chiark / gitweb /
journal: implement message catalog
[elogind.git] / src / journal / sd-journal.c
index bc6d255662adf21a98f63796ab6182673cc2b649..c86f1eaab15c957daac409bee1ff07ae18521b1b 100644 (file)
   Copyright 2011 Lennart Poettering
 
   systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU General Public License as published by
-  the Free Software Foundation; either version 2 of the License, or
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.
 
   systemd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  General Public License for more details.
+  Lesser General Public License for more details.
 
-  You should have received a copy of the GNU General Public License
+  You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stddef.h>
+#include <unistd.h>
+#include <sys/inotify.h>
+#include <sys/poll.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
 
 #include "sd-journal.h"
 #include "journal-def.h"
 #include "journal-file.h"
 #include "hashmap.h"
 #include "list.h"
+#include "path-util.h"
 #include "lookup3.h"
+#include "compress.h"
+#include "journal-internal.h"
+#include "missing.h"
+#include "catalog.h"
+#include "replace-var.h"
 
-typedef struct Match Match;
+#define JOURNAL_FILES_MAX 1024
 
-struct Match {
-        char *data;
-        size_t size;
-        uint64_t le_hash;
+#define JOURNAL_FILES_RECHECK_USEC (2 * USEC_PER_SEC)
 
-        LIST_FIELDS(Match, matches);
-};
+#define REPLACE_VAR_MAX 256
 
-struct sd_journal {
-        Hashmap *files;
+static void detach_location(sd_journal *j) {
+        Iterator i;
+        JournalFile *f;
 
-        JournalFile *current_file;
-        uint64_t current_field;
+        assert(j);
 
-        LIST_HEAD(Match, matches);
-        unsigned n_matches;
-};
+        j->current_file = NULL;
+        j->current_field = 0;
 
-int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
-        Match *m;
+        HASHMAP_FOREACH(f, j->files, i)
+                f->current_offset = 0;
+}
 
+static void reset_location(sd_journal *j) {
         assert(j);
 
-        if (size <= 0)
-                return -EINVAL;
+        detach_location(j);
+        zero(j->current_location);
+}
+
+static void init_location(Location *l, LocationType type, JournalFile *f, Object *o) {
+        assert(l);
+        assert(type == LOCATION_DISCRETE || type == LOCATION_SEEK);
+        assert(f);
+        assert(o->object.type == OBJECT_ENTRY);
+
+        l->type = type;
+        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 = 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, LocationType type, JournalFile *f, Object *o, uint64_t offset) {
+        assert(j);
+        assert(type == LOCATION_DISCRETE || type == LOCATION_SEEK);
+        assert(f);
+        assert(o);
+
+        init_location(&j->current_location, type, f, o);
+
+        j->current_file = f;
+        j->current_field = 0;
+
+        f->current_offset = offset;
+}
+
+static int match_is_valid(const void *data, size_t size) {
+        const char *b, *p;
 
         assert(data);
 
+        if (size < 2)
+                return false;
+
+        if (startswith(data, "__"))
+                return false;
+
+        b = data;
+        for (p = b; p < b + size; p++) {
+
+                if (*p == '=')
+                        return p > b;
+
+                if (*p == '_')
+                        continue;
+
+                if (*p >= 'A' && *p <= 'Z')
+                        continue;
+
+                if (*p >= '0' && *p <= '9')
+                        continue;
+
+                return false;
+        }
+
+        return false;
+}
+
+static bool same_field(const void *_a, size_t s, const void *_b, size_t t) {
+        const uint8_t *a = _a, *b = _b;
+        size_t j;
+
+        for (j = 0; j < s && j < t; j++) {
+
+                if (a[j] != b[j])
+                        return false;
+
+                if (a[j] == '=')
+                        return true;
+        }
+
+        return true;
+}
+
+static Match *match_new(Match *p, MatchType t) {
+        Match *m;
+
         m = new0(Match, 1);
         if (!m)
-                return -ENOMEM;
+                return NULL;
 
-        m->size = size;
+        m->type = t;
 
-        m->data = malloc(m->size);
-        if (!m->data) {
-                free(m);
-                return -ENOMEM;
+        if (p) {
+                m->parent = p;
+                LIST_PREPEND(Match, matches, p->matches, m);
+        }
+
+        return m;
+}
+
+static void match_free(Match *m) {
+        assert(m);
+
+        while (m->matches)
+                match_free(m->matches);
+
+        if (m->parent)
+                LIST_REMOVE(Match, matches, m->parent->matches, m);
+
+        free(m->data);
+        free(m);
+}
+
+static void match_free_if_empty(Match *m) {
+        assert(m);
+
+        if (m->matches)
+                return;
+
+        match_free(m);
+}
+
+_public_ int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
+        Match *l2, *l3, *add_here = NULL, *m;
+        le64_t le_hash;
+
+        if (!j)
+                return -EINVAL;
+
+        if (!data)
+                return -EINVAL;
+
+        if (size == 0)
+                size = strlen(data);
+
+        if (!match_is_valid(data, size))
+                return -EINVAL;
+
+        /* level 0: OR term
+         * level 1: AND terms
+         * level 2: OR terms
+         * level 3: concrete matches */
+
+        if (!j->level0) {
+                j->level0 = match_new(NULL, MATCH_OR_TERM);
+                if (!j->level0)
+                        return -ENOMEM;
+        }
+
+        if (!j->level1) {
+                j->level1 = match_new(j->level0, MATCH_AND_TERM);
+                if (!j->level1)
+                        return -ENOMEM;
+        }
+
+        assert(j->level0->type == MATCH_OR_TERM);
+        assert(j->level1->type == MATCH_AND_TERM);
+
+        le_hash = htole64(hash64(data, size));
+
+        LIST_FOREACH(matches, l2, j->level1->matches) {
+                assert(l2->type == MATCH_OR_TERM);
+
+                LIST_FOREACH(matches, l3, l2->matches) {
+                        assert(l3->type == MATCH_DISCRETE);
+
+                        /* Exactly the same match already? Then ignore
+                         * this addition */
+                        if (l3->le_hash == le_hash &&
+                            l3->size == size &&
+                            memcmp(l3->data, data, size) == 0)
+                                return 0;
+
+                        /* Same field? Then let's add this to this OR term */
+                        if (same_field(data, size, l3->data, l3->size)) {
+                                add_here = l2;
+                                break;
+                        }
+                }
+
+                if (add_here)
+                        break;
+        }
+
+        if (!add_here) {
+                add_here = match_new(j->level1, MATCH_OR_TERM);
+                if (!add_here)
+                        goto fail;
         }
 
-        memcpy(m->data, data, size);
-        m->le_hash = hash64(m->data, size);
+        m = match_new(add_here, MATCH_DISCRETE);
+        if (!m)
+                goto fail;
+
+        m->le_hash = le_hash;
+        m->size = size;
+        m->data = memdup(data, size);
+        if (!m->data)
+                goto fail;
 
-        LIST_PREPEND(Match, matches, j->matches, m);
-        j->n_matches ++;
+        detach_location(j);
 
         return 0;
+
+fail:
+        if (add_here)
+                match_free_if_empty(add_here);
+
+        if (j->level1)
+                match_free_if_empty(j->level1);
+
+        if (j->level0)
+                match_free_if_empty(j->level0);
+
+        return -ENOMEM;
 }
 
-void sd_journal_flush_matches(sd_journal *j) {
+_public_ int sd_journal_add_disjunction(sd_journal *j) {
+        Match *m;
+
         assert(j);
 
-        while (j->matches) {
-                Match *m = j->matches;
+        if (!j->level0)
+                return 0;
+
+        if (!j->level1)
+                return 0;
+
+        if (!j->level1->matches)
+                return 0;
+
+        m = match_new(j->level0, MATCH_AND_TERM);
+        if (!m)
+                return -ENOMEM;
+
+        j->level1 = m;
+        return 0;
+}
+
+static char *match_make_string(Match *m) {
+        char *p, *r;
+        Match *i;
+        bool enclose = false;
+
+        if (!m)
+                return strdup("");
+
+        if (m->type == MATCH_DISCRETE)
+                return strndup(m->data, m->size);
+
+        p = NULL;
+        LIST_FOREACH(matches, i, m->matches) {
+                char *t, *k;
+
+                t = match_make_string(i);
+                if (!t) {
+                        free(p);
+                        return NULL;
+                }
+
+                if (p) {
+                        k = strjoin(p, m->type == MATCH_OR_TERM ? " OR " : " AND ", t, NULL);
+                        free(p);
+                        free(t);
+
+                        if (!k)
+                                return NULL;
+
+                        p = k;
 
-                LIST_REMOVE(Match, matches, j->matches, m);
-                free(m->data);
-                free(m);
+                        enclose = true;
+                } else {
+                        free(p);
+                        p = t;
+                }
+        }
+
+        if (enclose) {
+                r = strjoin("(", p, ")", NULL);
+                free(p);
+                return r;
         }
 
-        j->n_matches = 0;
+        return p;
+}
+
+char *journal_make_match_string(sd_journal *j) {
+        assert(j);
+
+        return match_make_string(j->level0);
 }
 
-static int compare_order(JournalFile *af, Object *ao, uint64_t ap,
-                         JournalFile *bf, Object *bo, uint64_t bp) {
+_public_ void sd_journal_flush_matches(sd_journal *j) {
+
+        if (!j)
+                return;
+
+        if (j->level0)
+                match_free(j->level0);
+
+        j->level0 = j->level1 = NULL;
+
+        detach_location(j);
+}
+
+static int compare_entry_order(JournalFile *af, Object *_ao,
+                         JournalFile *bf, uint64_t bp) {
 
         uint64_t a, b;
+        Object *ao, *bo;
+        int r;
+
+        assert(af);
+        assert(bf);
+        assert(_ao);
+
+        /* The mmap cache might invalidate the object from the first
+         * file if we look at the one from the second file. Hence
+         * temporarily copy the header of the first one, and look at
+         * that only. */
+        ao = alloca(offsetof(EntryObject, items));
+        memcpy(ao, _ao, offsetof(EntryObject, items));
+
+        r = journal_file_move_to_object(bf, OBJECT_ENTRY, bp, &bo);
+        if (r < 0)
+                return strcmp(af->path, bf->path);
 
         /* We operate on two different files here, hence we can access
          * two objects at the same time, which we normally can't.
@@ -143,7 +433,7 @@ static int compare_order(JournalFile *af, Object *ao, uint64_t ap,
 
         /* Otherwise compare UTC time */
         a = le64toh(ao->entry.realtime);
-        b = le64toh(ao->entry.realtime);
+        b = le64toh(bo->entry.realtime);
 
         if (a < b)
                 return -1;
@@ -152,7 +442,7 @@ static int compare_order(JournalFile *af, Object *ao, uint64_t ap,
 
         /* Finally, compare by contents */
         a = le64toh(ao->entry.xor_hash);
-        b = le64toh(ao->entry.xor_hash);
+        b = le64toh(bo->entry.xor_hash);
 
         if (a < b)
                 return -1;
@@ -162,242 +452,496 @@ 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, Object **o, uint64_t *p) {
-        int r;
-        uint64_t cp;
-        Object *c;
-
-        assert(j);
-        assert(f);
-        assert(o);
-        assert(p);
+static int compare_with_location(JournalFile *af, Object *ao, Location *l) {
+        uint64_t a;
 
-        if (!j->matches) {
-                /* No matches is easy, just go on to the next entry */
-
-                if (f->current_offset > 0) {
-                        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &c);
-                        if (r < 0)
-                                return r;
-                } else
-                        c = NULL;
+        assert(af);
+        assert(ao);
+        assert(l);
+        assert(l->type == LOCATION_DISCRETE || l->type == LOCATION_SEEK);
 
-                return journal_file_next_entry(f, c, o, p);
-        }
+        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;
 
-        /* So there are matches we have to adhere to, let's find the
-         * first entry that matches all of them */
+        if (l->seqnum_set &&
+            sd_id128_equal(af->header->seqnum_id, l->seqnum_id)) {
 
-        if (f->current_offset > 0)
-                cp = f->current_offset;
-        else {
-                r = journal_file_find_first_entry(f, j->matches->data, j->matches->size, &c, &cp);
-                if (r <= 0)
-                        return r;
+                a = le64toh(ao->entry.seqnum);
 
-                /* We can shortcut this if there's only one match */
-                if (j->n_matches == 1) {
-                        *o = c;
-                        *p = cp;
-                        return r;
-                }
+                if (a < l->seqnum)
+                        return -1;
+                if (a > l->seqnum)
+                        return 1;
         }
 
-        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;
-
-                n = journal_file_entry_n_items(c);
-
-                /* Make sure we don't match the entry we are starting
-                 * from. */
-                found = f->current_offset != cp;
-
-                np = 0;
-                LIST_FOREACH(matches, m, j->matches) {
-                        uint64_t q, k;
+        if (l->monotonic_set &&
+            sd_id128_equal(ao->entry.boot_id, l->boot_id)) {
 
-                        for (k = 0; k < n; k++)
-                                if (c->entry.items[k].hash == m->le_hash)
-                                        break;
+                a = le64toh(ao->entry.monotonic);
 
-                        if (k >= n) {
-                                /* Hmm, didn't find any field that matched, so ignore
-                                 * this match. Go on with next match */
+                if (a < l->monotonic)
+                        return -1;
+                if (a > l->monotonic)
+                        return 1;
+        }
 
-                                found = false;
-                                continue;
-                        }
+        if (l->realtime_set) {
 
-                        /* Hmm, so, this field matched, let's remember
-                         * where we'd have to try next, in case the other
-                         * matches are not OK */
-                        q = le64toh(c->entry.items[k].next_entry_offset);
-                        if (q > np)
-                                np = q;
-                }
+                a = le64toh(ao->entry.realtime);
 
-                /* Did this entry match against all matches? */
-                if (found) {
-                        *o = c;
-                        *p = cp;
+                if (a < l->realtime)
+                        return -1;
+                if (a > l->realtime)
                         return 1;
-                }
+        }
 
-                /* Did we find a subsequent entry? */
-                if (np == 0)
-                        return 0;
+        if (l->xor_hash_set) {
+                a = le64toh(ao->entry.xor_hash);
 
-                /* Hmm, ok, this entry only matched partially, so
-                 * let's try another one */
-                cp = np;
+                if (a < l->xor_hash)
+                        return -1;
+                if (a > l->xor_hash)
+                        return 1;
         }
+
+        return 0;
 }
 
-int sd_journal_next(sd_journal *j) {
-        JournalFile *f, *new_current = NULL;
-        Iterator i;
+static int next_for_match(
+                sd_journal *j,
+                Match *m,
+                JournalFile *f,
+                uint64_t after_offset,
+                direction_t direction,
+                Object **ret,
+                uint64_t *offset) {
+
         int r;
-        uint64_t new_offset = 0;
-        Object *new_entry = NULL;
+        uint64_t np = 0;
+        Object *n;
 
         assert(j);
+        assert(m);
+        assert(f);
 
-        HASHMAP_FOREACH(f, j->files, i) {
-                Object *o;
-                uint64_t p;
+        if (m->type == MATCH_DISCRETE) {
+                uint64_t dp;
 
-                r = move_to_next_with_matches(j, f, &o, &p);
-                if (r < 0)
+                r = journal_file_find_data_object_with_hash(f, m->data, m->size, le64toh(m->le_hash), NULL, &dp);
+                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) {
-                        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;
+                return journal_file_move_to_entry_by_offset_for_data(f, dp, after_offset, direction, ret, offset);
 
-                /* Skip over any identical entries in the other files too */
+        } else if (m->type == MATCH_OR_TERM) {
+                Match *i;
 
-                HASHMAP_FOREACH(f, j->files, i) {
-                        Object *o;
-                        uint64_t p;
+                /* Find the earliest match beyond after_offset */
 
-                        if (j->current_file == f)
-                                continue;
+                LIST_FOREACH(matches, i, m->matches) {
+                        uint64_t cp;
 
-                        r = move_to_next_with_matches(j, f, &o, &p);
+                        r = next_for_match(j, i, f, after_offset, direction, NULL, &cp);
                         if (r < 0)
                                 return r;
-                        else if (r == 0)
-                                continue;
-
-                        if (compare_order(new_current, new_entry, new_offset, f, o, p) == 0)
-                                f->current_offset = p;
+                        else if (r > 0) {
+                                if (np == 0 || (direction == DIRECTION_DOWN ? np > cp : np < cp))
+                                        np = cp;
+                        }
                 }
 
-                return 1;
+        } else if (m->type == MATCH_AND_TERM) {
+                Match *i;
+                bool continue_looking;
+
+                /* Always jump to the next matching entry and repeat
+                 * this until we fine and offset that matches for all
+                 * matches. */
+
+                if (!m->matches)
+                        return 0;
+
+                np = 0;
+                do {
+                        continue_looking = false;
+
+                        LIST_FOREACH(matches, i, m->matches) {
+                                uint64_t cp, limit;
+
+                                if (np == 0)
+                                        limit = after_offset;
+                                else if (direction == DIRECTION_DOWN)
+                                        limit = MAX(np, after_offset);
+                                else
+                                        limit = MIN(np, after_offset);
+
+                                r = next_for_match(j, i, f, limit, direction, NULL, &cp);
+                                if (r <= 0)
+                                        return r;
+
+                                if ((direction == DIRECTION_DOWN ? cp >= after_offset : cp <= after_offset) &&
+                                    (np == 0 || (direction == DIRECTION_DOWN ? cp > np : np < cp))) {
+                                        np = cp;
+                                        continue_looking = true;
+                                }
+                        }
+
+                } while (continue_looking);
         }
 
-        return 0;
+        if (np == 0)
+                return 0;
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, np, &n);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = n;
+        if (offset)
+                *offset = np;
+
+        return 1;
 }
 
-int sd_journal_previous(sd_journal *j) {
-        JournalFile *f, *new_current = NULL;
-        Iterator i;
+static int find_location_for_match(
+                sd_journal *j,
+                Match *m,
+                JournalFile *f,
+                direction_t direction,
+                Object **ret,
+                uint64_t *offset) {
+
         int r;
-        uint64_t new_offset = 0;
-        Object *new_entry = NULL;
 
         assert(j);
+        assert(m);
+        assert(f);
 
-        HASHMAP_FOREACH(f, j->files, i) {
-                Object *o;
-                uint64_t p;
-
-                if (f->current_offset > 0) {
-                        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-                        if (r < 0)
-                                return r;
-                } else
-                        o = NULL;
+        if (m->type == MATCH_DISCRETE) {
+                uint64_t dp;
 
-                r = journal_file_prev_entry(f, o, &o, &p);
-                if (r < 0)
+                r = journal_file_find_data_object_with_hash(f, m->data, m->size, le64toh(m->le_hash), NULL, &dp);
+                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) {
-                        new_current = f;
-                        new_entry = o;
-                        new_offset = p;
+                /* FIXME: missing: find by monotonic */
+
+                if (j->current_location.type == LOCATION_HEAD)
+                        return journal_file_next_entry_for_data(f, NULL, 0, dp, DIRECTION_DOWN, ret, offset);
+                if (j->current_location.type == LOCATION_TAIL)
+                        return journal_file_next_entry_for_data(f, NULL, 0, dp, DIRECTION_UP, ret, offset);
+                if (j->current_location.seqnum_set && sd_id128_equal(j->current_location.seqnum_id, f->header->seqnum_id))
+                        return journal_file_move_to_entry_by_seqnum_for_data(f, dp, j->current_location.seqnum, direction, ret, offset);
+                if (j->current_location.monotonic_set) {
+                        r = journal_file_move_to_entry_by_monotonic_for_data(f, dp, j->current_location.boot_id, j->current_location.monotonic, direction, ret, offset);
+                        if (r != -ENOENT)
+                                return r;
                 }
-        }
-
-        if (new_current) {
-                j->current_file = new_current;
-                j->current_file->current_offset = new_offset;
-                j->current_field = 0;
+                if (j->current_location.realtime_set)
+                        return journal_file_move_to_entry_by_realtime_for_data(f, dp, j->current_location.realtime, direction, ret, offset);
 
-                /* Skip over any identical entries in the other files too */
+                return journal_file_next_entry_for_data(f, NULL, 0, dp, direction, ret, offset);
 
-                HASHMAP_FOREACH(f, j->files, i) {
-                        Object *o;
-                        uint64_t p;
+        } else if (m->type == MATCH_OR_TERM) {
+                uint64_t np = 0;
+                Object *n;
+                Match *i;
 
-                        if (j->current_file == f)
-                                continue;
+                /* Find the earliest match */
 
-                        if (f->current_offset > 0) {
-                                r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-                                if (r < 0)
-                                        return r;
-                        } else
-                                o = NULL;
+                LIST_FOREACH(matches, i, m->matches) {
+                        uint64_t cp;
 
-                        r = journal_file_prev_entry(f, o, &o, &p);
+                        r = find_location_for_match(j, i, f, direction, NULL, &cp);
                         if (r < 0)
                                 return r;
-                        else if (r == 0)
-                                continue;
-
-                        if (compare_order(new_current, new_entry, new_offset, f, o, p) == 0)
-                                f->current_offset = p;
+                        else if (r > 0) {
+                                if (np == 0 || (direction == DIRECTION_DOWN ? np > cp : np < cp))
+                                        np = cp;
+                        }
                 }
 
-                return 1;
-        }
+                if (np == 0)
+                        return 0;
 
-        return 0;
-}
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, np, &n);
+                if (r < 0)
+                        return r;
+
+                if (ret)
+                        *ret = n;
+                if (offset)
+                        *offset = np;
+
+                return 1;
+
+        } else {
+                Match *i;
+                uint64_t np = 0;
+
+                assert(m->type == MATCH_AND_TERM);
+
+                /* First jump to the last match, and then find the
+                 * next one where all matches match */
+
+                if (!m->matches)
+                        return 0;
+
+                LIST_FOREACH(matches, i, m->matches) {
+                        uint64_t cp;
+
+                        r = find_location_for_match(j, i, f, direction, NULL, &cp);
+                        if (r <= 0)
+                                return r;
+
+                        if (np == 0 || (direction == DIRECTION_DOWN ? np < cp : np > cp))
+                                np = cp;
+                }
+
+                return next_for_match(j, m, f, np, direction, ret, offset);
+        }
+}
+
+static int find_location_with_matches(
+                sd_journal *j,
+                JournalFile *f,
+                direction_t direction,
+                Object **ret,
+                uint64_t *offset) {
+
+        int r;
+
+        assert(j);
+        assert(f);
+        assert(ret);
+        assert(offset);
+
+        if (!j->level0) {
+                /* No matches is simple */
+
+                if (j->current_location.type == LOCATION_HEAD)
+                        return journal_file_next_entry(f, NULL, 0, DIRECTION_DOWN, ret, offset);
+                if (j->current_location.type == LOCATION_TAIL)
+                        return journal_file_next_entry(f, NULL, 0, DIRECTION_UP, ret, offset);
+                if (j->current_location.seqnum_set && sd_id128_equal(j->current_location.seqnum_id, f->header->seqnum_id))
+                        return journal_file_move_to_entry_by_seqnum(f, j->current_location.seqnum, direction, ret, offset);
+                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, ret, offset);
+                        if (r != -ENOENT)
+                                return r;
+                }
+                if (j->current_location.realtime_set)
+                        return journal_file_move_to_entry_by_realtime(f, j->current_location.realtime, direction, ret, offset);
+
+                return journal_file_next_entry(f, NULL, 0, direction, ret, offset);
+        } else
+                return find_location_for_match(j, j->level0, f, direction, ret, offset);
+}
+
+static int next_with_matches(
+                sd_journal *j,
+                JournalFile *f,
+                direction_t direction,
+                Object **ret,
+                uint64_t *offset) {
+
+        Object *c;
+        uint64_t cp;
+
+        assert(j);
+        assert(f);
+        assert(ret);
+        assert(offset);
+
+        c = *ret;
+        cp = *offset;
+
+        /* No matches is easy. We simple advance the file
+         * pointer by one. */
+        if (!j->level0)
+                return journal_file_next_entry(f, c, cp, direction, ret, offset);
+
+        /* If we have a match then we look for the next matching entry
+         * with an offset at least one step larger */
+        return next_for_match(j, j->level0, f, direction == DIRECTION_DOWN ? cp+1 : cp-1, direction, ret, offset);
+}
+
+static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direction, Object **ret, uint64_t *offset) {
+        Object *c;
+        uint64_t cp;
+        int r;
+
+        assert(j);
+        assert(f);
+
+        if (f->current_offset > 0) {
+                cp = f->current_offset;
+
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, cp, &c);
+                if (r < 0)
+                        return r;
+
+                r = next_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+        } else {
+                r = find_location_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+        }
+
+        /* OK, we found the spot, now let's advance until to an entry
+         * that is actually different from what we were previously
+         * looking at. This is necessary to handle entries which exist
+         * in two (or more) journal files, and which shall all be
+         * suppressed but one. */
+
+        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 > 0;
+                        else
+                                found = k < 0;
+                } 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_file = NULL;
+        uint64_t new_offset = 0;
+        Object *o;
+        uint64_t p;
+        Iterator i;
+        int r;
+
+        if (!j)
+                return -EINVAL;
+
+        HASHMAP_FOREACH(f, j->files, i) {
+                bool found;
+
+                r = next_beyond_location(j, f, direction, &o, &p);
+                if (r < 0) {
+                        log_debug("Can't iterate through %s, ignoring: %s", f->path, strerror(-r));
+                        continue;
+                } else if (r == 0)
+                        continue;
+
+                if (!new_file)
+                        found = true;
+                else {
+                        int k;
+
+                        k = compare_entry_order(f, o, new_file, new_offset);
+
+                        if (direction == DIRECTION_DOWN)
+                                found = k < 0;
+                        else
+                                found = k > 0;
+                }
+
+                if (found) {
+                        new_file = f;
+                        new_offset = p;
+                }
+        }
+
+        if (!new_file)
+                return 0;
+
+        r = journal_file_move_to_object(new_file, OBJECT_ENTRY, new_offset, &o);
+        if (r < 0)
+                return r;
+
+        set_location(j, LOCATION_DISCRETE, new_file, o, new_offset);
+
+        return 1;
+}
+
+_public_ int sd_journal_next(sd_journal *j) {
+        return real_journal_next(j, DIRECTION_DOWN);
+}
+
+_public_ int sd_journal_previous(sd_journal *j) {
+        return real_journal_next(j, DIRECTION_UP);
+}
+
+static int real_journal_next_skip(sd_journal *j, direction_t direction, uint64_t skip) {
+        int c = 0, r;
+
+        if (!j)
+                return -EINVAL;
+
+        if (skip == 0) {
+                /* If this is not a discrete skip, then at least
+                 * resolve the current location */
+                if (j->current_location.type != LOCATION_DISCRETE)
+                        return real_journal_next(j, direction);
+
+                return 0;
+        }
+
+        do {
+                r = real_journal_next(j, direction);
+                if (r < 0)
+                        return r;
+
+                if (r == 0)
+                        return c;
+
+                skip--;
+                c++;
+        } while (skip > 0);
+
+        return c;
+}
+
+_public_ int sd_journal_next_skip(sd_journal *j, uint64_t skip) {
+        return real_journal_next_skip(j, DIRECTION_DOWN, skip);
+}
 
-int sd_journal_get_cursor(sd_journal *j, char **cursor) {
+_public_ int sd_journal_previous_skip(sd_journal *j, uint64_t skip) {
+        return real_journal_next_skip(j, DIRECTION_UP, skip);
+}
+
+_public_ int sd_journal_get_cursor(sd_journal *j, char **cursor) {
         Object *o;
         int r;
         char bid[33], sid[33];
 
-        assert(j);
-        assert(cursor);
+        if (!j)
+                return -EINVAL;
+        if (!cursor)
+                return -EINVAL;
 
         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;
 
@@ -405,23 +949,271 @@ int sd_journal_get_cursor(sd_journal *j, char **cursor) {
         sd_id128_to_string(o->entry.boot_id, bid);
 
         if (asprintf(cursor,
-                     "s=%s;i=%llx;b=%s;m=%llx;t=%llx;x=%llx;p=%s",
+                     "s=%s;i=%llx;b=%s;m=%llx;t=%llx;x=%llx",
                      sid, (unsigned long long) le64toh(o->entry.seqnum),
                      bid, (unsigned long long) le64toh(o->entry.monotonic),
                      (unsigned long long) le64toh(o->entry.realtime),
-                     (unsigned long long) le64toh(o->entry.xor_hash),
-                     file_name_from_path(j->current_file->path)) < 0)
+                     (unsigned long long) le64toh(o->entry.xor_hash)) < 0)
                 return -ENOMEM;
 
         return 1;
 }
 
-int sd_journal_set_cursor(sd_journal *j, const char *cursor) {
-        return -EINVAL;
+_public_ int sd_journal_seek_cursor(sd_journal *j, const char *cursor) {
+        char *w, *state;
+        size_t l;
+        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;
+
+        if (!j)
+                return -EINVAL;
+        if (isempty(cursor))
+                return -EINVAL;
+
+        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(item+2, &seqnum_id);
+                        break;
+
+                case 'i':
+                        seqnum_set = true;
+                        if (sscanf(item+2, "%llx", &seqnum) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 'b':
+                        boot_id_set = true;
+                        k = sd_id128_from_string(item+2, &boot_id);
+                        break;
+
+                case 'm':
+                        monotonic_set = true;
+                        if (sscanf(item+2, "%llx", &monotonic) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 't':
+                        realtime_set = true;
+                        if (sscanf(item+2, "%llx", &realtime) != 1)
+                                k = -EINVAL;
+                        break;
+
+                case 'x':
+                        xor_hash_set = true;
+                        if (sscanf(item+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_SEEK;
+
+        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;
+}
+
+_public_ int sd_journal_test_cursor(sd_journal *j, const char *cursor) {
+        int r;
+        char *w, *state;
+        size_t l;
+        Object *o;
+
+        if (!j)
+                return -EINVAL;
+        if (isempty(cursor))
+                return -EINVAL;
+
+        if (!j->current_file || j->current_file->current_offset <= 0)
+                return -EADDRNOTAVAIL;
+
+        r = journal_file_move_to_object(j->current_file, OBJECT_ENTRY, j->current_file->current_offset, &o);
+        if (r < 0)
+                return r;
+
+        FOREACH_WORD_SEPARATOR(w, l, cursor, ";", state) {
+                _cleanup_free_ char *item = NULL;
+                sd_id128_t id;
+                unsigned long long ll;
+                int k = 0;
+
+                if (l < 2 || w[1] != '=')
+                        return -EINVAL;
+
+                item = strndup(w, l);
+                if (!item)
+                        return -ENOMEM;
+
+                switch (w[0]) {
+
+                case 's':
+                        k = sd_id128_from_string(item+2, &id);
+                        if (k < 0)
+                                return k;
+                        if (!sd_id128_equal(id, j->current_file->header->seqnum_id))
+                                return 0;
+                        break;
+
+                case 'i':
+                        if (sscanf(item+2, "%llx", &ll) != 1)
+                                return -EINVAL;
+                        if (ll != le64toh(o->entry.seqnum))
+                                return 0;
+                        break;
+
+                case 'b':
+                        k = sd_id128_from_string(item+2, &id);
+                        if (k < 0)
+                                return k;
+                        if (!sd_id128_equal(id, o->entry.boot_id))
+                                return 0;
+                        break;
+
+                case 'm':
+                        if (sscanf(item+2, "%llx", &ll) != 1)
+                                return -EINVAL;
+                        if (ll != le64toh(o->entry.monotonic))
+                                return 0;
+                        break;
+
+                case 't':
+                        if (sscanf(item+2, "%llx", &ll) != 1)
+                                return -EINVAL;
+                        if (ll != le64toh(o->entry.realtime))
+                                return 0;
+                        break;
+
+                case 'x':
+                        if (sscanf(item+2, "%llx", &ll) != 1)
+                                return -EINVAL;
+                        if (ll != le64toh(o->entry.xor_hash))
+                                return 0;
+                        break;
+                }
+        }
+
+        return 1;
+}
+
+
+_public_ int sd_journal_seek_monotonic_usec(sd_journal *j, sd_id128_t boot_id, uint64_t usec) {
+        if (!j)
+                return -EINVAL;
+
+        reset_location(j);
+        j->current_location.type = LOCATION_SEEK;
+        j->current_location.boot_id = boot_id;
+        j->current_location.monotonic = usec;
+        j->current_location.monotonic_set = true;
+
+        return 0;
+}
+
+_public_ int sd_journal_seek_realtime_usec(sd_journal *j, uint64_t usec) {
+        if (!j)
+                return -EINVAL;
+
+        reset_location(j);
+        j->current_location.type = LOCATION_SEEK;
+        j->current_location.realtime = usec;
+        j->current_location.realtime_set = true;
+
+        return 0;
+}
+
+_public_ int sd_journal_seek_head(sd_journal *j) {
+        if (!j)
+                return -EINVAL;
+
+        reset_location(j);
+        j->current_location.type = LOCATION_HEAD;
+
+        return 0;
+}
+
+_public_ int sd_journal_seek_tail(sd_journal *j) {
+        if (!j)
+                return -EINVAL;
+
+        reset_location(j);
+        j->current_location.type = LOCATION_TAIL;
+
+        return 0;
+}
+
+static void check_network(sd_journal *j, int fd) {
+        struct statfs sfs;
+
+        assert(j);
+
+        if (j->on_network)
+                return;
+
+        if (fstatfs(fd, &sfs) < 0)
+                return;
+
+        j->on_network =
+                sfs.f_type == CIFS_MAGIC_NUMBER ||
+                sfs.f_type == CODA_SUPER_MAGIC ||
+                sfs.f_type == NCP_SUPER_MAGIC ||
+                sfs.f_type == NFS_SUPER_MAGIC ||
+                sfs.f_type == SMB_SUPER_MAGIC;
 }
 
-static int add_file(sd_journal *j, const char *prefix, const char *dir, const char *filename) {
-        char *fn;
+static int add_file(sd_journal *j, const char *prefix, const char *filename) {
+        char *path;
         int r;
         JournalFile *f;
 
@@ -429,338 +1221,1231 @@ static int add_file(sd_journal *j, const char *prefix, const char *dir, const ch
         assert(prefix);
         assert(filename);
 
-        if (dir)
-                fn = join(prefix, "/", dir, "/", filename, NULL);
-        else
-                fn = join(prefix, "/", filename, NULL);
+        if ((j->flags & SD_JOURNAL_SYSTEM_ONLY) &&
+            !(streq(filename, "system.journal") ||
+              streq(filename, "system.journal~") ||
+              (startswith(filename, "system@") &&
+               (endswith(filename, ".journal") || endswith(filename, ".journal~")))))
+                return 0;
+
+        path = strjoin(prefix, "/", filename, NULL);
+        if (!path)
+                return -ENOMEM;
+
+        if (hashmap_get(j->files, path)) {
+                free(path);
+                return 0;
+        }
+
+        if (hashmap_size(j->files) >= JOURNAL_FILES_MAX) {
+                log_debug("Too many open journal files, not adding %s, ignoring.", path);
+                free(path);
+                return 0;
+        }
+
+        r = journal_file_open(path, O_RDONLY, 0, false, false, NULL, j->mmap, NULL, &f);
+        free(path);
+
+        if (r < 0) {
+                if (errno == ENOENT)
+                        return 0;
+
+                return r;
+        }
+
+        /* journal_file_dump(f); */
+
+        r = hashmap_put(j->files, f->path, f);
+        if (r < 0) {
+                journal_file_close(f);
+                return r;
+        }
+
+        check_network(j, f->fd);
+
+        j->current_invalidate_counter ++;
+
+        log_debug("File %s got added.", f->path);
+
+        return 0;
+}
+
+static int remove_file(sd_journal *j, const char *prefix, const char *filename) {
+        char *path;
+        JournalFile *f;
+
+        assert(j);
+        assert(prefix);
+        assert(filename);
+
+        path = strjoin(prefix, "/", filename, NULL);
+        if (!path)
+                return -ENOMEM;
+
+        f = hashmap_get(j->files, path);
+        free(path);
+        if (!f)
+                return 0;
+
+        hashmap_remove(j->files, f->path);
+
+        log_debug("File %s got removed.", f->path);
+
+        if (j->current_file == f) {
+                j->current_file = NULL;
+                j->current_field = 0;
+        }
+
+        if (j->unique_file == f) {
+                j->unique_file = NULL;
+                j->unique_offset = 0;
+        }
+
+        journal_file_close(f);
+
+        j->current_invalidate_counter ++;
+
+        return 0;
+}
+
+static int add_directory(sd_journal *j, const char *prefix, const char *dirname) {
+        char *path;
+        int r;
+        DIR *d;
+        sd_id128_t id, mid;
+        Directory *m;
+
+        assert(j);
+        assert(prefix);
+        assert(dirname);
+
+        if ((j->flags & SD_JOURNAL_LOCAL_ONLY) &&
+            (sd_id128_from_string(dirname, &id) < 0 ||
+             sd_id128_get_machine(&mid) < 0 ||
+             !sd_id128_equal(id, mid)))
+            return 0;
+
+        path = strjoin(prefix, "/", dirname, NULL);
+        if (!path)
+                return -ENOMEM;
+
+        d = opendir(path);
+        if (!d) {
+                log_debug("Failed to open %s: %m", path);
+                free(path);
+
+                if (errno == ENOENT)
+                        return 0;
+                return -errno;
+        }
+
+        m = hashmap_get(j->directories_by_path, path);
+        if (!m) {
+                m = new0(Directory, 1);
+                if (!m) {
+                        closedir(d);
+                        free(path);
+                        return -ENOMEM;
+                }
+
+                m->is_root = false;
+                m->path = path;
+
+                if (hashmap_put(j->directories_by_path, m->path, m) < 0) {
+                        closedir(d);
+                        free(m->path);
+                        free(m);
+                        return -ENOMEM;
+                }
+
+                j->current_invalidate_counter ++;
+
+                log_debug("Directory %s got added.", m->path);
+
+        } else if (m->is_root) {
+                free (path);
+                closedir(d);
+                return 0;
+        }  else
+                free(path);
+
+        if (m->wd <= 0 && j->inotify_fd >= 0) {
+
+                m->wd = inotify_add_watch(j->inotify_fd, m->path,
+                                          IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
+                                          IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT|IN_MOVED_FROM|
+                                          IN_ONLYDIR);
+
+                if (m->wd > 0 && hashmap_put(j->directories_by_wd, INT_TO_PTR(m->wd), m) < 0)
+                        inotify_rm_watch(j->inotify_fd, m->wd);
+        }
+
+        for (;;) {
+                struct dirent *de;
+                union dirent_storage buf;
+
+                r = readdir_r(d, &buf.de, &de);
+                if (r != 0 || !de)
+                        break;
+
+                if (dirent_is_file_with_suffix(de, ".journal") ||
+                    dirent_is_file_with_suffix(de, ".journal~")) {
+                        r = add_file(j, m->path, de->d_name);
+                        if (r < 0)
+                                log_debug("Failed to add file %s/%s: %s", m->path, de->d_name, strerror(-r));
+                }
+        }
+
+        check_network(j, dirfd(d));
+
+        closedir(d);
+
+        return 0;
+}
+
+static int add_root_directory(sd_journal *j, const char *p) {
+        DIR *d;
+        Directory *m;
+        int r;
+
+        assert(j);
+        assert(p);
+
+        if ((j->flags & SD_JOURNAL_RUNTIME_ONLY) &&
+            !path_startswith(p, "/run"))
+                return -EINVAL;
+
+        d = opendir(p);
+        if (!d)
+                return -errno;
+
+        m = hashmap_get(j->directories_by_path, p);
+        if (!m) {
+                m = new0(Directory, 1);
+                if (!m) {
+                        closedir(d);
+                        return -ENOMEM;
+                }
+
+                m->is_root = true;
+                m->path = strdup(p);
+                if (!m->path) {
+                        closedir(d);
+                        free(m);
+                        return -ENOMEM;
+                }
+
+                if (hashmap_put(j->directories_by_path, m->path, m) < 0) {
+                        closedir(d);
+                        free(m->path);
+                        free(m);
+                        return -ENOMEM;
+                }
+
+                j->current_invalidate_counter ++;
+
+                log_debug("Root directory %s got added.", m->path);
+
+        } else if (!m->is_root) {
+                closedir(d);
+                return 0;
+        }
+
+        if (m->wd <= 0 && j->inotify_fd >= 0) {
+
+                m->wd = inotify_add_watch(j->inotify_fd, m->path,
+                                          IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
+                                          IN_ONLYDIR);
+
+                if (m->wd > 0 && hashmap_put(j->directories_by_wd, INT_TO_PTR(m->wd), m) < 0)
+                        inotify_rm_watch(j->inotify_fd, m->wd);
+        }
+
+        for (;;) {
+                struct dirent *de;
+                union dirent_storage buf;
+                sd_id128_t id;
+
+                r = readdir_r(d, &buf.de, &de);
+                if (r != 0 || !de)
+                        break;
+
+                if (dirent_is_file_with_suffix(de, ".journal") ||
+                    dirent_is_file_with_suffix(de, ".journal~")) {
+                        r = add_file(j, m->path, de->d_name);
+                        if (r < 0)
+                                log_debug("Failed to add file %s/%s: %s", m->path, de->d_name, strerror(-r));
+
+                } else if ((de->d_type == DT_DIR || de->d_type == DT_LNK || de->d_type == DT_UNKNOWN) &&
+                           sd_id128_from_string(de->d_name, &id) >= 0) {
+
+                        r = add_directory(j, m->path, de->d_name);
+                        if (r < 0)
+                                log_debug("Failed to add directory %s/%s: %s", m->path, de->d_name, strerror(-r));
+                }
+        }
+
+        check_network(j, dirfd(d));
+
+        closedir(d);
+
+        return 0;
+}
+
+static int remove_directory(sd_journal *j, Directory *d) {
+        assert(j);
+
+        if (d->wd > 0) {
+                hashmap_remove(j->directories_by_wd, INT_TO_PTR(d->wd));
+
+                if (j->inotify_fd >= 0)
+                        inotify_rm_watch(j->inotify_fd, d->wd);
+        }
+
+        hashmap_remove(j->directories_by_path, d->path);
+
+        if (d->is_root)
+                log_debug("Root directory %s got removed.", d->path);
+        else
+                log_debug("Directory %s got removed.", d->path);
+
+        free(d->path);
+        free(d);
+
+        return 0;
+}
+
+static int add_search_paths(sd_journal *j) {
+
+        const char search_paths[] =
+                "/run/log/journal\0"
+                "/var/log/journal\0";
+        const char *p;
+
+        assert(j);
+
+        /* We ignore most errors here, since the idea is to only open
+         * what's actually accessible, and ignore the rest. */
+
+        NULSTR_FOREACH(p, search_paths)
+                add_root_directory(j, p);
+
+        return 0;
+}
+
+static int allocate_inotify(sd_journal *j) {
+        assert(j);
+
+        if (j->inotify_fd < 0) {
+                j->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
+                if (j->inotify_fd < 0)
+                        return -errno;
+        }
+
+        if (!j->directories_by_wd) {
+                j->directories_by_wd = hashmap_new(trivial_hash_func, trivial_compare_func);
+                if (!j->directories_by_wd)
+                        return -ENOMEM;
+        }
+
+        return 0;
+}
+
+static sd_journal *journal_new(int flags, const char *path) {
+        sd_journal *j;
+
+        j = new0(sd_journal, 1);
+        if (!j)
+                return NULL;
+
+        j->inotify_fd = -1;
+        j->flags = flags;
+
+        if (path) {
+                j->path = strdup(path);
+                if (!j->path) {
+                        free(j);
+                        return NULL;
+                }
+        }
+
+        j->files = hashmap_new(string_hash_func, string_compare_func);
+        if (!j->files) {
+                free(j->path);
+                free(j);
+                return NULL;
+        }
+
+        j->directories_by_path = hashmap_new(string_hash_func, string_compare_func);
+        if (!j->directories_by_path) {
+                hashmap_free(j->files);
+                free(j->path);
+                free(j);
+                return NULL;
+        }
+
+        j->mmap = mmap_cache_new();
+        if (!j->mmap) {
+                hashmap_free(j->files);
+                hashmap_free(j->directories_by_path);
+                free(j->path);
+                free(j);
+                return NULL;
+        }
+
+        return j;
+}
+
+_public_ int sd_journal_open(sd_journal **ret, int flags) {
+        sd_journal *j;
+        int r;
+
+        if (!ret)
+                return -EINVAL;
+
+        if (flags & ~(SD_JOURNAL_LOCAL_ONLY|
+                      SD_JOURNAL_RUNTIME_ONLY|
+                      SD_JOURNAL_SYSTEM_ONLY))
+                return -EINVAL;
+
+        j = journal_new(flags, NULL);
+        if (!j)
+                return -ENOMEM;
+
+        r = add_search_paths(j);
+        if (r < 0)
+                goto fail;
+
+        *ret = j;
+        return 0;
+
+fail:
+        sd_journal_close(j);
+
+        return r;
+}
+
+_public_ int sd_journal_open_directory(sd_journal **ret, const char *path, int flags) {
+        sd_journal *j;
+        int r;
+
+        if (!ret)
+                return -EINVAL;
+
+        if (!path || !path_is_absolute(path))
+                return -EINVAL;
+
+        if (flags != 0)
+                return -EINVAL;
+
+        j = journal_new(flags, path);
+        if (!j)
+                return -ENOMEM;
+
+        r = add_root_directory(j, path);
+        if (r < 0)
+                goto fail;
+
+        *ret = j;
+        return 0;
+
+fail:
+        sd_journal_close(j);
+
+        return r;
+}
+
+_public_ void sd_journal_close(sd_journal *j) {
+        Directory *d;
+        JournalFile *f;
+
+        if (!j)
+                return;
+
+        while ((f = hashmap_steal_first(j->files)))
+                journal_file_close(f);
+
+        hashmap_free(j->files);
+
+        while ((d = hashmap_first(j->directories_by_path)))
+                remove_directory(j, d);
+
+        while ((d = hashmap_first(j->directories_by_wd)))
+                remove_directory(j, d);
+
+        hashmap_free(j->directories_by_path);
+        hashmap_free(j->directories_by_wd);
+
+        if (j->inotify_fd >= 0)
+                close_nointr_nofail(j->inotify_fd);
+
+        sd_journal_flush_matches(j);
+
+        if (j->mmap)
+                mmap_cache_unref(j->mmap);
+
+        free(j->path);
+        free(j->unique_field);
+        free(j);
+}
+
+_public_ int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
+        Object *o;
+        JournalFile *f;
+        int r;
+
+        if (!j)
+                return -EINVAL;
+        if (!ret)
+                return -EINVAL;
+
+        f = j->current_file;
+        if (!f)
+                return -EADDRNOTAVAIL;
+
+        if (f->current_offset <= 0)
+                return -EADDRNOTAVAIL;
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
+        if (r < 0)
+                return r;
+
+        *ret = le64toh(o->entry.realtime);
+        return 0;
+}
+
+_public_ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id128_t *ret_boot_id) {
+        Object *o;
+        JournalFile *f;
+        int r;
+        sd_id128_t id;
+
+        if (!j)
+                return -EINVAL;
+
+        f = j->current_file;
+        if (!f)
+                return -EADDRNOTAVAIL;
+
+        if (f->current_offset <= 0)
+                return -EADDRNOTAVAIL;
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &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 -ESTALE;
+        }
+
+        if (ret)
+                *ret = le64toh(o->entry.monotonic);
+
+        return 0;
+}
+
+static bool field_is_valid(const char *field) {
+        const char *p;
+
+        assert(field);
+
+        if (isempty(field))
+                return false;
+
+        if (startswith(field, "__"))
+                return false;
+
+        for (p = field; *p; p++) {
+
+                if (*p == '_')
+                        continue;
+
+                if (*p >= 'A' && *p <= 'Z')
+                        continue;
+
+                if (*p >= '0' && *p <= '9')
+                        continue;
+
+                return false;
+        }
+
+        return true;
+}
+
+_public_ int sd_journal_get_data(sd_journal *j, const char *field, const void **data, size_t *size) {
+        JournalFile *f;
+        uint64_t i, n;
+        size_t field_length;
+        int r;
+        Object *o;
+
+        if (!j)
+                return -EINVAL;
+        if (!field)
+                return -EINVAL;
+        if (!data)
+                return -EINVAL;
+        if (!size)
+                return -EINVAL;
+
+        if (!field_is_valid(field))
+                return -EINVAL;
+
+        f = j->current_file;
+        if (!f)
+                return -EADDRNOTAVAIL;
+
+        if (f->current_offset <= 0)
+                return -EADDRNOTAVAIL;
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
+        if (r < 0)
+                return r;
+
+        field_length = strlen(field);
+
+        n = journal_file_entry_n_items(o);
+        for (i = 0; i < n; i++) {
+                uint64_t p, l;
+                le64_t le_hash;
+                size_t t;
+
+                p = le64toh(o->entry.items[i].object_offset);
+                le_hash = o->entry.items[i].hash;
+                r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+                if (r < 0)
+                        return r;
+
+                if (le_hash != o->data.hash)
+                        return -EBADMSG;
+
+                l = le64toh(o->object.size) - offsetof(Object, data.payload);
+
+                if (o->object.flags & OBJECT_COMPRESSED) {
+
+#ifdef HAVE_XZ
+                        if (uncompress_startswith(o->data.payload, l,
+                                                  &f->compress_buffer, &f->compress_buffer_size,
+                                                  field, field_length, '=')) {
+
+                                uint64_t rsize;
+
+                                if (!uncompress_blob(o->data.payload, l,
+                                                     &f->compress_buffer, &f->compress_buffer_size, &rsize))
+                                        return -EBADMSG;
+
+                                *data = f->compress_buffer;
+                                *size = (size_t) rsize;
+
+                                return 0;
+                        }
+#else
+                        return -EPROTONOSUPPORT;
+#endif
+
+                } else if (l >= field_length+1 &&
+                           memcmp(o->data.payload, field, field_length) == 0 &&
+                           o->data.payload[field_length] == '=') {
+
+                        t = (size_t) l;
+
+                        if ((uint64_t) t != l)
+                                return -E2BIG;
+
+                        *data = o->data.payload;
+                        *size = t;
+
+                        return 0;
+                }
+
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
+                if (r < 0)
+                        return r;
+        }
+
+        return -ENOENT;
+}
+
+static int return_data(JournalFile *f, Object *o, const void **data, size_t *size) {
+        size_t t;
+        uint64_t l;
+
+        l = le64toh(o->object.size) - offsetof(Object, data.payload);
+        t = (size_t) l;
+
+        /* We can't read objects larger than 4G on a 32bit machine */
+        if ((uint64_t) t != l)
+                return -E2BIG;
+
+        if (o->object.flags & OBJECT_COMPRESSED) {
+#ifdef HAVE_XZ
+                uint64_t rsize;
+
+                if (!uncompress_blob(o->data.payload, l, &f->compress_buffer, &f->compress_buffer_size, &rsize))
+                        return -EBADMSG;
+
+                *data = f->compress_buffer;
+                *size = (size_t) rsize;
+#else
+                return -EPROTONOSUPPORT;
+#endif
+        } else {
+                *data = o->data.payload;
+                *size = t;
+        }
+
+        return 0;
+}
+
+_public_ int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *size) {
+        JournalFile *f;
+        uint64_t p, n;
+        le64_t le_hash;
+        int r;
+        Object *o;
+
+        if (!j)
+                return -EINVAL;
+        if (!data)
+                return -EINVAL;
+        if (!size)
+                return -EINVAL;
+
+        f = j->current_file;
+        if (!f)
+                return -EADDRNOTAVAIL;
+
+        if (f->current_offset <= 0)
+                return -EADDRNOTAVAIL;
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, f->current_offset, &o);
+        if (r < 0)
+                return r;
+
+        n = journal_file_entry_n_items(o);
+        if (j->current_field >= n)
+                return 0;
+
+        p = le64toh(o->entry.items[j->current_field].object_offset);
+        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 (le_hash != o->data.hash)
+                return -EBADMSG;
+
+        r = return_data(f, o, data, size);
+        if (r < 0)
+                return r;
+
+        j->current_field ++;
+
+        return 1;
+}
+
+_public_ void sd_journal_restart_data(sd_journal *j) {
+        if (!j)
+                return;
+
+        j->current_field = 0;
+}
+
+_public_ int sd_journal_get_fd(sd_journal *j) {
+        int r;
+
+        if (!j)
+                return -EINVAL;
+
+        if (j->inotify_fd >= 0)
+                return j->inotify_fd;
+
+        r = allocate_inotify(j);
+        if (r < 0)
+                return r;
+
+        /* Iterate through all dirs again, to add them to the
+         * inotify */
+        if (j->path)
+                r = add_root_directory(j, j->path);
+        else
+                r = add_search_paths(j);
+        if (r < 0)
+                return r;
+
+        return j->inotify_fd;
+}
+
+static void process_inotify_event(sd_journal *j, struct inotify_event *e) {
+        Directory *d;
+        int r;
+
+        assert(j);
+        assert(e);
+
+        /* Is this a subdirectory we watch? */
+        d = hashmap_get(j->directories_by_wd, INT_TO_PTR(e->wd));
+        if (d) {
+                sd_id128_t id;
+
+                if (!(e->mask & IN_ISDIR) && e->len > 0 &&
+                    (endswith(e->name, ".journal") ||
+                     endswith(e->name, ".journal~"))) {
+
+                        /* Event for a journal file */
+
+                        if (e->mask & (IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB)) {
+                                r = add_file(j, d->path, e->name);
+                                if (r < 0)
+                                        log_debug("Failed to add file %s/%s: %s", d->path, e->name, strerror(-r));
+
+                        } else if (e->mask & (IN_DELETE|IN_MOVED_FROM|IN_UNMOUNT)) {
+
+                                r = remove_file(j, d->path, e->name);
+                                if (r < 0)
+                                        log_debug("Failed to remove file %s/%s: %s", d->path, e->name, strerror(-r));
+                        }
+
+                } else if (!d->is_root && e->len == 0) {
+
+                        /* Event for a subdirectory */
+
+                        if (e->mask & (IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT)) {
+                                r = remove_directory(j, d);
+                                if (r < 0)
+                                        log_debug("Failed to remove directory %s: %s", d->path, strerror(-r));
+                        }
+
+
+                } else if (d->is_root && (e->mask & IN_ISDIR) && e->len > 0 && sd_id128_from_string(e->name, &id) >= 0) {
+
+                        /* Event for root directory */
+
+                        if (e->mask & (IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB)) {
+                                r = add_directory(j, d->path, e->name);
+                                if (r < 0)
+                                        log_debug("Failed to add directory %s/%s: %s", d->path, e->name, strerror(-r));
+                        }
+                }
+
+                return;
+        }
+
+        if (e->mask & IN_IGNORED)
+                return;
+
+        log_warning("Unknown inotify event.");
+}
+
+static int determine_change(sd_journal *j) {
+        bool b;
+
+        assert(j);
+
+        b = j->current_invalidate_counter != j->last_invalidate_counter;
+        j->last_invalidate_counter = j->current_invalidate_counter;
+
+        return b ? SD_JOURNAL_INVALIDATE : SD_JOURNAL_APPEND;
+}
+
+_public_ int sd_journal_process(sd_journal *j) {
+        uint8_t buffer[sizeof(struct inotify_event) + FILENAME_MAX] _alignas_(struct inotify_event);
+        bool got_something = false;
+
+        if (!j)
+                return -EINVAL;
+
+        for (;;) {
+                struct inotify_event *e;
+                ssize_t l;
+
+                l = read(j->inotify_fd, buffer, sizeof(buffer));
+                if (l < 0) {
+                        if (errno == EAGAIN || errno == EINTR)
+                                return got_something ? determine_change(j) : SD_JOURNAL_NOP;
 
-        if (!fn)
-                return -ENOMEM;
+                        return -errno;
+                }
 
-        r = journal_file_open(fn, O_RDONLY, 0, NULL, &f);
-        free(fn);
+                got_something = true;
 
-        if (r < 0) {
-                if (errno == ENOENT)
-                        return 0;
+                e = (struct inotify_event*) buffer;
+                while (l > 0) {
+                        size_t step;
 
-                return r;
-        }
+                        process_inotify_event(j, e);
 
-        r = hashmap_put(j->files, f->path, f);
-        if (r < 0) {
-                journal_file_close(f);
-                return r;
+                        step = sizeof(struct inotify_event) + e->len;
+                        assert(step <= (size_t) l);
+
+                        e = (struct inotify_event*) ((uint8_t*) e + step);
+                        l -= step;
+                }
         }
 
-        return 0;
+        return determine_change(j);
 }
 
-static int add_directory(sd_journal *j, const char *prefix, const char *dir) {
-        char *fn;
+_public_ int sd_journal_wait(sd_journal *j, uint64_t timeout_usec) {
         int r;
-        DIR *d;
 
         assert(j);
-        assert(prefix);
-        assert(dir);
-
-        fn = join(prefix, "/", dir, NULL);
-        if (!fn)
-                return -ENOMEM;
 
-        d = opendir(fn);
-        free(fn);
+        if (j->inotify_fd < 0) {
 
-        if (!d) {
-                if (errno == ENOENT)
-                        return 0;
+                /* This is the first invocation, hence create the
+                 * inotify watch */
+                r = sd_journal_get_fd(j);
+                if (r < 0)
+                        return r;
 
-                return -errno;
+                /* The journal might have changed since the context
+                 * object was created and we weren't watching before,
+                 * hence don't wait for anything, and return
+                 * immediately. */
+                return determine_change(j);
         }
 
-        for (;;) {
-                struct dirent buf, *de;
-
-                r = readdir_r(d, &buf, &de);
-                if (r != 0 || !de)
-                        break;
-
-                if (!dirent_is_file_with_suffix(de, ".journal"))
-                        continue;
+        if (j->on_network) {
+                /* If we are on the network we need to regularly check
+                 * for changes manually */
 
-                r = add_file(j, prefix, dir, de->d_name);
-                if (r < 0)
-                        log_debug("Failed to add file %s/%s/%s: %s", prefix, dir, de->d_name, strerror(-r));
+                if (timeout_usec == (uint64_t) -1 || timeout_usec > JOURNAL_FILES_RECHECK_USEC)
+                        timeout_usec = JOURNAL_FILES_RECHECK_USEC;
         }
 
-        closedir(d);
+        do {
+                r = fd_wait_for_event(j->inotify_fd, POLLIN, timeout_usec);
+        } while (r == -EINTR);
 
-        return 0;
+        if (r < 0)
+                return r;
+
+        return sd_journal_process(j);
 }
 
-int sd_journal_open(sd_journal **ret) {
-        sd_journal *j;
-        const char *p;
-        const char search_paths[] =
-                "/run/log/journal\0"
-                "/var/log/journal\0";
+_public_ int sd_journal_get_cutoff_realtime_usec(sd_journal *j, uint64_t *from, uint64_t *to) {
+        Iterator i;
+        JournalFile *f;
+        bool first = true;
         int r;
 
-        assert(ret);
-
-        j = new0(sd_journal, 1);
         if (!j)
-                return -ENOMEM;
-
-        j->files = hashmap_new(string_hash_func, string_compare_func);
-        if (!j->files) {
-                r = -ENOMEM;
-                goto fail;
-        }
-
-        /* We ignore most errors here, since the idea is to only open
-         * what's actually accessible, and ignore the rest. */
+                return -EINVAL;
+        if (!from && !to)
+                return -EINVAL;
 
-        NULSTR_FOREACH(p, search_paths) {
-                DIR *d;
+        HASHMAP_FOREACH(f, j->files, i) {
+                usec_t fr, t;
 
-                d = opendir(p);
-                if (!d) {
-                        if (errno != ENOENT)
-                                log_debug("Failed to open %s: %m", p);
+                r = journal_file_get_cutoff_realtime_usec(f, &fr, &t);
+                if (r == -ENOENT)
                         continue;
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
+
+                if (first) {
+                        if (from)
+                                *from = fr;
+                        if (to)
+                                *to = t;
+                        first = false;
+                } else {
+                        if (from)
+                                *from = MIN(fr, *from);
+                        if (to)
+                                *to = MAX(t, *to);
                 }
+        }
 
-                for (;;) {
-                        struct dirent buf, *de;
-                        sd_id128_t id;
+        return first ? 0 : 1;
+}
 
-                        r = readdir_r(d, &buf, &de);
-                        if (r != 0 || !de)
-                                break;
+_public_ int sd_journal_get_cutoff_monotonic_usec(sd_journal *j, sd_id128_t boot_id, uint64_t *from, uint64_t *to) {
+        Iterator i;
+        JournalFile *f;
+        bool first = true;
+        int r;
 
-                        if (dirent_is_file_with_suffix(de, ".journal")) {
-                                r = add_file(j, p, NULL, de->d_name);
-                                if (r < 0)
-                                        log_debug("Failed to add file %s/%s: %s", p, de->d_name, strerror(-r));
+        if (!j)
+                return -EINVAL;
+        if (!from && !to)
+                return -EINVAL;
 
-                        } else if ((de->d_type == DT_DIR || de->d_type == DT_UNKNOWN) &&
-                                   sd_id128_from_string(de->d_name, &id) >= 0) {
+        HASHMAP_FOREACH(f, j->files, i) {
+                usec_t fr, t;
 
-                                r = add_directory(j, p, de->d_name);
-                                if (r < 0)
-                                        log_debug("Failed to add directory %s/%s: %s", p, de->d_name, strerror(-r));
-                        }
-                }
+                r = journal_file_get_cutoff_monotonic_usec(f, boot_id, &fr, &t);
+                if (r == -ENOENT)
+                        continue;
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
 
-                closedir(d);
+                if (first) {
+                        if (from)
+                                *from = fr;
+                        if (to)
+                                *to = t;
+                        first = false;
+                } else {
+                        if (from)
+                                *from = MIN(fr, *from);
+                        if (to)
+                                *to = MAX(t, *to);
+                }
         }
 
-        *ret = j;
-        return 0;
-
-fail:
-        sd_journal_close(j);
+        return first ? 0 : 1;
+}
 
-        return r;
-};
+void journal_print_header(sd_journal *j) {
+        Iterator i;
+        JournalFile *f;
+        bool newline = false;
 
-void sd_journal_close(sd_journal *j) {
         assert(j);
 
-        if (j->files) {
-                JournalFile *f;
-
-                while ((f = hashmap_steal_first(j->files)))
-                        journal_file_close(f);
+        HASHMAP_FOREACH(f, j->files, i) {
+                if (newline)
+                        putchar('\n');
+                else
+                        newline = true;
 
-                hashmap_free(j->files);
+                journal_file_print_header(f);
         }
-
-        sd_journal_flush_matches(j);
-
-        free(j);
 }
 
-int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
-        Object *o;
+_public_ int sd_journal_get_usage(sd_journal *j, uint64_t *bytes) {
+        Iterator i;
         JournalFile *f;
-        int r;
+        uint64_t sum = 0;
 
-        assert(j);
-        assert(ret);
+        if (!j)
+                return -EINVAL;
+        if (!bytes)
+                return -EINVAL;
 
-        f = j->current_file;
-        if (!f)
-                return 0;
+        HASHMAP_FOREACH(f, j->files, i) {
+                struct stat st;
 
-        if (f->current_offset <= 0)
-                return 0;
+                if (fstat(f->fd, &st) < 0)
+                        return -errno;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-        if (r < 0)
-                return r;
+                sum += (uint64_t) st.st_blocks * 512ULL;
+        }
 
-        *ret = le64toh(o->entry.realtime);
-        return 1;
+        *bytes = sum;
+        return 0;
 }
 
-int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret) {
-        Object *o;
-        JournalFile *f;
-        int r;
-        sd_id128_t id;
+_public_ int sd_journal_query_unique(sd_journal *j, const char *field) {
+        char *f;
 
-        assert(j);
-        assert(ret);
+        if (!j)
+                return -EINVAL;
+        if (isempty(field))
+                return -EINVAL;
+        if (!field_is_valid(field))
+                return -EINVAL;
 
-        f = j->current_file;
+        f = strdup(field);
         if (!f)
-                return 0;
-
-        if (f->current_offset <= 0)
-                return 0;
+                return -ENOMEM;
 
-        r = sd_id128_get_boot(&id);
-        if (r < 0)
-                return r;
+        free(j->unique_field);
+        j->unique_field = f;
+        j->unique_file = NULL;
+        j->unique_offset = 0;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-        if (r < 0)
-                return r;
+        return 0;
+}
 
-        if (!sd_id128_equal(id, o->entry.boot_id))
-                return 0;
+_public_ int sd_journal_enumerate_unique(sd_journal *j, const void **data, size_t *l) {
+        Object *o;
+        size_t k;
+        int r;
 
-        *ret = le64toh(o->entry.monotonic);
-        return 1;
+        if (!j)
+                return -EINVAL;
+        if (!data)
+                return -EINVAL;
+        if (!l)
+                return -EINVAL;
+        if (!j->unique_field)
+                return -EINVAL;
 
-}
+        k = strlen(j->unique_field);
 
-int sd_journal_get_field(sd_journal *j, const char *field, const void **data, size_t *size) {
-        JournalFile *f;
-        uint64_t i, n;
-        size_t field_length;
-        int r;
-        Object *o;
+        if (!j->unique_file) {
+                j->unique_file = hashmap_first(j->files);
+                if (!j->unique_file)
+                        return 0;
+                j->unique_offset = 0;
+        }
 
-        assert(j);
-        assert(field);
-        assert(data);
-        assert(size);
+        for (;;) {
+                JournalFile *of;
+                Iterator i;
+                const void *odata;
+                size_t ol;
+                bool found;
 
-        if (isempty(field) || strchr(field, '='))
-                return -EINVAL;
+                /* Proceed to next data object in the field's linked list */
+                if (j->unique_offset == 0) {
+                        r = journal_file_find_field_object(j->unique_file, j->unique_field, k, &o, NULL);
+                        if (r < 0)
+                                return r;
 
-        f = j->current_file;
-        if (!f)
-                return 0;
+                        j->unique_offset = r > 0 ? le64toh(o->field.head_data_offset) : 0;
+                } else {
+                        r = journal_file_move_to_object(j->unique_file, OBJECT_DATA, j->unique_offset, &o);
+                        if (r < 0)
+                                return r;
 
-        if (f->current_offset <= 0)
-                return 0;
+                        j->unique_offset = le64toh(o->data.next_field_offset);
+                }
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-        if (r < 0)
-                return r;
+                /* We reached the end of the list? Then start again, with the next file */
+                if (j->unique_offset == 0) {
+                        JournalFile *n;
 
-        field_length = strlen(field);
+                        n = hashmap_next(j->files, j->unique_file->path);
+                        if (!n)
+                                return 0;
 
-        n = journal_file_entry_n_items(o);
-        for (i = 0; i < n; i++) {
-                uint64_t p, l, h;
-                size_t t;
+                        j->unique_file = n;
+                        continue;
+                }
 
-                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);
+                /* We do not use the type context here, but 0 instead,
+                 * so that we can look at this data object at the same
+                 * time as one on another file */
+                r = journal_file_move_to_object(j->unique_file, 0, j->unique_offset, &o);
                 if (r < 0)
                         return r;
 
-                if (h != o->data.hash)
+                /* Let's do the type check by hand, since we used 0 context above. */
+                if (o->object.type != OBJECT_DATA)
                         return -EBADMSG;
 
-                l = le64toh(o->object.size) - offsetof(Object, data.payload);
+                r = return_data(j->unique_file, o, &odata, &ol);
+                if (r < 0)
+                        return r;
 
-                if (l >= field_length+1 &&
-                    memcmp(o->data.payload, field, field_length) == 0 &&
-                    o->data.payload[field_length] == '=') {
+                /* OK, now let's see if we already returned this data
+                 * object by checking if it exists in the earlier
+                 * traversed files. */
+                found = false;
+                HASHMAP_FOREACH(of, j->files, i) {
+                        Object *oo;
+                        uint64_t op;
 
-                        t = (size_t) l;
+                        if (of == j->unique_file)
+                                break;
 
-                        if ((uint64_t) t != l)
-                                return -E2BIG;
+                        /* Skip this file it didn't have any fields
+                         * indexed */
+                        if (JOURNAL_HEADER_CONTAINS(of->header, n_fields) &&
+                            le64toh(of->header->n_fields) <= 0)
+                                continue;
 
-                        *data = o->data.payload;
-                        *size = t;
+                        r = journal_file_find_data_object_with_hash(of, odata, ol, le64toh(o->data.hash), &oo, &op);
+                        if (r < 0)
+                                return r;
 
-                        return 1;
+                        if (r > 0)
+                                found = true;
                 }
 
-                r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
+                if (found)
+                        continue;
+
+                r = return_data(j->unique_file, o, data, l);
                 if (r < 0)
                         return r;
+
+                return 1;
         }
+}
 
-        return 0;
+_public_ void sd_journal_restart_unique(sd_journal *j) {
+        if (!j)
+                return;
+
+        j->unique_file = NULL;
+        j->unique_offset = 0;
 }
 
-int sd_journal_iterate_fields(sd_journal *j, const void **data, size_t *size) {
-        JournalFile *f;
-        uint64_t p, l, n, h;
-        size_t t;
+_public_ int sd_journal_reliable_fd(sd_journal *j) {
+        if (!j)
+                return -EINVAL;
+
+        return !j->on_network;
+}
+
+static char *lookup_field(const char *field, void *userdata) {
+        sd_journal *j = userdata;
+        const void *data;
+        size_t size, d;
         int r;
-        Object *o;
 
+        assert(field);
         assert(j);
-        assert(data);
-        assert(size);
 
-        f = j->current_file;
-        if (!f)
-                return 0;
+        r = sd_journal_get_data(j, field, &data, &size);
+        if (r < 0 ||
+            size > REPLACE_VAR_MAX)
+                return strdup(field);
 
-        if (f->current_offset <= 0)
-                return 0;
+        d = strlen(field) + 1;
 
-        r = journal_file_move_to_object(f, f->current_offset, OBJECT_ENTRY, &o);
-        if (r < 0)
-                return r;
+        return strndup((const char*) data + d, size - d);
+}
 
-        n = journal_file_entry_n_items(o);
-        if (j->current_field >= n)
-                return 0;
+_public_ int sd_journal_get_catalog(sd_journal *j, char **ret) {
+        const void *data;
+        size_t size;
+        sd_id128_t id;
+        _cleanup_free_ char *text = NULL, *cid = NULL;
+        char *t;
+        int r;
 
-        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);
+        if (!j)
+                return -EINVAL;
+        if (!ret)
+                return -EINVAL;
+
+        r = sd_journal_get_data(j, "MESSAGE_ID", &data, &size);
         if (r < 0)
                 return r;
 
-        if (h != o->data.hash)
-                return -EBADMSG;
-
-        l = le64toh(o->object.size) - offsetof(Object, data.payload);
-        t = (size_t) l;
-
-        /* We can't read objects larger than 4G on a 32bit machine */
-        if ((uint64_t) t != l)
-                return -E2BIG;
-
-        *data = o->data.payload;
-        *size = t;
+        cid = strndup((const char*) data + 11, size - 11);
+        if (!cid)
+                return -ENOMEM;
 
-        j->current_field ++;
+        r = sd_id128_from_string(cid, &id);
+        if (r < 0)
+                return r;
 
-        return 1;
-}
+        r = catalog_get(id, &text);
+        if (r < 0)
+                return r;
 
-int sd_journal_seek_head(sd_journal *j) {
-        assert(j);
-        return -EINVAL;
-}
+        t = replace_var(text, lookup_field, j);
+        if (!t)
+                return -ENOMEM;
 
-int sd_journal_seek_tail(sd_journal *j) {
-        assert(j);
-        return -EINVAL;
+        *ret = t;
+        return 0;
 }