config: apply linting feedback.

config/iniconf/iniconf.go

@@ -2,6 +2,7 @@ package iniconf
 
 import (
 	"bufio"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -23,30 +24,31 @@ var (
 var DefaultSection = "default"
 
 // ParseFile attempts to load the named config file.
-func ParseFile(fileName string) (cfg ConfigMap, err error) {
-	var file *os.File
-	file, err = os.Open(fileName)
+func ParseFile(fileName string) (ConfigMap, error) {
+	file, err := os.Open(fileName)
 	if err != nil {
-		return
+		return nil, err
 	}
 	defer file.Close()
+
 	return ParseReader(file)
 }
 
 // ParseReader reads a configuration from an io.Reader.
-func ParseReader(r io.Reader) (cfg ConfigMap, err error) {
-	cfg = ConfigMap{}
+func ParseReader(r io.Reader) (ConfigMap, error) {
+	cfg := ConfigMap{}
 	buf := bufio.NewReader(r)
 
 	var (
 		line           string
 		longLine       bool
 		currentSection string
+		err            error
 	)
 
 	for {
 		line, longLine, err = readConfigLine(buf, line, longLine)
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			err = nil
 			break
 		} else if err != nil {
@@ -62,11 +64,12 @@ func ParseReader(r io.Reader) (cfg ConfigMap, err error) {
 			break
 		}
 	}
-	return
+
+	return cfg, err
 }
 
 // readConfigLine reads and assembles a complete configuration line, handling long lines.
-func readConfigLine(buf *bufio.Reader, currentLine string, longLine bool) (line string, stillLong bool, err error) {
+func readConfigLine(buf *bufio.Reader, currentLine string, longLine bool) (string, bool, error) {
 	lineBytes, isPrefix, err := buf.ReadLine()
 	if err != nil {
 		return "", false, err
@@ -94,14 +97,14 @@ func processConfigLine(cfg ConfigMap, line string, currentSection string) (strin
 		return handleConfigLine(cfg, line, currentSection)
 	}
 
-	return currentSection, fmt.Errorf("invalid config file")
+	return currentSection, errors.New("invalid config file")
 }
 
 // handleSectionLine processes a section header line.
 func handleSectionLine(cfg ConfigMap, line string) (string, error) {
 	section := configSection.ReplaceAllString(line, "$1")
 	if section == "" {
-		return "", fmt.Errorf("invalid structure in file")
+		return "", errors.New("invalid structure in file")
 	}
 	if !cfg.SectionInConfig(section) {
 		cfg[section] = make(map[string]string, 0)
@@ -139,41 +142,39 @@ func (c ConfigMap) SectionInConfig(section string) bool {
 }
 
 // ListSections returns the list of sections in the config map.
-func (c ConfigMap) ListSections() (sections []string) {
+func (c ConfigMap) ListSections() []string {
+	sections := make([]string, 0, len(c))
 	for section := range c {
 		sections = append(sections, section)
 	}
-	return
+	return sections
 }
 
 // WriteFile writes out the configuration to a file.
-func (c ConfigMap) WriteFile(filename string) (err error) {
+func (c ConfigMap) WriteFile(filename string) error {
 	file, err := os.Create(filename)
 	if err != nil {
-		return
+		return err
 	}
 	defer file.Close()
 
 	for _, section := range c.ListSections() {
 		sName := fmt.Sprintf("[ %s ]\n", section)
-		_, err = file.Write([]byte(sName))
-		if err != nil {
-			return
+		if _, err = file.WriteString(sName); err != nil {
+			return err
 		}
 
 		for k, v := range c[section] {
 			line := fmt.Sprintf("%s = %s\n", k, v)
-			_, err = file.Write([]byte(line))
-			if err != nil {
-				return
+			if _, err = file.WriteString(line); err != nil {
+				return err
 			}
 		}
-		_, err = file.Write([]byte{0x0a})
-		if err != nil {
-			return
+		if _, err = file.Write([]byte{0x0a}); err != nil {
+			return err
 		}
 	}
-	return
+	return nil
 }
 
 // AddSection creates a new section in the config map.
@@ -197,27 +198,26 @@ func (c ConfigMap) AddKeyVal(section, key, val string) {
 }
 
 // GetValue retrieves the value from a key map.
-func (c ConfigMap) GetValue(section, key string) (val string, present bool) {
+func (c ConfigMap) GetValue(section, key string) (string, bool) {
 	if c == nil {
-		return
+		return "", false
 	}
 
 	if section == "" {
 		section = DefaultSection
 	}
 
-	_, ok := c[section]
-	if !ok {
-		return
+	if _, ok := c[section]; !ok {
+		return "", false
 	}
 
-	val, present = c[section][key]
-	return
+	val, present := c[section][key]
+	return val, present
 }
 
 // GetValueDefault retrieves the value from a key map if present,
 // otherwise the default value.
-func (c ConfigMap) GetValueDefault(section, key, value string) (val string) {
+func (c ConfigMap) GetValueDefault(section, key, value string) string {
 	kval, ok := c.GetValue(section, key)
 	if !ok {
 		return value
@@ -226,7 +226,7 @@ func (c ConfigMap) GetValueDefault(section, key, value string) (val string) {
 }
 
 // SectionKeys returns the sections in the config map.
-func (c ConfigMap) SectionKeys(section string) (keys []string, present bool) {
+func (c ConfigMap) SectionKeys(section string) ([]string, bool) {
 	if c == nil {
 		return nil, false
 	}
@@ -235,13 +235,12 @@ func (c ConfigMap) SectionKeys(section string) (keys []string, present bool) {
 		section = DefaultSection
 	}
 
-	cm := c
-	s, ok := cm[section]
+	s, ok := c[section]
 	if !ok {
 		return nil, false
 	}
 
-	keys = make([]string, 0, len(s))
+	keys := make([]string, 0, len(s))
 	for key := range s {
 		keys = append(keys, key)
 	}