misc/ios: improve detection of missing developer image

It turns out that a non-empty result from ideviceimagemounter does
not mean an image is mounted. Use ideviceimagemounter's xml output
mode to improve the check.

Also, iOS versions are reported as major.minor or major.minor.patch.
Developer images are only specific to major.minor version, so cut
off the patch number in the search, if present.

Change-Id: Ia182e6f4655b7e6aa6feb8005cd3b533535b73cd
Reviewed-on: https://go-review.googlesource.com/111235
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

misc/ios/go_darwin_arm_exec.go

@@ -207,14 +207,29 @@ func assembleApp(appdir, bin string) error {
 // to connect to.
 func mountDevImage() error {
 	// Check for existing mount.
-	cmd := idevCmd(exec.Command("ideviceimagemounter", "-l"))
+	cmd := idevCmd(exec.Command("ideviceimagemounter", "-l", "-x"))
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		os.Stderr.Write(out)
 		return fmt.Errorf("ideviceimagemounter: %v", err)
 	}
-	if len(out) > 0 {
-		// Assume there is an image mounted
+	var info struct {
+		Dict struct {
+			Data []byte `xml:",innerxml"`
+		} `xml:"dict"`
+	}
+	if err := xml.Unmarshal(out, &info); err != nil {
+		return fmt.Errorf("mountDevImage: failed to decode mount information: %v", err)
+	}
+	dict, err := parsePlistDict(info.Dict.Data)
+	if err != nil {
+		return fmt.Errorf("mountDevImage: failed to parse mount information: %v", err)
+	}
+	if dict["ImagePresent"] == "true" && dict["Status"] == "Complete" {
+		return nil
+	}
+	// Some devices only give us an ImageSignature key.
+	if _, exists := dict["ImageSignature"]; exists {
 		return nil
 	}
 	// No image is mounted. Find a suitable image.
@@ -257,6 +272,12 @@ func findDevImage() (string, error) {
 	if iosVer == "" || buildVer == "" {
 		return "", errors.New("failed to parse ideviceinfo output")
 	}
+	verSplit := strings.Split(iosVer, ".")
+	if len(verSplit) > 2 {
+		// Developer images are specific to major.minor ios version.
+		// Cut off the patch version.
+		iosVer = strings.Join(verSplit[:2], ".")
+	}
 	sdkBase := "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport"
 	patterns := []string{fmt.Sprintf("%s (%s)", iosVer, buildVer), fmt.Sprintf("%s (*)", iosVer), fmt.Sprintf("%s*", iosVer)}
 	for _, pattern := range patterns {
@@ -330,10 +351,25 @@ func findDeviceAppPath(bundleID string) (string, error) {
 		} `xml:"array>dict"`
 	}
 	if err := xml.Unmarshal(out, &list); err != nil {
-		return "", fmt.Errorf("failed to parse ideviceinstaller outout: %v", err)
+		return "", fmt.Errorf("failed to parse ideviceinstaller output: %v", err)
 	}
 	for _, app := range list.Apps {
-		d := xml.NewDecoder(bytes.NewReader(app.Data))
+		values, err := parsePlistDict(app.Data)
+		if err != nil {
+			return "", fmt.Errorf("findDeviceAppPath: failed to parse app dict: %v", err)
+		}
+		if values["CFBundleIdentifier"] == bundleID {
+			if path, ok := values["Path"]; ok {
+				return path, nil
+			}
+		}
+	}
+	return "", fmt.Errorf("failed to find device path for bundle: %s", bundleID)
+}
+
+// Parse an xml encoded plist. Plist values are mapped to string.
+func parsePlistDict(dict []byte) (map[string]string, error) {
+	d := xml.NewDecoder(bytes.NewReader(dict))
 	values := make(map[string]string)
 	var key string
 	var hasKey bool
@@ -343,35 +379,38 @@ func findDeviceAppPath(bundleID string) (string, error) {
 			break
 		}
 		if err != nil {
-				return "", fmt.Errorf("failed to device app data: %v", err)
+			return nil, err
 		}
 		if tok, ok := tok.(xml.StartElement); ok {
 			if tok.Name.Local == "key" {
 				if err := d.DecodeElement(&key, &tok); err != nil {
-						return "", fmt.Errorf("failed to device app data: %v", err)
+					return nil, err
 				}
 				hasKey = true
 			} else if hasKey {
 				var val string
-					if err := d.DecodeElement(&val, &tok); err != nil {
-						return "", fmt.Errorf("failed to device app data: %v", err)
+				var err error
+				switch n := tok.Name.Local; n {
+				case "true", "false":
+					// Bools are represented as <true/> and <false/>.
+					val = n
+					err = d.Skip()
+				default:
+					err = d.DecodeElement(&val, &tok)
+				}
+				if err != nil {
+					return nil, err
 				}
 				values[key] = val
 				hasKey = false
 			} else {
 				if err := d.Skip(); err != nil {
-						return "", fmt.Errorf("failed to device app data: %v", err)
-					}
-				}
-			}
+					return nil, err
 				}
-		if values["CFBundleIdentifier"] == bundleID {
-			if path, ok := values["Path"]; ok {
-				return path, nil
 			}
 		}
 	}
-	return "", fmt.Errorf("failed to find device path for bundle: %s", bundleID)
+	return values, nil
 }
 
 func install(appdir string) error {