journal: add ability to list values a specified field can take in all entries of the journal

The new 'unique' API allows listing all unique field values that a field
specified by a field name can take in all entries of the journal. This
allows answering queries such as "What units logged to the journal?",
"What hosts have logged into the journal?", "Which boot IDs have logged
into the journal?".

Ultimately this allows implementation of tools similar to lastlog based
on journal data.

Note that listing these field values will not work for journal files
created with older journald, as the field values are not indexed in
older files.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/journal/journal-authenticate.c b/src/journal/journal-authenticate.c
index 674f81218f..64bf96874e 100644
--- a/src/journal/journal-authenticate.c
+++ b/src/journal/journal-authenticate.c
@@ -260,6 +260,12 @@ int journal_file_hmac_put_object(JournalFile *f, int type, Object *o, uint64_t p
                 gcry_md_write(f->hmac, o->data.payload, le64toh(o->object.size) - offsetof(DataObject, payload));
                 break;
 
+        case OBJECT_FIELD:
+                /* Same here */
+                gcry_md_write(f->hmac, &o->field.hash, sizeof(o->field.hash));
+                gcry_md_write(f->hmac, o->field.payload, le64toh(o->object.size) - offsetof(FieldObject, payload));
+                break;
+
         case OBJECT_ENTRY:
                 /* All */
                 gcry_md_write(f->hmac, &o->entry.seqnum, le64toh(o->object.size) - offsetof(EntryObject, seqnum));
@@ -484,7 +490,6 @@ int journal_file_append_first_tag(JournalFile *f) {
         return 0;
 }
 
-
 int journal_file_parse_verification_key(JournalFile *f, const char *key) {
         uint8_t *seed;
         size_t seed_size, c;