Create destination directory if missing

Fixes: #14

file.go

@@ -14,11 +14,16 @@ import (
 // PetsFile is the central data structure of the system: it is the in-memory
 // representation of a configuration file (eg: sshd_config)
 type PetsFile struct {
+	// Absolute path to the configuration file
 	Source string
 	Pkgs   []PetsPackage
-	Dest   string
-	User   *user.User
-	Group  *user.Group
+	// Full destination path where the file has to be installed
+	Dest string
+	// Directory where the file has to be installed. This is only set in
+	// case we have to create the destination directory
+	Directory string
+	User      *user.User
+	Group     *user.Group
 	// use string instead of os.FileMode to avoid converting back and forth
 	Mode string
 	Pre  *exec.Cmd
@@ -116,6 +121,42 @@ func (pf *PetsFile) NeedsLink() PetsCause {
 	return NONE
 }
 
+// NeedsDir returns PetsCause DIR if there is no directory at Directory,
+// meaning that it has to be created. Most of this is suspiciously similar to
+// NeedsLink above.
+func (pf *PetsFile) NeedsDir() PetsCause {
+	if pf.Directory == "" {
+		return NONE
+	}
+
+	fi, err := os.Lstat(pf.Directory)
+
+	if os.IsNotExist(err) {
+		// Directory does not exist yet. Happy path, we are gonna create it!
+		return DIR
+	}
+
+	if err != nil {
+		// There was an error calling lstat, putting all my money on
+		// permission denied.
+		log.Printf("[ERROR] cannot lstat Directory %s: %v\n", pf.Directory, err)
+		return NONE
+	}
+
+	// We are here because Directory already exists and lstat succeeded. At this
+	// point there are two options:
+	// (1) Dest is a directory \o/
+	// (2) Dest is a file, a symlink, or something else (a squirrel?) /o\
+	//
+	// In any case there is no action to take, but let's come up with a valid
+	// excuse for not doing anything.
+
+	if !fi.IsDir() {
+		log.Printf("[ERROR] %s already exists and it is not a directory\n", pf.Directory)
+	}
+	return NONE
+}
+
 func (pf *PetsFile) IsValid(pathErrorOK bool) bool {
 	// Check if the specified package(s) exists
 	for _, pkg := range pf.Pkgs {
@@ -133,8 +174,8 @@ func (pf *PetsFile) IsValid(pathErrorOK bool) bool {
 }
 
 func (pf *PetsFile) AddDest(dest string) {
-	// TODO: create dest if missing
 	pf.Dest = dest
+	pf.Directory = filepath.Dir(dest)
 }
 
 func (pf *PetsFile) AddLink(dest string) {

file_test.go

@@ -128,3 +128,26 @@ func TestNeedsLinkDestIsSymlink(t *testing.T) {
 	f.AddLink("/etc/mtab")
 	assertEquals(t, int(f.NeedsLink()), int(NONE))
 }
+
+func TestNeedsDirNoDirectory(t *testing.T) {
+	f := NewPetsFile()
+	assertEquals(t, int(f.NeedsDir()), int(NONE))
+}
+
+func TestNeedsDirHappyPathDIR(t *testing.T) {
+	f := NewPetsFile()
+	f.Directory = "/etc/does/not/exist"
+	assertEquals(t, int(f.NeedsDir()), int(DIR))
+}
+
+func TestNeedsDirHappyPathNONE(t *testing.T) {
+	f := NewPetsFile()
+	f.Directory = "/etc"
+	assertEquals(t, int(f.NeedsDir()), int(NONE))
+}
+
+func TestNeedsDirDestIsFile(t *testing.T) {
+	f := NewPetsFile()
+	f.Directory = "/etc/passwd"
+	assertEquals(t, int(f.NeedsDir()), int(NONE))
+}

planner.go

@@ -20,6 +20,7 @@ const (
 	CREATE        // configuration file is missing and needs to be created
 	UPDATE        // configuration file differs and needs to be updated
 	LINK          // symbolic link needs to be created
+	DIR           // directory needs to be created
 	OWNER         // needs chown()
 	MODE          // needs chmod()
 	POST          // post-update command
@@ -31,6 +32,7 @@ func (pc PetsCause) String() string {
 		CREATE: "FILE_CREATE",
 		UPDATE: "FILE_UPDATE",
 		LINK:   "LINK_CREATE",
+		DIR:    "DIR_CREATE",
 		OWNER:  "OWNER",
 		MODE:   "CHMOD",
 		POST:   "POST_UPDATE",
@@ -137,6 +139,26 @@ func LinkToCreate(trigger *PetsFile) *PetsAction {
 	}
 }
 
+// DirToCreate figures out if the given trigger represents a directory that
+// needs to be created, and returns the corresponding PetsAction.
+func DirToCreate(trigger *PetsFile) *PetsAction {
+	if trigger.Directory == "" {
+		return nil
+	}
+
+	cause := trigger.NeedsDir()
+
+	if cause == NONE {
+		return nil
+	} else {
+		return &PetsAction{
+			Cause:   cause,
+			Command: NewCmd([]string{"/bin/mkdir", "-p", trigger.Directory}),
+			Trigger: trigger,
+		}
+	}
+}
+
 // Chown returns a chown PetsAction or nil if none is needed.
 func Chown(trigger *PetsFile) *PetsAction {
 	// Build arg (eg: 'root:staff', 'root', ':staff')
@@ -273,6 +295,12 @@ func NewPetsActions(triggers []*PetsFile) []*PetsAction {
 			actionFired = true
 		}
 
+		// Any directory to create
+		if dirAction := DirToCreate(trigger); dirAction != nil {
+			actions = append(actions, dirAction)
+			actionFired = true
+		}
+
 		// Any owner changes needed
 		if chown := Chown(trigger); chown != nil {
 			actions = append(actions, chown)

planner_test.go

@@ -139,3 +139,29 @@ func TestLn(t *testing.T) {
 	assertEquals(t, pa.Cause.String(), "LINK_CREATE")
 	assertEquals(t, pa.Command.String(), "/bin/ln -s sample_pet/vimrc /tmp/vimrc")
 }
+
+func TestMkdir(t *testing.T) {
+	pf := NewPetsFile()
+
+	pa := DirToCreate(pf)
+	if pa != nil {
+		t.Errorf("Expecting nil, got %v instead", pa)
+	}
+
+	pf.Directory = "/etc"
+
+	pa = DirToCreate(pf)
+	if pa != nil {
+		t.Errorf("Expecting nil, got %v instead", pa)
+	}
+
+	pf.Directory = "/etc/polpette/al/sugo"
+
+	pa = DirToCreate(pf)
+	if pa == nil {
+		t.Errorf("Expecting some action, got nil instead")
+	}
+
+	assertEquals(t, pa.Cause.String(), "DIR_CREATE")
+	assertEquals(t, pa.Command.String(), "/bin/mkdir -p /etc/polpette/al/sugo")
+}