1 files changed, 37 insertions, 0 deletions
diff --git a/internal/tui/keys.go b/internal/tui/keys.go
new file mode 100644
index 0000000..e88a326
--- /dev/null
+++ b/internal/tui/keys.go
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package tui
+
+import (
+	"fmt"
+	"os"
+
+	"golang.org/x/term"
+)
+
+// ReadKey reads one keypress without Enter, restoring the terminal before
+// it returns - on every path, including an error. It always reads a
+// single byte; only a terminal is first put into raw mode, so a
+// non-terminal (a pipe, in tests) needs no pty to exercise it.
+func ReadKey(in *os.File) (rune, error) {
+	fd := int(in.Fd())
+	if !isTerminal(fd) {
+		return readByte(in)
+	}
+
+	state, err := term.MakeRaw(fd)
+	if err != nil {
+		return 0, fmt.Errorf("tui: %w", err)
+	}
+	defer term.Restore(fd, state)
+
+	return readByte(in)
+}
+
+func readByte(in *os.File) (rune, error) {
+	var b [1]byte
+	if _, err := in.Read(b[:]); err != nil {
+		return 0, err
+	}
+	return rune(b[0]), nil
+}