fix: lazysecrets starts from fzf's become, on a non-blocking terminal (#67)

fzf's become hands lazysecrets its /dev/tty still non-blocking. Go can't poll /dev/tty on macOS, so it reads it directly, and the TUI's first read failed with "resource temporarily unavailable" (EAGAIN). lazysecrets now makes a terminal on stdin blocking before the TUI starts (Unix; nothing on Windows).

Reviewed-on: #67
Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>

cmd/lazysecrets/main.go

@@ -436,6 +436,7 @@ Flags:
 		Styles:         &theme,
 		DefaultFg:      defaultFg,
 	})
+	blockingStdin()
 	p = tea.NewProgram(m)
 	final, err := p.Run()
 	if fm, ok := final.(app.Model); ok {

cmd/lazysecrets/stdin_other.go

@@ -0,0 +1,5 @@
+//go:build !unix
+
+package main
+
+func blockingStdin() {}

cmd/lazysecrets/stdin_unix.go

@@ -0,0 +1,20 @@
+//go:build unix
+
+package main
+
+import (
+	"os"
+	"syscall"
+
+	"golang.org/x/term"
+)
+
+// blockingStdin makes a terminal on stdin blocking again. fzf's become
+// hands on its /dev/tty non-blocking; Go can't poll /dev/tty on macOS,
+// so it reads it directly, and the TUI's first read would fail with
+// EAGAIN ("resource temporarily unavailable").
+func blockingStdin() {
+	if fd := int(os.Stdin.Fd()); term.IsTerminal(fd) {
+		_ = syscall.SetNonblock(fd, false)
+	}
+}