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package app
import (
"encoding/gob"
"errors"
"fmt"
"io"
"io/fs"
"os"
"strconv"
"syscall"
"hakurei.app/container/check"
"hakurei.app/hst"
"hakurei.app/message"
)
const pulseCookieSizeMax = 1 << 8
func init() { gob.Register(new(spPulseOp)) }
// spPulseOp exports the PulseAudio server to the container.
// Runs after spRuntimeOp.
type spPulseOp struct {
// PulseAudio cookie data, populated during toSystem if a cookie is present.
Cookie *[pulseCookieSizeMax]byte
// PulseAudio cookie size, populated during toSystem if a cookie is present.
CookieSize int
}
func (s *spPulseOp) toSystem(state *outcomeStateSys) error {
if state.et&hst.EPulse == 0 {
return errNotEnabled
}
pulseRuntimeDir, pulseSocket := s.commonPaths(state.outcomeState)
if _, err := state.k.stat(pulseRuntimeDir.String()); err != nil {
if !errors.Is(err, fs.ErrNotExist) {
return &hst.AppError{Step: fmt.Sprintf("access PulseAudio directory %q", pulseRuntimeDir), Err: err}
}
return newWithMessageError(fmt.Sprintf("PulseAudio directory %q not found", pulseRuntimeDir), err)
}
if fi, err := state.k.stat(pulseSocket.String()); err != nil {
if !errors.Is(err, fs.ErrNotExist) {
return &hst.AppError{Step: fmt.Sprintf("access PulseAudio socket %q", pulseSocket), Err: err}
}
return newWithMessageError(fmt.Sprintf("PulseAudio directory %q found but socket does not exist", pulseRuntimeDir), err)
} else {
if m := fi.Mode(); m&0o006 != 0o006 {
return newWithMessage(fmt.Sprintf("unexpected permissions on %q: %s", pulseSocket, m))
}
}
// pulse socket is world writable and its parent directory DAC permissions prevents access;
// hard link to target-executable share directory to grant access
state.sys.Link(pulseSocket, state.runtime().Append("pulse"))
// load up to pulseCookieSizeMax bytes of pulse cookie for transmission to shim
if a, err := discoverPulseCookie(state.k); err != nil {
return err
} else if a != nil {
s.Cookie = new([pulseCookieSizeMax]byte)
if s.CookieSize, err = loadFile(state.msg, state.k, "PulseAudio cookie", a.String(), s.Cookie[:]); err != nil {
return err
}
} else {
state.msg.Verbose("cannot locate PulseAudio cookie (tried " +
"$PULSE_COOKIE, " +
"$XDG_CONFIG_HOME/pulse/cookie, " +
"$HOME/.pulse-cookie)")
}
return nil
}
func (s *spPulseOp) toContainer(state *outcomeStateParams) error {
innerPulseSocket := state.runtimeDir.Append("pulse", "native")
state.params.Bind(state.runtimePath().Append("pulse"), innerPulseSocket, 0)
state.env["PULSE_SERVER"] = "unix:" + innerPulseSocket.String()
if s.Cookie != nil {
innerDst := hst.AbsPrivateTmp.Append("/pulse-cookie")
if s.CookieSize < 0 || s.CookieSize > pulseCookieSizeMax {
return newWithMessage("unexpected PulseAudio cookie size")
}
state.env["PULSE_COOKIE"] = innerDst.String()
state.params.Place(innerDst, s.Cookie[:s.CookieSize])
}
return nil
}
func (s *spPulseOp) commonPaths(state *outcomeState) (pulseRuntimeDir, pulseSocket *check.Absolute) {
// PulseAudio runtime directory (usually `/run/user/%d/pulse`)
pulseRuntimeDir = state.sc.RuntimePath.Append("pulse")
// PulseAudio socket (usually `/run/user/%d/pulse/native`)
pulseSocket = pulseRuntimeDir.Append("native")
return
}
// discoverPulseCookie attempts to discover the pathname of the PulseAudio cookie of the current user.
// If both returned pathname and error are nil, the cookie is likely unavailable and can be silently skipped.
func discoverPulseCookie(k syscallDispatcher) (*check.Absolute, error) {
const paLocateStep = "locate PulseAudio cookie"
// from environment
if p, ok := k.lookupEnv("PULSE_COOKIE"); ok {
if a, err := check.NewAbs(p); err != nil {
return nil, &hst.AppError{Step: paLocateStep, Err: err}
} else {
// this takes precedence, do not verify whether the file is accessible
return a, nil
}
}
// $HOME/.pulse-cookie
if p, ok := k.lookupEnv("HOME"); ok {
var pulseCookiePath *check.Absolute
if a, err := check.NewAbs(p); err != nil {
return nil, &hst.AppError{Step: paLocateStep, Err: err}
} else {
pulseCookiePath = a.Append(".pulse-cookie")
}
if fi, err := k.stat(pulseCookiePath.String()); err != nil {
if !errors.Is(err, fs.ErrNotExist) {
return nil, &hst.AppError{Step: "access PulseAudio cookie", Err: err}
}
// fallthrough
} else if fi.IsDir() {
// fallthrough
} else {
return pulseCookiePath, nil
}
}
// $XDG_CONFIG_HOME/pulse/cookie
if p, ok := k.lookupEnv("XDG_CONFIG_HOME"); ok {
var pulseCookiePath *check.Absolute
if a, err := check.NewAbs(p); err != nil {
return nil, &hst.AppError{Step: paLocateStep, Err: err}
} else {
pulseCookiePath = a.Append("pulse", "cookie")
}
if fi, err := k.stat(pulseCookiePath.String()); err != nil {
if !errors.Is(err, fs.ErrNotExist) {
return nil, &hst.AppError{Step: "access PulseAudio cookie", Err: err}
}
// fallthrough
} else if fi.IsDir() {
// fallthrough
} else {
return pulseCookiePath, nil
}
}
// cookie not present
// not fatal: authentication is disabled
return nil, nil
}
// loadFile reads up to len(buf) bytes from the file at pathname.
func loadFile(
msg message.Msg, k syscallDispatcher,
description, pathname string, buf []byte,
) (int, error) {
n := len(buf)
if n == 0 {
return -1, errors.New("invalid buffer")
}
if fi, err := k.stat(pathname); err != nil {
return -1, &hst.AppError{Step: "access " + description, Err: err}
} else {
if fi.IsDir() {
return -1, &hst.AppError{Step: "read " + description,
Err: &os.PathError{Op: "stat", Path: pathname, Err: syscall.EISDIR}}
}
if s := fi.Size(); s > int64(n) {
return -1, newWithMessageError(
description+" at "+strconv.Quote(pathname)+" exceeds expected size",
&os.PathError{Op: "stat", Path: pathname, Err: syscall.ENOMEM},
)
} else if s < int64(n) {
msg.Verbosef("%s at %q is %d bytes shorter than expected", description, pathname, int64(n)-s)
} else {
msg.Verbosef("loading %d bytes from %q", n, pathname)
}
}
if f, err := k.open(pathname); err != nil {
return -1, &hst.AppError{Step: "open " + description, Err: err}
} else {
if n, err = f.Read(buf); err != nil {
if !errors.Is(err, io.EOF) {
_ = f.Close()
return n, &hst.AppError{Step: "read " + description, Err: err}
}
}
if err = f.Close(); err != nil {
return n, &hst.AppError{Step: "close " + description, Err: err}
}
return n, nil
}
}
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