forked from kubernetes/kops
/
vfssync.go
199 lines (168 loc) · 4.43 KB
/
vfssync.go
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package vfs
import (
"bytes"
"fmt"
"github.com/golang/glog"
"k8s.io/kops/util/pkg/hashing"
"os"
)
// VFSScan scans a source Path for changes files
type VFSScan struct {
Base Path
hashes map[string]*hashing.Hash
}
func NewVFSScan(base Path) *VFSScan {
return &VFSScan{Base: base}
}
type ChangeType string
const ChangeType_Added ChangeType = "ADDED"
const ChangeType_Removed ChangeType = "REMOVED"
const ChangeType_Modified ChangeType = "MODIFIED"
type Change struct {
ChangeType ChangeType
Path Path
Hash *hashing.Hash
}
// Scans for changes files. On the first call will return all files as ChangeType_Added.
// On subsequent calls will return any changed files (using their hashes)
func (v *VFSScan) Scan() ([]Change, error) {
allFiles, err := v.Base.ReadTree()
if err != nil {
return nil, fmt.Errorf("Error reading dir %q: %v", v.Base, err)
}
files := make(map[string]Path)
hashes := make(map[string]*hashing.Hash)
for _, f := range allFiles {
key := f.Path()
files[key] = f
hasHash, ok := f.(HasHash)
if !ok {
return nil, fmt.Errorf("Source must support hashing: %T", f)
}
hash, err := hasHash.PreferredHash()
if err != nil {
return nil, fmt.Errorf("Error hashing %q: %v", key, err)
}
hashes[key] = hash
}
if v.hashes == nil {
v.hashes = hashes
var changes []Change
for k, f := range files {
hash := hashes[k]
changes = append(changes, Change{ChangeType: ChangeType_Added, Path: f, Hash: hash})
}
return changes, nil
}
var changes []Change
for k, f := range files {
oldHash := v.hashes[k]
newHash := hashes[k]
if oldHash == nil {
changes = append(changes, Change{ChangeType: ChangeType_Added, Path: f, Hash: newHash})
} else if !oldHash.Equal(newHash) {
changes = append(changes, Change{ChangeType: ChangeType_Modified, Path: f, Hash: newHash})
}
}
for k := range v.hashes {
newHash := hashes[k]
f := files[k]
if newHash == nil {
changes = append(changes, Change{ChangeType: ChangeType_Removed, Path: f, Hash: newHash})
}
}
v.hashes = hashes
return changes, nil
}
func SyncDir(src *VFSScan, destBase Path) error {
changes, err := src.Scan()
if err != nil {
return fmt.Errorf("Error scanning source dir %q: %v", src, err)
}
for _, change := range changes {
f := change.Path
relativePath, err := RelativePath(f, src.Base)
if err != nil {
return err
}
destFile := destBase.Join(relativePath)
switch change.ChangeType {
case ChangeType_Removed:
err := destFile.Remove()
if err != nil {
if !os.IsNotExist(err) {
return fmt.Errorf("error removing file %q: %v", destFile, err)
}
}
continue
case ChangeType_Modified, ChangeType_Added:
break
default:
return fmt.Errorf("unknown change type: %q", change.ChangeType)
}
hashMatch, err := hashesMatch(f, destFile)
if err != nil {
return err
}
if hashMatch {
glog.V(2).Infof("File hashes match: %s and %s", f, destFile)
continue
}
srcData, err := f.ReadFile()
if err != nil {
return fmt.Errorf("error reading source file %q: %v", f, err)
}
destData, err := destFile.ReadFile()
if err != nil {
if !os.IsNotExist(err) {
return fmt.Errorf("error reading dest file %q: %v", f, err)
}
}
if destData == nil || !bytes.Equal(srcData, destData) {
glog.V(2).Infof("Copying data from %s to %s", f, destFile)
err = destFile.WriteFile(srcData)
if err != nil {
return fmt.Errorf("error writing dest file %q: %v", f, err)
}
}
}
return nil
}
func hashesMatch(src, dest Path) (bool, error) {
sh, ok := src.(HasHash)
if !ok {
return false, nil
}
dh, ok := dest.(HasHash)
if !ok {
return false, nil
}
{
srcHash, err := sh.PreferredHash()
if err != nil {
glog.Warningf("error getting hash of source file %s: %v", src, err)
} else if srcHash != nil {
destHash, err := dh.Hash(srcHash.Algorithm)
if err != nil {
glog.Warningf("error comparing hash of dest file %s: %v", dest, err)
} else if destHash != nil {
return destHash.Equal(srcHash), nil
}
}
}
{
destHash, err := dh.PreferredHash()
if err != nil {
glog.Warningf("error getting hash of dest file %s: %v", src, err)
} else if destHash != nil {
srcHash, err := dh.Hash(destHash.Algorithm)
if err != nil {
glog.Warningf("error comparing hash of src file %s: %v", dest, err)
} else if srcHash != nil {
return srcHash.Equal(destHash), nil
}
}
}
glog.Infof("No compatible hash: %s and %s", src, dest)
return false, nil
}