cli/command/container: use strings.Cut

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/container/cp.go

@@ -386,13 +386,12 @@ func splitCpArg(arg string) (container, path string) {
 		return "", arg
 	}
 
-	parts := strings.SplitN(arg, ":", 2)
-
-	if len(parts) == 1 || strings.HasPrefix(parts[0], ".") {
+	container, path, ok := strings.Cut(arg, ":")
+	if !ok || strings.HasPrefix(container, ".") {
 		// Either there's no `:` in the arg
 		// OR it's an explicit local relative path like `./file:name.txt`.
 		return "", arg
 	}
 
-	return parts[0], parts[1]
+	return container, path
 }

cli/command/container/opts.go

@@ -354,14 +354,13 @@ func parse(flags *pflag.FlagSet, copts *containerOptions, serverOS string) (*con
 			toBind := bind
 
 			if parsed.Type == string(mounttypes.TypeBind) {
-				if arr := strings.SplitN(bind, ":", 2); len(arr) == 2 {
-					hostPart := arr[0]
+				if hostPart, targetPath, ok := strings.Cut(bind, ":"); ok {
 					if strings.HasPrefix(hostPart, "."+string(filepath.Separator)) || hostPart == "." {
 						if absHostPart, err := filepath.Abs(hostPart); err == nil {
 							hostPart = absHostPart
 						}
 					}
-					toBind = hostPart + ":" + arr[1]
+					toBind = hostPart + ":" + targetPath
 				}
 			}
 
@@ -377,11 +376,8 @@ func parse(flags *pflag.FlagSet, copts *containerOptions, serverOS string) (*con
 	// Can't evaluate options passed into --tmpfs until we actually mount
 	tmpfs := make(map[string]string)
 	for _, t := range copts.tmpfs.GetAll() {
-		if arr := strings.SplitN(t, ":", 2); len(arr) > 1 {
-			tmpfs[arr[0]] = arr[1]
-		} else {
-			tmpfs[arr[0]] = ""
-		}
+		k, v, _ := strings.Cut(t, ":")
+		tmpfs[k] = v
 	}
 
 	var (
@@ -820,12 +816,11 @@ func convertToStandardNotation(ports []string) ([]string, error) {
 		if strings.Contains(publish, "=") {
 			params := map[string]string{"protocol": "tcp"}
 			for _, param := range strings.Split(publish, ",") {
-				opt := strings.Split(param, "=")
-				if len(opt) < 2 {
+				k, v, ok := strings.Cut(param, "=")
+				if !ok || k == "" {
 					return optsList, errors.Errorf("invalid publish opts format (should be name=value but got '%s')", param)
 				}
-
-				params[opt[0]] = opt[1]
+				params[k] = v
 			}
 			optsList = append(optsList, fmt.Sprintf("%s:%s/%s", params["published"], params["target"], params["protocol"]))
 		} else {
@@ -846,22 +841,22 @@ func parseLoggingOpts(loggingDriver string, loggingOpts []string) (map[string]st
 // takes a local seccomp daemon, reads the file contents for sending to the daemon
 func parseSecurityOpts(securityOpts []string) ([]string, error) {
 	for key, opt := range securityOpts {
-		con := strings.SplitN(opt, "=", 2)
-		if len(con) == 1 && con[0] != "no-new-privileges" {
-			if strings.Contains(opt, ":") {
-				con = strings.SplitN(opt, ":", 2)
-			} else {
+		k, v, ok := strings.Cut(opt, "=")
+		if !ok && k != "no-new-privileges" {
+			k, v, ok = strings.Cut(opt, ":")
+		}
+		if (!ok || v == "") && k != "no-new-privileges" {
+			// "no-new-privileges" is the only option that does not require a value.
 			return securityOpts, errors.Errorf("Invalid --security-opt: %q", opt)
 		}
-		}
-		if con[0] == "seccomp" && con[1] != "unconfined" {
-			f, err := os.ReadFile(con[1])
+		if k == "seccomp" && v != "unconfined" {
+			f, err := os.ReadFile(v)
 			if err != nil {
-				return securityOpts, errors.Errorf("opening seccomp profile (%s) failed: %v", con[1], err)
+				return securityOpts, errors.Errorf("opening seccomp profile (%s) failed: %v", v, err)
 			}
 			b := bytes.NewBuffer(nil)
 			if err := json.Compact(b, f); err != nil {
-				return securityOpts, errors.Errorf("compacting json for seccomp profile (%s) failed: %v", con[1], err)
+				return securityOpts, errors.Errorf("compacting json for seccomp profile (%s) failed: %v", v, err)
 			}
 			securityOpts[key] = fmt.Sprintf("seccomp=%s", b.Bytes())
 		}
@@ -893,12 +888,11 @@ func parseSystemPaths(securityOpts []string) (filtered, maskedPaths, readonlyPat
 func parseStorageOpts(storageOpts []string) (map[string]string, error) {
 	m := make(map[string]string)
 	for _, option := range storageOpts {
-		if strings.Contains(option, "=") {
-			opt := strings.SplitN(option, "=", 2)
-			m[opt[0]] = opt[1]
-		} else {
+		k, v, ok := strings.Cut(option, "=")
+		if !ok {
 			return nil, errors.Errorf("invalid storage option")
 		}
+		m[k] = v
 	}
 	return m, nil
 }
@@ -919,7 +913,8 @@ func parseDevice(device, serverOS string) (container.DeviceMapping, error) {
 func parseLinuxDevice(device string) (container.DeviceMapping, error) {
 	var src, dst string
 	permissions := "rwm"
-	arr := strings.Split(device, ":")
+	// We expect 3 parts at maximum; limit to 4 parts to detect invalid options.
+	arr := strings.SplitN(device, ":", 4)
 	switch len(arr) {
 	case 3:
 		permissions = arr[2]