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tree_walker.go
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tree_walker.go
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package loader
import (
"fmt"
"github.com/golang/glog"
"k8s.io/kops/util/pkg/vfs"
"os"
"path"
"strings"
)
type TreeWalker struct {
Contexts map[string]Handler
Extensions map[string]Handler
DefaultHandler Handler
Tags map[string]struct{}
}
type TreeWalkItem struct {
Context string
Name string
Path vfs.Path
RelativePath string
Meta string
Tags []string
}
func (i *TreeWalkItem) ReadString() (string, error) {
b, err := i.ReadBytes()
if err != nil {
return "", err
}
return string(b), nil
}
func (i *TreeWalkItem) ReadBytes() ([]byte, error) {
b, err := i.Path.ReadFile()
if err != nil {
return nil, fmt.Errorf("error reading file %q: %v", i.Path, err)
}
return b, nil
}
type Handler func(item *TreeWalkItem) error
func IsTag(name string) bool {
return len(name) != 0 && name[0] == '_'
}
func (t *TreeWalker) Walk(basedir vfs.Path) error {
i := &TreeWalkItem{
Context: "",
Path: basedir,
RelativePath: "",
Tags: nil,
}
return t.walkDirectory(i)
}
func (t *TreeWalker) walkDirectory(parent *TreeWalkItem) error {
files, err := parent.Path.ReadDir()
if err != nil {
return fmt.Errorf("error reading directory %q: %v", parent.Path, err)
}
for _, f := range files {
var err error
fileName := f.Base()
i := &TreeWalkItem{
Context: parent.Context,
Path: f,
RelativePath: path.Join(parent.RelativePath, fileName),
Name: fileName,
Tags: parent.Tags,
}
glog.V(4).Infof("visit %q", f)
hasMeta := false
{
metaPath := parent.Path.Join(fileName + ".meta")
metaBytes, err := metaPath.ReadFile()
if err != nil {
if !os.IsNotExist(err) {
return fmt.Errorf("error reading file %q: %v", metaPath, err)
}
metaBytes = nil
}
if metaBytes != nil {
hasMeta = true
i.Meta = string(metaBytes)
}
}
if _, err := f.ReadDir(); err == nil {
if IsTag(fileName) {
// Only descend into the tag directory if we have the tag
_, found := t.Tags[fileName]
if !found {
glog.V(2).Infof("Skipping directory as tag not present: %q", f)
continue
} else {
i.Tags = append(i.Tags, fileName)
glog.V(2).Infof("Descending into directory, as tag is present: %q", f)
err = t.walkDirectory(i)
}
} else if _, found := t.Contexts[fileName]; found {
// Entering a new context (mode of operation)
if parent.Context != "" {
return fmt.Errorf("found context %q inside context %q at %q", fileName, parent.Context, f)
}
i.Context = fileName
i.RelativePath = ""
err = t.walkDirectory(i)
} else {
// Simple directory for organization / structure
err = t.walkDirectory(i)
}
if err != nil {
return err
}
// So that we can manage directories, we do not ignore directories which have a .meta file
if hasMeta {
glog.V(4).Infof("Found .meta file for directory %q; will process", f)
} else {
continue
}
}
if strings.HasSuffix(fileName, ".meta") {
// We'll read it when we see the actual file
// But check the actual file is there
primaryPath := strings.TrimSuffix(f.Base(), ".meta")
if _, err := parent.Path.Join(primaryPath).ReadFile(); os.IsNotExist(err) {
return fmt.Errorf("found .meta file without corresponding file: %q", f)
}
continue
}
var handler Handler
if i.Context != "" {
handler = t.Contexts[i.Context]
} else {
// TODO: Just remove extensions.... we barely use them!
// (or remove default handler and replace with lots of small files?)
extension := path.Ext(fileName)
handler = t.Extensions[extension]
if handler == nil {
handler = t.DefaultHandler
}
}
err = handler(i)
if err != nil {
return fmt.Errorf("error handling file %q: %v", f, err)
}
}
return nil
}