writing
the first block.

Modify all callers of the function to anticipate a return type and
handle it accordingly. Add a unit test to also ensure the function
returns the error as expected.

Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Karthik Nayak
2025-01-22 06:35:49 +01:00
committed by Junio C Hamano
parent e7c1b9f123
commit 017bd89239
6 changed files with 99 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
reftable/stack.c
View File

@ -1058,8 +1058,10 @@ static int stack_write_compact(struct reftable_stack *st,
for (size_t i = first; i <= last; i++)
st->stats.bytes += st->readers[i]->size;
reftable_writer_set_limits(wr, st->readers[first]->min_update_index,
st->readers[last]->max_update_index);
err = reftable_writer_set_limits(wr, st->readers[first]->min_update_index,
st->readers[last]->max_update_index);
if (err < 0)
goto done;
err = reftable_merged_table_new(&mt, st->readers + first, subtabs_len,
st->opts.hash_id);