buffer: Resolve symlinks in file paths

Otherwise we can't identify if we have the same file open multiple times via
different symlinks.
The test must be adapted to resolve symlinks in `findBuffer()`.

cmd/micro/micro_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/micro-editor/micro/v2/internal/buffer"
 	"github.com/micro-editor/micro/v2/internal/config"
 	"github.com/micro-editor/micro/v2/internal/screen"
+	"github.com/micro-editor/micro/v2/internal/util"
 	"github.com/micro-editor/tcell/v2"
 	"github.com/stretchr/testify/assert"
 )
@@ -157,8 +158,9 @@ func openFile(file string) {
 
 func findBuffer(file string) *buffer.Buffer {
 	var buf *buffer.Buffer
+	file = util.ResolvePath(file)
 	for _, b := range buffer.OpenBuffers {
-		if b.Path == file {
+		if b.AbsPath == file {
 			buf = b
 		}
 	}

internal/buffer/buffer.go

@@ -355,9 +355,9 @@ func NewBufferFromString(text, path string, btype BufType) *Buffer {
 // Places the cursor at startcursor. If startcursor is -1, -1 places the
 // cursor at an autodetected location (based on savecursor or :LINE:COL)
 func NewBuffer(r io.Reader, size int64, path string, btype BufType, cmd Command) *Buffer {
-	absPath, err := filepath.Abs(path)
-	if err != nil {
-		absPath = path
+	absPath := path
+	if btype == BTDefault && path != "" {
+		absPath = util.ResolvePath(path)
 	}
 
 	b := new(Buffer)
@@ -391,6 +391,7 @@ func NewBuffer(r io.Reader, size int64, path string, btype BufType, cmd Command)
 		}
 		config.UpdatePathGlobLocals(b.Settings, absPath)
 
+		var err error
 		b.encoding, err = htmlindex.Get(b.Settings["encoding"].(string))
 		if err != nil {
 			b.encoding = unicode.UTF8
@@ -489,7 +490,7 @@ func NewBuffer(r io.Reader, size int64, path string, btype BufType, cmd Command)
 		}
 	}
 
-	err = config.RunPluginFn("onBufferOpen", luar.New(ulua.L, b))
+	err := config.RunPluginFn("onBufferOpen", luar.New(ulua.L, b))
 	if err != nil {
 		screen.TermMessage(err)
 	}

internal/buffer/save.go

@@ -285,10 +285,7 @@ func (b *Buffer) saveToFile(filename string, withSudo bool, autoSave bool) error
 		return errors.New("Error: " + filename + " is not a regular file and cannot be saved")
 	}
 
-	absFilename, err := filepath.Abs(filename)
-	if err != nil {
-		return err
-	}
+	absFilename := util.ResolvePath(filename)
 
 	// Get the leading path to the file | "." is returned if there's no leading path provided
 	if dirname := filepath.Dir(absFilename); dirname != "." {

internal/util/util.go

@@ -489,6 +489,39 @@ func DetermineEscapePath(dir string, path string) (string, string) {
 	return url, ""
 }
 
+// ResolvePath provides the absolute file path for the given relative file path
+// as well as resolves symlinks. If it fails to get the absolute path or to
+// resolve symlinks, it returns unresolved path in place of resolved one.
+func ResolvePath(path string) string {
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		absPath = path
+	}
+
+	var remainder []string
+	for {
+		resolvedPath, err := filepath.EvalSymlinks(absPath)
+		if err == nil {
+			absPath = resolvedPath
+			break
+		}
+		if !errors.Is(err, fs.ErrNotExist) {
+			break
+		}
+
+		remainder = append([]string{filepath.Base(absPath)}, remainder...)
+		absPath = filepath.Dir(absPath)
+	}
+
+	if len(remainder) > 0 {
+		remainder = append([]string{absPath}, remainder...)
+		absPath = filepath.Join(remainder...)
+		absPath = filepath.Clean(absPath)
+	}
+
+	return absPath
+}
+
 // GetLeadingWhitespace returns the leading whitespace of the given byte array
 func GetLeadingWhitespace(b []byte) []byte {
 	ws := []byte{}