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moby--moby/image/image.go

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package image
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path"
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"strconv"
"time"
log "github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/tarsum"
"github.com/docker/docker/runconfig"
"github.com/docker/docker/utils"
)
// Set the max depth to the aufs default that most
// kernels are compiled with
// For more information see: http://sourceforge.net/p/aufs/aufs3-standalone/ci/aufs3.12/tree/config.mk
const MaxImageDepth = 127
type Image struct {
ID string `json:"id"`
Parent string `json:"parent,omitempty"`
Comment string `json:"comment,omitempty"`
Created time.Time `json:"created"`
Container string `json:"container,omitempty"`
ContainerConfig runconfig.Config `json:"container_config,omitempty"`
DockerVersion string `json:"docker_version,omitempty"`
Author string `json:"author,omitempty"`
Config *runconfig.Config `json:"config,omitempty"`
Architecture string `json:"architecture,omitempty"`
OS string `json:"os,omitempty"`
Checksum string `json:"checksum"`
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Size int64
graph Graph
}
func LoadImage(root string) (*Image, error) {
// Open the JSON file to decode by streaming
jsonSource, err := os.Open(jsonPath(root))
if err != nil {
return nil, err
}
defer jsonSource.Close()
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img := &Image{}
dec := json.NewDecoder(jsonSource)
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// Decode the JSON data
if err := dec.Decode(img); err != nil {
return nil, err
}
if err := utils.ValidateID(img.ID); err != nil {
return nil, err
}
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if buf, err := ioutil.ReadFile(path.Join(root, "layersize")); err != nil {
if !os.IsNotExist(err) {
return nil, err
}
// If the layersize file does not exist then set the size to a negative number
// because a layer size of 0 (zero) is valid
img.Size = -1
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} else {
// Using Atoi here instead would temporarily convert the size to a machine
// dependent integer type, which causes images larger than 2^31 bytes to
// display negative sizes on 32-bit machines:
size, err := strconv.ParseInt(string(buf), 10, 64)
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if err != nil {
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return nil, err
}
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img.Size = int64(size)
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}
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return img, nil
}
// StoreImage stores file system layer data for the given image to the
// image's registered storage driver. Image metadata is stored in a file
// at the specified root directory. This function also computes the TarSum
// of `layerData` (currently using tarsum.dev).
func StoreImage(img *Image, layerData archive.ArchiveReader, root string) error {
// Store the layer
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var (
size int64
err error
driver = img.graph.Driver()
layerTarSum tarsum.TarSum
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)
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// If layerData is not nil, unpack it into the new layer
if layerData != nil {
// If the image doesn't have a checksum, we should add it. The layer
// checksums are verified when they are pulled from a remote, but when
// a container is committed it should be added here.
if img.Checksum == "" {
layerDataDecompressed, err := archive.DecompressStream(layerData)
if err != nil {
return err
}
defer layerDataDecompressed.Close()
if layerTarSum, err = tarsum.NewTarSum(layerDataDecompressed, true, tarsum.VersionDev); err != nil {
return err
}
if size, err = driver.ApplyDiff(img.ID, img.Parent, layerTarSum); err != nil {
return err
}
img.Checksum = layerTarSum.Sum(nil)
} else if size, err = driver.ApplyDiff(img.ID, img.Parent, layerData); err != nil {
return err
}
}
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img.Size = size
if err := img.SaveSize(root); err != nil {
return err
}
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f, err := os.OpenFile(jsonPath(root), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(0600))
if err != nil {
return err
}
defer f.Close()
return json.NewEncoder(f).Encode(img)
}
func (img *Image) SetGraph(graph Graph) {
img.graph = graph
}
// SaveSize stores the current `size` value of `img` in the directory `root`.
func (img *Image) SaveSize(root string) error {
if err := ioutil.WriteFile(path.Join(root, "layersize"), []byte(strconv.Itoa(int(img.Size))), 0600); err != nil {
return fmt.Errorf("Error storing image size in %s/layersize: %s", root, err)
}
return nil
}
func jsonPath(root string) string {
return path.Join(root, "json")
}
func (img *Image) RawJson() ([]byte, error) {
root, err := img.root()
if err != nil {
return nil, fmt.Errorf("Failed to get root for image %s: %s", img.ID, err)
}
fh, err := os.Open(jsonPath(root))
if err != nil {
return nil, fmt.Errorf("Failed to open json for image %s: %s", img.ID, err)
}
buf, err := ioutil.ReadAll(fh)
if err != nil {
return nil, fmt.Errorf("Failed to read json for image %s: %s", img.ID, err)
}
return buf, nil
}
// TarLayer returns a tar archive of the image's filesystem layer.
func (img *Image) TarLayer() (arch archive.Archive, err error) {
if img.graph == nil {
return nil, fmt.Errorf("Can't load storage driver for unregistered image %s", img.ID)
}
driver := img.graph.Driver()
return driver.Diff(img.ID, img.Parent)
}
// Image includes convenience proxy functions to its graph
// These functions will return an error if the image is not registered
// (ie. if image.graph == nil)
func (img *Image) History() ([]*Image, error) {
var parents []*Image
if err := img.WalkHistory(
func(img *Image) error {
parents = append(parents, img)
return nil
},
); err != nil {
return nil, err
}
return parents, nil
}
func (img *Image) WalkHistory(handler func(*Image) error) (err error) {
currentImg := img
for currentImg != nil {
if handler != nil {
if err := handler(currentImg); err != nil {
return err
}
}
currentImg, err = currentImg.GetParent()
if err != nil {
return fmt.Errorf("Error while getting parent image: %v", err)
}
}
return nil
}
func (img *Image) GetParent() (*Image, error) {
if img.Parent == "" {
return nil, nil
}
if img.graph == nil {
return nil, fmt.Errorf("Can't lookup parent of unregistered image")
}
return img.graph.Get(img.Parent)
}
func (img *Image) root() (string, error) {
if img.graph == nil {
return "", fmt.Errorf("Can't lookup root of unregistered image")
}
return img.graph.ImageRoot(img.ID), nil
}
func (img *Image) GetParentsSize(size int64) int64 {
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parentImage, err := img.GetParent()
if err != nil || parentImage == nil {
return size
}
size += parentImage.Size
return parentImage.GetParentsSize(size)
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}
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// Depth returns the number of parents for a
// current image
func (img *Image) Depth() (int, error) {
var (
count = 0
parent = img
err error
)
for parent != nil {
count++
parent, err = parent.GetParent()
if err != nil {
return -1, err
}
}
return count, nil
}
// CheckDepth returns an error if the depth of an image, as returned
// by ImageDepth, is too large to support creating a container from it
// on this daemon.
func (img *Image) CheckDepth() error {
// We add 2 layers to the depth because the container's rw and
// init layer add to the restriction
depth, err := img.Depth()
if err != nil {
return err
}
if depth+2 >= MaxImageDepth {
return fmt.Errorf("Cannot create container with more than %d parents", MaxImageDepth)
}
return nil
}
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// Build an Image object from raw json data
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func NewImgJSON(src []byte) (*Image, error) {
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ret := &Image{}
log.Debugf("Json string: {%s}", src)
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// FIXME: Is there a cleaner way to "purify" the input json?
if err := json.Unmarshal(src, ret); err != nil {
return nil, err
}
return ret, nil
}