config: ReadConfig and LoadConfig from scopes

3 files changed, 94 insertions, 15 deletions

diff --git a/config/config.go b/config/config.go
index e17ec5d..7d6ab58 100644
--- a/config/config.go
+++ b/config/config.go
@@ -5,11 +5,16 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"sort"
 	"strconv"
 
 	"github.com/go-git/go-git/v5/internal/url"
 	format "github.com/go-git/go-git/v5/plumbing/format/config"
+	"github.com/mitchellh/go-homedir"
 )
 
 const (
@@ -32,6 +37,16 @@ var (
 	ErrRemoteConfigEmptyName = errors.New("remote config: empty name")
 )
 
+// Scope defines the scope of a config file, such as local, global or system.
+type Scope int
+
+// Available ConfigScope's
+const (
+	LocalScope Scope = iota
+	GlobalScope
+	SystemScope
+)
+
 // Config contains the repository configuration
 // https://www.kernel.org/pub/software/scm/git/docs/git-config.html#FILES
 type Config struct {
@@ -103,6 +118,77 @@ func NewConfig() *Config {
 	return config
 }
 
+// ReadConfig reads a config file from a io.Reader.
+func ReadConfig(r io.Reader) (*Config, error) {
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+
+	cfg := NewConfig()
+	if err = cfg.Unmarshal(b); err != nil {
+		return nil, err
+	}
+
+	return cfg, nil
+}
+
+// LoadConfig loads a config file from a given scope. The returned Config,
+// contains exclusively information fom the given scope. If couldn't find a
+// config file to the given scope, a empty one is returned.
+func LoadConfig(scope Scope) (*Config, error) {
+	if scope == LocalScope {
+		return nil, fmt.Errorf("LocalScope should be read from the a ConfigStorer.")
+	}
+
+	files, err := Paths(scope)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, file := range files {
+		f, err := os.Open(file)
+		if err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+
+			return nil, err
+		}
+
+		defer f.Close()
+		return ReadConfig(f)
+	}
+
+	return NewConfig(), nil
+}
+
+// Paths returns the config file location for a given scope.
+func Paths(scope Scope) ([]string, error) {
+	var files []string
+	switch scope {
+	case GlobalScope:
+		xdg := os.Getenv("XDG_CONFIG_HOME")
+		if xdg != "" {
+			files = append(files, filepath.Join(xdg, "git/config"))
+		}
+
+		home, err := homedir.Dir()
+		if err != nil {
+			return nil, err
+		}
+
+		files = append(files,
+			filepath.Join(home, ".gitconfig"),
+			filepath.Join(home, ".config/git/config"),
+		)
+	case SystemScope:
+		files = append(files, "/etc/gitconfig")
+	}
+
+	return files, nil
+}
+
 // Validate validates the fields and sets the default values.
 func (c *Config) Validate() error {
 	for name, r := range c.Remotes {
diff --git a/config/config_test.go b/config/config_test.go
index 157be95..e68626b 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -170,6 +170,12 @@ func (s *ConfigSuite) TestUnmarshalMarshal(c *C) {
 	c.Assert(string(output), DeepEquals, string(input))
 }
 
+func (s *ConfigSuite) TestLoadConfig(c *C) {
+	cfg, err := LoadConfig(GlobalScope)
+	c.Assert(err, IsNil)
+	c.Assert(cfg.User.Email, Not(Equals), "")
+}
+
 func (s *ConfigSuite) TestValidateConfig(c *C) {
 	config := &Config{
 		Remotes: map[string]*RemoteConfig{
diff --git a/storage/filesystem/config.go b/storage/filesystem/config.go
index 01b35b4..78a6464 100644
--- a/storage/filesystem/config.go
+++ b/storage/filesystem/config.go
@@ -1,7 +1,6 @@
 package filesystem
 
 import (
-	stdioutil "io/ioutil"
 	"os"
 
 	"github.com/go-git/go-git/v5/config"
@@ -14,29 +13,17 @@ type ConfigStorage struct {
 }
 
 func (c *ConfigStorage) Config() (conf *config.Config, err error) {
-	cfg := config.NewConfig()
-
 	f, err := c.dir.Config()
 	if err != nil {
 		if os.IsNotExist(err) {
-			return cfg, nil
+			return config.NewConfig(), nil
 		}
 
 		return nil, err
 	}
 
 	defer ioutil.CheckClose(f, &err)
-
-	b, err := stdioutil.ReadAll(f)
-	if err != nil {
-		return nil, err
-	}
-
-	if err = cfg.Unmarshal(b); err != nil {
-		return nil, err
-	}
-
-	return cfg, err
+	return config.ReadConfig(f)
 }
 
 func (c *ConfigStorage) SetConfig(cfg *config.Config) (err error) {