journal: implement multiple field matches

1 files changed, 665 insertions, 136 deletions

diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
index 5d518a3870..85c57170d5 100644
--- a/src/journal/sd-journal.c
+++ b/src/journal/sd-journal.c
@@ -40,9 +40,34 @@ struct Match {
         LIST_FIELDS(Match, matches);
 };
 
+typedef enum location_type {
+        LOCATION_HEAD,
+        LOCATION_TAIL,
+        LOCATION_DISCRETE
+} location_type_t;
+
+typedef struct Location {
+        location_type_t type;
+
+        uint64_t seqnum;
+        sd_id128_t seqnum_id;
+        bool seqnum_set;
+
+        uint64_t realtime;
+        bool realtime_set;
+
+        uint64_t monotonic;
+        sd_id128_t boot_id;
+        bool monotonic_set;
+
+        uint64_t xor_hash;
+        bool xor_hash_set;
+} Location;
+
 struct sd_journal {
         Hashmap *files;
 
+        Location current_location;
         JournalFile *current_file;
         uint64_t current_field;
 
@@ -50,7 +75,7 @@ struct sd_journal {
         unsigned n_matches;
 };
 
-static void reset_location(sd_journal *j) {
+static void detach_location(sd_journal *j) {
         Iterator i;
         JournalFile *f;
 
@@ -63,8 +88,66 @@ static void reset_location(sd_journal *j) {
                 f->current_offset = 0;
 }
 
+static void reset_location(sd_journal *j) {
+        assert(j);
+
+        detach_location(j);
+        zero(j->current_location);
+}
+
+static void init_location(Location *l, JournalFile *f, Object *o) {
+        assert(l);
+        assert(f);
+        assert(o->object.type == OBJECT_ENTRY);
+
+        l->type = LOCATION_DISCRETE;
+        l->seqnum = le64toh(o->entry.seqnum);
+        l->seqnum_id = f->header->seqnum_id;
+        l->realtime = le64toh(o->entry.realtime);
+        l->monotonic = le64toh(o->entry.monotonic);
+        l->boot_id = le64toh(o->entry.boot_id);
+        l->xor_hash = le64toh(o->entry.xor_hash);
+
+        l->seqnum_set = l->realtime_set = l->monotonic_set = l->xor_hash_set = true;
+}
+
+static void set_location(sd_journal *j, JournalFile *f, Object *o, uint64_t offset) {
+        assert(j);
+        assert(f);
+        assert(o);
+
+        init_location(&j->current_location, f, o);
+
+        j->current_file = f;
+        j->current_field = 0;
+
+        f->current_offset = offset;
+}
+
+static int same_field(const void *_a, size_t s, const void *_b, size_t t) {
+        const uint8_t *a = _a, *b = _b;
+        size_t j;
+        bool a_good = false, b_good = false, different = false;
+
+        for (j = 0; j < s && j < t; j++) {
+
+                if (a[j] == '=')
+                        a_good = true;
+                if (b[j] == '=')
+                        b_good = true;
+                if (a[j] != b[j])
+                        different = true;
+
+                if (a_good && b_good)
+                        return different ? 0 : 1;
+        }
+
+        return -EINVAL;
+}
+
 int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
-        Match *m;
+        Match *m, *after = NULL;
+        uint64_t le_hash;
 
         assert(j);
 
@@ -73,6 +156,23 @@ int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
 
         assert(data);
 
+        le_hash = htole64(hash64(data, size));
+
+        LIST_FOREACH(matches, m, j->matches) {
+                int r;
+
+                if (m->le_hash == le_hash &&
+                    m->size == size &&
+                    memcmp(m->data, data, size) == 0)
+                        return 0;
+
+                r = same_field(data, size, m->data, m->size);
+                if (r < 0)
+                        return r;
+                else if (r > 0)
+                        after = m;
+        }
+
         m = new0(Match, 1);
         if (!m)
                 return -ENOMEM;
@@ -86,12 +186,14 @@ int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
         }
 
         memcpy(m->data, data, size);
-        m->le_hash = hash64(m->data, size);
+        m->le_hash = le_hash;
 
-        LIST_PREPEND(Match, matches, j->matches, m);
+        /* Matches for the same fields we order adjacent to each
+         * other */
+        LIST_INSERT_AFTER(Match, matches, j->matches, after, m);
         j->n_matches ++;
 
-        reset_location(j);
+        detach_location(j);
 
         return 0;
 }
@@ -109,14 +211,19 @@ void sd_journal_flush_matches(sd_journal *j) {
 
         j->n_matches = 0;
 
-        reset_location(j);
+        detach_location(j);
 }
 
-static int compare_order(JournalFile *af, Object *ao, uint64_t ap,
-                         JournalFile *bf, Object *bo, uint64_t bp) {
+static int compare_order(JournalFile *af, Object *ao,
+                         JournalFile *bf, Object *bo) {
 
         uint64_t a, b;
 
+        assert(af);
+        assert(ao);
+        assert(bf);
+        assert(bo);
+
         /* We operate on two different files here, hence we can access
          * two objects at the same time, which we normally can't.
          *
@@ -179,99 +286,302 @@ static int compare_order(JournalFile *af, Object *ao, uint64_t ap,
         return 0;
 }
 
-static int move_to_next_with_matches(sd_journal *j, JournalFile *f, direction_t direction, Object **o, uint64_t *p) {
+static int compare_with_location(JournalFile *af, Object *ao, Location *l) {
+        uint64_t a;
+
+        assert(af);
+        assert(ao);
+        assert(l);
+        assert(l->type == LOCATION_DISCRETE);
+
+        if (l->monotonic_set &&
+            sd_id128_equal(ao->entry.boot_id, l->boot_id) &&
+            l->realtime_set &&
+            le64toh(ao->entry.realtime) == l->realtime &&
+            l->xor_hash_set &&
+            le64toh(ao->entry.xor_hash) == l->xor_hash)
+                return 0;
+
+        if (l->seqnum_set &&
+            sd_id128_equal(af->header->seqnum_id, l->seqnum_id)) {
+
+                a = le64toh(ao->entry.seqnum);
+
+                if (a < l->seqnum)
+                        return -1;
+                if (a > l->seqnum)
+                        return 1;
+        }
+
+        if (l->monotonic_set &&
+            sd_id128_equal(ao->entry.boot_id, l->boot_id)) {
+
+                a = le64toh(ao->entry.monotonic);
+
+                if (a < l->monotonic)
+                        return -1;
+                if (a > l->monotonic)
+                        return 1;
+        }
+
+        if (l->realtime_set) {
+
+                a = le64toh(ao->entry.realtime);
+
+                if (a < l->realtime)
+                        return -1;
+                if (a > l->realtime)
+                        return 1;
+        }
+
+        if (l->xor_hash_set) {
+                a = le64toh(ao->entry.xor_hash);
+
+                if (a < l->xor_hash)
+                        return -1;
+                if (a > l->xor_hash)
+                        return 1;
+        }
+
+        return 0;
+}
+
+static int find_location(sd_journal *j, JournalFile *f, direction_t direction, Object **ret, uint64_t *offset) {
+        Object *o = NULL;
+        uint64_t p = 0;
         int r;
-        uint64_t cp;
-        Object *c;
 
         assert(j);
-        assert(f);
-        assert(o);
-        assert(p);
 
         if (!j->matches) {
-                /* No matches is easy, just go on to the next entry */
+                /* No matches is simple */
+
+                if (j->current_location.type == LOCATION_HEAD)
+                        r = journal_file_next_entry(f, NULL, 0, DIRECTION_DOWN, &o, &p);
+                else if (j->current_location.type == LOCATION_TAIL)
+                        r = journal_file_next_entry(f, NULL, 0, DIRECTION_UP, &o, &p);
+                else if (j->current_location.seqnum_set &&
+                         sd_id128_equal(j->current_location.seqnum_id, f->header->seqnum_id))
+                        r = journal_file_move_to_entry_by_seqnum(f, j->current_location.seqnum, direction, &o, &p);
+                else if (j->current_location.monotonic_set)
+                        r = journal_file_move_to_entry_by_monotonic(f, j->current_location.boot_id, j->current_location.monotonic, direction, &o, &p);
+                else if (j->current_location.realtime_set)
+                        r = journal_file_move_to_entry_by_realtime(f, j->current_location.realtime, direction, &o, &p);
+                else
+                        r = journal_file_next_entry(f, NULL, 0, direction, &o, &p);
+
+                if (r <= 0)
+                        return r;
+
+        } else  {
+                Match *m, *term_match = NULL;
+                Object *to = NULL;
+                uint64_t tp = 0;
+
+                /* We have matches, first, let's jump to the monotonic
+                 * position if we have any, since it implies a
+                 * match. */
 
-                if (f->current_offset > 0) {
-                        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &c);
-                        if (r < 0)
+                if (j->current_location.type == LOCATION_DISCRETE &&
+                    j->current_location.monotonic_set) {
+
+                        r = journal_file_move_to_entry_by_monotonic(f, j->current_location.boot_id, j->current_location.monotonic, direction, &o, &p);
+                        if (r <= 0)
                                 return r;
-                } else
-                        c = NULL;
+                }
+
+                LIST_FOREACH(matches, m, j->matches) {
+                        Object *c, *d;
+                        uint64_t cp, dp;
+
+                        r = journal_file_find_data_object_with_hash(f, m->data, m->size, m->le_hash, &d, &dp);
+                        if (r <= 0)
+                                return r;
+
+                        if (j->current_location.type == LOCATION_HEAD)
+                                r = journal_file_next_entry_for_data(f, NULL, 0, dp, DIRECTION_DOWN, &c, &cp);
+                        else if (j->current_location.type == LOCATION_TAIL)
+                                r = journal_file_next_entry_for_data(f, NULL, 0, dp, DIRECTION_UP, &c, &cp);
+                        else if (j->current_location.seqnum_set &&
+                                 sd_id128_equal(j->current_location.seqnum_id, f->header->seqnum_id))
+                                r = journal_file_move_to_entry_by_seqnum_for_data(f, dp, j->current_location.seqnum, direction, &c, &cp);
+                        else if (j->current_location.realtime_set)
+                                r = journal_file_move_to_entry_by_realtime_for_data(f, dp, j->current_location.realtime, direction, &c, &cp);
+                        else
+                                r = journal_file_next_entry_for_data(f, NULL, 0, dp, direction, &c, &cp);
+
+                        if (!term_match) {
+                                term_match = m;
+
+                                if (r > 0) {
+                                        to = c;
+                                        tp = cp;
+                                }
+                        } else if (same_field(term_match->data, term_match->size, m->data, m->size)) {
+
+                                /* Same field as previous match... */
+                                if (r > 0) {
+
+                                        /* Find the earliest of the OR matches */
+
+                                        if (!to ||
+                                            (direction == DIRECTION_DOWN && cp < tp) ||
+                                            (direction == DIRECTION_UP && cp > tp)) {
+                                                to = c;
+                                                tp = tp;
+                                        }
+
+                                }
 
-                return journal_file_next_entry(f, c, direction, o, p);
+                        } else {
+
+                                /* Previous term is finished, did anything match? */
+                                if (!to)
+                                        return 0;
+
+                                /* Find the last of the AND matches */
+                                if (!o ||
+                                    (direction == DIRECTION_DOWN && tp > p) ||
+                                    (direction == DIRECTION_UP && tp < p)) {
+                                        o = to;
+                                        p = tp;
+                                }
+
+                                term_match = m;
+
+                                if (r > 0) {
+                                        to = c;
+                                        tp = cp;
+                                } else {
+                                        to = NULL;
+                                        tp = 0;
+                                }
+                        }
+                }
+
+                /* Last term is finished, did anything match? */
+                if (!to)
+                        return 0;
+
+                if (!o ||
+                    (direction == DIRECTION_DOWN && tp > p) ||
+                    (direction == DIRECTION_UP && tp < p)) {
+                        o = to;
+                        p = tp;
+                }
+
+                if (!o)
+                        return 0;
         }
 
-        /* So there are matches we have to adhere to, let's find the
-         * first entry that matches all of them */
+        if (ret)
+                *ret = o;
 
-        if (f->current_offset > 0)
-                cp = f->current_offset;
-        else {
-                r = journal_file_find_first_entry(f, j->matches->data, j->matches->size, direction, &c, &cp);
+        if (offset)
+                *offset = p;
+
+        return 1;
+}
+
+static int next_with_matches(sd_journal *j, JournalFile *f, direction_t direction, Object **ret, uint64_t *offset) {
+        int r;
+        uint64_t cp;
+        Object *c;
+
+        assert(j);
+        assert(f);
+        assert(ret);
+        assert(offset);
+
+        c = *ret;
+        cp = *offset;
+
+        if (!j->matches) {
+                /* No matches is easy */
+
+                r = journal_file_next_entry(f, c, cp, direction, &c, &cp);
                 if (r <= 0)
                         return r;
 
-                /* We can shortcut this if there's only one match */
-                if (j->n_matches == 1) {
-                        *o = c;
-                        *p = cp;
-                        return r;
-                }
+                if (ret)
+                        *ret = c;
+                if (offset)
+                        *offset = cp;
+                return 1;
         }
 
+        /* So there are matches we have to adhere to, let's find the
+         * first entry that matches all of them */
+
         for (;;) {
                 uint64_t np, n;
-                bool found;
-                Match *m;
-
-                r = journal_file_move_to_object(f, cp, OBJECT_ENTRY, &c);
-                if (r < 0)
-                        return r;
+                bool found, term_result = false;
+                Match *m, *term_match = NULL;
 
                 n = journal_file_entry_n_items(c);
 
                 /* Make sure we don't match the entry we are starting
                  * from. */
-                found = f->current_offset != cp;
+                found = cp > *offset;
 
                 np = 0;
                 LIST_FOREACH(matches, m, j->matches) {
                         uint64_t q, k;
 
+                        /* Let's check if this is the beginning of a
+                         * new term, i.e. has a different field prefix
+                         * as the preceeding match. */
+                        if (!term_match) {
+                                term_match = m;
+                                term_result = false;
+                        } else if (!same_field(term_match->data, term_match->size, m->data, m->size)) {
+                                if (!term_result)
+                                        found = false;
+
+                                term_match = m;
+                                term_result = false;
+                        }
+
                         for (k = 0; k < n; k++)
                                 if (c->entry.items[k].hash == m->le_hash)
                                         break;
 
                         if (k >= n) {
-                                /* Hmm, didn't find any field that matched, so ignore
-                                 * this match. Go on with next match */
-
-                                found = false;
+                                /* Hmm, didn't find any field that
+                                 * matched this rule, so ignore this
+                                 * match. Go on with next match */
                                 continue;
                         }
 
+                        term_result = true;
+
                         /* Hmm, so, this field matched, let's remember
                          * where we'd have to try next, in case the other
                          * matches are not OK */
 
-                        if (direction == DIRECTION_DOWN) {
-                                q = le64toh(c->entry.items[k].next_entry_offset);
-
-                                if (q > np)
-                                        np = q;
-                        } else {
-                                q = le64toh(c->entry.items[k].prev_entry_offset);
+                        r = journal_file_next_entry_for_data(f, c, cp, le64toh(c->entry.items[k].object_offset), direction, NULL, &q);
+                        if (r > 0) {
 
-                                if (q != 0 && (np == 0 || q < np))
-                                        np = q;
+                                if (direction == DIRECTION_DOWN) {
+                                        if (q > np)
+                                                np = q;
+                                } else {
+                                        if (np == 0 || q < np)
+                                                np = q;
+                                }
                         }
                 }
 
+                /* Check the last term */
+                if (term_match && term_result)
+                        found = true;
+
                 /* Did this entry match against all matches? */
                 if (found) {
-                        *o = c;
-                        *p = cp;
+                        if (ret)
+                                *ret = c;
+                        if (offset)
+                                *offset = cp;
                         return 1;
                 }
 
@@ -285,6 +595,62 @@ static int move_to_next_with_matches(sd_journal *j, JournalFile *f, direction_t
         }
 }
 
+static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direction, Object **ret, uint64_t *offset) {
+        Object *c;
+        uint64_t cp;
+        int compare_value, r;
+
+        assert(j);
+        assert(f);
+
+        if (f->current_offset > 0) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &c);
+                if (r < 0)
+                        return r;
+
+                cp = f->current_offset;
+
+                r = next_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+
+                compare_value = 1;
+        } else {
+                r = find_location(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+
+                compare_value = 0;
+        }
+
+        for (;;) {
+                bool found;
+
+                if (j->current_location.type == LOCATION_DISCRETE) {
+                        int k;
+
+                        k = compare_with_location(f, c, &j->current_location);
+                        if (direction == DIRECTION_DOWN)
+                                found = k >= compare_value;
+                        else
+                                found = k <= -compare_value;
+                } else
+                        found = true;
+
+                if (found) {
+                        if (ret)
+                                *ret = c;
+                        if (offset)
+                                *offset = cp;
+                        return 1;
+                }
+
+                r = next_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+        }
+}
+
 static int real_journal_next(sd_journal *j, direction_t direction) {
         JournalFile *f, *new_current = NULL;
         Iterator i;
@@ -297,57 +663,88 @@ static int real_journal_next(sd_journal *j, direction_t direction) {
         HASHMAP_FOREACH(f, j->files, i) {
                 Object *o;
                 uint64_t p;
+                bool found;
 
-                r = move_to_next_with_matches(j, f, direction, &o, &p);
+                r = next_beyond_location(j, f, direction, &o, &p);
                 if (r < 0)
                         return r;
                 else if (r == 0)
                         continue;
 
-                if (!new_current ||
-                    compare_order(new_current, new_entry, new_offset, f, o, p) > 0) {
+                if (!new_current)
+                        found = true;
+                else {
+                        int k;
+
+                        k = compare_order(f, o, new_current, new_entry);
+
+                        if (direction == DIRECTION_DOWN)
+                                found = k < 0;
+                        else
+                                found = k > 0;
+                }
+
+                if (found) {
                         new_current = f;
                         new_entry = o;
                         new_offset = p;
                 }
         }
 
-        if (new_current) {
-                j->current_file = new_current;
-                j->current_file->current_offset = new_offset;
-                j->current_field = 0;
+        if (!new_current)
+                return 0;
 
-                /* Skip over any identical entries in the other files too */
+        set_location(j, new_current, new_entry, new_offset);
 
-                HASHMAP_FOREACH(f, j->files, i) {
-                        Object *o;
-                        uint64_t p;
+        return 1;
+}
 
-                        if (j->current_file == f)
-                                continue;
+int sd_journal_next(sd_journal *j) {
+        return real_journal_next(j, DIRECTION_DOWN);
+}
 
-                        r = move_to_next_with_matches(j, f, direction, &o, &p);
-                        if (r < 0)
-                                return r;
-                        else if (r == 0)
-                                continue;
+int sd_journal_previous(sd_journal *j) {
+        return real_journal_next(j, DIRECTION_UP);
+}
 
-                        if (compare_order(new_current, new_entry, new_offset, f, o, p) == 0)
-                                f->current_offset = p;
-                }
+int sd_journal_next_skip(sd_journal *j, uint64_t skip) {
+        int c = 0, r;
 
-                return 1;
+        assert(j);
+
+        while (skip > 0) {
+                r = sd_journal_next(j);
+                if (r < 0)
+                        return r;
+
+                if (r == 0)
+                        return c;
+
+                skip--;
+                c++;
         }
 
-        return 0;
+        return c;
 }
 
-int sd_journal_next(sd_journal *j) {
-        return real_journal_next(j, DIRECTION_DOWN);
-}
+int sd_journal_previous_skip(sd_journal *j, uint64_t skip) {
+        int c = 0, r;
 
-int sd_journal_previous(sd_journal *j) {
-        return real_journal_next(j, DIRECTION_UP);
+        assert(j);
+
+        while (skip > 0) {
+                r = sd_journal_previous(j);
+                if (r < 0)
+                        return r;
+
+                if (r == 0)
+                        return c;
+
+                skip--;
+                c++;
+        }
+
+        return 1;
 }
 
 int sd_journal_get_cursor(sd_journal *j, char **cursor) {
@@ -361,7 +758,7 @@ int sd_journal_get_cursor(sd_journal *j, char **cursor) {
         if (!j->current_file || j->current_file->current_offset <= 0)
                 return -EADDRNOTAVAIL;
 
-        r = journal_file_move_to_object(j->current_file, j->current_file->current_offset, OBJECT_ENTRY, &o);
+        r = journal_file_move_to_object(j->current_file, OBJECT_ENTRY, j->current_file->current_offset, &o);
         if (r < 0)
                 return r;
 
@@ -380,8 +777,150 @@ int sd_journal_get_cursor(sd_journal *j, char **cursor) {
         return 1;
 }
 
-int sd_journal_set_cursor(sd_journal *j, const char *cursor) {
-        return -EINVAL;
+int sd_journal_seek_cursor(sd_journal *j, const char *cursor) {
+        char *w;
+        size_t l;
+        char *state;
+        unsigned long long seqnum, monotonic, realtime, xor_hash;
+        bool
+                seqnum_id_set = false,
+                seqnum_set = false,
+                boot_id_set = false,
+                monotonic_set = false,
+                realtime_set = false,
+                xor_hash_set = false;
+        sd_id128_t seqnum_id, boot_id;
+
+        assert(j);
+        assert(cursor);
+
+        FOREACH_WORD_SEPARATOR(w, l, cursor, ";", state) {
+                char *item;
+                int k = 0;
+
+                if (l < 2 || w[1] != '=')
+                        return -EINVAL;
+
+                item = strndup(w, l);
+                if (!item)
+                        return -ENOMEM;
+
+                switch (w[0]) {
+
+                case 's':
+                        seqnum_id_set = true;
+                        k = sd_id128_from_string(w+2, &seqnum_id);
+                        break;
+
+                case 'i':
+                        seqnum_set = true;
+                        if (sscanf(w+2, "%llx", &seqnum) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 'b':
+                        boot_id_set = true;
+                        k = sd_id128_from_string(w+2, &boot_id);
+                        break;
+
+                case 'm':
+                        monotonic_set = true;
+                        if (sscanf(w+2, "%llx", &monotonic) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 't':
+                        realtime_set = true;
+                        if (sscanf(w+2, "%llx", &realtime) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 'x':
+                        xor_hash_set = true;
+                        if (sscanf(w+2, "%llx", &xor_hash) != 1)
+                                k = -EINVAL;
+                        break;
+                }
+
+                free(item);
+
+                if (k < 0)
+                        return k;
+        }
+
+        if ((!seqnum_set || !seqnum_id_set) &&
+            (!monotonic_set || !boot_id_set) &&
+            !realtime_set)
+                return -EINVAL;
+
+        reset_location(j);
+
+        j->current_location.type = LOCATION_DISCRETE;
+
+        if (realtime_set) {
+                j->current_location.realtime = (uint64_t) realtime;
+                j->current_location.realtime_set = true;
+        }
+
+        if (seqnum_set && seqnum_id_set) {
+                j->current_location.seqnum = (uint64_t) seqnum;
+                j->current_location.seqnum_id = seqnum_id;
+                j->current_location.seqnum_set = true;
+        }
+
+        if (monotonic_set && boot_id_set) {
+                j->current_location.monotonic = (uint64_t) monotonic;
+                j->current_location.boot_id = boot_id;
+                j->current_location.monotonic_set = true;
+        }
+
+        if (xor_hash_set) {
+                j->current_location.xor_hash = (uint64_t) xor_hash;
+                j->current_location.xor_hash_set = true;
+        }
+
+        return 0;
+}
+
+int sd_journal_seek_monotonic_usec(sd_journal *j, sd_id128_t boot_id, uint64_t usec) {
+        assert(j);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_DISCRETE;
+        j->current_location.boot_id = boot_id;
+        j->current_location.monotonic = usec;
+        j->current_location.monotonic_set = true;
+
+        return 0;
+}
+
+int sd_journal_seek_realtime_usec(sd_journal *j, uint64_t usec) {
+        assert(j);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_DISCRETE;
+        j->current_location.realtime = usec;
+        j->current_location.realtime_set = true;
+
+        return 0;
+}
+
+int sd_journal_seek_head(sd_journal *j) {
+        assert(j);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_HEAD;
+
+        return 0;
+}
+
+int sd_journal_seek_tail(sd_journal *j) {
+        assert(j);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_TAIL;
+
+        return 0;
 }
 
 static int add_file(sd_journal *j, const char *prefix, const char *dir, const char *filename) {
@@ -411,6 +950,9 @@ static int add_file(sd_journal *j, const char *prefix, const char *dir, const ch
                 return r;
         }
 
+        journal_file_dump(f);
+
+
         r = hashmap_put(j->files, f->path, f);
         if (r < 0) {
                 journal_file_close(f);
@@ -557,20 +1099,20 @@ int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
 
         f = j->current_file;
         if (!f)
-                return 0;
+                return -EADDRNOTAVAIL;
 
         if (f->current_offset <= 0)
-                return 0;
+                return -EADDRNOTAVAIL;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
         if (r < 0)
                 return r;
 
         *ret = le64toh(o->entry.realtime);
-        return 1;
+        return 0;
 }
 
-int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret) {
+int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id128_t *ret_boot_id) {
         Object *o;
         JournalFile *f;
         int r;
@@ -581,25 +1123,28 @@ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret) {
 
         f = j->current_file;
         if (!f)
-                return 0;
+                return -EADDRNOTAVAIL;
 
         if (f->current_offset <= 0)
-                return 0;
+                return -EADDRNOTAVAIL;
 
-        r = sd_id128_get_boot(&id);
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
         if (r < 0)
                 return r;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-        if (r < 0)
-                return r;
+        if (ret_boot_id)
+                *ret_boot_id = o->entry.boot_id;
+        else {
+                r = sd_id128_get_boot(&id);
+                if (r < 0)
+                        return r;
 
-        if (!sd_id128_equal(id, o->entry.boot_id))
-                return 0;
+                if (!sd_id128_equal(id, o->entry.boot_id))
+                        return -ENOENT;
+        }
 
         *ret = le64toh(o->entry.monotonic);
-        return 1;
-
+        return 0;
 }
 
 int sd_journal_get_data(sd_journal *j, const char *field, const void **data, size_t *size) {
@@ -619,12 +1164,12 @@ int sd_journal_get_data(sd_journal *j, const char *field, const void **data, siz
 
         f = j->current_file;
         if (!f)
-                return 0;
+                return -EADDRNOTAVAIL;
 
         if (f->current_offset <= 0)
-                return 0;
+                return -EADDRNOTAVAIL;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
         if (r < 0)
                 return r;
 
@@ -632,16 +1177,16 @@ int sd_journal_get_data(sd_journal *j, const char *field, const void **data, siz
 
         n = journal_file_entry_n_items(o);
         for (i = 0; i < n; i++) {
-                uint64_t p, l, h;
+                uint64_t p, l, le_hash;
                 size_t t;
 
                 p = le64toh(o->entry.items[i].object_offset);
-                h = o->entry.items[j->current_field].hash;
-                r = journal_file_move_to_object(f, p, OBJECT_DATA, &o);
+                le_hash = o->entry.items[j->current_field].hash;
+                r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
                 if (r < 0)
                         return r;
 
-                if (h != o->data.hash)
+                if (le_hash != o->data.hash)
                         return -EBADMSG;
 
                 l = le64toh(o->object.size) - offsetof(Object, data.payload);
@@ -658,23 +1203,23 @@ int sd_journal_get_data(sd_journal *j, const char *field, const void **data, siz
                         *data = o->data.payload;
                         *size = t;
 
-                        return 1;
+                        return 0;
                 }
 
-                r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
                 if (r < 0)
                         return r;
         }
 
-        return 0;
+        return -ENOENT;
 }
 
 int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *size) {
         JournalFile *f;
-        uint64_t p, l, n, h;
-        size_t t;
+        uint64_t p, l, n, le_hash;
         int r;
         Object *o;
+        size_t t;
 
         assert(j);
         assert(data);
@@ -682,12 +1227,12 @@ int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *size) {
 
         f = j->current_file;
         if (!f)
-                return 0;
+                return -EADDRNOTAVAIL;
 
         if (f->current_offset <= 0)
-                return 0;
+                return -EADDRNOTAVAIL;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
         if (r < 0)
                 return r;
 
@@ -696,12 +1241,12 @@ int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *size) {
                 return 0;
 
         p = le64toh(o->entry.items[j->current_field].object_offset);
-        h = o->entry.items[j->current_field].hash;
-        r = journal_file_move_to_object(f, p, OBJECT_DATA, &o);
+        le_hash = o->entry.items[j->current_field].hash;
+        r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
         if (r < 0)
                 return r;
 
-        if (h != o->data.hash)
+        if (le_hash != o->data.hash)
                 return -EBADMSG;
 
         l = le64toh(o->object.size) - offsetof(Object, data.payload);
@@ -719,24 +1264,8 @@ int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *size) {
         return 1;
 }
 
-void sd_journal_start_data(sd_journal *j) {
+void sd_journal_restart_data(sd_journal *j) {
         assert(j);
 
         j->current_field = 0;
 }
-
-int sd_journal_seek_head(sd_journal *j) {
-        assert(j);
-
-        reset_location(j);
-
-        return real_journal_next(j, DIRECTION_DOWN);
-}
-
-int sd_journal_seek_tail(sd_journal *j) {
-        assert(j);
-
-        reset_location(j);
-
-        return real_journal_next(j, DIRECTION_UP);
-}