perkeep/lib/go/schema/schema.go

/*
Copyright 2011 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package schema

import (
	"bufio"
	"bytes"
	"camli/blobref"
	"crypto/sha1"
	"fmt"
	"io"
	"json"
	"os"
	"rand"
	"strconv"
	"strings"
	"sync"
	"time"
)

var NoCamliVersionError = os.NewError("No camliVersion key in map")
var UnimplementedError = os.NewError("Unimplemented")

type StatHasher interface {
	Lstat(fileName string) (*os.FileInfo, os.Error)
	Hash(fileName string) (*blobref.BlobRef, os.Error)
}

var DefaultStatHasher = &defaultStatHasher{}

type defaultStatHasher struct{}

func (d *defaultStatHasher) Lstat(fileName string) (*os.FileInfo, os.Error) {
	return os.Lstat(fileName)
}

func (d *defaultStatHasher) Hash(fileName string) (*blobref.BlobRef, os.Error) {
	s1 := sha1.New()
	file, err := os.Open(fileName, os.O_RDONLY, 0)
	if err != nil {
		return nil, err
	}
	defer file.Close()
	_, err = io.Copy(s1, file)
        if err != nil {
                return nil, err
        }
	return blobref.FromHash("sha1", s1), nil
}

type StaticSet struct {
	l  sync.Mutex
	refs []*blobref.BlobRef
}

func (ss *StaticSet) Add(ref *blobref.BlobRef) {
	ss.l.Lock()
	defer ss.l.Unlock()
	ss.refs = append(ss.refs, ref)
}

func newCamliMap(version int, ctype string) map[string]interface{} {
	m := make(map[string]interface{})
        m["camliVersion"] = version
        m["camliType"] = ctype
	return m
}

func NewUnsignedPermanode() map[string]interface{} {
	m := newCamliMap(1, "permanode")
	chars := make([]byte, 20)
	// Don't need cryptographically secure random here, as this
	// will be GPG signed anyway.
	rnd := rand.New(rand.NewSource(time.Nanoseconds()))
	for idx, _ := range chars {
		chars[idx] = byte(32 + rnd.Intn(126 - 32))
	}
	m["random"] = string(chars)
	return m
}

// Map returns a Camli map of camliType "static-set"
func (ss *StaticSet) Map() map[string]interface{} {
	m := newCamliMap(1, "static-set")
	ss.l.Lock()
	defer ss.l.Unlock()

	members := make([]string, 0, len(ss.refs))
	if ss.refs != nil {
		for _, ref := range ss.refs {
			members = append(members, ref.String())
		}
	}
	m["members"] = members
	return m
}

func MapToCamliJson(m map[string]interface{}) (string, os.Error) {
	version, hasVersion := m["camliVersion"]
	if !hasVersion {
		return "", NoCamliVersionError
	}
	m["camliVersion"] = 0, false
	jsonBytes, err := json.MarshalIndent(m, "", "  ")
	if err != nil {
		return "", err
	}
	m["camliVersion"] = version
	buf := new(bytes.Buffer)
	fmt.Fprintf(buf, "{\"camliVersion\": %v,\n", version)
	buf.Write(jsonBytes[2:])
	return string(buf.Bytes()), nil
}

func NewCommonFileMap(fileName string, fi *os.FileInfo) map[string]interface{} {
	m := newCamliMap(1, "" /* no type yet */)
	
	lastSlash := strings.LastIndex(fileName, "/")
	baseName := fileName[lastSlash+1:]
	if isValidUtf8(baseName) {
		m["fileName"] = baseName
	} else {
		m["fileNameBytes"] = []uint8(baseName)
	}

	// Common elements (from file-common.txt)
	if !fi.IsSymlink() {
		m["unixPermission"] = fmt.Sprintf("0%o", fi.Permission())
	}
	if fi.Uid != -1 {
		m["unixOwnerId"] = fi.Uid
		if user := getUserFromUid(fi.Uid); user != "" {
			m["unixOwner"] = user
		}
	}
	if fi.Gid != -1 {
		m["unixGroupId"] = fi.Gid
		if group := getGroupFromGid(fi.Gid); group != "" {
			m["unixGroup"] = group
		}
	}
	if mtime := fi.Mtime_ns; mtime != 0 {
		m["unixMtime"] = rfc3339FromNanos(mtime)
	}
	// Include the ctime too, if it differs.
	if ctime := fi.Ctime_ns; ctime != 0 && fi.Mtime_ns != fi.Ctime_ns {
		m["unixCtime"] = rfc3339FromNanos(ctime)
	}

	return m
}

type ContentPart struct {
	BlobRef   *blobref.BlobRef
	Size      int64
	Offset    int64
}

type InvalidContentPartsError struct {
	StatSize   int64
	SumOfParts int64
}

func (e *InvalidContentPartsError) String() string {
	return fmt.Sprintf("Invalid ContentPart slice in PopulateRegularFileMap; file stat size is %d but sum of parts was %d", e.StatSize, e.SumOfParts)
}

func PopulateRegularFileMap(m map[string]interface{}, fi *os.FileInfo, parts []ContentPart) os.Error {
	m["camliType"] = "file"
	m["size"] = fi.Size

	sumSize := int64(0)
	mparts := make([]map[string]interface{}, len(parts))
	for idx, part := range parts {
		mpart := make(map[string]interface{})
		mparts[idx] = mpart
		mpart["blobRef"] = part.BlobRef.String()
		mpart["size"] = part.Size
		sumSize += part.Size
		if part.Offset != 0 {
			mpart["offset"] = part.Offset
		}
	}
	if sumSize != fi.Size {
		return &InvalidContentPartsError{fi.Size, sumSize}
	}
	m["contentParts"] = mparts
	return nil
}

func PopulateSymlinkMap(m map[string]interface{}, fileName string) os.Error {
	m["camliType"] = "symlink"
	target, err := os.Readlink(fileName)
	if err != nil {
		return err
	}
	if isValidUtf8(target) {
		m["symlinkTarget"] = target
	} else {
		m["symlinkTargetBytes"] = []uint8(target)
	}
	return nil
}

func PopulateDirectoryMap(m map[string]interface{}, staticSetRef *blobref.BlobRef) {
	m["camliType"] = "directory"
	m["entries"] = staticSetRef.String()
}

func NewShareRef(authType string, target *blobref.BlobRef, transitive bool) map[string]interface{} {
	m := newCamliMap(1, "" /* no type yet */)
	m["camliType"] = "share"
	m["authType"] = authType
	m["target"] = target.String()
	m["transitive"] = transitive
	return m
}

// Types of ShareRefs
const ShareHaveRef = "haveref"

func rfc3339FromNanos(epochnanos int64) string {
	nanos := epochnanos % 1e9
	esec := epochnanos / 1e9
	t := time.SecondsToUTC(esec)
	timeStr := t.Format(time.RFC3339)
	if nanos == 0 {
		return timeStr
	}
	nanoStr := fmt.Sprintf("%09d", nanos)
	nanoStr = strings.TrimRight(nanoStr, "0")
	return timeStr[:len(timeStr)-1] + "." + nanoStr + "Z"
}

func populateMap(m map[int]string, file string) {
	f, err := os.Open(file, os.O_RDONLY, 0)
	if err != nil {
		return
	}
	bufr := bufio.NewReader(f)
	for {
		line, err := bufr.ReadString('\n')
		if err != nil {
			return
		}
		parts := strings.Split(line, ":", 4)
		if len(parts) >= 3 {
			idstr := parts[2]
			id, err := strconv.Atoi(idstr)
			if err == nil {
				m[id] = parts[0]
			}
		}
	}
}

var uidToUsernameMap map[int]string
var getUserFromUidOnce sync.Once
func getUserFromUid(uid int) string {
	getUserFromUidOnce.Do(func() {
		uidToUsernameMap = make(map[int]string)
		populateMap(uidToUsernameMap, "/etc/passwd")
	})
	return uidToUsernameMap[uid]
}

var gidToUsernameMap map[int]string
var getGroupFromGidOnce sync.Once
func getGroupFromGid(uid int) string {
	getGroupFromGidOnce.Do(func() {
		gidToUsernameMap = make(map[int]string)
		populateMap(gidToUsernameMap, "/etc/group")
	})
	return gidToUsernameMap[uid]
}

func isValidUtf8(s string) bool {
	for _, rune := range []int(s) {
		if rune == 0xfffd {
			return false
		}
	}
	return true
}