1 files changed, 170 insertions, 0 deletions
diff --git a/internal/app/sppulse.go b/internal/app/sppulse.go
new file mode 100644
index 00000000..d3742db0
--- /dev/null
+++ b/internal/app/sppulse.go
@@ -0,0 +1,170 @@
+package app
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"syscall"
+
+	"hakurei.app/container"
+	"hakurei.app/hst"
+)
+
+const pulseCookieSizeMax = 1 << 8
+
+// spPulseOp exports the PulseAudio server to the container.
+type spPulseOp struct {
+	// PulseAudio cookie data, populated during toSystem if a cookie is present.
+	Cookie *[pulseCookieSizeMax]byte
+}
+
+func (s *spPulseOp) toSystem(state *outcomeStateSys, _ *hst.Config) error {
+	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 newWithMessage(fmt.Sprintf("PulseAudio directory %q not found", pulseRuntimeDir))
+	}
+
+	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 newWithMessage(fmt.Sprintf("PulseAudio directory %q found but socket does not exist", pulseRuntimeDir))
+	} else {
+		if m := fi.Mode(); m&0o006 != 0o006 {
+			return newWithMessage(fmt.Sprintf("unexpected permissions on %q: %s", pulseSocket, m))
+		}
+	}
+
+	// hard link pulse socket into target-executable share
+	state.sys.Link(pulseSocket, state.runtime().Append("pulse"))
+
+	// publish current user's pulse cookie for target user
+	var paCookiePath *container.Absolute
+	{
+		const paLocateStep = "locate PulseAudio cookie"
+
+		// from environment
+		if p, ok := state.k.lookupEnv("PULSE_COOKIE"); ok {
+			if a, err := container.NewAbs(p); err != nil {
+				return &hst.AppError{Step: paLocateStep, Err: err}
+			} else {
+				// this takes precedence, do not verify whether the file is accessible
+				paCookiePath = a
+				goto out
+			}
+		}
+
+		// $HOME/.pulse-cookie
+		if p, ok := state.k.lookupEnv("HOME"); ok {
+			if a, err := container.NewAbs(p); err != nil {
+				return &hst.AppError{Step: paLocateStep, Err: err}
+			} else {
+				paCookiePath = a.Append(".pulse-cookie")
+			}
+
+			if fi, err := state.k.stat(paCookiePath.String()); err != nil {
+				paCookiePath = nil
+				if !errors.Is(err, fs.ErrNotExist) {
+					return &hst.AppError{Step: "access PulseAudio cookie", Err: err}
+				}
+				// fallthrough
+			} else if fi.IsDir() {
+				paCookiePath = nil
+			} else {
+				goto out
+			}
+		}
+
+		// $XDG_CONFIG_HOME/pulse/cookie
+		if p, ok := state.k.lookupEnv("XDG_CONFIG_HOME"); ok {
+			if a, err := container.NewAbs(p); err != nil {
+				return &hst.AppError{Step: paLocateStep, Err: err}
+			} else {
+				paCookiePath = a.Append("pulse", "cookie")
+			}
+			if fi, err := state.k.stat(paCookiePath.String()); err != nil {
+				paCookiePath = nil
+				if !errors.Is(err, fs.ErrNotExist) {
+					return &hst.AppError{Step: "access PulseAudio cookie", Err: err}
+				}
+				// fallthrough
+			} else if fi.IsDir() {
+				paCookiePath = nil
+			} else {
+				goto out
+			}
+		}
+	out:
+	}
+
+	if paCookiePath != nil {
+		if b, err := state.k.stat(paCookiePath.String()); err != nil {
+			return &hst.AppError{Step: "access PulseAudio cookie", Err: err}
+		} else {
+			if b.IsDir() {
+				return &hst.AppError{Step: "read PulseAudio cookie", Err: &os.PathError{Op: "stat", Path: paCookiePath.String(), Err: syscall.EISDIR}}
+			}
+			if b.Size() > pulseCookieSizeMax {
+				return newWithMessageError(
+					fmt.Sprintf("PulseAudio cookie at %q exceeds maximum expected size", paCookiePath),
+					&os.PathError{Op: "stat", Path: paCookiePath.String(), Err: syscall.ENOMEM},
+				)
+			}
+		}
+
+		var r io.ReadCloser
+		if f, err := state.k.open(paCookiePath.String()); err != nil {
+			return &hst.AppError{Step: "open PulseAudio cookie", Err: err}
+		} else {
+			r = f
+		}
+
+		s.Cookie = new([pulseCookieSizeMax]byte)
+		if n, err := r.Read(s.Cookie[:]); err != nil {
+			if !errors.Is(err, io.EOF) {
+				_ = r.Close()
+				return &hst.AppError{Step: "read PulseAudio cookie", Err: err}
+			}
+			state.msg.Verbosef("copied %d bytes from %q", n, paCookiePath)
+		}
+
+		if err := r.Close(); err != nil {
+			return &hst.AppError{Step: "close PulseAudio cookie", Err: err}
+		}
+	} else {
+		state.msg.Verbose("cannot locate PulseAudio cookie (tried " +
+			"$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.AbsTmp.Append("/pulse-cookie")
+		state.env["PULSE_COOKIE"] = innerDst.String()
+		state.params.Place(innerDst, s.Cookie[:])
+	}
+
+	return nil
+}
+
+func (s *spPulseOp) commonPaths(state *outcomeState) (pulseRuntimeDir, pulseSocket *container.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
+}