Add support for switching between crlf and lf

Dos and Unix line endings are now both supported (previously on unix
line endings were supported) and can be accessed via the `fileformat`
option. The file format will be automatically detected and displayed in
the statusline but can be overriden.

Possible values for the `fileformat` option are `dos` and `unix`.

Closes #443
Closes #755

cmd/micro/buffer.go

@@ -19,6 +19,13 @@ import (
 	"github.com/zyedidia/micro/cmd/micro/highlight"
 )
 
+var (
+	// 0 - no line type detected
+	// 1 - lf detected
+	// 2 - crlf detected
+	fileformat = 0
+)
+
 // Buffer stores the text for files that are loaded into the text editor
 // It uses a rope to efficiently store the string and contains some
 // simple functions for saving and wrapper functions for modifying the rope
@@ -88,6 +95,12 @@ func NewBuffer(reader io.Reader, size int64, path string) *Buffer {
 		}
 	}
 
+	if fileformat == 1 {
+		b.Settings["fileformat"] = "unix"
+	} else if fileformat == 2 {
+		b.Settings["fileformat"] = "dos"
+	}
+
 	absPath, _ := filepath.Abs(path)
 
 	b.Path = path
@@ -355,7 +368,7 @@ func (b *Buffer) Serialize() error {
 				b.ModTime,
 			})
 		}
-		file.Close()
+		err = file.Close()
 		return err
 	}
 	return nil
@@ -383,7 +396,7 @@ func (b *Buffer) SaveAs(filename string) error {
 			b.Insert(end, "\n")
 		}
 	}
-	str := b.String()
+	str := b.SaveString(b.Settings["fileformat"] == "dos")
 	data := []byte(str)
 	err := ioutil.WriteFile(filename, data, 0644)
 	if err == nil {
@@ -408,7 +421,7 @@ func (b *Buffer) SaveAsWithSudo(filename string) error {
 
 	// Set up everything for the command
 	cmd := exec.Command("sudo", "tee", filename)
-	cmd.Stdin = bytes.NewBufferString(b.String())
+	cmd.Stdin = bytes.NewBufferString(b.SaveString(b.Settings["fileformat"] == "dos"))
 
 	// This is a trap for Ctrl-C so that it doesn't kill micro
 	// Instead we trap Ctrl-C to kill the program we're running

cmd/micro/lineArray.go

@@ -71,6 +71,12 @@ func NewLineArray(size int64, reader io.Reader) *LineArray {
 	n := 0
 	for {
 		data, err := br.ReadBytes('\n')
+		if len(data) > 0 && data[len(data)-2] == '\r' {
+			data = append(data[:len(data)-2], '\n')
+			fileformat = 2
+		} else if len(data) > 0 {
+			fileformat = 1
+		}
 
 		if n >= 1000 && loaded >= 0 {
 			totalLinesNum := int(float64(size) * (float64(n) / float64(loaded)))
@@ -114,6 +120,23 @@ func (la *LineArray) String() string {
 	return str
 }
 
+// SaveString returns the string that should be written to disk when
+// the line array is saved
+// It is the same as string but uses crlf or lf line endings depending
+func (la *LineArray) SaveString(useCrlf bool) string {
+	str := ""
+	for i, l := range la.lines {
+		str += string(l.data)
+		if i != len(la.lines)-1 {
+			if useCrlf {
+				str += "\r"
+			}
+			str += "\n"
+		}
+	}
+	return str
+}
+
 // NewlineBelow adds a newline below the given line number
 func (la *LineArray) NewlineBelow(y int) {
 	la.lines = append(la.lines, Line{[]byte(" "), nil, nil, false})

cmd/micro/settings.go

@@ -27,6 +27,7 @@ var optionValidators = map[string]optionValidator{
 	"scrollspeed":  validateNonNegativeValue,
 	"colorscheme":  validateColorscheme,
 	"colorcolumn":  validateNonNegativeValue,
+	"fileformat":   validateLineEnding,
 }
 
 // InitGlobalSettings initializes the options map and sets all options to their default values
@@ -220,6 +221,7 @@ func DefaultGlobalSettings() map[string]interface{} {
 		},
 		"pluginrepos": []string{},
 		"useprimary":  true,
+		"fileformat":  "unix",
 	}
 }
 
@@ -251,6 +253,7 @@ func DefaultLocalSettings() map[string]interface{} {
 		"tabsize":        float64(4),
 		"tabstospaces":   false,
 		"useprimary":     true,
+		"fileformat":     "unix",
 	}
 }
 
@@ -365,6 +368,10 @@ func SetLocalOption(option, value string, view *View) error {
 		buf.UpdateRules()
 	}
 
+	if option == "fileformat" {
+		buf.IsModified = true
+	}
+
 	if option == "syntax" {
 		if !nativeValue.(bool) {
 			buf.ClearMatches()
@@ -445,3 +452,17 @@ func validateColorscheme(option string, value interface{}) error {
 
 	return nil
 }
+
+func validateLineEnding(option string, value interface{}) error {
+	endingType, ok := value.(string)
+
+	if !ok {
+		return errors.New("Expected string type for file format")
+	}
+
+	if endingType != "unix" && endingType != "dos" {
+		return errors.New("File format must be either 'unix' or 'dos'")
+	}
+
+	return nil
+}

cmd/micro/statusline.go

@@ -36,6 +36,8 @@ func (sline *Statusline) Display() {
 	// Add the filetype
 	file += " " + sline.view.Buf.FileType()
 
+	file += " " + sline.view.Buf.Settings["fileformat"].(string)
+
 	rightText := ""
 	if len(helpBinding) > 0 {
 		rightText = helpBinding + " for help "

runtime/help/options.md

@@ -173,6 +173,13 @@ Default plugin options:
 
 	default value: `on`
 
+* `fileformat`: this determines what kind of line endings micro will use for the file. Unix line endings
+   are just `\n` (lf) whereas dos line endings are `\r\n` (crlf). The two possible values for this option
+   are `unix` and `dos`. The fileformat will be automatically detected and displayed on the statusline but
+   this option is useful if you would like to change the line endings or if you are starting a new file.
+
+    default value: `unix`
+
 Any option you set in the editor will be saved to the file 
 ~/.config/micro/settings.json so, in effect, your configuration file will be 
 created for you. If you'd like to take your configuration with you to another