reftable/stack: do not overwrite errors when compacting

In order to compact multiple stacks we iterate through the merged ref
and log records. When there is any error either when reading the records
from the old merged table or when writing the records to the new table
then we break out of the respective loops. When breaking out of the loop
for the ref records though the error code will be overwritten, which may
cause us to inadvertently skip over bad ref records. In the worst case,
this can lead to a compacted stack that is missing records.

Fix the code by using `goto done` instead so that any potential error
codes are properly returned to the caller.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/reftable/stack.c b/reftable/stack.c
index 16bab82063d2b3e228abe05b3a8a26ffd310767c..8729508dc35a85a5f49aa256974100d4fc2d980b 100644 (file)
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -801,18 +801,16 @@ static int stack_write_compact(struct reftable_stack *st,
                        err = 0;
                        break;
                }
-               if (err < 0) {
-                       break;
-               }
+               if (err < 0)
+                       goto done;
 
                if (first == 0 && reftable_ref_record_is_deletion(&ref)) {
                        continue;
                }
 
                err = reftable_writer_add_ref(wr, &ref);
-               if (err < 0) {
-                       break;
-               }
+               if (err < 0)
+                       goto done;
                entries++;
        }
        reftable_iterator_destroy(&it);
@@ -827,9 +825,8 @@ static int stack_write_compact(struct reftable_stack *st,
                        err = 0;
                        break;
                }
-               if (err < 0) {
-                       break;
-               }
+               if (err < 0)
+                       goto done;
                if (first == 0 && reftable_log_record_is_deletion(&log)) {
                        continue;
                }
@@ -845,9 +842,8 @@ static int stack_write_compact(struct reftable_stack *st,
                }
 
                err = reftable_writer_add_log(wr, &log);
-               if (err < 0) {
-                       break;
-               }
+               if (err < 0)
+                       goto done;
                entries++;
        }