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moby--moby/utils/utils.go
Michael Crosby 8c39db8f96 Move proxy into pkg
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
2014-02-14 15:48:05 -08:00

974 lines
23 KiB
Go

package utils
import (
"bytes"
"crypto/sha1"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"github.com/dotcloud/docker/dockerversion"
"index/suffixarray"
"io"
"io/ioutil"
"net/http"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"strconv"
"strings"
"sync"
"time"
)
// A common interface to access the Fatal method of
// both testing.B and testing.T.
type Fataler interface {
Fatal(args ...interface{})
}
// Go is a basic promise implementation: it wraps calls a function in a goroutine,
// and returns a channel which will later return the function's return value.
func Go(f func() error) chan error {
ch := make(chan error)
go func() {
ch <- f()
}()
return ch
}
// Request a given URL and return an io.Reader
func Download(url string) (resp *http.Response, err error) {
if resp, err = http.Get(url); err != nil {
return nil, err
}
if resp.StatusCode >= 400 {
return nil, fmt.Errorf("Got HTTP status code >= 400: %s", resp.Status)
}
return resp, nil
}
func logf(level string, format string, a ...interface{}) {
// Retrieve the stack infos
_, file, line, ok := runtime.Caller(2)
if !ok {
file = "<unknown>"
line = -1
} else {
file = file[strings.LastIndex(file, "/")+1:]
}
fmt.Fprintf(os.Stderr, fmt.Sprintf("[%s] %s:%d %s\n", level, file, line, format), a...)
}
// Debug function, if the debug flag is set, then display. Do nothing otherwise
// If Docker is in damon mode, also send the debug info on the socket
func Debugf(format string, a ...interface{}) {
if os.Getenv("DEBUG") != "" {
logf("debug", format, a...)
}
}
func Errorf(format string, a ...interface{}) {
logf("error", format, a...)
}
// HumanDuration returns a human-readable approximation of a duration
// (eg. "About a minute", "4 hours ago", etc.)
func HumanDuration(d time.Duration) string {
if seconds := int(d.Seconds()); seconds < 1 {
return "Less than a second"
} else if seconds < 60 {
return fmt.Sprintf("%d seconds", seconds)
} else if minutes := int(d.Minutes()); minutes == 1 {
return "About a minute"
} else if minutes < 60 {
return fmt.Sprintf("%d minutes", minutes)
} else if hours := int(d.Hours()); hours == 1 {
return "About an hour"
} else if hours < 48 {
return fmt.Sprintf("%d hours", hours)
} else if hours < 24*7*2 {
return fmt.Sprintf("%d days", hours/24)
} else if hours < 24*30*3 {
return fmt.Sprintf("%d weeks", hours/24/7)
} else if hours < 24*365*2 {
return fmt.Sprintf("%d months", hours/24/30)
}
return fmt.Sprintf("%f years", d.Hours()/24/365)
}
// HumanSize returns a human-readable approximation of a size
// using SI standard (eg. "44kB", "17MB")
func HumanSize(size int64) string {
i := 0
var sizef float64
sizef = float64(size)
units := []string{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"}
for sizef >= 1000.0 {
sizef = sizef / 1000.0
i++
}
return fmt.Sprintf("%.4g %s", sizef, units[i])
}
// Parses a human-readable string representing an amount of RAM
// in bytes, kibibytes, mebibytes or gibibytes, and returns the
// number of bytes, or -1 if the string is unparseable.
// Units are case-insensitive, and the 'b' suffix is optional.
func RAMInBytes(size string) (bytes int64, err error) {
re, error := regexp.Compile("^(\\d+)([kKmMgG])?[bB]?$")
if error != nil {
return -1, error
}
matches := re.FindStringSubmatch(size)
if len(matches) != 3 {
return -1, fmt.Errorf("Invalid size: '%s'", size)
}
memLimit, error := strconv.ParseInt(matches[1], 10, 0)
if error != nil {
return -1, error
}
unit := strings.ToLower(matches[2])
if unit == "k" {
memLimit *= 1024
} else if unit == "m" {
memLimit *= 1024 * 1024
} else if unit == "g" {
memLimit *= 1024 * 1024 * 1024
}
return memLimit, nil
}
func Trunc(s string, maxlen int) string {
if len(s) <= maxlen {
return s
}
return s[:maxlen]
}
// Figure out the absolute path of our own binary (if it's still around).
func SelfPath() string {
path, err := exec.LookPath(os.Args[0])
if err != nil {
if os.IsNotExist(err) {
return ""
}
if execErr, ok := err.(*exec.Error); ok && os.IsNotExist(execErr.Err) {
return ""
}
panic(err)
}
path, err = filepath.Abs(path)
if err != nil {
if os.IsNotExist(err) {
return ""
}
panic(err)
}
return path
}
func dockerInitSha1(target string) string {
f, err := os.Open(target)
if err != nil {
return ""
}
defer f.Close()
h := sha1.New()
_, err = io.Copy(h, f)
if err != nil {
return ""
}
return hex.EncodeToString(h.Sum(nil))
}
func isValidDockerInitPath(target string, selfPath string) bool { // target and selfPath should be absolute (InitPath and SelfPath already do this)
if target == "" {
return false
}
if dockerversion.IAMSTATIC {
if selfPath == "" {
return false
}
if target == selfPath {
return true
}
targetFileInfo, err := os.Lstat(target)
if err != nil {
return false
}
selfPathFileInfo, err := os.Lstat(selfPath)
if err != nil {
return false
}
return os.SameFile(targetFileInfo, selfPathFileInfo)
}
return dockerversion.INITSHA1 != "" && dockerInitSha1(target) == dockerversion.INITSHA1
}
// Figure out the path of our dockerinit (which may be SelfPath())
func DockerInitPath(localCopy string) string {
selfPath := SelfPath()
if isValidDockerInitPath(selfPath, selfPath) {
// if we're valid, don't bother checking anything else
return selfPath
}
var possibleInits = []string{
localCopy,
dockerversion.INITPATH,
filepath.Join(filepath.Dir(selfPath), "dockerinit"),
// FHS 3.0 Draft: "/usr/libexec includes internal binaries that are not intended to be executed directly by users or shell scripts. Applications may use a single subdirectory under /usr/libexec."
// http://www.linuxbase.org/betaspecs/fhs/fhs.html#usrlibexec
"/usr/libexec/docker/dockerinit",
"/usr/local/libexec/docker/dockerinit",
// FHS 2.3: "/usr/lib includes object files, libraries, and internal binaries that are not intended to be executed directly by users or shell scripts."
// http://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html#USRLIBLIBRARIESFORPROGRAMMINGANDPA
"/usr/lib/docker/dockerinit",
"/usr/local/lib/docker/dockerinit",
}
for _, dockerInit := range possibleInits {
if dockerInit == "" {
continue
}
path, err := exec.LookPath(dockerInit)
if err == nil {
path, err = filepath.Abs(path)
if err != nil {
// LookPath already validated that this file exists and is executable (following symlinks), so how could Abs fail?
panic(err)
}
if isValidDockerInitPath(path, selfPath) {
return path
}
}
}
return ""
}
type NopWriter struct{}
func (*NopWriter) Write(buf []byte) (int, error) {
return len(buf), nil
}
type nopWriteCloser struct {
io.Writer
}
func (w *nopWriteCloser) Close() error { return nil }
func NopWriteCloser(w io.Writer) io.WriteCloser {
return &nopWriteCloser{w}
}
type bufReader struct {
sync.Mutex
buf *bytes.Buffer
reader io.Reader
err error
wait sync.Cond
}
func NewBufReader(r io.Reader) *bufReader {
reader := &bufReader{
buf: &bytes.Buffer{},
reader: r,
}
reader.wait.L = &reader.Mutex
go reader.drain()
return reader
}
func (r *bufReader) drain() {
buf := make([]byte, 1024)
for {
n, err := r.reader.Read(buf)
r.Lock()
if err != nil {
r.err = err
} else {
r.buf.Write(buf[0:n])
}
r.wait.Signal()
r.Unlock()
if err != nil {
break
}
}
}
func (r *bufReader) Read(p []byte) (n int, err error) {
r.Lock()
defer r.Unlock()
for {
n, err = r.buf.Read(p)
if n > 0 {
return n, err
}
if r.err != nil {
return 0, r.err
}
r.wait.Wait()
}
}
func (r *bufReader) Close() error {
closer, ok := r.reader.(io.ReadCloser)
if !ok {
return nil
}
return closer.Close()
}
type WriteBroadcaster struct {
sync.Mutex
buf *bytes.Buffer
writers map[StreamWriter]bool
}
type StreamWriter struct {
wc io.WriteCloser
stream string
}
func (w *WriteBroadcaster) AddWriter(writer io.WriteCloser, stream string) {
w.Lock()
sw := StreamWriter{wc: writer, stream: stream}
w.writers[sw] = true
w.Unlock()
}
type JSONLog struct {
Log string `json:"log,omitempty"`
Stream string `json:"stream,omitempty"`
Created time.Time `json:"time"`
}
func (w *WriteBroadcaster) Write(p []byte) (n int, err error) {
w.Lock()
defer w.Unlock()
w.buf.Write(p)
for sw := range w.writers {
lp := p
if sw.stream != "" {
lp = nil
for {
line, err := w.buf.ReadString('\n')
if err != nil {
w.buf.Write([]byte(line))
break
}
b, err := json.Marshal(&JSONLog{Log: line, Stream: sw.stream, Created: time.Now().UTC()})
if err != nil {
// On error, evict the writer
delete(w.writers, sw)
continue
}
lp = append(lp, b...)
lp = append(lp, '\n')
}
}
if n, err := sw.wc.Write(lp); err != nil || n != len(lp) {
// On error, evict the writer
delete(w.writers, sw)
}
}
return len(p), nil
}
func (w *WriteBroadcaster) CloseWriters() error {
w.Lock()
defer w.Unlock()
for sw := range w.writers {
sw.wc.Close()
}
w.writers = make(map[StreamWriter]bool)
return nil
}
func NewWriteBroadcaster() *WriteBroadcaster {
return &WriteBroadcaster{writers: make(map[StreamWriter]bool), buf: bytes.NewBuffer(nil)}
}
func GetTotalUsedFds() int {
if fds, err := ioutil.ReadDir(fmt.Sprintf("/proc/%d/fd", os.Getpid())); err != nil {
Errorf("Error opening /proc/%d/fd: %s", os.Getpid(), err)
} else {
return len(fds)
}
return -1
}
// TruncIndex allows the retrieval of string identifiers by any of their unique prefixes.
// This is used to retrieve image and container IDs by more convenient shorthand prefixes.
type TruncIndex struct {
sync.RWMutex
index *suffixarray.Index
ids map[string]bool
bytes []byte
}
func NewTruncIndex() *TruncIndex {
return &TruncIndex{
index: suffixarray.New([]byte{' '}),
ids: make(map[string]bool),
bytes: []byte{' '},
}
}
func (idx *TruncIndex) Add(id string) error {
idx.Lock()
defer idx.Unlock()
if strings.Contains(id, " ") {
return fmt.Errorf("Illegal character: ' '")
}
if _, exists := idx.ids[id]; exists {
return fmt.Errorf("Id already exists: %s", id)
}
idx.ids[id] = true
idx.bytes = append(idx.bytes, []byte(id+" ")...)
idx.index = suffixarray.New(idx.bytes)
return nil
}
func (idx *TruncIndex) Delete(id string) error {
idx.Lock()
defer idx.Unlock()
if _, exists := idx.ids[id]; !exists {
return fmt.Errorf("No such id: %s", id)
}
before, after, err := idx.lookup(id)
if err != nil {
return err
}
delete(idx.ids, id)
idx.bytes = append(idx.bytes[:before], idx.bytes[after:]...)
idx.index = suffixarray.New(idx.bytes)
return nil
}
func (idx *TruncIndex) lookup(s string) (int, int, error) {
offsets := idx.index.Lookup([]byte(" "+s), -1)
//log.Printf("lookup(%s): %v (index bytes: '%s')\n", s, offsets, idx.index.Bytes())
if offsets == nil || len(offsets) == 0 || len(offsets) > 1 {
return -1, -1, fmt.Errorf("No such id: %s", s)
}
offsetBefore := offsets[0] + 1
offsetAfter := offsetBefore + strings.Index(string(idx.bytes[offsetBefore:]), " ")
return offsetBefore, offsetAfter, nil
}
func (idx *TruncIndex) Get(s string) (string, error) {
idx.RLock()
defer idx.RUnlock()
before, after, err := idx.lookup(s)
//log.Printf("Get(%s) bytes=|%s| before=|%d| after=|%d|\n", s, idx.bytes, before, after)
if err != nil {
return "", err
}
return string(idx.bytes[before:after]), err
}
// TruncateID returns a shorthand version of a string identifier for convenience.
// A collision with other shorthands is very unlikely, but possible.
// In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
// will need to use a langer prefix, or the full-length Id.
func TruncateID(id string) string {
shortLen := 12
if len(id) < shortLen {
shortLen = len(id)
}
return id[:shortLen]
}
// Code c/c from io.Copy() modified to handle escape sequence
func CopyEscapable(dst io.Writer, src io.ReadCloser) (written int64, err error) {
buf := make([]byte, 32*1024)
for {
nr, er := src.Read(buf)
if nr > 0 {
// ---- Docker addition
// char 16 is C-p
if nr == 1 && buf[0] == 16 {
nr, er = src.Read(buf)
// char 17 is C-q
if nr == 1 && buf[0] == 17 {
if err := src.Close(); err != nil {
return 0, err
}
return 0, nil
}
}
// ---- End of docker
nw, ew := dst.Write(buf[0:nr])
if nw > 0 {
written += int64(nw)
}
if ew != nil {
err = ew
break
}
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er == io.EOF {
break
}
if er != nil {
err = er
break
}
}
return written, err
}
func HashData(src io.Reader) (string, error) {
h := sha256.New()
if _, err := io.Copy(h, src); err != nil {
return "", err
}
return "sha256:" + hex.EncodeToString(h.Sum(nil)), nil
}
type KernelVersionInfo struct {
Kernel int
Major int
Minor int
Flavor string
}
func (k *KernelVersionInfo) String() string {
return fmt.Sprintf("%d.%d.%d%s", k.Kernel, k.Major, k.Minor, k.Flavor)
}
// Compare two KernelVersionInfo struct.
// Returns -1 if a < b, 0 if a == b, 1 it a > b
func CompareKernelVersion(a, b *KernelVersionInfo) int {
if a.Kernel < b.Kernel {
return -1
} else if a.Kernel > b.Kernel {
return 1
}
if a.Major < b.Major {
return -1
} else if a.Major > b.Major {
return 1
}
if a.Minor < b.Minor {
return -1
} else if a.Minor > b.Minor {
return 1
}
return 0
}
func GetKernelVersion() (*KernelVersionInfo, error) {
var (
err error
)
uts, err := uname()
if err != nil {
return nil, err
}
release := make([]byte, len(uts.Release))
i := 0
for _, c := range uts.Release {
release[i] = byte(c)
i++
}
// Remove the \x00 from the release for Atoi to parse correctly
release = release[:bytes.IndexByte(release, 0)]
return ParseRelease(string(release))
}
func ParseRelease(release string) (*KernelVersionInfo, error) {
var (
kernel, major, minor, parsed int
flavor string
)
// Ignore error from Sscanf to allow an empty flavor. Instead, just
// make sure we got all the version numbers.
parsed, _ = fmt.Sscanf(release, "%d.%d.%d%s", &kernel, &major, &minor, &flavor)
if parsed < 3 {
return nil, errors.New("Can't parse kernel version " + release)
}
return &KernelVersionInfo{
Kernel: kernel,
Major: major,
Minor: minor,
Flavor: flavor,
}, nil
}
// FIXME: this is deprecated by CopyWithTar in archive.go
func CopyDirectory(source, dest string) error {
if output, err := exec.Command("cp", "-ra", source, dest).CombinedOutput(); err != nil {
return fmt.Errorf("Error copy: %s (%s)", err, output)
}
return nil
}
type NopFlusher struct{}
func (f *NopFlusher) Flush() {}
type WriteFlusher struct {
sync.Mutex
w io.Writer
flusher http.Flusher
}
func (wf *WriteFlusher) Write(b []byte) (n int, err error) {
wf.Lock()
defer wf.Unlock()
n, err = wf.w.Write(b)
wf.flusher.Flush()
return n, err
}
// Flush the stream immediately.
func (wf *WriteFlusher) Flush() {
wf.Lock()
defer wf.Unlock()
wf.flusher.Flush()
}
func NewWriteFlusher(w io.Writer) *WriteFlusher {
var flusher http.Flusher
if f, ok := w.(http.Flusher); ok {
flusher = f
} else {
flusher = &NopFlusher{}
}
return &WriteFlusher{w: w, flusher: flusher}
}
func NewHTTPRequestError(msg string, res *http.Response) error {
return &JSONError{
Message: msg,
Code: res.StatusCode,
}
}
func IsURL(str string) bool {
return strings.HasPrefix(str, "http://") || strings.HasPrefix(str, "https://")
}
func IsGIT(str string) bool {
return strings.HasPrefix(str, "git://") || strings.HasPrefix(str, "github.com/")
}
// GetResolvConf opens and read the content of /etc/resolv.conf.
// It returns it as byte slice.
func GetResolvConf() ([]byte, error) {
resolv, err := ioutil.ReadFile("/etc/resolv.conf")
if err != nil {
Errorf("Error openning resolv.conf: %s", err)
return nil, err
}
return resolv, nil
}
// CheckLocalDns looks into the /etc/resolv.conf,
// it returns true if there is a local nameserver or if there is no nameserver.
func CheckLocalDns(resolvConf []byte) bool {
var parsedResolvConf = StripComments(resolvConf, []byte("#"))
if !bytes.Contains(parsedResolvConf, []byte("nameserver")) {
return true
}
for _, ip := range [][]byte{
[]byte("127.0.0.1"),
[]byte("127.0.1.1"),
} {
if bytes.Contains(parsedResolvConf, ip) {
return true
}
}
return false
}
// StripComments parses input into lines and strips away comments.
func StripComments(input []byte, commentMarker []byte) []byte {
lines := bytes.Split(input, []byte("\n"))
var output []byte
for _, currentLine := range lines {
var commentIndex = bytes.Index(currentLine, commentMarker)
if commentIndex == -1 {
output = append(output, currentLine...)
} else {
output = append(output, currentLine[:commentIndex]...)
}
output = append(output, []byte("\n")...)
}
return output
}
// GetNameserversAsCIDR returns nameservers (if any) listed in
// /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32")
// This function's output is intended for net.ParseCIDR
func GetNameserversAsCIDR(resolvConf []byte) []string {
var parsedResolvConf = StripComments(resolvConf, []byte("#"))
nameservers := []string{}
re := regexp.MustCompile(`^\s*nameserver\s*(([0-9]+\.){3}([0-9]+))\s*$`)
for _, line := range bytes.Split(parsedResolvConf, []byte("\n")) {
var ns = re.FindSubmatch(line)
if len(ns) > 0 {
nameservers = append(nameservers, string(ns[1])+"/32")
}
}
return nameservers
}
// FIXME: Change this not to receive default value as parameter
func ParseHost(defaultHost string, defaultUnix, addr string) (string, error) {
var (
proto string
host string
port int
)
addr = strings.TrimSpace(addr)
switch {
case addr == "tcp://":
return "", fmt.Errorf("Invalid bind address format: %s", addr)
case strings.HasPrefix(addr, "unix://"):
proto = "unix"
addr = strings.TrimPrefix(addr, "unix://")
if addr == "" {
addr = defaultUnix
}
case strings.HasPrefix(addr, "tcp://"):
proto = "tcp"
addr = strings.TrimPrefix(addr, "tcp://")
case strings.HasPrefix(addr, "fd://"):
return addr, nil
case addr == "":
proto = "unix"
addr = defaultUnix
default:
if strings.Contains(addr, "://") {
return "", fmt.Errorf("Invalid bind address protocol: %s", addr)
}
proto = "tcp"
}
if proto != "unix" && strings.Contains(addr, ":") {
hostParts := strings.Split(addr, ":")
if len(hostParts) != 2 {
return "", fmt.Errorf("Invalid bind address format: %s", addr)
}
if hostParts[0] != "" {
host = hostParts[0]
} else {
host = defaultHost
}
if p, err := strconv.Atoi(hostParts[1]); err == nil && p != 0 {
port = p
} else {
return "", fmt.Errorf("Invalid bind address format: %s", addr)
}
} else if proto == "tcp" && !strings.Contains(addr, ":") {
return "", fmt.Errorf("Invalid bind address format: %s", addr)
} else {
host = addr
}
if proto == "unix" {
return fmt.Sprintf("%s://%s", proto, host), nil
}
return fmt.Sprintf("%s://%s:%d", proto, host, port), nil
}
func GetReleaseVersion() string {
resp, err := http.Get("https://get.docker.io/latest")
if err != nil {
return ""
}
defer resp.Body.Close()
if resp.ContentLength > 24 || resp.StatusCode != 200 {
return ""
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return ""
}
return strings.TrimSpace(string(body))
}
// Get a repos name and returns the right reposName + tag
// The tag can be confusing because of a port in a repository name.
// Ex: localhost.localdomain:5000/samalba/hipache:latest
func ParseRepositoryTag(repos string) (string, string) {
n := strings.LastIndex(repos, ":")
if n < 0 {
return repos, ""
}
if tag := repos[n+1:]; !strings.Contains(tag, "/") {
return repos[:n], tag
}
return repos, ""
}
// An StatusError reports an unsuccessful exit by a command.
type StatusError struct {
Status string
StatusCode int
}
func (e *StatusError) Error() string {
return fmt.Sprintf("Status: %s, Code: %d", e.Status, e.StatusCode)
}
func quote(word string, buf *bytes.Buffer) {
// Bail out early for "simple" strings
if word != "" && !strings.ContainsAny(word, "\\'\"`${[|&;<>()~*?! \t\n") {
buf.WriteString(word)
return
}
buf.WriteString("'")
for i := 0; i < len(word); i++ {
b := word[i]
if b == '\'' {
// Replace literal ' with a close ', a \', and a open '
buf.WriteString("'\\''")
} else {
buf.WriteByte(b)
}
}
buf.WriteString("'")
}
// Take a list of strings and escape them so they will be handled right
// when passed as arguments to an program via a shell
func ShellQuoteArguments(args []string) string {
var buf bytes.Buffer
for i, arg := range args {
if i != 0 {
buf.WriteByte(' ')
}
quote(arg, &buf)
}
return buf.String()
}
func PartParser(template, data string) (map[string]string, error) {
// ip:public:private
var (
templateParts = strings.Split(template, ":")
parts = strings.Split(data, ":")
out = make(map[string]string, len(templateParts))
)
if len(parts) != len(templateParts) {
return nil, fmt.Errorf("Invalid format to parse. %s should match template %s", data, template)
}
for i, t := range templateParts {
value := ""
if len(parts) > i {
value = parts[i]
}
out[t] = value
}
return out, nil
}
var globalTestID string
// TestDirectory creates a new temporary directory and returns its path.
// The contents of directory at path `templateDir` is copied into the
// new directory.
func TestDirectory(templateDir string) (dir string, err error) {
if globalTestID == "" {
globalTestID = RandomString()[:4]
}
prefix := fmt.Sprintf("docker-test%s-%s-", globalTestID, GetCallerName(2))
if prefix == "" {
prefix = "docker-test-"
}
dir, err = ioutil.TempDir("", prefix)
if err = os.Remove(dir); err != nil {
return
}
if templateDir != "" {
if err = CopyDirectory(templateDir, dir); err != nil {
return
}
}
return
}
// GetCallerName introspects the call stack and returns the name of the
// function `depth` levels down in the stack.
func GetCallerName(depth int) string {
// Use the caller function name as a prefix.
// This helps trace temp directories back to their test.
pc, _, _, _ := runtime.Caller(depth + 1)
callerLongName := runtime.FuncForPC(pc).Name()
parts := strings.Split(callerLongName, ".")
callerShortName := parts[len(parts)-1]
return callerShortName
}
func CopyFile(src, dst string) (int64, error) {
if src == dst {
return 0, nil
}
sf, err := os.Open(src)
if err != nil {
return 0, err
}
defer sf.Close()
if err := os.Remove(dst); err != nil && !os.IsNotExist(err) {
return 0, err
}
df, err := os.Create(dst)
if err != nil {
return 0, err
}
defer df.Close()
return io.Copy(df, sf)
}
type readCloserWrapper struct {
io.Reader
closer func() error
}
func (r *readCloserWrapper) Close() error {
return r.closer()
}
func NewReadCloserWrapper(r io.Reader, closer func() error) io.ReadCloser {
return &readCloserWrapper{
Reader: r,
closer: closer,
}
}