Add graphviz generation and visualization

This requires graphviz to be installed on your machine. If you run the
command with sudo, it will create the files with the original user
ownership to make it easier to remove them without root.

file.go

@@ -55,6 +55,10 @@ func NewFileType(name, path, content, state string) *FileType {
 	}
 }
 
+func (obj *FileType) GetType() string {
+	return "File"
+}
+
 // File watcher for files and directories
 // Modify with caution, probably important to write some test cases first!
 // obj.Path: file or directory

main.go

@@ -102,6 +102,12 @@ func run(c *cli.Context) {
 				log.Fatal("Graph failure")
 			}
 			log.Printf("Graph: %v\n", G) // show graph
+			err := G.ExecGraphviz(c.String("graphviz-filter"), c.String("graphviz"))
+			if err != nil {
+				log.Printf("Graphviz: %v", err)
+			} else {
+				log.Printf("Graphviz: Successfully generated graph!")
+			}
 			G.SetVertex()
 			if first {
 				// G.Start(...) needs to be synchronous or wait,
@@ -174,6 +180,16 @@ func main() {
 					Value: "",
 					Usage: "code definition to run",
 				},
+				cli.StringFlag{
+					Name:  "graphviz, g",
+					Value: "",
+					Usage: "output file for graphviz data",
+				},
+				cli.StringFlag{
+					Name:  "graphviz-filter, gf",
+					Value: "dot", // directed graph default
+					Usage: "graphviz filter to use",
+				},
 				// useful for testing multiple instances on same machine
 				cli.StringFlag{
 					Name:  "hostname",

pgraph.go

@@ -19,10 +19,15 @@
 package main
 
 import (
-	//"container/list" // doubly linked list
+	"errors"
 	"fmt"
+	"io/ioutil"
 	"log"
+	"os"
+	"os/exec"
+	"strconv"
 	"sync"
+	"syscall"
 )
 
 //go:generate stringer -type=graphState -output=graphstate_stringer.go
@@ -81,6 +86,11 @@ func NewEdge(name string) *Edge {
 	}
 }
 
+// returns the name of the graph
+func (g *Graph) GetName() string {
+	return g.Name
+}
+
 // set name of the graph
 func (g *Graph) SetName(name string) {
 	g.Name = name
@@ -208,6 +218,88 @@ func (g *Graph) String() string {
 	return fmt.Sprintf("Vertices(%d), Edges(%d)", g.NumVertices(), g.NumEdges())
 }
 
+// output the graph in graphviz format
+// https://en.wikipedia.org/wiki/DOT_%28graph_description_language%29
+func (g *Graph) Graphviz() (out string) {
+	//digraph g {
+	//	label="hello world";
+	//	node [shape=box];
+	//	A [label="A"];
+	//	B [label="B"];
+	//	C [label="C"];
+	//	D [label="D"];
+	//	E [label="E"];
+	//	A -> B [label=f];
+	//	B -> C [label=g];
+	//	D -> E [label=h];
+	//}
+	out += fmt.Sprintf("digraph %v {\n", g.GetName())
+	out += fmt.Sprintf("\tlabel=\"%v\";\n", g.GetName())
+	//out += "\tnode [shape=box];\n"
+	str := ""
+	for i, _ := range g.Adjacency { // reverse paths
+		out += fmt.Sprintf("\t%v [label=\"%v[%v]\"];\n", i.GetName(), i.GetType(), i.GetName())
+		for j, _ := range g.Adjacency[i] {
+			k := g.Adjacency[i][j]
+			// use str for clearer output ordering
+			str += fmt.Sprintf("\t%v -> %v [label=%v];\n", i.GetName(), j.GetName(), k.Name)
+		}
+	}
+	out += str
+	out += "}\n"
+	return
+}
+
+// write out the graphviz data and run the correct graphviz filter command
+func (g *Graph) ExecGraphviz(program, filename string) error {
+
+	switch program {
+	case "dot", "neato", "twopi", "circo", "fdp":
+	default:
+		return errors.New("Invalid graphviz program selected!")
+	}
+
+	if filename == "" {
+		return errors.New("No filename given!")
+	}
+
+	// run as a normal user if possible when run with sudo
+	uid, err1 := strconv.Atoi(os.Getenv("SUDO_UID"))
+	gid, err2 := strconv.Atoi(os.Getenv("SUDO_GID"))
+
+	err := ioutil.WriteFile(filename, []byte(g.Graphviz()), 0644)
+	if err != nil {
+		return errors.New("Error writing to filename!")
+	}
+
+	if err1 == nil && err2 == nil {
+		if err := os.Chown(filename, uid, gid); err != nil {
+			return errors.New("Error changing file owner!")
+		}
+	}
+
+	path, err := exec.LookPath(program)
+	if err != nil {
+		return errors.New("Graphviz is missing!")
+	}
+
+	out := fmt.Sprintf("%v.png", filename)
+	cmd := exec.Command(path, "-Tpng", fmt.Sprintf("-o%v", out), filename)
+
+	if err1 == nil && err2 == nil {
+		cmd.SysProcAttr = &syscall.SysProcAttr{}
+		cmd.SysProcAttr.Credential = &syscall.Credential{
+			Uid: uint32(uid),
+			Gid: uint32(gid),
+		}
+	}
+	_, err = cmd.Output()
+	if err != nil {
+		return errors.New("Error writing to image!")
+	}
+	return nil
+}
+
 // google/golang hackers apparently do not think contains should be a built-in!
 func Contains(s []*Vertex, element *Vertex) bool {
 	for _, v := range s {

service.go

@@ -45,6 +45,10 @@ func NewServiceType(name, state, startup string) *ServiceType {
 	}
 }
 
+func (obj *ServiceType) GetType() string {
+	return "Service"
+}
+
 // Service watcher
 func (obj *ServiceType) Watch() {
 	// obj.Name: service name

types.go

@@ -26,6 +26,7 @@ import (
 type Type interface {
 	Init()
 	GetName() string // can't be named "Name()" because of struct field
+	GetType() string
 	Watch()
 	StateOK() bool // TODO: can we rename this to something better?
 	Apply() bool
@@ -71,6 +72,10 @@ func (obj *BaseType) GetName() string {
 	return obj.Name
 }
 
+func (obj *BaseType) GetType() string {
+	return "Base"
+}
+
 func (obj *BaseType) GetVertex() *Vertex {
 	return obj.vertex
 }
@@ -198,6 +203,10 @@ func (obj *BaseType) Process(typ Type) {
 
 }
 
+func (obj *NoopType) GetType() string {
+	return "Noop"
+}
+
 func (obj *NoopType) Watch() {
 	//vertex := obj.vertex // stored with SetVertex
 	var send = false // send event?