implement with self-implemented scanf

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

cmd/oras/root/login.go

@@ -16,9 +16,9 @@ limitations under the License.
 package root
 
 import (
-	"bufio"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"strings"
 
@@ -134,27 +134,34 @@ func runLogin(opts loginOptions) (err error) {
 func readLine(prompt string, silent bool) (string, error) {
 	fmt.Print(prompt)
 	fd := int(os.Stdin.Fd())
-	var line []byte
-	var err error
+	line := ""
 	if silent && term.IsTerminal(fd) {
-		line, err = term.ReadPassword(fd)
+		bytes, err := term.ReadPassword(fd)
 		if err != nil {
 			return "", err
 		}
+		line = string(bytes)
 	} else {
-		reader := bufio.NewReader(os.Stdin)
-		var part []byte
-		for more := true; more; {
-			// read until no more
-			part, more, err = reader.ReadLine()
+		// implement per-byte scanf here since fmt.Fscanln skips all the
+		// newline before scanning
+		for b := [1]byte{}; ; {
+			fmt.Print(len(b))
+			_, err := os.Stdin.Read(b[:])
 			if err != nil {
+				if err == io.EOF {
+					break
+				}
 				return "", err
 			}
-			line = append(line, part...)
+			s := string(b[:])
+			if s == "\n" {
+				break
+			}
+			line += s
 		}
 	}
 	if silent {
 		fmt.Println()
 	}
-	return string(line), nil
+	return line, nil
 }

test/e2e/suite/auth/auth.go

@@ -69,32 +69,33 @@ var _ = Describe("Common registry user", Ordered, func() {
 		It("should fail if no password input", func() {
 			ORAS("login", Host, "--registry-config", AuthConfigPath).
 				WithTimeOut(20*time.Second).
-				MatchKeyWords("username: ", "password: ").
+				MatchKeyWords("Username: ", "Password: ").
 				WithInput(strings.NewReader(fmt.Sprintf("%s\n", Username))).ExpectFailure().Exec()
 		})
 
 		It("should fail if password is empty", func() {
 			ORAS("login", Host, "--registry-config", AuthConfigPath).
 				WithTimeOut(20*time.Second).
-				MatchKeyWords("username: ", "password: ").
+				MatchKeyWords("Username: ", "Password: ").
 				MatchErrKeyWords("Error: password required").
 				WithInput(strings.NewReader(fmt.Sprintf("%s\n\n", Username))).ExpectFailure().Exec()
 		})
 
 		It("should fail if no token input", func() {
 			ORAS("login", Host, "--registry-config", AuthConfigPath).
 				WithTimeOut(20*time.Second).
-				MatchKeyWords("username: ", "token: ").
+				MatchKeyWords("Username: ", "Token: ").
 				WithInput(strings.NewReader("\n")).ExpectFailure().Exec()
 		})
 
 		It("should fail if token is empty", func() {
 			ORAS("login", Host, "--registry-config", AuthConfigPath).
 				WithTimeOut(20*time.Second).
-				MatchKeyWords("username: ", "token: ").
+				MatchKeyWords("Username: ", "Token: ").
 				MatchErrKeyWords("Error: token required").
 				WithInput(strings.NewReader("\n\n")).ExpectFailure().Exec()
 		})
+
 		It("should use prompted input", func() {
 			ORAS("login", Host, "--registry-config", AuthConfigPath).
 				WithTimeOut(20*time.Second).