[PATCH] rerere: fix crash in during clear

["Marcel Röthke" <marcel@roethke.info>]

When rerere_clear is called, for instance when aborting a rebase, and
the current conflict does not have a pre or postimage recorded git
crashes with a SEGFAULT in has_rerere_resolution when accessing the
status member of struct rerere_dir. This happens because scan_rerere_dir
only allocates the status field in struct rerere_dir when a post or
preimage was found. In some cases a segfault may happen even if a post
or preimage was recorded if it was not for the variant of interest and
the number of the variant that is present is lower than the variant of
interest.

This patch solves this by making sure the status field is large enough
to accommodate for the variant of interest so it can be accesses without
checking if it is large enough.

An alternative solution would be to always check before accessing the
status field, but I think the chosen solution aligns better with the
assumptions made elsewhere in the code.

Signed-off-by: Marcel Röthke <marcel@roethke.info>
---
 rerere.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rerere.c b/rerere.c
index ca7e77ba68..3973ccce37 100644
--- a/rerere.c
+++ b/rerere.c
@@ -219,6 +219,9 @@ static void read_rr(struct repository *r, struct string_list *rr)
 		buf.buf[hexsz] = '\0';
 		id = new_rerere_id_hex(buf.buf);
 		id->variant = variant;
+		/* make sure id->collection->status has enough space
+		 * for the variant we are interested in */
+		fit_variant(id->collection, variant);
 		string_list_insert(rr, path)->util = id;
 	}
 	strbuf_release(&buf);
-- 
2.43.2