Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3137 insertions, 0 deletions

diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
new file mode 100644
index 0000000..0f99628
--- /dev/null
+++ b/src/journal/sd-journal.c
@@ -0,0 +1,3137 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <linux/magic.h>
+#include <poll.h>
+#include <stddef.h>
+#include <sys/inotify.h>
+#include <sys/vfs.h>
+#include <unistd.h>
+
+#include "sd-journal.h"
+
+#include "alloc-util.h"
+#include "catalog.h"
+#include "compress.h"
+#include "dirent-util.h"
+#include "env-file.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "hashmap.h"
+#include "hostname-util.h"
+#include "id128-util.h"
+#include "io-util.h"
+#include "journal-def.h"
+#include "journal-file.h"
+#include "journal-internal.h"
+#include "list.h"
+#include "lookup3.h"
+#include "missing.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "replace-var.h"
+#include "stat-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+
+#define JOURNAL_FILES_MAX 7168
+
+#define JOURNAL_FILES_RECHECK_USEC (2 * USEC_PER_SEC)
+
+#define REPLACE_VAR_MAX 256
+
+#define DEFAULT_DATA_THRESHOLD (64*1024)
+
+static void remove_file_real(sd_journal *j, JournalFile *f);
+
+static bool journal_pid_changed(sd_journal *j) {
+        assert(j);
+
+        /* We don't support people creating a journal object and
+         * keeping it around over a fork(). Let's complain. */
+
+        return j->original_pid != getpid_cached();
+}
+
+static int journal_put_error(sd_journal *j, int r, const char *path) {
+        char *copy;
+        int k;
+
+        /* Memorize an error we encountered, and store which
+         * file/directory it was generated from. Note that we store
+         * only *one* path per error code, as the error code is the
+         * key into the hashmap, and the path is the value. This means
+         * we keep track only of all error kinds, but not of all error
+         * locations. This has the benefit that the hashmap cannot
+         * grow beyond bounds.
+         *
+         * We return an error here only if we didn't manage to
+         * memorize the real error. */
+
+        if (r >= 0)
+                return r;
+
+        k = hashmap_ensure_allocated(&j->errors, NULL);
+        if (k < 0)
+                return k;
+
+        if (path) {
+                copy = strdup(path);
+                if (!copy)
+                        return -ENOMEM;
+        } else
+                copy = NULL;
+
+        k = hashmap_put(j->errors, INT_TO_PTR(r), copy);
+        if (k < 0) {
+                free(copy);
+
+                if (k == -EEXIST)
+                        return 0;
+
+                return k;
+        }
+
+        return 0;
+}
+
+static void detach_location(sd_journal *j) {
+        Iterator i;
+        JournalFile *f;
+
+        assert(j);
+
+        j->current_file = NULL;
+        j->current_field = 0;
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i)
+                journal_file_reset_location(f);
+}
+
+static void reset_location(sd_journal *j) {
+        assert(j);
+
+        detach_location(j);
+        zero(j->current_location);
+}
+
+static void init_location(Location *l, LocationType type, JournalFile *f, Object *o) {
+        assert(l);
+        assert(IN_SET(type, LOCATION_DISCRETE, 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, JournalFile *f, Object *o) {
+        assert(j);
+        assert(f);
+        assert(o);
+
+        init_location(&j->current_location, LOCATION_DISCRETE, f, o);
+
+        j->current_file = f;
+        j->current_field = 0;
+
+        /* Let f know its candidate entry was picked. */
+        assert(f->location_type == LOCATION_SEEK);
+        f->location_type = LOCATION_DISCRETE;
+}
+
+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;
+        }
+
+        assert_not_reached("\"=\" not found");
+}
+
+static Match *match_new(Match *p, MatchType t) {
+        Match *m;
+
+        m = new0(Match, 1);
+        if (!m)
+                return NULL;
+
+        m->type = t;
+
+        if (p) {
+                m->parent = p;
+                LIST_PREPEND(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(matches, m->parent->matches, m);
+
+        free(m->data);
+        free(m);
+}
+
+static void match_free_if_empty(Match *m) {
+        if (!m || m->matches)
+                return;
+
+        match_free(m);
+}
+
+_public_ int sd_journal_add_match(sd_journal *j, const void *data, size_t size) {
+        Match *l3, *l4, *add_here = NULL, *m;
+        le64_t le_hash;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(data, -EINVAL);
+
+        if (size == 0)
+                size = strlen(data);
+
+        assert_return(match_is_valid(data, size), -EINVAL);
+
+        /* level 0: AND term
+         * level 1: OR terms
+         * level 2: AND terms
+         * level 3: OR terms
+         * level 4: concrete matches */
+
+        if (!j->level0) {
+                j->level0 = match_new(NULL, MATCH_AND_TERM);
+                if (!j->level0)
+                        return -ENOMEM;
+        }
+
+        if (!j->level1) {
+                j->level1 = match_new(j->level0, MATCH_OR_TERM);
+                if (!j->level1)
+                        return -ENOMEM;
+        }
+
+        if (!j->level2) {
+                j->level2 = match_new(j->level1, MATCH_AND_TERM);
+                if (!j->level2)
+                        return -ENOMEM;
+        }
+
+        assert(j->level0->type == MATCH_AND_TERM);
+        assert(j->level1->type == MATCH_OR_TERM);
+        assert(j->level2->type == MATCH_AND_TERM);
+
+        le_hash = htole64(hash64(data, size));
+
+        LIST_FOREACH(matches, l3, j->level2->matches) {
+                assert(l3->type == MATCH_OR_TERM);
+
+                LIST_FOREACH(matches, l4, l3->matches) {
+                        assert(l4->type == MATCH_DISCRETE);
+
+                        /* Exactly the same match already? Then ignore
+                         * this addition */
+                        if (l4->le_hash == le_hash &&
+                            l4->size == size &&
+                            memcmp(l4->data, data, size) == 0)
+                                return 0;
+
+                        /* Same field? Then let's add this to this OR term */
+                        if (same_field(data, size, l4->data, l4->size)) {
+                                add_here = l3;
+                                break;
+                        }
+                }
+
+                if (add_here)
+                        break;
+        }
+
+        if (!add_here) {
+                add_here = match_new(j->level2, MATCH_OR_TERM);
+                if (!add_here)
+                        goto fail;
+        }
+
+        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;
+
+        detach_location(j);
+
+        return 0;
+
+fail:
+        match_free_if_empty(add_here);
+        match_free_if_empty(j->level2);
+        match_free_if_empty(j->level1);
+        match_free_if_empty(j->level0);
+
+        return -ENOMEM;
+}
+
+_public_ int sd_journal_add_conjunction(sd_journal *j) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (!j->level0)
+                return 0;
+
+        if (!j->level1)
+                return 0;
+
+        if (!j->level1->matches)
+                return 0;
+
+        j->level1 = NULL;
+        j->level2 = NULL;
+
+        return 0;
+}
+
+_public_ int sd_journal_add_disjunction(sd_journal *j) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (!j->level0)
+                return 0;
+
+        if (!j->level1)
+                return 0;
+
+        if (!j->level2)
+                return 0;
+
+        if (!j->level2->matches)
+                return 0;
+
+        j->level2 = NULL;
+        return 0;
+}
+
+static char *match_make_string(Match *m) {
+        char *p = NULL, *r;
+        Match *i;
+        bool enclose = false;
+
+        if (!m)
+                return strdup("none");
+
+        if (m->type == MATCH_DISCRETE)
+                return cescape_length(m->data, m->size);
+
+        LIST_FOREACH(matches, i, m->matches) {
+                char *t, *k;
+
+                t = match_make_string(i);
+                if (!t)
+                        return mfree(p);
+
+                if (p) {
+                        k = strjoin(p, m->type == MATCH_OR_TERM ? " OR " : " AND ", t);
+                        free(p);
+                        free(t);
+
+                        if (!k)
+                                return NULL;
+
+                        p = k;
+
+                        enclose = true;
+                } else
+                        p = t;
+        }
+
+        if (enclose) {
+                r = strjoin("(", p, ")");
+                free(p);
+                return r;
+        }
+
+        return p;
+}
+
+char *journal_make_match_string(sd_journal *j) {
+        assert(j);
+
+        return match_make_string(j->level0);
+}
+
+_public_ void sd_journal_flush_matches(sd_journal *j) {
+        if (!j)
+                return;
+
+        if (j->level0)
+                match_free(j->level0);
+
+        j->level0 = j->level1 = j->level2 = NULL;
+
+        detach_location(j);
+}
+
+_pure_ static int compare_with_location(JournalFile *f, Location *l) {
+        int r;
+
+        assert(f);
+        assert(l);
+        assert(f->location_type == LOCATION_SEEK);
+        assert(IN_SET(l->type, LOCATION_DISCRETE, LOCATION_SEEK));
+
+        if (l->monotonic_set &&
+            sd_id128_equal(f->current_boot_id, l->boot_id) &&
+            l->realtime_set &&
+            f->current_realtime == l->realtime &&
+            l->xor_hash_set &&
+            f->current_xor_hash == l->xor_hash)
+                return 0;
+
+        if (l->seqnum_set &&
+            sd_id128_equal(f->header->seqnum_id, l->seqnum_id)) {
+
+                r = CMP(f->current_seqnum, l->seqnum);
+                if (r != 0)
+                        return r;
+        }
+
+        if (l->monotonic_set &&
+            sd_id128_equal(f->current_boot_id, l->boot_id)) {
+
+                r = CMP(f->current_monotonic, l->monotonic);
+                if (r != 0)
+                        return r;
+        }
+
+        if (l->realtime_set) {
+
+                r = CMP(f->current_realtime, l->realtime);
+                if (r != 0)
+                        return r;
+        }
+
+        if (l->xor_hash_set) {
+
+                r = CMP(f->current_xor_hash, l->xor_hash);
+                if (r != 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+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 np = 0;
+        Object *n;
+
+        assert(j);
+        assert(m);
+        assert(f);
+
+        if (m->type == MATCH_DISCRETE) {
+                uint64_t dp;
+
+                r = journal_file_find_data_object_with_hash(f, m->data, m->size, le64toh(m->le_hash), NULL, &dp);
+                if (r <= 0)
+                        return r;
+
+                return journal_file_move_to_entry_by_offset_for_data(f, dp, after_offset, direction, ret, offset);
+
+        } else if (m->type == MATCH_OR_TERM) {
+                Match *i;
+
+                /* Find the earliest match beyond after_offset */
+
+                LIST_FOREACH(matches, i, m->matches) {
+                        uint64_t cp;
+
+                        r = next_for_match(j, i, f, after_offset, direction, NULL, &cp);
+                        if (r < 0)
+                                return r;
+                        else if (r > 0) {
+                                if (np == 0 || (direction == DIRECTION_DOWN ? cp < np : cp > np))
+                                        np = cp;
+                        }
+                }
+
+                if (np == 0)
+                        return 0;
+
+        } else if (m->type == MATCH_AND_TERM) {
+                Match *i, *last_moved;
+
+                /* Always jump to the next matching entry and repeat
+                 * this until we find an offset that matches for all
+                 * matches. */
+
+                if (!m->matches)
+                        return 0;
+
+                r = next_for_match(j, m->matches, f, after_offset, direction, NULL, &np);
+                if (r <= 0)
+                        return r;
+
+                assert(direction == DIRECTION_DOWN ? np >= after_offset : np <= after_offset);
+                last_moved = m->matches;
+
+                LIST_LOOP_BUT_ONE(matches, i, m->matches, last_moved) {
+                        uint64_t cp;
+
+                        r = next_for_match(j, i, f, np, direction, NULL, &cp);
+                        if (r <= 0)
+                                return r;
+
+                        assert(direction == DIRECTION_DOWN ? cp >= np : cp <= np);
+                        if (direction == DIRECTION_DOWN ? cp > np : cp < np) {
+                                np = cp;
+                                last_moved = i;
+                        }
+                }
+        }
+
+        assert(np > 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;
+}
+
+static int find_location_for_match(
+                sd_journal *j,
+                Match *m,
+                JournalFile *f,
+                direction_t direction,
+                Object **ret,
+                uint64_t *offset) {
+
+        int r;
+
+        assert(j);
+        assert(m);
+        assert(f);
+
+        if (m->type == MATCH_DISCRETE) {
+                uint64_t dp;
+
+                r = journal_file_find_data_object_with_hash(f, m->data, m->size, le64toh(m->le_hash), NULL, &dp);
+                if (r <= 0)
+                        return r;
+
+                /* 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 (j->current_location.realtime_set)
+                        return journal_file_move_to_entry_by_realtime_for_data(f, dp, j->current_location.realtime, direction, ret, offset);
+
+                return journal_file_next_entry_for_data(f, NULL, 0, dp, direction, ret, offset);
+
+        } else if (m->type == MATCH_OR_TERM) {
+                uint64_t np = 0;
+                Object *n;
+                Match *i;
+
+                /* Find the earliest match */
+
+                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;
+                        else if (r > 0) {
+                                if (np == 0 || (direction == DIRECTION_DOWN ? np > cp : np < cp))
+                                        np = cp;
+                        }
+                }
+
+                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;
+
+        } 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 ? cp > np : cp < np))
+                                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, 0, DIRECTION_DOWN, ret, offset);
+                if (j->current_location.type == LOCATION_TAIL)
+                        return journal_file_next_entry(f, 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, 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) {
+
+        assert(j);
+        assert(f);
+        assert(ret);
+        assert(offset);
+
+        /* No matches is easy. We simple advance the file
+         * pointer by one. */
+        if (!j->level0)
+                return journal_file_next_entry(f, f->current_offset, 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 ? f->current_offset + 1
+                                                          : f->current_offset - 1,
+                              direction, ret, offset);
+}
+
+static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direction) {
+        Object *c;
+        uint64_t cp, n_entries;
+        int r;
+
+        assert(j);
+        assert(f);
+
+        n_entries = le64toh(f->header->n_entries);
+
+        /* If we hit EOF before, we don't need to look into this file again
+         * unless direction changed or new entries appeared. */
+        if (f->last_direction == direction && f->location_type == LOCATION_TAIL &&
+            n_entries == f->last_n_entries)
+                return 0;
+
+        f->last_n_entries = n_entries;
+
+        if (f->last_direction == direction && f->current_offset > 0) {
+                /* LOCATION_SEEK here means we did the work in a previous
+                 * iteration and the current location already points to a
+                 * candidate entry. */
+                if (f->location_type != LOCATION_SEEK) {
+                        r = next_with_matches(j, f, direction, &c, &cp);
+                        if (r <= 0)
+                                return r;
+
+                        journal_file_save_location(f, c, cp);
+                }
+        } else {
+                f->last_direction = direction;
+
+                r = find_location_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+
+                journal_file_save_location(f, c, cp);
+        }
+
+        /* OK, we found the spot, now let's advance until 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, &j->current_location);
+
+                        found = direction == DIRECTION_DOWN ? k > 0 : k < 0;
+                } else
+                        found = true;
+
+                if (found)
+                        return 1;
+
+                r = next_with_matches(j, f, direction, &c, &cp);
+                if (r <= 0)
+                        return r;
+
+                journal_file_save_location(f, c, cp);
+        }
+}
+
+static int real_journal_next(sd_journal *j, direction_t direction) {
+        JournalFile *new_file = NULL;
+        unsigned i, n_files;
+        const void **files;
+        Object *o;
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        r = iterated_cache_get(j->files_cache, NULL, &files, &n_files);
+        if (r < 0)
+                return r;
+
+        for (i = 0; i < n_files; i++) {
+                JournalFile *f = (JournalFile *)files[i];
+                bool found;
+
+                r = next_beyond_location(j, f, direction);
+                if (r < 0) {
+                        log_debug_errno(r, "Can't iterate through %s, ignoring: %m", f->path);
+                        remove_file_real(j, f);
+                        continue;
+                } else if (r == 0) {
+                        f->location_type = LOCATION_TAIL;
+                        continue;
+                }
+
+                if (!new_file)
+                        found = true;
+                else {
+                        int k;
+
+                        k = journal_file_compare_locations(f, new_file);
+
+                        found = direction == DIRECTION_DOWN ? k < 0 : k > 0;
+                }
+
+                if (found)
+                        new_file = f;
+        }
+
+        if (!new_file)
+                return 0;
+
+        r = journal_file_move_to_object(new_file, OBJECT_ENTRY, new_file->current_offset, &o);
+        if (r < 0)
+                return r;
+
+        set_location(j, new_file, o);
+
+        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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (skip == 0) {
+                /* If this is not a discrete skip, then at least
+                 * resolve the current location */
+                if (j->current_location.type != LOCATION_DISCRETE) {
+                        r = real_journal_next(j, direction);
+                        if (r < 0)
+                                return r;
+                }
+
+                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);
+}
+
+_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_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(cursor, -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;
+
+        sd_id128_to_string(j->current_file->header->seqnum_id, sid);
+        sd_id128_to_string(o->entry.boot_id, bid);
+
+        if (asprintf(cursor,
+                     "s=%s;i=%"PRIx64";b=%s;m=%"PRIx64";t=%"PRIx64";x=%"PRIx64,
+                     sid, le64toh(o->entry.seqnum),
+                     bid, le64toh(o->entry.monotonic),
+                     le64toh(o->entry.realtime),
+                     le64toh(o->entry.xor_hash)) < 0)
+                return -ENOMEM;
+
+        return 0;
+}
+
+_public_ int sd_journal_seek_cursor(sd_journal *j, const char *cursor) {
+        const char *word, *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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!isempty(cursor), -EINVAL);
+
+        FOREACH_WORD_SEPARATOR(word, l, cursor, ";", state) {
+                char *item;
+                int k = 0;
+
+                if (l < 2 || word[1] != '=')
+                        return -EINVAL;
+
+                item = strndup(word, l);
+                if (!item)
+                        return -ENOMEM;
+
+                switch (word[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;
+        Object *o;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!isempty(cursor), -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;
+
+        for (;;) {
+                _cleanup_free_ char *item = NULL;
+                unsigned long long ll;
+                sd_id128_t id;
+                int k = 0;
+
+                r = extract_first_word(&cursor, &item, ";", EXTRACT_DONT_COALESCE_SEPARATORS);
+                if (r < 0)
+                        return r;
+
+                if (r == 0)
+                        break;
+
+                if (strlen(item) < 2 || item[1] != '=')
+                        return -EINVAL;
+
+                switch (item[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) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        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) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        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) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_HEAD;
+
+        return 0;
+}
+
+_public_ int sd_journal_seek_tail(sd_journal *j) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        reset_location(j);
+        j->current_location.type = LOCATION_TAIL;
+
+        return 0;
+}
+
+static void check_network(sd_journal *j, int fd) {
+        assert(j);
+
+        if (j->on_network)
+                return;
+
+        j->on_network = fd_is_network_fs(fd);
+}
+
+static bool file_has_type_prefix(const char *prefix, const char *filename) {
+        const char *full, *tilded, *atted;
+
+        full = strjoina(prefix, ".journal");
+        tilded = strjoina(full, "~");
+        atted = strjoina(prefix, "@");
+
+        return STR_IN_SET(filename, full, tilded) ||
+               startswith(filename, atted);
+}
+
+static bool file_type_wanted(int flags, const char *filename) {
+        assert(filename);
+
+        if (!endswith(filename, ".journal") && !endswith(filename, ".journal~"))
+                return false;
+
+        /* no flags set → every type is OK */
+        if (!(flags & (SD_JOURNAL_SYSTEM | SD_JOURNAL_CURRENT_USER)))
+                return true;
+
+        if (flags & SD_JOURNAL_SYSTEM && file_has_type_prefix("system", filename))
+                return true;
+
+        if (flags & SD_JOURNAL_CURRENT_USER) {
+                char prefix[5 + DECIMAL_STR_MAX(uid_t) + 1];
+
+                xsprintf(prefix, "user-"UID_FMT, getuid());
+
+                if (file_has_type_prefix(prefix, filename))
+                        return true;
+        }
+
+        return false;
+}
+
+static bool path_has_prefix(sd_journal *j, const char *path, const char *prefix) {
+        assert(j);
+        assert(path);
+        assert(prefix);
+
+        if (j->toplevel_fd >= 0)
+                return false;
+
+        return path_startswith(path, prefix);
+}
+
+static void track_file_disposition(sd_journal *j, JournalFile *f) {
+        assert(j);
+        assert(f);
+
+        if (!j->has_runtime_files && path_has_prefix(j, f->path, "/run"))
+                j->has_runtime_files = true;
+        else if (!j->has_persistent_files && path_has_prefix(j, f->path, "/var"))
+                j->has_persistent_files = true;
+}
+
+static const char *skip_slash(const char *p) {
+
+        if (!p)
+                return NULL;
+
+        while (*p == '/')
+                p++;
+
+        return p;
+}
+
+static int add_any_file(
+                sd_journal *j,
+                int fd,
+                const char *path) {
+
+        bool close_fd = false;
+        JournalFile *f;
+        struct stat st;
+        int r, k;
+
+        assert(j);
+        assert(fd >= 0 || path);
+
+        if (fd < 0) {
+                if (j->toplevel_fd >= 0)
+                        /* If there's a top-level fd defined make the path relative, explicitly, since otherwise
+                         * openat() ignores the first argument. */
+
+                        fd = openat(j->toplevel_fd, skip_slash(path), O_RDONLY|O_CLOEXEC|O_NONBLOCK);
+                else
+                        fd = open(path, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
+                if (fd < 0) {
+                        r = log_debug_errno(errno, "Failed to open journal file %s: %m", path);
+                        goto finish;
+                }
+
+                close_fd = true;
+
+                r = fd_nonblock(fd, false);
+                if (r < 0) {
+                        r = log_debug_errno(errno, "Failed to turn off O_NONBLOCK for %s: %m", path);
+                        goto finish;
+                }
+        }
+
+        if (fstat(fd, &st) < 0) {
+                r = log_debug_errno(errno, "Failed to fstat file '%s': %m", path);
+                goto finish;
+        }
+
+        r = stat_verify_regular(&st);
+        if (r < 0) {
+                log_debug_errno(r, "Refusing to open '%s', as it is not a regular file.", path);
+                goto finish;
+        }
+
+        f = ordered_hashmap_get(j->files, path);
+        if (f) {
+                if (f->last_stat.st_dev == st.st_dev &&
+                    f->last_stat.st_ino == st.st_ino) {
+
+                        /* We already track this file, under the same path and with the same device/inode numbers, it's
+                         * hence really the same. Mark this file as seen in this generation. This is used to GC old
+                         * files in process_q_overflow() to detect journal files that are still there and discern them
+                         * from those which are gone. */
+
+                        f->last_seen_generation = j->generation;
+                        r = 0;
+                        goto finish;
+                }
+
+                /* So we tracked a file under this name, but it has a different inode/device. In that case, it got
+                 * replaced (probably due to rotation?), let's drop it hence from our list. */
+                remove_file_real(j, f);
+                f = NULL;
+        }
+
+        if (ordered_hashmap_size(j->files) >= JOURNAL_FILES_MAX) {
+                log_debug("Too many open journal files, not adding %s.", path);
+                r = -ETOOMANYREFS;
+                goto finish;
+        }
+
+        r = journal_file_open(fd, path, O_RDONLY, 0, false, 0, false, NULL, j->mmap, NULL, NULL, &f);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to open journal file %s: %m", path);
+                goto finish;
+        }
+
+        /* journal_file_dump(f); */
+
+        r = ordered_hashmap_put(j->files, f->path, f);
+        if (r < 0) {
+                f->close_fd = false; /* make sure journal_file_close() doesn't close the caller's fd (or our own). We'll let the caller do that, or ourselves */
+                (void) journal_file_close(f);
+                goto finish;
+        }
+
+        close_fd = false; /* the fd is now owned by the JournalFile object */
+
+        f->last_seen_generation = j->generation;
+
+        track_file_disposition(j, f);
+        check_network(j, f->fd);
+
+        j->current_invalidate_counter++;
+
+        log_debug("File %s added.", f->path);
+
+        r = 0;
+
+finish:
+        if (close_fd)
+                safe_close(fd);
+
+        if (r < 0) {
+                k = journal_put_error(j, r, path);
+                if (k < 0)
+                        return k;
+        }
+
+        return r;
+}
+
+static int add_file_by_name(
+                sd_journal *j,
+                const char *prefix,
+                const char *filename) {
+
+        const char *path;
+
+        assert(j);
+        assert(prefix);
+        assert(filename);
+
+        if (j->no_new_files)
+                return 0;
+
+        if (!file_type_wanted(j->flags, filename))
+                return 0;
+
+        path = strjoina(prefix, "/", filename);
+        return add_any_file(j, -1, path);
+}
+
+static void remove_file_by_name(
+                sd_journal *j,
+                const char *prefix,
+                const char *filename) {
+
+        const char *path;
+        JournalFile *f;
+
+        assert(j);
+        assert(prefix);
+        assert(filename);
+
+        path = strjoina(prefix, "/", filename);
+        f = ordered_hashmap_get(j->files, path);
+        if (!f)
+                return;
+
+        remove_file_real(j, f);
+}
+
+static void remove_file_real(sd_journal *j, JournalFile *f) {
+        assert(j);
+        assert(f);
+
+        (void) ordered_hashmap_remove(j->files, f->path);
+
+        log_debug("File %s removed.", f->path);
+
+        if (j->current_file == f) {
+                j->current_file = NULL;
+                j->current_field = 0;
+        }
+
+        if (j->unique_file == f) {
+                /* Jump to the next unique_file or NULL if that one was last */
+                j->unique_file = ordered_hashmap_next(j->files, j->unique_file->path);
+                j->unique_offset = 0;
+                if (!j->unique_file)
+                        j->unique_file_lost = true;
+        }
+
+        if (j->fields_file == f) {
+                j->fields_file = ordered_hashmap_next(j->files, j->fields_file->path);
+                j->fields_offset = 0;
+                if (!j->fields_file)
+                        j->fields_file_lost = true;
+        }
+
+        (void) journal_file_close(f);
+
+        j->current_invalidate_counter++;
+}
+
+static int dirname_is_machine_id(const char *fn) {
+        sd_id128_t id, machine;
+        int r;
+
+        r = sd_id128_get_machine(&machine);
+        if (r < 0)
+                return r;
+
+        r = sd_id128_from_string(fn, &id);
+        if (r < 0)
+                return r;
+
+        return sd_id128_equal(id, machine);
+}
+
+static bool dirent_is_journal_file(const struct dirent *de) {
+        assert(de);
+
+        if (!IN_SET(de->d_type, DT_REG, DT_LNK, DT_UNKNOWN))
+                return false;
+
+        return endswith(de->d_name, ".journal") ||
+                endswith(de->d_name, ".journal~");
+}
+
+static bool dirent_is_id128_subdir(const struct dirent *de) {
+        assert(de);
+
+        if (!IN_SET(de->d_type, DT_DIR, DT_LNK, DT_UNKNOWN))
+                return false;
+
+        return id128_is_valid(de->d_name);
+}
+
+static int directory_open(sd_journal *j, const char *path, DIR **ret) {
+        DIR *d;
+
+        assert(j);
+        assert(path);
+        assert(ret);
+
+        if (j->toplevel_fd < 0)
+                d = opendir(path);
+        else
+                /* Open the specified directory relative to the toplevel fd. Enforce that the path specified is
+                 * relative, by dropping the initial slash */
+                d = xopendirat(j->toplevel_fd, skip_slash(path), 0);
+        if (!d)
+                return -errno;
+
+        *ret = d;
+        return 0;
+}
+
+static int add_directory(sd_journal *j, const char *prefix, const char *dirname);
+
+static void directory_enumerate(sd_journal *j, Directory *m, DIR *d) {
+        struct dirent *de;
+
+        assert(j);
+        assert(m);
+        assert(d);
+
+        FOREACH_DIRENT_ALL(de, d, goto fail) {
+
+                if (dirent_is_journal_file(de))
+                        (void) add_file_by_name(j, m->path, de->d_name);
+
+                if (m->is_root && dirent_is_id128_subdir(de))
+                        (void) add_directory(j, m->path, de->d_name);
+        }
+
+        return;
+
+fail:
+        log_debug_errno(errno, "Failed to enumerate directory %s, ignoring: %m", m->path);
+}
+
+static void directory_watch(sd_journal *j, Directory *m, int fd, uint32_t mask) {
+        int r;
+
+        assert(j);
+        assert(m);
+        assert(fd >= 0);
+
+        /* Watch this directory if that's enabled and if it not being watched yet. */
+
+        if (m->wd > 0) /* Already have a watch? */
+                return;
+        if (j->inotify_fd < 0) /* Not watching at all? */
+                return;
+
+        m->wd = inotify_add_watch_fd(j->inotify_fd, fd, mask);
+        if (m->wd < 0) {
+                log_debug_errno(errno, "Failed to watch journal directory '%s', ignoring: %m", m->path);
+                return;
+        }
+
+        r = hashmap_put(j->directories_by_wd, INT_TO_PTR(m->wd), m);
+        if (r == -EEXIST)
+                log_debug_errno(r, "Directory '%s' already being watched under a different path, ignoring: %m", m->path);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to add watch for journal directory '%s' to hashmap, ignoring: %m", m->path);
+                (void) inotify_rm_watch(j->inotify_fd, m->wd);
+                m->wd = -1;
+        }
+}
+
+static int add_directory(sd_journal *j, const char *prefix, const char *dirname) {
+        _cleanup_free_ char *path = NULL;
+        _cleanup_closedir_ DIR *d = NULL;
+        Directory *m;
+        int r, k;
+
+        assert(j);
+        assert(prefix);
+
+        /* Adds a journal file directory to watch. If the directory is already tracked this updates the inotify watch
+         * and reenumerates directory contents */
+
+        if (dirname)
+                path = strjoin(prefix, "/", dirname);
+        else
+                path = strdup(prefix);
+        if (!path) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        log_debug("Considering directory '%s'.", path);
+
+        /* We consider everything local that is in a directory for the local machine ID, or that is stored in /run */
+        if ((j->flags & SD_JOURNAL_LOCAL_ONLY) &&
+            !((dirname && dirname_is_machine_id(dirname) > 0) || path_has_prefix(j, path, "/run")))
+                return 0;
+
+        r = directory_open(j, path, &d);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to open directory '%s': %m", path);
+                goto fail;
+        }
+
+        m = hashmap_get(j->directories_by_path, path);
+        if (!m) {
+                m = new0(Directory, 1);
+                if (!m) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                m->is_root = false;
+                m->path = path;
+
+                if (hashmap_put(j->directories_by_path, m->path, m) < 0) {
+                        free(m);
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                path = NULL; /* avoid freeing in cleanup */
+                j->current_invalidate_counter++;
+
+                log_debug("Directory %s added.", m->path);
+
+        } else if (m->is_root)
+                return 0; /* Don't 'downgrade' from root directory */
+
+        m->last_seen_generation = j->generation;
+
+        directory_watch(j, m, dirfd(d),
+                        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 (!j->no_new_files)
+                directory_enumerate(j, m, d);
+
+        check_network(j, dirfd(d));
+
+        return 0;
+
+fail:
+        k = journal_put_error(j, r, path ?: prefix);
+        if (k < 0)
+                return k;
+
+        return r;
+}
+
+static int add_root_directory(sd_journal *j, const char *p, bool missing_ok) {
+
+        _cleanup_closedir_ DIR *d = NULL;
+        Directory *m;
+        int r, k;
+
+        assert(j);
+
+        /* Adds a root directory to our set of directories to use. If the root directory is already in the set, we
+         * update the inotify logic, and renumerate the directory entries. This call may hence be called to initially
+         * populate the set, as well as to update it later. */
+
+        if (p) {
+                /* If there's a path specified, use it. */
+
+                log_debug("Considering root directory '%s'.", p);
+
+                if ((j->flags & SD_JOURNAL_RUNTIME_ONLY) &&
+                    !path_has_prefix(j, p, "/run"))
+                        return -EINVAL;
+
+                if (j->prefix)
+                        p = strjoina(j->prefix, p);
+
+                r = directory_open(j, p, &d);
+                if (r == -ENOENT && missing_ok)
+                        return 0;
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to open root directory %s: %m", p);
+                        goto fail;
+                }
+        } else {
+                int dfd;
+
+                /* If there's no path specified, then we use the top-level fd itself. We duplicate the fd here, since
+                 * opendir() will take possession of the fd, and close it, which we don't want. */
+
+                p = "."; /* store this as "." in the directories hashmap */
+
+                dfd = fcntl(j->toplevel_fd, F_DUPFD_CLOEXEC, 3);
+                if (dfd < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+
+                d = fdopendir(dfd);
+                if (!d) {
+                        r = -errno;
+                        safe_close(dfd);
+                        goto fail;
+                }
+
+                rewinddir(d);
+        }
+
+        m = hashmap_get(j->directories_by_path, p);
+        if (!m) {
+                m = new0(Directory, 1);
+                if (!m) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                m->is_root = true;
+
+                m->path = strdup(p);
+                if (!m->path) {
+                        free(m);
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                if (hashmap_put(j->directories_by_path, m->path, m) < 0) {
+                        free(m->path);
+                        free(m);
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                j->current_invalidate_counter++;
+
+                log_debug("Root directory %s added.", m->path);
+
+        } else if (!m->is_root)
+                return 0;
+
+        directory_watch(j, m, dirfd(d),
+                        IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB|IN_DELETE|
+                        IN_ONLYDIR);
+
+        if (!j->no_new_files)
+                directory_enumerate(j, m, d);
+
+        check_network(j, dirfd(d));
+
+        return 0;
+
+fail:
+        k = journal_put_error(j, r, p);
+        if (k < 0)
+                return k;
+
+        return r;
+}
+
+static void 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 removed.", d->path);
+        else
+                log_debug("Directory %s removed.", d->path);
+
+        free(d->path);
+        free(d);
+}
+
+static int add_search_paths(sd_journal *j) {
+
+        static 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)
+                (void) add_root_directory(j, p, true);
+
+        if (!(j->flags & SD_JOURNAL_LOCAL_ONLY))
+                (void) add_root_directory(j, "/var/log/journal/remote", true);
+
+        return 0;
+}
+
+static int add_current_paths(sd_journal *j) {
+        Iterator i;
+        JournalFile *f;
+
+        assert(j);
+        assert(j->no_new_files);
+
+        /* Simply adds all directories for files we have open as directories. We don't expect errors here, so we
+         * treat them as fatal. */
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+                _cleanup_free_ char *dir;
+                int r;
+
+                dir = dirname_malloc(f->path);
+                if (!dir)
+                        return -ENOMEM;
+
+                r = add_directory(j, dir, NULL);
+                if (r < 0)
+                        return r;
+        }
+
+        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;
+        }
+
+        return hashmap_ensure_allocated(&j->directories_by_wd, NULL);
+}
+
+static sd_journal *journal_new(int flags, const char *path) {
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+
+        j = new0(sd_journal, 1);
+        if (!j)
+                return NULL;
+
+        j->original_pid = getpid_cached();
+        j->toplevel_fd = -1;
+        j->inotify_fd = -1;
+        j->flags = flags;
+        j->data_threshold = DEFAULT_DATA_THRESHOLD;
+
+        if (path) {
+                char *t;
+
+                t = strdup(path);
+                if (!t)
+                        return NULL;
+
+                if (flags & SD_JOURNAL_OS_ROOT)
+                        j->prefix = t;
+                else
+                        j->path = t;
+        }
+
+        j->files = ordered_hashmap_new(&path_hash_ops);
+        if (!j->files)
+                return NULL;
+
+        j->files_cache = ordered_hashmap_iterated_cache_new(j->files);
+        j->directories_by_path = hashmap_new(&path_hash_ops);
+        j->mmap = mmap_cache_new();
+        if (!j->files_cache || !j->directories_by_path || !j->mmap)
+                return NULL;
+
+        return TAKE_PTR(j);
+}
+
+#define OPEN_ALLOWED_FLAGS                              \
+        (SD_JOURNAL_LOCAL_ONLY |                        \
+         SD_JOURNAL_RUNTIME_ONLY |                      \
+         SD_JOURNAL_SYSTEM | SD_JOURNAL_CURRENT_USER)
+
+_public_ int sd_journal_open(sd_journal **ret, int flags) {
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return((flags & ~OPEN_ALLOWED_FLAGS) == 0, -EINVAL);
+
+        j = journal_new(flags, NULL);
+        if (!j)
+                return -ENOMEM;
+
+        r = add_search_paths(j);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+}
+
+#define OPEN_CONTAINER_ALLOWED_FLAGS                    \
+        (SD_JOURNAL_LOCAL_ONLY | SD_JOURNAL_SYSTEM)
+
+_public_ int sd_journal_open_container(sd_journal **ret, const char *machine, int flags) {
+        _cleanup_free_ char *root = NULL, *class = NULL;
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        char *p;
+        int r;
+
+        /* This is pretty much deprecated, people should use machined's OpenMachineRootDirectory() call instead in
+         * combination with sd_journal_open_directory_fd(). */
+
+        assert_return(machine, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return((flags & ~OPEN_CONTAINER_ALLOWED_FLAGS) == 0, -EINVAL);
+        assert_return(machine_name_is_valid(machine), -EINVAL);
+
+        p = strjoina("/run/systemd/machines/", machine);
+        r = parse_env_file(NULL, p,
+                           "ROOT", &root,
+                           "CLASS", &class);
+        if (r == -ENOENT)
+                return -EHOSTDOWN;
+        if (r < 0)
+                return r;
+        if (!root)
+                return -ENODATA;
+
+        if (!streq_ptr(class, "container"))
+                return -EIO;
+
+        j = journal_new(flags, root);
+        if (!j)
+                return -ENOMEM;
+
+        r = add_search_paths(j);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+}
+
+#define OPEN_DIRECTORY_ALLOWED_FLAGS                    \
+        (SD_JOURNAL_OS_ROOT |                           \
+         SD_JOURNAL_SYSTEM | SD_JOURNAL_CURRENT_USER )
+
+_public_ int sd_journal_open_directory(sd_journal **ret, const char *path, int flags) {
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(path, -EINVAL);
+        assert_return((flags & ~OPEN_DIRECTORY_ALLOWED_FLAGS) == 0, -EINVAL);
+
+        j = journal_new(flags, path);
+        if (!j)
+                return -ENOMEM;
+
+        if (flags & SD_JOURNAL_OS_ROOT)
+                r = add_search_paths(j);
+        else
+                r = add_root_directory(j, path, false);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+}
+
+_public_ int sd_journal_open_files(sd_journal **ret, const char **paths, int flags) {
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        const char **path;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(flags == 0, -EINVAL);
+
+        j = journal_new(flags, NULL);
+        if (!j)
+                return -ENOMEM;
+
+        STRV_FOREACH(path, paths) {
+                r = add_any_file(j, -1, *path);
+                if (r < 0)
+                        return r;
+        }
+
+        j->no_new_files = true;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+}
+
+#define OPEN_DIRECTORY_FD_ALLOWED_FLAGS         \
+        (SD_JOURNAL_OS_ROOT |                           \
+         SD_JOURNAL_SYSTEM | SD_JOURNAL_CURRENT_USER )
+
+_public_ int sd_journal_open_directory_fd(sd_journal **ret, int fd, int flags) {
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        struct stat st;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(fd >= 0, -EBADF);
+        assert_return((flags & ~OPEN_DIRECTORY_FD_ALLOWED_FLAGS) == 0, -EINVAL);
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (!S_ISDIR(st.st_mode))
+                return -EBADFD;
+
+        j = journal_new(flags, NULL);
+        if (!j)
+                return -ENOMEM;
+
+        j->toplevel_fd = fd;
+
+        if (flags & SD_JOURNAL_OS_ROOT)
+                r = add_search_paths(j);
+        else
+                r = add_root_directory(j, NULL, false);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+}
+
+_public_ int sd_journal_open_files_fd(sd_journal **ret, int fds[], unsigned n_fds, int flags) {
+        Iterator iterator;
+        JournalFile *f;
+        _cleanup_(sd_journal_closep) sd_journal *j = NULL;
+        unsigned i;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(n_fds > 0, -EBADF);
+        assert_return(flags == 0, -EINVAL);
+
+        j = journal_new(flags, NULL);
+        if (!j)
+                return -ENOMEM;
+
+        for (i = 0; i < n_fds; i++) {
+                struct stat st;
+
+                if (fds[i] < 0) {
+                        r = -EBADF;
+                        goto fail;
+                }
+
+                if (fstat(fds[i], &st) < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+
+                r = stat_verify_regular(&st);
+                if (r < 0)
+                        goto fail;
+
+                r = add_any_file(j, fds[i], NULL);
+                if (r < 0)
+                        goto fail;
+        }
+
+        j->no_new_files = true;
+        j->no_inotify = true;
+
+        *ret = TAKE_PTR(j);
+        return 0;
+
+fail:
+        /* If we fail, make sure we don't take possession of the files we managed to make use of successfully, and they
+         * remain open */
+        ORDERED_HASHMAP_FOREACH(f, j->files, iterator)
+                f->close_fd = false;
+
+        return r;
+}
+
+_public_ void sd_journal_close(sd_journal *j) {
+        Directory *d;
+
+        if (!j)
+                return;
+
+        sd_journal_flush_matches(j);
+
+        ordered_hashmap_free_with_destructor(j->files, journal_file_close);
+        iterated_cache_free(j->files_cache);
+
+        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);
+
+        safe_close(j->inotify_fd);
+
+        if (j->mmap) {
+                log_debug("mmap cache statistics: %u hit, %u miss", mmap_cache_get_hit(j->mmap), mmap_cache_get_missed(j->mmap));
+                mmap_cache_unref(j->mmap);
+        }
+
+        hashmap_free_free(j->errors);
+
+        free(j->path);
+        free(j->prefix);
+        free(j->unique_field);
+        free(j->fields_buffer);
+        free(j);
+}
+
+_public_ int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
+        Object *o;
+        JournalFile *f;
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(ret, -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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(field, -EINVAL);
+        assert_return(data, -EINVAL);
+        assert_return(size, -EINVAL);
+        assert_return(field_is_valid(field), -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;
+                int compression;
+
+                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);
+
+                compression = o->object.flags & OBJECT_COMPRESSION_MASK;
+                if (compression) {
+#if HAVE_XZ || HAVE_LZ4
+                        r = decompress_startswith(compression,
+                                                  o->data.payload, l,
+                                                  &f->compress_buffer, &f->compress_buffer_size,
+                                                  field, field_length, '=');
+                        if (r < 0)
+                                log_debug_errno(r, "Cannot decompress %s object of length %"PRIu64" at offset "OFSfmt": %m",
+                                                object_compressed_to_string(compression), l, p);
+                        else if (r > 0) {
+
+                                size_t rsize;
+
+                                r = decompress_blob(compression,
+                                                    o->data.payload, l,
+                                                    &f->compress_buffer, &f->compress_buffer_size, &rsize,
+                                                    j->data_threshold);
+                                if (r < 0)
+                                        return r;
+
+                                *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(sd_journal *j, JournalFile *f, Object *o, const void **data, size_t *size) {
+        size_t t;
+        uint64_t l;
+        int compression;
+
+        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;
+
+        compression = o->object.flags & OBJECT_COMPRESSION_MASK;
+        if (compression) {
+#if HAVE_XZ || HAVE_LZ4
+                size_t rsize;
+                int r;
+
+                r = decompress_blob(compression,
+                                    o->data.payload, l, &f->compress_buffer,
+                                    &f->compress_buffer_size, &rsize, j->data_threshold);
+                if (r < 0)
+                        return r;
+
+                *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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(data, -EINVAL);
+        assert_return(size, -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(j, 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;
+}
+
+static int reiterate_all_paths(sd_journal *j) {
+        assert(j);
+
+        if (j->no_new_files)
+                return add_current_paths(j);
+
+        if (j->flags & SD_JOURNAL_OS_ROOT)
+                return add_search_paths(j);
+
+        if (j->toplevel_fd >= 0)
+                return add_root_directory(j, NULL, false);
+
+        if (j->path)
+                return add_root_directory(j, j->path, true);
+
+        return add_search_paths(j);
+}
+
+_public_ int sd_journal_get_fd(sd_journal *j) {
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (j->no_inotify)
+                return -EMEDIUMTYPE;
+
+        if (j->inotify_fd >= 0)
+                return j->inotify_fd;
+
+        r = allocate_inotify(j);
+        if (r < 0)
+                return r;
+
+        log_debug("Reiterating files to get inotify watches established.");
+
+        /* Iterate through all dirs again, to add them to the inotify */
+        r = reiterate_all_paths(j);
+        if (r < 0)
+                return r;
+
+        return j->inotify_fd;
+}
+
+_public_ int sd_journal_get_events(sd_journal *j) {
+        int fd;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        fd = sd_journal_get_fd(j);
+        if (fd < 0)
+                return fd;
+
+        return POLLIN;
+}
+
+_public_ int sd_journal_get_timeout(sd_journal *j, uint64_t *timeout_usec) {
+        int fd;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(timeout_usec, -EINVAL);
+
+        fd = sd_journal_get_fd(j);
+        if (fd < 0)
+                return fd;
+
+        if (!j->on_network) {
+                *timeout_usec = (uint64_t) -1;
+                return 0;
+        }
+
+        /* If we are on the network we need to regularly check for
+         * changes manually */
+
+        *timeout_usec = j->last_process_usec + JOURNAL_FILES_RECHECK_USEC;
+        return 1;
+}
+
+static void process_q_overflow(sd_journal *j) {
+        JournalFile *f;
+        Directory *m;
+        Iterator i;
+
+        assert(j);
+
+        /* When the inotify queue overruns we need to enumerate and re-validate all journal files to bring our list
+         * back in sync with what's on disk. For this we pick a new generation counter value. It'll be assigned to all
+         * journal files we encounter. All journal files and all directories that don't carry it after reenumeration
+         * are subject for unloading. */
+
+        log_debug("Inotify queue overrun, reiterating everything.");
+
+        j->generation++;
+        (void) reiterate_all_paths(j);
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+
+                if (f->last_seen_generation == j->generation)
+                        continue;
+
+                log_debug("File '%s' hasn't been seen in this enumeration, removing.", f->path);
+                remove_file_real(j, f);
+        }
+
+        HASHMAP_FOREACH(m, j->directories_by_path, i) {
+
+                if (m->last_seen_generation == j->generation)
+                        continue;
+
+                if (m->is_root) /* Never GC root directories */
+                        continue;
+
+                log_debug("Directory '%s' hasn't been seen in this enumeration, removing.", f->path);
+                remove_directory(j, m);
+        }
+
+        log_debug("Reiteration complete.");
+}
+
+static void process_inotify_event(sd_journal *j, struct inotify_event *e) {
+        Directory *d;
+
+        assert(j);
+        assert(e);
+
+        if (e->mask & IN_Q_OVERFLOW) {
+                process_q_overflow(j);
+                return;
+        }
+
+        /* Is this a subdirectory we watch? */
+        d = hashmap_get(j->directories_by_wd, INT_TO_PTR(e->wd));
+        if (d) {
+                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))
+                                (void) add_file_by_name(j, d->path, e->name);
+                        else if (e->mask & (IN_DELETE|IN_MOVED_FROM|IN_UNMOUNT))
+                                remove_file_by_name(j, d->path, e->name);
+
+                } else if (!d->is_root && e->len == 0) {
+
+                        /* Event for a subdirectory */
+
+                        if (e->mask & (IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT))
+                                remove_directory(j, d);
+
+                } else if (d->is_root && (e->mask & IN_ISDIR) && e->len > 0 && id128_is_valid(e->name)) {
+
+                        /* Event for root directory */
+
+                        if (e->mask & (IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB))
+                                (void) add_directory(j, d->path, e->name);
+                }
+
+                return;
+        }
+
+        if (e->mask & IN_IGNORED)
+                return;
+
+        log_debug("Unexpected 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) {
+        bool got_something = false;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (j->inotify_fd < 0) /* We have no inotify fd yet? Then there's noting to process. */
+                return 0;
+
+        j->last_process_usec = now(CLOCK_MONOTONIC);
+        j->last_invalidate_counter = j->current_invalidate_counter;
+
+        for (;;) {
+                union inotify_event_buffer buffer;
+                struct inotify_event *e;
+                ssize_t l;
+
+                l = read(j->inotify_fd, &buffer, sizeof(buffer));
+                if (l < 0) {
+                        if (IN_SET(errno, EAGAIN, EINTR))
+                                return got_something ? determine_change(j) : SD_JOURNAL_NOP;
+
+                        return -errno;
+                }
+
+                got_something = true;
+
+                FOREACH_INOTIFY_EVENT(e, buffer, l)
+                        process_inotify_event(j, e);
+        }
+}
+
+_public_ int sd_journal_wait(sd_journal *j, uint64_t timeout_usec) {
+        int r;
+        uint64_t t;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        if (j->inotify_fd < 0) {
+
+                /* This is the first invocation, hence create the
+                 * inotify watch */
+                r = sd_journal_get_fd(j);
+                if (r < 0)
+                        return r;
+
+                /* 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);
+        }
+
+        r = sd_journal_get_timeout(j, &t);
+        if (r < 0)
+                return r;
+
+        if (t != (uint64_t) -1) {
+                usec_t n;
+
+                n = now(CLOCK_MONOTONIC);
+                t = t > n ? t - n : 0;
+
+                if (timeout_usec == (uint64_t) -1 || timeout_usec > t)
+                        timeout_usec = t;
+        }
+
+        do {
+                r = fd_wait_for_event(j->inotify_fd, POLLIN, timeout_usec);
+        } while (r == -EINTR);
+
+        if (r < 0)
+                return r;
+
+        return sd_journal_process(j);
+}
+
+_public_ int sd_journal_get_cutoff_realtime_usec(sd_journal *j, uint64_t *from, uint64_t *to) {
+        Iterator i;
+        JournalFile *f;
+        bool first = true;
+        uint64_t fmin = 0, tmax = 0;
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(from || to, -EINVAL);
+        assert_return(from != to, -EINVAL);
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+                usec_t fr, t;
+
+                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) {
+                        fmin = fr;
+                        tmax = t;
+                        first = false;
+                } else {
+                        fmin = MIN(fr, fmin);
+                        tmax = MAX(t, tmax);
+                }
+        }
+
+        if (from)
+                *from = fmin;
+        if (to)
+                *to = tmax;
+
+        return first ? 0 : 1;
+}
+
+_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 found = false;
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(from || to, -EINVAL);
+        assert_return(from != to, -EINVAL);
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+                usec_t fr, t;
+
+                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;
+
+                if (found) {
+                        if (from)
+                                *from = MIN(fr, *from);
+                        if (to)
+                                *to = MAX(t, *to);
+                } else {
+                        if (from)
+                                *from = fr;
+                        if (to)
+                                *to = t;
+                        found = true;
+                }
+        }
+
+        return found;
+}
+
+void journal_print_header(sd_journal *j) {
+        Iterator i;
+        JournalFile *f;
+        bool newline = false;
+
+        assert(j);
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+                if (newline)
+                        putchar('\n');
+                else
+                        newline = true;
+
+                journal_file_print_header(f);
+        }
+}
+
+_public_ int sd_journal_get_usage(sd_journal *j, uint64_t *bytes) {
+        Iterator i;
+        JournalFile *f;
+        uint64_t sum = 0;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(bytes, -EINVAL);
+
+        ORDERED_HASHMAP_FOREACH(f, j->files, i) {
+                struct stat st;
+
+                if (fstat(f->fd, &st) < 0)
+                        return -errno;
+
+                sum += (uint64_t) st.st_blocks * 512ULL;
+        }
+
+        *bytes = sum;
+        return 0;
+}
+
+_public_ int sd_journal_query_unique(sd_journal *j, const char *field) {
+        char *f;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!isempty(field), -EINVAL);
+        assert_return(field_is_valid(field), -EINVAL);
+
+        f = strdup(field);
+        if (!f)
+                return -ENOMEM;
+
+        free(j->unique_field);
+        j->unique_field = f;
+        j->unique_file = NULL;
+        j->unique_offset = 0;
+        j->unique_file_lost = false;
+
+        return 0;
+}
+
+_public_ int sd_journal_enumerate_unique(sd_journal *j, const void **data, size_t *l) {
+        size_t k;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(data, -EINVAL);
+        assert_return(l, -EINVAL);
+        assert_return(j->unique_field, -EINVAL);
+
+        k = strlen(j->unique_field);
+
+        if (!j->unique_file) {
+                if (j->unique_file_lost)
+                        return 0;
+
+                j->unique_file = ordered_hashmap_first(j->files);
+                if (!j->unique_file)
+                        return 0;
+
+                j->unique_offset = 0;
+        }
+
+        for (;;) {
+                JournalFile *of;
+                Iterator i;
+                Object *o;
+                const void *odata;
+                size_t ol;
+                bool found;
+                int r;
+
+                /* 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;
+
+                        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;
+
+                        j->unique_offset = le64toh(o->data.next_field_offset);
+                }
+
+                /* We reached the end of the list? Then start again, with the next file */
+                if (j->unique_offset == 0) {
+                        j->unique_file = ordered_hashmap_next(j->files, j->unique_file->path);
+                        if (!j->unique_file)
+                                return 0;
+
+                        continue;
+                }
+
+                /* We do not use OBJECT_DATA context here, but OBJECT_UNUSED
+                 * 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, OBJECT_UNUSED, j->unique_offset, &o);
+                if (r < 0)
+                        return r;
+
+                /* Let's do the type check by hand, since we used 0 context above. */
+                if (o->object.type != OBJECT_DATA)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "%s:offset " OFSfmt ": object has type %d, expected %d",
+                                               j->unique_file->path,
+                                               j->unique_offset,
+                                               o->object.type, OBJECT_DATA);
+
+                r = return_data(j, j->unique_file, o, &odata, &ol);
+                if (r < 0)
+                        return r;
+
+                /* Check if we have at least the field name and "=". */
+                if (ol <= k)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "%s:offset " OFSfmt ": object has size %zu, expected at least %zu",
+                                               j->unique_file->path,
+                                               j->unique_offset, ol, k + 1);
+
+                if (memcmp(odata, j->unique_field, k) || ((const char*) odata)[k] != '=')
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "%s:offset " OFSfmt ": object does not start with \"%s=\"",
+                                               j->unique_file->path,
+                                               j->unique_offset,
+                                               j->unique_field);
+
+                /* OK, now let's see if we already returned this data
+                 * object by checking if it exists in the earlier
+                 * traversed files. */
+                found = false;
+                ORDERED_HASHMAP_FOREACH(of, j->files, i) {
+                        if (of == j->unique_file)
+                                break;
+
+                        /* 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;
+
+                        r = journal_file_find_data_object_with_hash(of, odata, ol, le64toh(o->data.hash), NULL, NULL);
+                        if (r < 0)
+                                return r;
+                        if (r > 0) {
+                                found = true;
+                                break;
+                        }
+                }
+
+                if (found)
+                        continue;
+
+                r = return_data(j, j->unique_file, o, data, l);
+                if (r < 0)
+                        return r;
+
+                return 1;
+        }
+}
+
+_public_ void sd_journal_restart_unique(sd_journal *j) {
+        if (!j)
+                return;
+
+        j->unique_file = NULL;
+        j->unique_offset = 0;
+        j->unique_file_lost = false;
+}
+
+_public_ int sd_journal_enumerate_fields(sd_journal *j, const char **field) {
+        int r;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(field, -EINVAL);
+
+        if (!j->fields_file) {
+                if (j->fields_file_lost)
+                        return 0;
+
+                j->fields_file = ordered_hashmap_first(j->files);
+                if (!j->fields_file)
+                        return 0;
+
+                j->fields_hash_table_index = 0;
+                j->fields_offset = 0;
+        }
+
+        for (;;) {
+                JournalFile *f, *of;
+                Iterator i;
+                uint64_t m;
+                Object *o;
+                size_t sz;
+                bool found;
+
+                f = j->fields_file;
+
+                if (j->fields_offset == 0) {
+                        bool eof = false;
+
+                        /* We are not yet positioned at any field. Let's pick the first one */
+                        r = journal_file_map_field_hash_table(f);
+                        if (r < 0)
+                                return r;
+
+                        m = le64toh(f->header->field_hash_table_size) / sizeof(HashItem);
+                        for (;;) {
+                                if (j->fields_hash_table_index >= m) {
+                                        /* Reached the end of the hash table, go to the next file. */
+                                        eof = true;
+                                        break;
+                                }
+
+                                j->fields_offset = le64toh(f->field_hash_table[j->fields_hash_table_index].head_hash_offset);
+
+                                if (j->fields_offset != 0)
+                                        break;
+
+                                /* Empty hash table bucket, go to next one */
+                                j->fields_hash_table_index++;
+                        }
+
+                        if (eof) {
+                                /* Proceed with next file */
+                                j->fields_file = ordered_hashmap_next(j->files, f->path);
+                                if (!j->fields_file) {
+                                        *field = NULL;
+                                        return 0;
+                                }
+
+                                j->fields_offset = 0;
+                                j->fields_hash_table_index = 0;
+                                continue;
+                        }
+
+                } else {
+                        /* We are already positioned at a field. If so, let's figure out the next field from it */
+
+                        r = journal_file_move_to_object(f, OBJECT_FIELD, j->fields_offset, &o);
+                        if (r < 0)
+                                return r;
+
+                        j->fields_offset = le64toh(o->field.next_hash_offset);
+                        if (j->fields_offset == 0) {
+                                /* Reached the end of the hash table chain */
+                                j->fields_hash_table_index++;
+                                continue;
+                        }
+                }
+
+                /* We use OBJECT_UNUSED here, so that the iterator below doesn't remove our mmap window */
+                r = journal_file_move_to_object(f, OBJECT_UNUSED, j->fields_offset, &o);
+                if (r < 0)
+                        return r;
+
+                /* Because we used OBJECT_UNUSED above, we need to do our type check manually */
+                if (o->object.type != OBJECT_FIELD)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "%s:offset " OFSfmt ": object has type %i, expected %i",
+                                               f->path, j->fields_offset,
+                                               o->object.type, OBJECT_FIELD);
+
+                sz = le64toh(o->object.size) - offsetof(Object, field.payload);
+
+                /* Let's see if we already returned this field name before. */
+                found = false;
+                ORDERED_HASHMAP_FOREACH(of, j->files, i) {
+                        if (of == f)
+                                break;
+
+                        /* 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;
+
+                        r = journal_file_find_field_object_with_hash(of, o->field.payload, sz, le64toh(o->field.hash), NULL, NULL);
+                        if (r < 0)
+                                return r;
+                        if (r > 0) {
+                                found = true;
+                                break;
+                        }
+                }
+
+                if (found)
+                        continue;
+
+                /* Check if this is really a valid string containing no NUL byte */
+                if (memchr(o->field.payload, 0, sz))
+                        return -EBADMSG;
+
+                if (sz > j->data_threshold)
+                        sz = j->data_threshold;
+
+                if (!GREEDY_REALLOC(j->fields_buffer, j->fields_buffer_allocated, sz + 1))
+                        return -ENOMEM;
+
+                memcpy(j->fields_buffer, o->field.payload, sz);
+                j->fields_buffer[sz] = 0;
+
+                if (!field_is_valid(j->fields_buffer))
+                        return -EBADMSG;
+
+                *field = j->fields_buffer;
+                return 1;
+        }
+}
+
+_public_ void sd_journal_restart_fields(sd_journal *j) {
+        if (!j)
+                return;
+
+        j->fields_file = NULL;
+        j->fields_hash_table_index = 0;
+        j->fields_offset = 0;
+        j->fields_file_lost = false;
+}
+
+_public_ int sd_journal_reliable_fd(sd_journal *j) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        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;
+
+        assert(field);
+        assert(j);
+
+        r = sd_journal_get_data(j, field, &data, &size);
+        if (r < 0 ||
+            size > REPLACE_VAR_MAX)
+                return strdup(field);
+
+        d = strlen(field) + 1;
+
+        return strndup((const char*) data + d, size - d);
+}
+
+_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;
+
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(ret, -EINVAL);
+
+        r = sd_journal_get_data(j, "MESSAGE_ID", &data, &size);
+        if (r < 0)
+                return r;
+
+        cid = strndup((const char*) data + 11, size - 11);
+        if (!cid)
+                return -ENOMEM;
+
+        r = sd_id128_from_string(cid, &id);
+        if (r < 0)
+                return r;
+
+        r = catalog_get(CATALOG_DATABASE, id, &text);
+        if (r < 0)
+                return r;
+
+        t = replace_var(text, lookup_field, j);
+        if (!t)
+                return -ENOMEM;
+
+        *ret = t;
+        return 0;
+}
+
+_public_ int sd_journal_get_catalog_for_message_id(sd_id128_t id, char **ret) {
+        assert_return(ret, -EINVAL);
+
+        return catalog_get(CATALOG_DATABASE, id, ret);
+}
+
+_public_ int sd_journal_set_data_threshold(sd_journal *j, size_t sz) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+
+        j->data_threshold = sz;
+        return 0;
+}
+
+_public_ int sd_journal_get_data_threshold(sd_journal *j, size_t *sz) {
+        assert_return(j, -EINVAL);
+        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(sz, -EINVAL);
+
+        *sz = j->data_threshold;
+        return 0;
+}
+
+_public_ int sd_journal_has_runtime_files(sd_journal *j) {
+        assert_return(j, -EINVAL);
+
+        return j->has_runtime_files;
+}
+
+_public_ int sd_journal_has_persistent_files(sd_journal *j) {
+        assert_return(j, -EINVAL);
+
+        return j->has_persistent_files;
+}