pkg/config: make newLocked() unit testable

Define a helper struct which contains the search paths. That way unit
tests can mock the paths by setting them to something else so we don't
actually end up reading the paths under /usr and /etc and $HOME.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Author: Luap99

pkg/config/new.go

@@ -41,6 +41,31 @@ type Options struct {
 	additionalConfigs []string
 }
 
+// paths defines the search paths used for config reading.
+type paths struct {
+	usr  string
+	etc  string
+	home string
+	uid  int
+}
+
+func defaultPaths() (*paths, error) {
+	etcPath, err := overrideContainersConfigPath()
+	if err != nil {
+		return nil, err
+	}
+	homePath, err := userConfigPath()
+	if err != nil {
+		return nil, err
+	}
+	return &paths{
+		usr:  defaultContainersConfig,
+		etc:  etcPath,
+		home: homePath,
+		uid:  unshare.GetRootlessUID(),
+	}, nil
+}
+
 // New returns a Config as described in the containers.conf(5) man page.
 func New(options *Options) (*Config, error) {
 	if options == nil {
@@ -49,7 +74,11 @@ func New(options *Options) (*Config, error) {
 		cachedConfigMutex.Lock()
 		defer cachedConfigMutex.Unlock()
 	}
-	return newLocked(options)
+	paths, err := defaultPaths()
+	if err != nil {
+		return nil, err
+	}
+	return newLocked(options, paths)
 }
 
 // Default returns the default container config.  If no default config has been
@@ -62,21 +91,25 @@ func Default() (*Config, error) {
 	if cachedConfig != nil || cachedConfigError != nil {
 		return cachedConfig, cachedConfigError
 	}
-	cachedConfig, cachedConfigError = newLocked(&Options{SetDefault: true})
+	paths, err := defaultPaths()
+	if err != nil {
+		return nil, err
+	}
+	cachedConfig, cachedConfigError = newLocked(&Options{SetDefault: true}, paths)
 	return cachedConfig, cachedConfigError
 }
 
 // A helper function for New() expecting the caller to hold the
 // cachedConfigMutex if options.SetDefault is set..
-func newLocked(options *Options) (*Config, error) {
+func newLocked(options *Options, paths *paths) (*Config, error) {
 	// Start with the built-in defaults
 	config, err := defaultConfig()
 	if err != nil {
 		return nil, err
 	}
 
 	// Now, gather the system configs and merge them as needed.
-	configs, err := systemConfigs()
+	configs, err := systemConfigs(paths)
 	if err != nil {
 		return nil, fmt.Errorf("finding config on system: %w", err)
 	}
@@ -152,24 +185,18 @@ func NewConfig(userConfigPath string) (*Config, error) {
 // Returns the list of configuration files, if they exist in order of hierarchy.
 // The files are read in order and each new file can/will override previous
 // file settings.
-func systemConfigs() (configs []string, finalErr error) {
+func systemConfigs(paths *paths) (configs []string, finalErr error) {
 	if path := os.Getenv(containersConfEnv); path != "" {
 		if err := fileutils.Exists(path); err != nil {
 			return nil, fmt.Errorf("%s file: %w", containersConfEnv, err)
 		}
 		return append(configs, path), nil
 	}
 
-	configs = append(configs, defaultContainersConfig)
-
-	var err error
-	path, err := overrideContainersConfigPath()
-	if err != nil {
-		return nil, err
-	}
-	configs = append(configs, path)
+	configs = append(configs, paths.usr)
+	configs = append(configs, paths.etc)
 
-	configs, err = addConfigs(path+".d", configs)
+	configs, err := addConfigs(paths.etc+".d", configs)
 	if err != nil {
 		return nil, err
 	}
@@ -178,27 +205,21 @@ func systemConfigs() (configs []string, finalErr error) {
 	// /etc/containers/containers.rootless.conf
 	// /etc/containers/containers.rootless.conf.d/
 	// /etc/containers/containers.rootless.conf.d/<UID>/
-	uid := unshare.GetRootlessUID()
-	if uid > 0 {
-		rootlessOverwritePath := filepath.Join(filepath.Dir(path), "containers.rootless.conf")
+	if paths.uid > 0 {
+		rootlessOverwritePath := filepath.Join(filepath.Dir(paths.etc), "containers.rootless.conf")
 		configs = append(configs, rootlessOverwritePath)
 		rootlessOverwritePathD := rootlessOverwritePath + ".d"
 		configs, err = addConfigs(rootlessOverwritePathD, configs)
 		if err != nil {
 			return nil, err
 		}
-		configs, err = addConfigs(filepath.Join(rootlessOverwritePathD, strconv.Itoa(uid)), configs)
+		configs, err = addConfigs(filepath.Join(rootlessOverwritePathD, strconv.Itoa(paths.uid)), configs)
 		if err != nil {
 			return nil, err
 		}
 	}
-
-	path, err = userConfigPath()
-	if err != nil {
-		return nil, err
-	}
-	configs = append(configs, path)
-	configs, err = addConfigs(path+".d", configs)
+	configs = append(configs, paths.home)
+	configs, err = addConfigs(paths.home+".d", configs)
 	if err != nil {
 		return nil, err
 	}