update systemd & dbus dependencies

Update the outdated systemd and dbus dependencies which are now provided
as go modules.  This will further tighten our dependencies and releases
and pave the way for the upcoming auto-update feature.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

3 files changed, 1458 insertions, 0 deletions

diff --git a/vendor/github.com/coreos/go-systemd/v22/sdjournal/functions.go b/vendor/github.com/coreos/go-systemd/v22/sdjournal/functions.go
new file mode 100644
index 000000000..3cbd05658
--- /dev/null
+++ b/vendor/github.com/coreos/go-systemd/v22/sdjournal/functions.go
@@ -0,0 +1,66 @@
+// Copyright 2015 RedHat, Inc.
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sdjournal
+
+import (
+	"github.com/coreos/go-systemd/v22/internal/dlopen"
+	"sync"
+	"unsafe"
+)
+
+var (
+	// lazy initialized
+	libsystemdHandle *dlopen.LibHandle
+
+	libsystemdMutex     = &sync.Mutex{}
+	libsystemdFunctions = map[string]unsafe.Pointer{}
+	libsystemdNames     = []string{
+		// systemd < 209
+		"libsystemd-journal.so.0",
+		"libsystemd-journal.so",
+
+		// systemd >= 209 merged libsystemd-journal into libsystemd proper
+		"libsystemd.so.0",
+		"libsystemd.so",
+	}
+)
+
+func getFunction(name string) (unsafe.Pointer, error) {
+	libsystemdMutex.Lock()
+	defer libsystemdMutex.Unlock()
+
+	if libsystemdHandle == nil {
+		h, err := dlopen.GetHandle(libsystemdNames)
+		if err != nil {
+			return nil, err
+		}
+
+		libsystemdHandle = h
+	}
+
+	f, ok := libsystemdFunctions[name]
+	if !ok {
+		var err error
+		f, err = libsystemdHandle.GetSymbolPointer(name)
+		if err != nil {
+			return nil, err
+		}
+
+		libsystemdFunctions[name] = f
+	}
+
+	return f, nil
+}
diff --git a/vendor/github.com/coreos/go-systemd/v22/sdjournal/journal.go b/vendor/github.com/coreos/go-systemd/v22/sdjournal/journal.go
new file mode 100644
index 000000000..7f840def8
--- /dev/null
+++ b/vendor/github.com/coreos/go-systemd/v22/sdjournal/journal.go
@@ -0,0 +1,1120 @@
+// Copyright 2015 RedHat, Inc.
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package sdjournal provides a low-level Go interface to the
+// systemd journal wrapped around the sd-journal C API.
+//
+// All public read methods map closely to the sd-journal API functions. See the
+// sd-journal.h documentation[1] for information about each function.
+//
+// To write to the journal, see the pure-Go "journal" package
+//
+// [1] http://www.freedesktop.org/software/systemd/man/sd-journal.html
+package sdjournal
+
+// #include <systemd/sd-journal.h>
+// #include <systemd/sd-id128.h>
+// #include <stdlib.h>
+// #include <syslog.h>
+//
+// int
+// my_sd_journal_open(void *f, sd_journal **ret, int flags)
+// {
+//   int (*sd_journal_open)(sd_journal **, int);
+//
+//   sd_journal_open = f;
+//   return sd_journal_open(ret, flags);
+// }
+//
+// int
+// my_sd_journal_open_directory(void *f, sd_journal **ret, const char *path, int flags)
+// {
+//   int (*sd_journal_open_directory)(sd_journal **, const char *, int);
+//
+//   sd_journal_open_directory = f;
+//   return sd_journal_open_directory(ret, path, flags);
+// }
+//
+// int
+// my_sd_journal_open_files(void *f, sd_journal **ret, const char **paths, int flags)
+// {
+//   int (*sd_journal_open_files)(sd_journal **, const char **, int);
+//
+//   sd_journal_open_files = f;
+//   return sd_journal_open_files(ret, paths, flags);
+// }
+//
+// void
+// my_sd_journal_close(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_close)(sd_journal *);
+//
+//   sd_journal_close = f;
+//   sd_journal_close(j);
+// }
+//
+// int
+// my_sd_journal_get_usage(void *f, sd_journal *j, uint64_t *bytes)
+// {
+//   int (*sd_journal_get_usage)(sd_journal *, uint64_t *);
+//
+//   sd_journal_get_usage = f;
+//   return sd_journal_get_usage(j, bytes);
+// }
+//
+// int
+// my_sd_journal_add_match(void *f, sd_journal *j, const void *data, size_t size)
+// {
+//   int (*sd_journal_add_match)(sd_journal *, const void *, size_t);
+//
+//   sd_journal_add_match = f;
+//   return sd_journal_add_match(j, data, size);
+// }
+//
+// int
+// my_sd_journal_add_disjunction(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_add_disjunction)(sd_journal *);
+//
+//   sd_journal_add_disjunction = f;
+//   return sd_journal_add_disjunction(j);
+// }
+//
+// int
+// my_sd_journal_add_conjunction(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_add_conjunction)(sd_journal *);
+//
+//   sd_journal_add_conjunction = f;
+//   return sd_journal_add_conjunction(j);
+// }
+//
+// void
+// my_sd_journal_flush_matches(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_flush_matches)(sd_journal *);
+//
+//   sd_journal_flush_matches = f;
+//   sd_journal_flush_matches(j);
+// }
+//
+// int
+// my_sd_journal_next(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_next)(sd_journal *);
+//
+//   sd_journal_next = f;
+//   return sd_journal_next(j);
+// }
+//
+// int
+// my_sd_journal_next_skip(void *f, sd_journal *j, uint64_t skip)
+// {
+//   int (*sd_journal_next_skip)(sd_journal *, uint64_t);
+//
+//   sd_journal_next_skip = f;
+//   return sd_journal_next_skip(j, skip);
+// }
+//
+// int
+// my_sd_journal_previous(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_previous)(sd_journal *);
+//
+//   sd_journal_previous = f;
+//   return sd_journal_previous(j);
+// }
+//
+// int
+// my_sd_journal_previous_skip(void *f, sd_journal *j, uint64_t skip)
+// {
+//   int (*sd_journal_previous_skip)(sd_journal *, uint64_t);
+//
+//   sd_journal_previous_skip = f;
+//   return sd_journal_previous_skip(j, skip);
+// }
+//
+// int
+// my_sd_journal_get_data(void *f, sd_journal *j, const char *field, const void **data, size_t *length)
+// {
+//   int (*sd_journal_get_data)(sd_journal *, const char *, const void **, size_t *);
+//
+//   sd_journal_get_data = f;
+//   return sd_journal_get_data(j, field, data, length);
+// }
+//
+// int
+// my_sd_journal_set_data_threshold(void *f, sd_journal *j, size_t sz)
+// {
+//   int (*sd_journal_set_data_threshold)(sd_journal *, size_t);
+//
+//   sd_journal_set_data_threshold = f;
+//   return sd_journal_set_data_threshold(j, sz);
+// }
+//
+// int
+// my_sd_journal_get_cursor(void *f, sd_journal *j, char **cursor)
+// {
+//   int (*sd_journal_get_cursor)(sd_journal *, char **);
+//
+//   sd_journal_get_cursor = f;
+//   return sd_journal_get_cursor(j, cursor);
+// }
+//
+// int
+// my_sd_journal_test_cursor(void *f, sd_journal *j, const char *cursor)
+// {
+//   int (*sd_journal_test_cursor)(sd_journal *, const char *);
+//
+//   sd_journal_test_cursor = f;
+//   return sd_journal_test_cursor(j, cursor);
+// }
+//
+// int
+// my_sd_journal_get_realtime_usec(void *f, sd_journal *j, uint64_t *usec)
+// {
+//   int (*sd_journal_get_realtime_usec)(sd_journal *, uint64_t *);
+//
+//   sd_journal_get_realtime_usec = f;
+//   return sd_journal_get_realtime_usec(j, usec);
+// }
+//
+// int
+// my_sd_journal_get_monotonic_usec(void *f, sd_journal *j, uint64_t *usec, sd_id128_t *boot_id)
+// {
+//   int (*sd_journal_get_monotonic_usec)(sd_journal *, uint64_t *, sd_id128_t *);
+//
+//   sd_journal_get_monotonic_usec = f;
+//   return sd_journal_get_monotonic_usec(j, usec, boot_id);
+// }
+//
+// int
+// my_sd_journal_seek_head(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_seek_head)(sd_journal *);
+//
+//   sd_journal_seek_head = f;
+//   return sd_journal_seek_head(j);
+// }
+//
+// int
+// my_sd_journal_seek_tail(void *f, sd_journal *j)
+// {
+//   int (*sd_journal_seek_tail)(sd_journal *);
+//
+//   sd_journal_seek_tail = f;
+//   return sd_journal_seek_tail(j);
+// }
+//
+//
+// int
+// my_sd_journal_seek_cursor(void *f, sd_journal *j, const char *cursor)
+// {
+//   int (*sd_journal_seek_cursor)(sd_journal *, const char *);
+//
+//   sd_journal_seek_cursor = f;
+//   return sd_journal_seek_cursor(j, cursor);
+// }
+//
+// int
+// my_sd_journal_seek_realtime_usec(void *f, sd_journal *j, uint64_t usec)
+// {
+//   int (*sd_journal_seek_realtime_usec)(sd_journal *, uint64_t);
+//
+//   sd_journal_seek_realtime_usec = f;
+//   return sd_journal_seek_realtime_usec(j, usec);
+// }
+//
+// int
+// my_sd_journal_wait(void *f, sd_journal *j, uint64_t timeout_usec)
+// {
+//   int (*sd_journal_wait)(sd_journal *, uint64_t);
+//
+//   sd_journal_wait = f;
+//   return sd_journal_wait(j, timeout_usec);
+// }
+//
+// void
+// my_sd_journal_restart_data(void *f, sd_journal *j)
+// {
+//   void (*sd_journal_restart_data)(sd_journal *);
+//
+//   sd_journal_restart_data = f;
+//   sd_journal_restart_data(j);
+// }
+//
+// int
+// my_sd_journal_enumerate_data(void *f, sd_journal *j, const void **data, size_t *length)
+// {
+//   int (*sd_journal_enumerate_data)(sd_journal *, const void **, size_t *);
+//
+//   sd_journal_enumerate_data = f;
+//   return sd_journal_enumerate_data(j, data, length);
+// }
+//
+// int
+// my_sd_journal_query_unique(void *f, sd_journal *j, const char *field)
+// {
+//   int(*sd_journal_query_unique)(sd_journal *, const char *);
+//
+//   sd_journal_query_unique = f;
+//   return sd_journal_query_unique(j, field);
+// }
+//
+// int
+// my_sd_journal_enumerate_unique(void *f, sd_journal *j, const void **data, size_t *length)
+// {
+//   int(*sd_journal_enumerate_unique)(sd_journal *, const void **, size_t *);
+//
+//   sd_journal_enumerate_unique = f;
+//   return sd_journal_enumerate_unique(j, data, length);
+// }
+//
+// void
+// my_sd_journal_restart_unique(void *f, sd_journal *j)
+// {
+//   void(*sd_journal_restart_unique)(sd_journal *);
+//
+//   sd_journal_restart_unique = f;
+//   sd_journal_restart_unique(j);
+// }
+//
+// int
+// my_sd_journal_get_catalog(void *f, sd_journal *j, char **ret)
+// {
+//   int(*sd_journal_get_catalog)(sd_journal *, char **);
+//
+//   sd_journal_get_catalog = f;
+//   return sd_journal_get_catalog(j, ret);
+// }
+//
+import "C"
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+// Journal entry field strings which correspond to:
+// http://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html
+const (
+	// User Journal Fields
+	SD_JOURNAL_FIELD_MESSAGE           = "MESSAGE"
+	SD_JOURNAL_FIELD_MESSAGE_ID        = "MESSAGE_ID"
+	SD_JOURNAL_FIELD_PRIORITY          = "PRIORITY"
+	SD_JOURNAL_FIELD_CODE_FILE         = "CODE_FILE"
+	SD_JOURNAL_FIELD_CODE_LINE         = "CODE_LINE"
+	SD_JOURNAL_FIELD_CODE_FUNC         = "CODE_FUNC"
+	SD_JOURNAL_FIELD_ERRNO             = "ERRNO"
+	SD_JOURNAL_FIELD_SYSLOG_FACILITY   = "SYSLOG_FACILITY"
+	SD_JOURNAL_FIELD_SYSLOG_IDENTIFIER = "SYSLOG_IDENTIFIER"
+	SD_JOURNAL_FIELD_SYSLOG_PID        = "SYSLOG_PID"
+
+	// Trusted Journal Fields
+	SD_JOURNAL_FIELD_PID                       = "_PID"
+	SD_JOURNAL_FIELD_UID                       = "_UID"
+	SD_JOURNAL_FIELD_GID                       = "_GID"
+	SD_JOURNAL_FIELD_COMM                      = "_COMM"
+	SD_JOURNAL_FIELD_EXE                       = "_EXE"
+	SD_JOURNAL_FIELD_CMDLINE                   = "_CMDLINE"
+	SD_JOURNAL_FIELD_CAP_EFFECTIVE             = "_CAP_EFFECTIVE"
+	SD_JOURNAL_FIELD_AUDIT_SESSION             = "_AUDIT_SESSION"
+	SD_JOURNAL_FIELD_AUDIT_LOGINUID            = "_AUDIT_LOGINUID"
+	SD_JOURNAL_FIELD_SYSTEMD_CGROUP            = "_SYSTEMD_CGROUP"
+	SD_JOURNAL_FIELD_SYSTEMD_SESSION           = "_SYSTEMD_SESSION"
+	SD_JOURNAL_FIELD_SYSTEMD_UNIT              = "_SYSTEMD_UNIT"
+	SD_JOURNAL_FIELD_SYSTEMD_USER_UNIT         = "_SYSTEMD_USER_UNIT"
+	SD_JOURNAL_FIELD_SYSTEMD_OWNER_UID         = "_SYSTEMD_OWNER_UID"
+	SD_JOURNAL_FIELD_SYSTEMD_SLICE             = "_SYSTEMD_SLICE"
+	SD_JOURNAL_FIELD_SELINUX_CONTEXT           = "_SELINUX_CONTEXT"
+	SD_JOURNAL_FIELD_SOURCE_REALTIME_TIMESTAMP = "_SOURCE_REALTIME_TIMESTAMP"
+	SD_JOURNAL_FIELD_BOOT_ID                   = "_BOOT_ID"
+	SD_JOURNAL_FIELD_MACHINE_ID                = "_MACHINE_ID"
+	SD_JOURNAL_FIELD_HOSTNAME                  = "_HOSTNAME"
+	SD_JOURNAL_FIELD_TRANSPORT                 = "_TRANSPORT"
+
+	// Address Fields
+	SD_JOURNAL_FIELD_CURSOR              = "__CURSOR"
+	SD_JOURNAL_FIELD_REALTIME_TIMESTAMP  = "__REALTIME_TIMESTAMP"
+	SD_JOURNAL_FIELD_MONOTONIC_TIMESTAMP = "__MONOTONIC_TIMESTAMP"
+)
+
+// Journal event constants
+const (
+	SD_JOURNAL_NOP        = int(C.SD_JOURNAL_NOP)
+	SD_JOURNAL_APPEND     = int(C.SD_JOURNAL_APPEND)
+	SD_JOURNAL_INVALIDATE = int(C.SD_JOURNAL_INVALIDATE)
+)
+
+const (
+	// IndefiniteWait is a sentinel value that can be passed to
+	// sdjournal.Wait() to signal an indefinite wait for new journal
+	// events. It is implemented as the maximum value for a time.Duration:
+	// https://github.com/golang/go/blob/e4dcf5c8c22d98ac9eac7b9b226596229624cb1d/src/time/time.go#L434
+	IndefiniteWait time.Duration = 1<<63 - 1
+)
+
+var (
+	// ErrNoTestCursor gets returned when using TestCursor function and cursor
+	// parameter is not the same as the current cursor position.
+	ErrNoTestCursor = errors.New("Cursor parameter is not the same as current position")
+)
+
+// Journal is a Go wrapper of an sd_journal structure.
+type Journal struct {
+	cjournal *C.sd_journal
+	mu       sync.Mutex
+}
+
+// JournalEntry represents all fields of a journal entry plus address fields.
+type JournalEntry struct {
+	Fields             map[string]string
+	Cursor             string
+	RealtimeTimestamp  uint64
+	MonotonicTimestamp uint64
+}
+
+// Match is a convenience wrapper to describe filters supplied to AddMatch.
+type Match struct {
+	Field string
+	Value string
+}
+
+// String returns a string representation of a Match suitable for use with AddMatch.
+func (m *Match) String() string {
+	return m.Field + "=" + m.Value
+}
+
+// NewJournal returns a new Journal instance pointing to the local journal
+func NewJournal() (j *Journal, err error) {
+	j = &Journal{}
+
+	sd_journal_open, err := getFunction("sd_journal_open")
+	if err != nil {
+		return nil, err
+	}
+
+	r := C.my_sd_journal_open(sd_journal_open, &j.cjournal, C.SD_JOURNAL_LOCAL_ONLY)
+
+	if r < 0 {
+		return nil, fmt.Errorf("failed to open journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return j, nil
+}
+
+// NewJournalFromDir returns a new Journal instance pointing to a journal residing
+// in a given directory.
+func NewJournalFromDir(path string) (j *Journal, err error) {
+	j = &Journal{}
+
+	sd_journal_open_directory, err := getFunction("sd_journal_open_directory")
+	if err != nil {
+		return nil, err
+	}
+
+	p := C.CString(path)
+	defer C.free(unsafe.Pointer(p))
+
+	r := C.my_sd_journal_open_directory(sd_journal_open_directory, &j.cjournal, p, 0)
+	if r < 0 {
+		return nil, fmt.Errorf("failed to open journal in directory %q: %s", path, syscall.Errno(-r).Error())
+	}
+
+	return j, nil
+}
+
+// NewJournalFromFiles returns a new Journal instance pointing to a journals residing
+// in a given files.
+func NewJournalFromFiles(paths ...string) (j *Journal, err error) {
+	j = &Journal{}
+
+	sd_journal_open_files, err := getFunction("sd_journal_open_files")
+	if err != nil {
+		return nil, err
+	}
+
+	// by making the slice 1 elem too long, we guarantee it'll be null-terminated
+	cPaths := make([]*C.char, len(paths)+1)
+	for idx, path := range paths {
+		p := C.CString(path)
+		cPaths[idx] = p
+		defer C.free(unsafe.Pointer(p))
+	}
+
+	r := C.my_sd_journal_open_files(sd_journal_open_files, &j.cjournal, &cPaths[0], 0)
+	if r < 0 {
+		return nil, fmt.Errorf("failed to open journals in paths %q: %s", paths, syscall.Errno(-r).Error())
+	}
+
+	return j, nil
+}
+
+// Close closes a journal opened with NewJournal.
+func (j *Journal) Close() error {
+	sd_journal_close, err := getFunction("sd_journal_close")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	C.my_sd_journal_close(sd_journal_close, j.cjournal)
+	j.mu.Unlock()
+
+	return nil
+}
+
+// AddMatch adds a match by which to filter the entries of the journal.
+func (j *Journal) AddMatch(match string) error {
+	sd_journal_add_match, err := getFunction("sd_journal_add_match")
+	if err != nil {
+		return err
+	}
+
+	m := C.CString(match)
+	defer C.free(unsafe.Pointer(m))
+
+	j.mu.Lock()
+	r := C.my_sd_journal_add_match(sd_journal_add_match, j.cjournal, unsafe.Pointer(m), C.size_t(len(match)))
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to add match: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// AddDisjunction inserts a logical OR in the match list.
+func (j *Journal) AddDisjunction() error {
+	sd_journal_add_disjunction, err := getFunction("sd_journal_add_disjunction")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_add_disjunction(sd_journal_add_disjunction, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to add a disjunction in the match list: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// AddConjunction inserts a logical AND in the match list.
+func (j *Journal) AddConjunction() error {
+	sd_journal_add_conjunction, err := getFunction("sd_journal_add_conjunction")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_add_conjunction(sd_journal_add_conjunction, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to add a conjunction in the match list: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// FlushMatches flushes all matches, disjunctions and conjunctions.
+func (j *Journal) FlushMatches() {
+	sd_journal_flush_matches, err := getFunction("sd_journal_flush_matches")
+	if err != nil {
+		return
+	}
+
+	j.mu.Lock()
+	C.my_sd_journal_flush_matches(sd_journal_flush_matches, j.cjournal)
+	j.mu.Unlock()
+}
+
+// Next advances the read pointer into the journal by one entry.
+func (j *Journal) Next() (uint64, error) {
+	sd_journal_next, err := getFunction("sd_journal_next")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_next(sd_journal_next, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to iterate journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(r), nil
+}
+
+// NextSkip advances the read pointer by multiple entries at once,
+// as specified by the skip parameter.
+func (j *Journal) NextSkip(skip uint64) (uint64, error) {
+	sd_journal_next_skip, err := getFunction("sd_journal_next_skip")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_next_skip(sd_journal_next_skip, j.cjournal, C.uint64_t(skip))
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to iterate journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(r), nil
+}
+
+// Previous sets the read pointer into the journal back by one entry.
+func (j *Journal) Previous() (uint64, error) {
+	sd_journal_previous, err := getFunction("sd_journal_previous")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_previous(sd_journal_previous, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to iterate journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(r), nil
+}
+
+// PreviousSkip sets back the read pointer by multiple entries at once,
+// as specified by the skip parameter.
+func (j *Journal) PreviousSkip(skip uint64) (uint64, error) {
+	sd_journal_previous_skip, err := getFunction("sd_journal_previous_skip")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_previous_skip(sd_journal_previous_skip, j.cjournal, C.uint64_t(skip))
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to iterate journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(r), nil
+}
+
+func (j *Journal) getData(field string) (unsafe.Pointer, C.int, error) {
+	sd_journal_get_data, err := getFunction("sd_journal_get_data")
+	if err != nil {
+		return nil, 0, err
+	}
+
+	f := C.CString(field)
+	defer C.free(unsafe.Pointer(f))
+
+	var d unsafe.Pointer
+	var l C.size_t
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_data(sd_journal_get_data, j.cjournal, f, &d, &l)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return nil, 0, fmt.Errorf("failed to read message: %s", syscall.Errno(-r).Error())
+	}
+
+	return d, C.int(l), nil
+}
+
+// GetData gets the data object associated with a specific field from the
+// the journal entry referenced by the last completed Next/Previous function
+// call. To call GetData, you must have first called one of these functions.
+func (j *Journal) GetData(field string) (string, error) {
+	d, l, err := j.getData(field)
+	if err != nil {
+		return "", err
+	}
+
+	return C.GoStringN((*C.char)(d), l), nil
+}
+
+// GetDataValue gets the data object associated with a specific field from the
+// journal entry referenced by the last completed Next/Previous function call,
+// returning only the value of the object. To call GetDataValue, you must first
+// have called one of the Next/Previous functions.
+func (j *Journal) GetDataValue(field string) (string, error) {
+	val, err := j.GetData(field)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.SplitN(val, "=", 2)[1], nil
+}
+
+// GetDataBytes gets the data object associated with a specific field from the
+// journal entry referenced by the last completed Next/Previous function call.
+// To call GetDataBytes, you must first have called one of these functions.
+func (j *Journal) GetDataBytes(field string) ([]byte, error) {
+	d, l, err := j.getData(field)
+	if err != nil {
+		return nil, err
+	}
+
+	return C.GoBytes(d, l), nil
+}
+
+// GetDataValueBytes gets the data object associated with a specific field from the
+// journal entry referenced by the last completed Next/Previous function call,
+// returning only the value of the object. To call GetDataValueBytes, you must first
+// have called one of the Next/Previous functions.
+func (j *Journal) GetDataValueBytes(field string) ([]byte, error) {
+	val, err := j.GetDataBytes(field)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.SplitN(val, []byte("="), 2)[1], nil
+}
+
+// GetEntry returns a full representation of the journal entry referenced by the
+// last completed Next/Previous function call, with all key-value pairs of data
+// as well as address fields (cursor, realtime timestamp and monotonic timestamp).
+// To call GetEntry, you must first have called one of the Next/Previous functions.
+func (j *Journal) GetEntry() (*JournalEntry, error) {
+	sd_journal_get_realtime_usec, err := getFunction("sd_journal_get_realtime_usec")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_get_monotonic_usec, err := getFunction("sd_journal_get_monotonic_usec")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_get_cursor, err := getFunction("sd_journal_get_cursor")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_restart_data, err := getFunction("sd_journal_restart_data")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_enumerate_data, err := getFunction("sd_journal_enumerate_data")
+	if err != nil {
+		return nil, err
+	}
+
+	j.mu.Lock()
+	defer j.mu.Unlock()
+
+	var r C.int
+	entry := &JournalEntry{Fields: make(map[string]string)}
+
+	var realtimeUsec C.uint64_t
+	r = C.my_sd_journal_get_realtime_usec(sd_journal_get_realtime_usec, j.cjournal, &realtimeUsec)
+	if r < 0 {
+		return nil, fmt.Errorf("failed to get realtime timestamp: %s", syscall.Errno(-r).Error())
+	}
+
+	entry.RealtimeTimestamp = uint64(realtimeUsec)
+
+	var monotonicUsec C.uint64_t
+	var boot_id C.sd_id128_t
+
+	r = C.my_sd_journal_get_monotonic_usec(sd_journal_get_monotonic_usec, j.cjournal, &monotonicUsec, &boot_id)
+	if r < 0 {
+		return nil, fmt.Errorf("failed to get monotonic timestamp: %s", syscall.Errno(-r).Error())
+	}
+
+	entry.MonotonicTimestamp = uint64(monotonicUsec)
+
+	var c *C.char
+	// since the pointer is mutated by sd_journal_get_cursor, need to wait
+	// until after the call to free the memory
+	r = C.my_sd_journal_get_cursor(sd_journal_get_cursor, j.cjournal, &c)
+	defer C.free(unsafe.Pointer(c))
+	if r < 0 {
+		return nil, fmt.Errorf("failed to get cursor: %s", syscall.Errno(-r).Error())
+	}
+
+	entry.Cursor = C.GoString(c)
+
+	// Implements the JOURNAL_FOREACH_DATA_RETVAL macro from journal-internal.h
+	var d unsafe.Pointer
+	var l C.size_t
+	C.my_sd_journal_restart_data(sd_journal_restart_data, j.cjournal)
+	for {
+		r = C.my_sd_journal_enumerate_data(sd_journal_enumerate_data, j.cjournal, &d, &l)
+		if r == 0 {
+			break
+		}
+
+		if r < 0 {
+			return nil, fmt.Errorf("failed to read message field: %s", syscall.Errno(-r).Error())
+		}
+
+		msg := C.GoStringN((*C.char)(d), C.int(l))
+		kv := strings.SplitN(msg, "=", 2)
+		if len(kv) < 2 {
+			return nil, fmt.Errorf("failed to parse field")
+		}
+
+		entry.Fields[kv[0]] = kv[1]
+	}
+
+	return entry, nil
+}
+
+// SetDataThreshold sets the data field size threshold for data returned by
+// GetData. To retrieve the complete data fields this threshold should be
+// turned off by setting it to 0, so that the library always returns the
+// complete data objects.
+func (j *Journal) SetDataThreshold(threshold uint64) error {
+	sd_journal_set_data_threshold, err := getFunction("sd_journal_set_data_threshold")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_set_data_threshold(sd_journal_set_data_threshold, j.cjournal, C.size_t(threshold))
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to set data threshold: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// GetRealtimeUsec gets the realtime (wallclock) timestamp of the journal
+// entry referenced by the last completed Next/Previous function call. To
+// call GetRealtimeUsec, you must first have called one of the Next/Previous
+// functions.
+func (j *Journal) GetRealtimeUsec() (uint64, error) {
+	var usec C.uint64_t
+
+	sd_journal_get_realtime_usec, err := getFunction("sd_journal_get_realtime_usec")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_realtime_usec(sd_journal_get_realtime_usec, j.cjournal, &usec)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to get realtime timestamp: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(usec), nil
+}
+
+// GetMonotonicUsec gets the monotonic timestamp of the journal entry
+// referenced by the last completed Next/Previous function call. To call
+// GetMonotonicUsec, you must first have called one of the Next/Previous
+// functions.
+func (j *Journal) GetMonotonicUsec() (uint64, error) {
+	var usec C.uint64_t
+	var boot_id C.sd_id128_t
+
+	sd_journal_get_monotonic_usec, err := getFunction("sd_journal_get_monotonic_usec")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_monotonic_usec(sd_journal_get_monotonic_usec, j.cjournal, &usec, &boot_id)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to get monotonic timestamp: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(usec), nil
+}
+
+// GetCursor gets the cursor of the last journal entry reeferenced by the
+// last completed Next/Previous function call. To call GetCursor, you must
+// first have called one of the Next/Previous functions.
+func (j *Journal) GetCursor() (string, error) {
+	sd_journal_get_cursor, err := getFunction("sd_journal_get_cursor")
+	if err != nil {
+		return "", err
+	}
+
+	var d *C.char
+	// since the pointer is mutated by sd_journal_get_cursor, need to wait
+	// until after the call to free the memory
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_cursor(sd_journal_get_cursor, j.cjournal, &d)
+	j.mu.Unlock()
+	defer C.free(unsafe.Pointer(d))
+
+	if r < 0 {
+		return "", fmt.Errorf("failed to get cursor: %s", syscall.Errno(-r).Error())
+	}
+
+	cursor := C.GoString(d)
+
+	return cursor, nil
+}
+
+// TestCursor checks whether the current position in the journal matches the
+// specified cursor
+func (j *Journal) TestCursor(cursor string) error {
+	sd_journal_test_cursor, err := getFunction("sd_journal_test_cursor")
+	if err != nil {
+		return err
+	}
+
+	c := C.CString(cursor)
+	defer C.free(unsafe.Pointer(c))
+
+	j.mu.Lock()
+	r := C.my_sd_journal_test_cursor(sd_journal_test_cursor, j.cjournal, c)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to test to cursor %q: %s", cursor, syscall.Errno(-r).Error())
+	} else if r == 0 {
+		return ErrNoTestCursor
+	}
+
+	return nil
+}
+
+// SeekHead seeks to the beginning of the journal, i.e. the oldest available
+// entry. This call must be followed by a call to Next before any call to
+// Get* will return data about the first element.
+func (j *Journal) SeekHead() error {
+	sd_journal_seek_head, err := getFunction("sd_journal_seek_head")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_seek_head(sd_journal_seek_head, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to seek to head of journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// SeekTail may be used to seek to the end of the journal, i.e. the most recent
+// available entry. This call must be followed by a call to Next before any
+// call to Get* will return data about the last element.
+func (j *Journal) SeekTail() error {
+	sd_journal_seek_tail, err := getFunction("sd_journal_seek_tail")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_seek_tail(sd_journal_seek_tail, j.cjournal)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to seek to tail of journal: %s", syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// SeekRealtimeUsec seeks to the entry with the specified realtime (wallclock)
+// timestamp, i.e. CLOCK_REALTIME. This call must be followed by a call to
+// Next/Previous before any call to Get* will return data about the sought entry.
+func (j *Journal) SeekRealtimeUsec(usec uint64) error {
+	sd_journal_seek_realtime_usec, err := getFunction("sd_journal_seek_realtime_usec")
+	if err != nil {
+		return err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_seek_realtime_usec(sd_journal_seek_realtime_usec, j.cjournal, C.uint64_t(usec))
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to seek to %d: %s", usec, syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// SeekCursor seeks to a concrete journal cursor. This call must be
+// followed by a call to Next/Previous before any call to Get* will return
+// data about the sought entry.
+func (j *Journal) SeekCursor(cursor string) error {
+	sd_journal_seek_cursor, err := getFunction("sd_journal_seek_cursor")
+	if err != nil {
+		return err
+	}
+
+	c := C.CString(cursor)
+	defer C.free(unsafe.Pointer(c))
+
+	j.mu.Lock()
+	r := C.my_sd_journal_seek_cursor(sd_journal_seek_cursor, j.cjournal, c)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return fmt.Errorf("failed to seek to cursor %q: %s", cursor, syscall.Errno(-r).Error())
+	}
+
+	return nil
+}
+
+// Wait will synchronously wait until the journal gets changed. The maximum time
+// this call sleeps may be controlled with the timeout parameter.  If
+// sdjournal.IndefiniteWait is passed as the timeout parameter, Wait will
+// wait indefinitely for a journal change.
+func (j *Journal) Wait(timeout time.Duration) int {
+	var to uint64
+
+	sd_journal_wait, err := getFunction("sd_journal_wait")
+	if err != nil {
+		return -1
+	}
+
+	if timeout == IndefiniteWait {
+		// sd_journal_wait(3) calls for a (uint64_t) -1 to be passed to signify
+		// indefinite wait, but using a -1 overflows our C.uint64_t, so we use an
+		// equivalent hex value.
+		to = 0xffffffffffffffff
+	} else {
+		to = uint64(timeout / time.Microsecond)
+	}
+	j.mu.Lock()
+	r := C.my_sd_journal_wait(sd_journal_wait, j.cjournal, C.uint64_t(to))
+	j.mu.Unlock()
+
+	return int(r)
+}
+
+// GetUsage returns the journal disk space usage, in bytes.
+func (j *Journal) GetUsage() (uint64, error) {
+	var out C.uint64_t
+
+	sd_journal_get_usage, err := getFunction("sd_journal_get_usage")
+	if err != nil {
+		return 0, err
+	}
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_usage(sd_journal_get_usage, j.cjournal, &out)
+	j.mu.Unlock()
+
+	if r < 0 {
+		return 0, fmt.Errorf("failed to get journal disk space usage: %s", syscall.Errno(-r).Error())
+	}
+
+	return uint64(out), nil
+}
+
+// GetUniqueValues returns all unique values for a given field.
+func (j *Journal) GetUniqueValues(field string) ([]string, error) {
+	var result []string
+
+	sd_journal_query_unique, err := getFunction("sd_journal_query_unique")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_enumerate_unique, err := getFunction("sd_journal_enumerate_unique")
+	if err != nil {
+		return nil, err
+	}
+
+	sd_journal_restart_unique, err := getFunction("sd_journal_restart_unique")
+	if err != nil {
+		return nil, err
+	}
+
+	j.mu.Lock()
+	defer j.mu.Unlock()
+
+	f := C.CString(field)
+	defer C.free(unsafe.Pointer(f))
+
+	r := C.my_sd_journal_query_unique(sd_journal_query_unique, j.cjournal, f)
+
+	if r < 0 {
+		return nil, fmt.Errorf("failed to query journal: %s", syscall.Errno(-r).Error())
+	}
+
+	// Implements the SD_JOURNAL_FOREACH_UNIQUE macro from sd-journal.h
+	var d unsafe.Pointer
+	var l C.size_t
+	C.my_sd_journal_restart_unique(sd_journal_restart_unique, j.cjournal)
+	for {
+		r = C.my_sd_journal_enumerate_unique(sd_journal_enumerate_unique, j.cjournal, &d, &l)
+		if r == 0 {
+			break
+		}
+
+		if r < 0 {
+			return nil, fmt.Errorf("failed to read message field: %s", syscall.Errno(-r).Error())
+		}
+
+		msg := C.GoStringN((*C.char)(d), C.int(l))
+		kv := strings.SplitN(msg, "=", 2)
+		if len(kv) < 2 {
+			return nil, fmt.Errorf("failed to parse field")
+		}
+
+		result = append(result, kv[1])
+	}
+
+	return result, nil
+}
+
+// GetCatalog retrieves a message catalog entry for the journal entry referenced
+// by the last completed Next/Previous function call. To call GetCatalog, you
+// must first have called one of these functions.
+func (j *Journal) GetCatalog() (string, error) {
+	sd_journal_get_catalog, err := getFunction("sd_journal_get_catalog")
+	if err != nil {
+		return "", err
+	}
+
+	var c *C.char
+
+	j.mu.Lock()
+	r := C.my_sd_journal_get_catalog(sd_journal_get_catalog, j.cjournal, &c)
+	j.mu.Unlock()
+	defer C.free(unsafe.Pointer(c))
+
+	if r < 0 {
+		return "", fmt.Errorf("failed to retrieve catalog entry for current journal entry: %s", syscall.Errno(-r).Error())
+	}
+
+	catalog := C.GoString(c)
+
+	return catalog, nil
+}
diff --git a/vendor/github.com/coreos/go-systemd/v22/sdjournal/read.go b/vendor/github.com/coreos/go-systemd/v22/sdjournal/read.go
new file mode 100644
index 000000000..51a060fb5
--- /dev/null
+++ b/vendor/github.com/coreos/go-systemd/v22/sdjournal/read.go
@@ -0,0 +1,272 @@
+// Copyright 2015 RedHat, Inc.
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sdjournal
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"strings"
+	"sync"
+	"time"
+)
+
+var (
+	// ErrExpired gets returned when the Follow function runs into the
+	// specified timeout.
+	ErrExpired = errors.New("Timeout expired")
+)
+
+// JournalReaderConfig represents options to drive the behavior of a JournalReader.
+type JournalReaderConfig struct {
+	// The Since, NumFromTail and Cursor options are mutually exclusive and
+	// determine where the reading begins within the journal. The order in which
+	// options are written is exactly the order of precedence.
+	Since       time.Duration // start relative to a Duration from now
+	NumFromTail uint64        // start relative to the tail
+	Cursor      string        // start relative to the cursor
+
+	// Show only journal entries whose fields match the supplied values. If
+	// the array is empty, entries will not be filtered.
+	Matches []Match
+
+	// If not empty, the journal instance will point to a journal residing
+	// in this directory. The supplied path may be relative or absolute.
+	Path string
+
+	// If not nil, Formatter will be used to translate the resulting entries
+	// into strings. If not set, the default format (timestamp and message field)
+	// will be used. If Formatter returns an error, Read will stop and return the error.
+	Formatter func(entry *JournalEntry) (string, error)
+}
+
+// JournalReader is an io.ReadCloser which provides a simple interface for iterating through the
+// systemd journal. A JournalReader is not safe for concurrent use by multiple goroutines.
+type JournalReader struct {
+	journal   *Journal
+	msgReader *strings.Reader
+	formatter func(entry *JournalEntry) (string, error)
+}
+
+// NewJournalReader creates a new JournalReader with configuration options that are similar to the
+// systemd journalctl tool's iteration and filtering features.
+func NewJournalReader(config JournalReaderConfig) (*JournalReader, error) {
+	// use simpleMessageFormatter as default formatter.
+	if config.Formatter == nil {
+		config.Formatter = simpleMessageFormatter
+	}
+
+	r := &JournalReader{
+		formatter: config.Formatter,
+	}
+
+	// Open the journal
+	var err error
+	if config.Path != "" {
+		r.journal, err = NewJournalFromDir(config.Path)
+	} else {
+		r.journal, err = NewJournal()
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Add any supplied matches
+	for _, m := range config.Matches {
+		if err = r.journal.AddMatch(m.String()); err != nil {
+			return nil, err
+		}
+	}
+
+	// Set the start position based on options
+	if config.Since != 0 {
+		// Start based on a relative time
+		start := time.Now().Add(config.Since)
+		if err := r.journal.SeekRealtimeUsec(uint64(start.UnixNano() / 1000)); err != nil {
+			return nil, err
+		}
+	} else if config.NumFromTail != 0 {
+		// Start based on a number of lines before the tail
+		if err := r.journal.SeekTail(); err != nil {
+			return nil, err
+		}
+
+		// Move the read pointer into position near the tail. Go one further than
+		// the option so that the initial cursor advancement positions us at the
+		// correct starting point.
+		skip, err := r.journal.PreviousSkip(config.NumFromTail + 1)
+		if err != nil {
+			return nil, err
+		}
+		// If we skipped fewer lines than expected, we have reached journal start.
+		// Thus, we seek to head so that next invocation can read the first line.
+		if skip != config.NumFromTail+1 {
+			if err := r.journal.SeekHead(); err != nil {
+				return nil, err
+			}
+		}
+	} else if config.Cursor != "" {
+		// Start based on a custom cursor
+		if err := r.journal.SeekCursor(config.Cursor); err != nil {
+			return nil, err
+		}
+	}
+
+	return r, nil
+}
+
+// Read reads entries from the journal. Read follows the Reader interface so
+// it must be able to read a specific amount of bytes. Journald on the other
+// hand only allows us to read full entries of arbitrary size (without byte
+// granularity). JournalReader is therefore internally buffering entries that
+// don't fit in the read buffer. Callers should keep calling until 0 and/or an
+// error is returned.
+func (r *JournalReader) Read(b []byte) (int, error) {
+	if r.msgReader == nil {
+		// Advance the journal cursor. It has to be called at least one time
+		// before reading
+		c, err := r.journal.Next()
+
+		// An unexpected error
+		if err != nil {
+			return 0, err
+		}
+
+		// EOF detection
+		if c == 0 {
+			return 0, io.EOF
+		}
+
+		entry, err := r.journal.GetEntry()
+		if err != nil {
+			return 0, err
+		}
+
+		// Build a message
+		msg, err := r.formatter(entry)
+		if err != nil {
+			return 0, err
+		}
+		r.msgReader = strings.NewReader(msg)
+	}
+
+	// Copy and return the message
+	sz, err := r.msgReader.Read(b)
+	if err == io.EOF {
+		// The current entry has been fully read. Don't propagate this
+		// EOF, so the next entry can be read at the next Read()
+		// iteration.
+		r.msgReader = nil
+		return sz, nil
+	}
+	if err != nil {
+		return sz, err
+	}
+	if r.msgReader.Len() == 0 {
+		r.msgReader = nil
+	}
+
+	return sz, nil
+}
+
+// Close closes the JournalReader's handle to the journal.
+func (r *JournalReader) Close() error {
+	return r.journal.Close()
+}
+
+// Rewind attempts to rewind the JournalReader to the first entry.
+func (r *JournalReader) Rewind() error {
+	r.msgReader = nil
+	return r.journal.SeekHead()
+}
+
+// Follow synchronously follows the JournalReader, writing each new journal entry to writer. The
+// follow will continue until a single time.Time is received on the until channel.
+func (r *JournalReader) Follow(until <-chan time.Time, writer io.Writer) error {
+
+	// Process journal entries and events. Entries are flushed until the tail or
+	// timeout is reached, and then we wait for new events or the timeout.
+	var msg = make([]byte, 64*1<<(10))
+	var waitCh = make(chan int, 1)
+	var waitGroup sync.WaitGroup
+	defer waitGroup.Wait()
+
+process:
+	for {
+		c, err := r.Read(msg)
+		if err != nil && err != io.EOF {
+			return err
+		}
+
+		select {
+		case <-until:
+			return ErrExpired
+		default:
+		}
+		if c > 0 {
+			if _, err = writer.Write(msg[:c]); err != nil {
+				return err
+			}
+			continue process
+		}
+
+		// We're at the tail, so wait for new events or time out.
+		// Holds journal events to process. Tightly bounded for now unless there's a
+		// reason to unblock the journal watch routine more quickly.
+		for {
+			waitGroup.Add(1)
+			go func() {
+				status := r.journal.Wait(100 * time.Millisecond)
+				waitCh <- status
+				waitGroup.Done()
+			}()
+
+			select {
+			case <-until:
+				return ErrExpired
+			case e := <-waitCh:
+				switch e {
+				case SD_JOURNAL_NOP:
+					// the journal did not change since the last invocation
+				case SD_JOURNAL_APPEND, SD_JOURNAL_INVALIDATE:
+					continue process
+				default:
+					if e < 0 {
+						return fmt.Errorf("received error event: %d", e)
+					}
+
+					log.Printf("received unknown event: %d\n", e)
+				}
+			}
+		}
+	}
+}
+
+// simpleMessageFormatter is the default formatter.
+// It returns a string representing the current journal entry in a simple format which
+// includes the entry timestamp and MESSAGE field.
+func simpleMessageFormatter(entry *JournalEntry) (string, error) {
+	msg, ok := entry.Fields["MESSAGE"]
+	if !ok {
+		return "", fmt.Errorf("no MESSAGE field present in journal entry")
+	}
+
+	usec := entry.RealtimeTimestamp
+	timestamp := time.Unix(0, int64(usec)*int64(time.Microsecond))
+
+	return fmt.Sprintf("%s %s\n", timestamp, msg), nil
+}