Trash Plugin bugs

dovecot v2.2.16

I've found a few bugs in Trash plugin.

1. If Quota set only messages limit (without storage limit) then Trash plugin does not expunge any message because Quota plugin sets too_large_r=TRUE. It's because quota_default_test_alloc function does not check if bytes_limit is set.

            /* if size is bigger than any limit, then
               it is bigger than the lowest limit */

•           if (size > bytes_limit) {

•           if (bytes_limit > 0 && size > bytes_limit) {
                    *too_large_r = TRUE;
                    break;
            }

2. Trash plugin does not use bytes_ceil/count_ceil to calculate size_needed/count_needed to expunge. Trash plugin may expunge more messages that nedeed.

•           if (ctx->bytes_ceil!=(uint64_t)-1 && ctx->bytes_ceil < size + ctx->bytes_over) {

•                   size_needed = size + ctx->bytes_over - ctx->bytes_ceil;

•           }

•           if (ctx->count_ceil!=(uint64_t)-1 && ctx->count_ceil < 1 + ctx->count_over) {

•                   count_needed = 1 + ctx->count_over - ctx->count_ceil;

•           }

•           /* not enough space. try deleting some from mailbox. */

•           ret = trash_try_clean_mails(ctx, size + ctx->bytes_over,

•                                       1 + ctx->count_over);

•           ret = trash_try_clean_mails(ctx, size_needed, count_needed);

3. Trash plugin does not check 'unlimited' values in bytes_ceil/count_ceil and may overflow them when add expunged size/messages

•   ctx->bytes_ceil += size_expunged;

•   ctx->count_ceil += expunged_count;

•   if (ctx->bytes_ceil!=(uint64_t)-1) {

•           ctx->bytes_ceil += size_expunged;

•   }

•   if (ctx->count_ceil!=(uint64_t)-1) {

•           ctx->count_ceil += expunged_count;

•   }

See attached patch.