1 files changed, 35 insertions, 0 deletions
diff --git a/internal/pipewire/pipewire.go b/internal/pipewire/pipewire.go
index 5473797c..636c7590 100644
--- a/internal/pipewire/pipewire.go
+++ b/internal/pipewire/pipewire.go
@@ -16,6 +16,7 @@ package pipewire
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -786,6 +787,40 @@ func (ctx *Context) Close() (err error) {
 	}
 }
 
+// expectsCoreError returns a function that inspects an error value and
+// returns the address of a [CoreError] if it is the only error present
+// and targets the specified proxy and sequence.
+//
+// The behaviour of expectsCoreError is only correct for an empty buf
+// prior to calling. If buf is not empty, [Core.Sync] is called, with
+// its return value stored to the value pointed to by errP if not nil,
+// and the function is not populated.
+//
+// The caller must queue a message and call [Core.Sync] immediately
+// after calling expectsCoreError.
+func (ctx *Context) expectsCoreError(id Int, errP *error) (asCoreError func() (coreError *CoreError)) {
+	if len(ctx.buf) > 0 {
+		if err := ctx.GetCore().Sync(); err != nil {
+			*errP = err
+			return nil
+		}
+	}
+
+	sequence := ctx.sequence
+	return func() (coreError *CoreError) {
+		if proxyErrors, ok := (*errP).(ProxyConsumeError); !ok ||
+			len(proxyErrors) != 1 ||
+			!errors.As(proxyErrors[0], &coreError) ||
+			coreError == nil ||
+			coreError.ID != id ||
+			coreError.Sequence != sequence {
+			// do not return a non-matching CoreError
+			coreError = nil
+		}
+		return
+	}
+}
+
 // A PermissionError describes an error emitted by the server when trying to
 // perform an operation that the client has no permission for.
 type PermissionError struct {