Add support for writing to a file (and creating it if not existent)

http.go

@@ -269,6 +269,24 @@ func (rt *Router) routeServerListDirectory(w http.ResponseWriter, r *http.Reques
 	json.NewEncoder(w).Encode(stats)
 }
 
+// Writes a file to the system for the server.
+func (rt *Router) routeServerWriteFile(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
+	s := rt.Servers.Get(ps.ByName("server"))
+
+	p := r.URL.Query().Get("file")
+	defer r.Body.Close()
+	err := s.Filesystem.Writefile(p, r.Body)
+
+	if err != nil {
+		zap.S().Errorw("failed to write file to directory", zap.String("server", s.Uuid), zap.String("path", p), zap.Error(err))
+
+		http.Error(w, "failed to write file to directory", http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
 // Creates a new directory for the server.
 func (rt *Router) routeServerCreateDirectory(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 	s := rt.Servers.Get(ps.ByName("server"))
@@ -374,6 +392,7 @@ func (rt *Router) ConfigureRouter() *httprouter.Router {
 	router.GET("/api/servers/:server/files/list-directory", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerListDirectory)))
 	router.PUT("/api/servers/:server/files/rename", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerRenameFile)))
 	router.POST("/api/servers/:server/files/copy", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerCopyFile)))
+	router.POST("/api/servers/:server/files/write", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerWriteFile)))
 	router.POST("/api/servers/:server/files/create-directory", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerCreateDirectory)))
 	router.POST("/api/servers/:server/files/delete", rt.AuthenticateToken("s:files", rt.AuthenticateServer(rt.routeServerDeleteFile)))
 	router.POST("/api/servers/:server/power", rt.AuthenticateToken("s:power", rt.AuthenticateServer(rt.routeServerPower)))

server/filesystem.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"bufio"
 	"bytes"
 	"encoding/json"
 	"errors"
@@ -196,6 +197,68 @@ func (fs *Filesystem) Readfile(p string) (io.Reader, error) {
 	return bytes.NewReader(b), nil
 }
 
+// Writes a file to the system. If the file does not already exist one will be created.
+//
+// @todo should probably have a write lock here so we don't write twice at once.
+func (fs *Filesystem) Writefile(p string, r io.Reader) error {
+	cleaned, err := fs.SafePath(p)
+	if err != nil {
+		return err
+	}
+
+	// If the file does not exist on the system already go ahead and create the pathway
+	// to it and an empty file. We'll then write to it later on after this completes.
+	if stat, err := os.Stat(cleaned); err != nil && os.IsNotExist(err) {
+		if err := os.MkdirAll(filepath.Dir(cleaned), 0755); err != nil {
+			return err
+		}
+
+		if err := fs.Chown(filepath.Dir(cleaned)); err != nil {
+			return err
+		}
+	} else if err != nil {
+		return err
+	} else if stat.IsDir() {
+		return errors.New("cannot use a directory as a file for writing")
+	}
+
+	// This will either create the file if it does not already exist, or open and
+	// truncate the existing file.
+	file, err := os.OpenFile(cleaned, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	// Create a new buffered writer that will write to the file we just opened
+	// and stream in the contents from the reader.
+	w := bufio.NewWriter(file)
+
+	buf := make([]byte, 1024)
+	for {
+		n, err := r.Read(buf)
+		if err != nil && err != io.EOF {
+			return err
+		}
+
+		if n == 0 {
+			break
+		}
+
+		if _, err := w.Write(buf[:n]); err != nil {
+			return err
+		}
+	}
+
+	if err := w.Flush(); err != nil {
+		return err
+	}
+
+	// Finally, chown the file to ensure the permissions don't end up out-of-whack
+	// if we had just created it.
+	return fs.Chown(p)
+}
+
 // Defines the stat struct object.
 type Stat struct {
 	Info     os.FileInfo