admin: share stdin reader across password prompts

readPassword created a fresh bufio.Reader on every call. bufio reads
ahead into its buffer, so the first prompt consumed the password line
and buffered the confirmation line, which was then discarded with the
reader. The second prompt built a new reader on an already-drained pipe
and failed with EOF.

This stayed hidden as long as the two lines arrived far enough apart
that only the first was available at the initial read. Any startup delay
that let both lines queue up first exposed it.

Keep a single package-level reader so buffered read-ahead survives
between prompts.

Signed-off-by: Robin Jarry <robin@jarry.cc>

Author: rjarry

cmd/pw/admin/users.go

@@ -213,14 +213,18 @@ func readLine(prompt string) (string, error) {
 	return strings.TrimSpace(line), err
 }
 
+// stdinReader is shared across readPassword calls so that a single reader's
+// buffered read-ahead is not discarded between the password and confirmation
+// prompts. A fresh bufio.Reader per call would swallow the second line.
+var stdinReader = bufio.NewReader(os.Stdin)
+
 func readPassword(prompt string) (string, error) {
 	fmt.Fprint(os.Stderr, prompt)
 	if term.IsTerminal(int(os.Stdin.Fd())) {
 		pw, err := term.ReadPassword(int(os.Stdin.Fd()))
 		fmt.Fprintln(os.Stderr)
 		return string(pw), err
 	}
-	reader := bufio.NewReader(os.Stdin)
-	line, err := reader.ReadString('\n')
+	line, err := stdinReader.ReadString('\n')
 	return strings.TrimSpace(line), err
 }

smoke/_init.sh

@@ -183,7 +183,6 @@ pw() {
 
 set_password() {
 	printf '%s\n' "$PASSWORD"
-	sleep 0.1
 	printf '%s\n' "$PASSWORD"
 }