gotosocial/vendor/github.com/godbus/dbus/v5/transport_unix.go
Daniele Sluijters acc333c40b
[feature] Inherit resource limits from cgroups ()
When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.
2023-01-17 20:59:04 +00:00

215 lines
5.3 KiB
Go

//+build !windows,!solaris
package dbus
import (
"bytes"
"encoding/binary"
"errors"
"io"
"net"
"syscall"
)
type oobReader struct {
conn *net.UnixConn
oob []byte
buf [4096]byte
}
func (o *oobReader) Read(b []byte) (n int, err error) {
n, oobn, flags, _, err := o.conn.ReadMsgUnix(b, o.buf[:])
if err != nil {
return n, err
}
if flags&syscall.MSG_CTRUNC != 0 {
return n, errors.New("dbus: control data truncated (too many fds received)")
}
o.oob = append(o.oob, o.buf[:oobn]...)
return n, nil
}
type unixTransport struct {
*net.UnixConn
rdr *oobReader
hasUnixFDs bool
}
func newUnixTransport(keys string) (transport, error) {
var err error
t := new(unixTransport)
abstract := getKey(keys, "abstract")
path := getKey(keys, "path")
switch {
case abstract == "" && path == "":
return nil, errors.New("dbus: invalid address (neither path nor abstract set)")
case abstract != "" && path == "":
t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: "@" + abstract, Net: "unix"})
if err != nil {
return nil, err
}
return t, nil
case abstract == "" && path != "":
t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: path, Net: "unix"})
if err != nil {
return nil, err
}
return t, nil
default:
return nil, errors.New("dbus: invalid address (both path and abstract set)")
}
}
func init() {
transports["unix"] = newUnixTransport
}
func (t *unixTransport) EnableUnixFDs() {
t.hasUnixFDs = true
}
func (t *unixTransport) ReadMessage() (*Message, error) {
var (
blen, hlen uint32
csheader [16]byte
headers []header
order binary.ByteOrder
unixfds uint32
)
// To be sure that all bytes of out-of-band data are read, we use a special
// reader that uses ReadUnix on the underlying connection instead of Read
// and gathers the out-of-band data in a buffer.
if t.rdr == nil {
t.rdr = &oobReader{conn: t.UnixConn}
} else {
t.rdr.oob = nil
}
// read the first 16 bytes (the part of the header that has a constant size),
// from which we can figure out the length of the rest of the message
if _, err := io.ReadFull(t.rdr, csheader[:]); err != nil {
return nil, err
}
switch csheader[0] {
case 'l':
order = binary.LittleEndian
case 'B':
order = binary.BigEndian
default:
return nil, InvalidMessageError("invalid byte order")
}
// csheader[4:8] -> length of message body, csheader[12:16] -> length of
// header fields (without alignment)
binary.Read(bytes.NewBuffer(csheader[4:8]), order, &blen)
binary.Read(bytes.NewBuffer(csheader[12:]), order, &hlen)
if hlen%8 != 0 {
hlen += 8 - (hlen % 8)
}
// decode headers and look for unix fds
headerdata := make([]byte, hlen+4)
copy(headerdata, csheader[12:])
if _, err := io.ReadFull(t.rdr, headerdata[4:]); err != nil {
return nil, err
}
dec := newDecoder(bytes.NewBuffer(headerdata), order)
dec.pos = 12
vs, err := dec.Decode(Signature{"a(yv)"})
if err != nil {
return nil, err
}
Store(vs, &headers)
for _, v := range headers {
if v.Field == byte(FieldUnixFDs) {
unixfds, _ = v.Variant.value.(uint32)
}
}
all := make([]byte, 16+hlen+blen)
copy(all, csheader[:])
copy(all[16:], headerdata[4:])
if _, err := io.ReadFull(t.rdr, all[16+hlen:]); err != nil {
return nil, err
}
if unixfds != 0 {
if !t.hasUnixFDs {
return nil, errors.New("dbus: got unix fds on unsupported transport")
}
// read the fds from the OOB data
scms, err := syscall.ParseSocketControlMessage(t.rdr.oob)
if err != nil {
return nil, err
}
if len(scms) != 1 {
return nil, errors.New("dbus: received more than one socket control message")
}
fds, err := syscall.ParseUnixRights(&scms[0])
if err != nil {
return nil, err
}
msg, err := DecodeMessage(bytes.NewBuffer(all))
if err != nil {
return nil, err
}
// substitute the values in the message body (which are indices for the
// array receiver via OOB) with the actual values
for i, v := range msg.Body {
switch v.(type) {
case UnixFDIndex:
j := v.(UnixFDIndex)
if uint32(j) >= unixfds {
return nil, InvalidMessageError("invalid index for unix fd")
}
msg.Body[i] = UnixFD(fds[j])
case []UnixFDIndex:
idxArray := v.([]UnixFDIndex)
fdArray := make([]UnixFD, len(idxArray))
for k, j := range idxArray {
if uint32(j) >= unixfds {
return nil, InvalidMessageError("invalid index for unix fd")
}
fdArray[k] = UnixFD(fds[j])
}
msg.Body[i] = fdArray
}
}
return msg, nil
}
return DecodeMessage(bytes.NewBuffer(all))
}
func (t *unixTransport) SendMessage(msg *Message) error {
fds := make([]int, 0)
for i, v := range msg.Body {
if fd, ok := v.(UnixFD); ok {
msg.Body[i] = UnixFDIndex(len(fds))
fds = append(fds, int(fd))
}
}
if len(fds) != 0 {
if !t.hasUnixFDs {
return errors.New("dbus: unix fd passing not enabled")
}
msg.Headers[FieldUnixFDs] = MakeVariant(uint32(len(fds)))
oob := syscall.UnixRights(fds...)
buf := new(bytes.Buffer)
msg.EncodeTo(buf, nativeEndian)
n, oobn, err := t.UnixConn.WriteMsgUnix(buf.Bytes(), oob, nil)
if err != nil {
return err
}
if n != buf.Len() || oobn != len(oob) {
return io.ErrShortWrite
}
} else {
if err := msg.EncodeTo(t, nativeEndian); err != nil {
return err
}
}
return nil
}
func (t *unixTransport) SupportsUnixFDs() bool {
return true
}