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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2018 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package systemd
import (
"fmt"
"log/syslog"
"net"
"os"
"github.com/snapcore/snapd/dirs"
"github.com/snapcore/snapd/gadget/quantity"
)
// JournalStreamFileParams contains configuration parameters for the journal stream.
// Most of these are optional, but a stream must have a proper Identifier specified to
// be opened. If a namespace is provided, then the stream will connect to that specific
// journal namespace instead.
type JournalStreamFileParams struct {
Namespace string
Identifier string
UnitName string
Priority syslog.Priority
LevelPrefix bool
}
// NewJournalStreamFile creates log stream file descriptor to the journal. The
// semantics is identical to that of sd_journal_stream_fd(3) call.
func NewJournalStreamFile(params JournalStreamFileParams) (*os.File, error) {
// an identifier must be provided
if params.Identifier == "" {
return nil, fmt.Errorf("internal error: cannot setup a journal stream without an identifier")
}
var journalPath string
if params.Namespace != "" {
journalPath = fmt.Sprintf("%s/journal.%s/stdout", dirs.SnapSystemdRunDir, params.Namespace)
} else {
journalPath = fmt.Sprintf("%s/journal/stdout", dirs.SnapSystemdRunDir)
}
conn, err := net.DialUnix("unix", nil, &net.UnixAddr{Name: journalPath})
if err != nil {
return nil, err
}
// does not affect *os.File created through conn.File() later on
defer conn.Close()
// systemd closes the read side
// https://github.com/systemd/systemd/blob/2e8a581b9cc1132743c2341fc334461096266ad4/src/core/exec-invoke.c#L228
if err := conn.CloseRead(); err != nil {
return nil, err
}
// journald actually tries to force this into 8mb in spite of kernel
// limits, however let us not do that.
// https://github.com/systemd/systemd/blob/2e8a581b9cc1132743c2341fc334461096266ad4/src/core/exec-invoke.c#L231
// intentionally ignore the error like systemd does.
_ = conn.SetWriteBuffer(int(8 * quantity.SizeMiB))
var levelPrefix int
if params.LevelPrefix {
levelPrefix = 1
}
// setup contents taken from the original systemd code:
// https://github.com/systemd/systemd/blob/2e8a581b9cc1132743c2341fc334461096266ad4/src/core/exec-invoke.c#L233
setupStr := fmt.Sprintf("%s\n%s\n%d\n%d\n%d\n%d\n%d\n",
params.Identifier, /* syslog_identifier */
params.UnitName, /* unit-name */
params.Priority, /* syslog_priority */
levelPrefix, /* syslog_level_prefix */
0, /* false */
0, /* is_kmsg_output */
0, /* is_terminal_output */
)
if _, err := conn.Write([]byte(setupStr)); err != nil {
return nil, fmt.Errorf("failed to write header: %v", err)
}
return conn.File()
}
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