Switch to new vendor directory layout
Fixes #113 Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>
This commit is contained in:
Marcos Lilljedahl
270
vendor/github.com/coreos/go-systemd/util/util.go
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270
vendor/github.com/coreos/go-systemd/util/util.go
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// Copyright 2015 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package util contains utility functions related to systemd that applications
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// can use to check things like whether systemd is running. Note that some of
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// these functions attempt to manually load systemd libraries at runtime rather
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// than linking against them.
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package util
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// #cgo LDFLAGS: -ldl
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// #include <stdlib.h>
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// #include <dlfcn.h>
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// #include <sys/types.h>
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// #include <unistd.h>
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//
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// int
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// my_sd_pid_get_owner_uid(void *f, pid_t pid, uid_t *uid)
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// {
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// int (*sd_pid_get_owner_uid)(pid_t, uid_t *);
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//
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// sd_pid_get_owner_uid = (int (*)(pid_t, uid_t *))f;
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// return sd_pid_get_owner_uid(pid, uid);
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// }
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//
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// int
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// my_sd_pid_get_unit(void *f, pid_t pid, char **unit)
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// {
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// int (*sd_pid_get_unit)(pid_t, char **);
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//
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// sd_pid_get_unit = (int (*)(pid_t, char **))f;
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// return sd_pid_get_unit(pid, unit);
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// }
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//
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// int
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// my_sd_pid_get_slice(void *f, pid_t pid, char **slice)
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// {
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// int (*sd_pid_get_slice)(pid_t, char **);
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//
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// sd_pid_get_slice = (int (*)(pid_t, char **))f;
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// return sd_pid_get_slice(pid, slice);
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// }
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//
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// int
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// am_session_leader()
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// {
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// return (getsid(0) == getpid());
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// }
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import "C"
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"strings"
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"syscall"
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"unsafe"
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)
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var ErrSoNotFound = errors.New("unable to open a handle to libsystemd")
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// libHandle represents an open handle to the systemd C library
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type libHandle struct {
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handle unsafe.Pointer
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libname string
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}
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func (h *libHandle) Close() error {
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if r := C.dlclose(h.handle); r != 0 {
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return fmt.Errorf("error closing %v: %d", h.libname, r)
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}
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return nil
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}
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// getHandle tries to get a handle to a systemd library (.so), attempting to
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// access it by several different names and returning the first that is
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// successfully opened. Callers are responsible for closing the handler.
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// If no library can be successfully opened, an error is returned.
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func getHandle() (*libHandle, error) {
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for _, name := range []string{
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// systemd < 209
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"libsystemd-login.so",
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"libsystemd-login.so.0",
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// systemd >= 209 merged libsystemd-login into libsystemd proper
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"libsystemd.so",
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"libsystemd.so.0",
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} {
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libname := C.CString(name)
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defer C.free(unsafe.Pointer(libname))
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handle := C.dlopen(libname, C.RTLD_LAZY)
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if handle != nil {
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h := &libHandle{
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handle: handle,
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libname: name,
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}
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return h, nil
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}
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}
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return nil, ErrSoNotFound
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}
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// GetRunningSlice attempts to retrieve the name of the systemd slice in which
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// the current process is running.
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// This function is a wrapper around the libsystemd C library; if it cannot be
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// opened, an error is returned.
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func GetRunningSlice() (slice string, err error) {
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var h *libHandle
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h, err = getHandle()
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if err != nil {
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return
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}
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defer func() {
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if err1 := h.Close(); err1 != nil {
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err = err1
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}
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}()
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sym := C.CString("sd_pid_get_slice")
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defer C.free(unsafe.Pointer(sym))
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sd_pid_get_slice := C.dlsym(h.handle, sym)
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if sd_pid_get_slice == nil {
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err = fmt.Errorf("error resolving sd_pid_get_slice function")
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return
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}
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var s string
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sl := C.CString(s)
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defer C.free(unsafe.Pointer(sl))
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ret := C.my_sd_pid_get_slice(sd_pid_get_slice, 0, &sl)
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if ret < 0 {
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err = fmt.Errorf("error calling sd_pid_get_slice: %v", syscall.Errno(-ret))
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return
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}
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return C.GoString(sl), nil
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}
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// RunningFromSystemService tries to detect whether the current process has
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// been invoked from a system service. The condition for this is whether the
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// process is _not_ a user process. User processes are those running in session
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// scopes or under per-user `systemd --user` instances.
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//
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// To avoid false positives on systems without `pam_systemd` (which is
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// responsible for creating user sessions), this function also uses a heuristic
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// to detect whether it's being invoked from a session leader process. This is
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// the case if the current process is executed directly from a service file
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// (e.g. with `ExecStart=/this/cmd`). Note that this heuristic will fail if the
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// command is instead launched in a subshell or similar so that it is not
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// session leader (e.g. `ExecStart=/bin/bash -c "/this/cmd"`)
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//
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// This function is a wrapper around the libsystemd C library; if this is
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// unable to successfully open a handle to the library for any reason (e.g. it
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// cannot be found), an errr will be returned
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func RunningFromSystemService() (ret bool, err error) {
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var h *libHandle
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h, err = getHandle()
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if err != nil {
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return
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}
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defer func() {
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if err1 := h.Close(); err1 != nil {
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err = err1
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}
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}()
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sym := C.CString("sd_pid_get_owner_uid")
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defer C.free(unsafe.Pointer(sym))
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sd_pid_get_owner_uid := C.dlsym(h.handle, sym)
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if sd_pid_get_owner_uid == nil {
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err = fmt.Errorf("error resolving sd_pid_get_owner_uid function")
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return
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}
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var uid C.uid_t
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errno := C.my_sd_pid_get_owner_uid(sd_pid_get_owner_uid, 0, &uid)
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serrno := syscall.Errno(-errno)
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// when we're running from a unit file, sd_pid_get_owner_uid returns
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// ENOENT (systemd <220) or ENXIO (systemd >=220)
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switch {
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case errno >= 0:
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ret = false
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case serrno == syscall.ENOENT, serrno == syscall.ENXIO:
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// Since the implementation of sessions in systemd relies on
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// the `pam_systemd` module, using the sd_pid_get_owner_uid
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// heuristic alone can result in false positives if that module
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// (or PAM itself) is not present or properly configured on the
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// system. As such, we also check if we're the session leader,
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// which should be the case if we're invoked from a unit file,
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// but not if e.g. we're invoked from the command line from a
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// user's login session
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ret = C.am_session_leader() == 1
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default:
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err = fmt.Errorf("error calling sd_pid_get_owner_uid: %v", syscall.Errno(-errno))
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}
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return
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}
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// CurrentUnitName attempts to retrieve the name of the systemd system unit
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// from which the calling process has been invoked. It wraps the systemd
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// `sd_pid_get_unit` call, with the same caveat: for processes not part of a
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// systemd system unit, this function will return an error.
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func CurrentUnitName() (unit string, err error) {
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var h *libHandle
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h, err = getHandle()
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if err != nil {
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return
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}
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defer func() {
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if err1 := h.Close(); err1 != nil {
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err = err1
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}
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}()
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sym := C.CString("sd_pid_get_unit")
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defer C.free(unsafe.Pointer(sym))
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sd_pid_get_unit := C.dlsym(h.handle, sym)
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if sd_pid_get_unit == nil {
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err = fmt.Errorf("error resolving sd_pid_get_unit function")
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return
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}
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var s string
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u := C.CString(s)
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defer C.free(unsafe.Pointer(u))
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ret := C.my_sd_pid_get_unit(sd_pid_get_unit, 0, &u)
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if ret < 0 {
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err = fmt.Errorf("error calling sd_pid_get_unit: %v", syscall.Errno(-ret))
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return
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}
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unit = C.GoString(u)
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return
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}
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// IsRunningSystemd checks whether the host was booted with systemd as its init
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// system. This functions similarly to systemd's `sd_booted(3)`: internally, it
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// checks whether /run/systemd/system/ exists and is a directory.
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// http://www.freedesktop.org/software/systemd/man/sd_booted.html
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func IsRunningSystemd() bool {
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fi, err := os.Lstat("/run/systemd/system")
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if err != nil {
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return false
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}
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return fi.IsDir()
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}
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// GetMachineID returns a host's 128-bit machine ID as a string. This functions
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// similarly to systemd's `sd_id128_get_machine`: internally, it simply reads
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// the contents of /etc/machine-id
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// http://www.freedesktop.org/software/systemd/man/sd_id128_get_machine.html
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func GetMachineID() (string, error) {
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machineID, err := ioutil.ReadFile("/etc/machine-id")
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if err != nil {
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return "", fmt.Errorf("failed to read /etc/machine-id: %v", err)
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}
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return strings.TrimSpace(string(machineID)), nil
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}
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