journal: Deduplicate entry items before they are stored in the entry object

If the iovec contains the same data more than once, we'll end up with
duplicate offsets in the items array. Let's make sure we remove any
duplicates before we store the items in an entry object.

diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
index 9a3e3579d1d6a469425aee17647d92a08cbd5db1..3722519dc4234bee071358b2c5e8da646ad791fc 100644 (file)
--- a/src/libsystemd/sd-journal/journal-file.c
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -2078,6 +2078,21 @@ static int entry_item_cmp(const EntryItem *a, const EntryItem *b) {
         return CMP(le64toh(a->object_offset), le64toh(b->object_offset));
 }
 
+static size_t remove_duplicate_entry_items(EntryItem items[], size_t n) {
+
+        /* This function relies on the items array being sorted. */
+        size_t j = 1;
+
+        if (n <= 1)
+                return n;
+
+        for (size_t i = 1; i < n; i++)
+                if (items[i].object_offset != items[j - 1].object_offset)
+                        items[j++] = items[i];
+
+        return j;
+}
+
 int journal_file_append_entry(
                 JournalFile *f,
                 const dual_timestamp *ts,
@@ -2148,6 +2163,7 @@ int journal_file_append_entry(
         /* Order by the position on disk, in order to improve seek
          * times for rotating media. */
         typesafe_qsort(items, n_iovec, entry_item_cmp);
+        n_iovec = remove_duplicate_entry_items(items, n_iovec);
 
         r = journal_file_append_entry_internal(f, ts, boot_id, xor_hash, items, n_iovec, seqnum, ret, ret_offset);