1 files changed, 83 insertions, 4 deletions

diff --git a/plumbing/format/gitignore/dir.go b/plumbing/format/gitignore/dir.go
index 41dd624..1e88970 100644
--- a/plumbing/format/gitignore/dir.go
+++ b/plumbing/format/gitignore/dir.go
@@ -1,24 +1,31 @@
 package gitignore
 
 import (
+	"bytes"
 	"io/ioutil"
 	"os"
+	"os/user"
 	"strings"
 
 	"gopkg.in/src-d/go-billy.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/config"
+	gioutil "gopkg.in/src-d/go-git.v4/utils/ioutil"
 )
 
 const (
 	commentPrefix = "#"
+	coreSection   = "core"
 	eol           = "\n"
+	excludesfile  = "excludesfile"
 	gitDir        = ".git"
 	gitignoreFile = ".gitignore"
+	gitconfigFile = ".gitconfig"
+	systemFile    = "/etc/gitconfig"
 )
 
-// ReadPatterns reads gitignore patterns recursively traversing through the directory
-// structure. The result is in the ascending order of priority (last higher).
-func ReadPatterns(fs billy.Filesystem, path []string) (ps []Pattern, err error) {
-	f, err := fs.Open(fs.Join(append(path, gitignoreFile)...))
+// readIgnoreFile reads a specific git ignore file.
+func readIgnoreFile(fs billy.Filesystem, path []string, ignoreFile string) (ps []Pattern, err error) {
+	f, err := fs.Open(fs.Join(append(path, ignoreFile)...))
 	if err == nil {
 		defer f.Close()
 
@@ -33,6 +40,14 @@ func ReadPatterns(fs billy.Filesystem, path []string) (ps []Pattern, err error)
 		return nil, err
 	}
 
+	return
+}
+
+// ReadPatterns reads gitignore patterns recursively traversing through the directory
+// structure. The result is in the ascending order of priority (last higher).
+func ReadPatterns(fs billy.Filesystem, path []string) (ps []Pattern, err error) {
+	ps, _ = readIgnoreFile(fs, path, gitignoreFile)
+
 	var fis []os.FileInfo
 	fis, err = fs.ReadDir(fs.Join(path...))
 	if err != nil {
@@ -55,3 +70,67 @@ func ReadPatterns(fs billy.Filesystem, path []string) (ps []Pattern, err error)
 
 	return
 }
+
+func loadPatterns(fs billy.Filesystem, path string) (ps []Pattern, err error) {
+	f, err := fs.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	defer gioutil.CheckClose(f, &err)
+
+	b, err := ioutil.ReadAll(f)
+	if err != nil {
+		return
+	}
+
+	d := config.NewDecoder(bytes.NewBuffer(b))
+
+	raw := config.New()
+	if err = d.Decode(raw); err != nil {
+		return
+	}
+
+	s := raw.Section(coreSection)
+	efo := s.Options.Get(excludesfile)
+	if efo == "" {
+		return nil, nil
+	}
+
+	ps, err = readIgnoreFile(fs, nil, efo)
+	if os.IsNotExist(err) {
+		return nil, nil
+	}
+
+	return
+}
+
+// LoadGlobalPatterns loads gitignore patterns from from the gitignore file
+// declared in a user's ~/.gitconfig file.  If the ~/.gitconfig file does not
+// exist the function will return nil.  If the core.excludesfile property
+// is not declared, the function will return nil.  If the file pointed to by
+// the core.excludesfile property does not exist, the function will return nil.
+//
+// The function assumes fs is rooted at the root filesystem.
+func LoadGlobalPatterns(fs billy.Filesystem) (ps []Pattern, err error) {
+	usr, err := user.Current()
+	if err != nil {
+		return
+	}
+
+	return loadPatterns(fs, fs.Join(usr.HomeDir, gitconfigFile))
+}
+
+// LoadSystemPatterns loads gitignore patterns from from the gitignore file
+// declared in a system's /etc/gitconfig file.  If the ~/.gitconfig file does
+// not exist the function will return nil.  If the core.excludesfile property
+// is not declared, the function will return nil.  If the file pointed to by
+// the core.excludesfile property does not exist, the function will return nil.
+//
+// The function assumes fs is rooted at the root filesystem.
+func LoadSystemPatterns(fs billy.Filesystem) (ps []Pattern, err error) {
+	return loadPatterns(fs, systemFile)
+}