package utils import ( "bytes" "crypto/rand" "crypto/sha1" "crypto/sha256" "encoding/hex" "encoding/json" "errors" "fmt" "index/suffixarray" "io" "io/ioutil" "net/http" "os" "os/exec" "path/filepath" "regexp" "runtime" "strconv" "strings" "sync" "time" "github.com/dotcloud/docker/dockerversion" ) type KeyValuePair struct { Key string Value string } // 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, 1) 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 = "" 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 streams map[string](map[io.WriteCloser]struct{}) } func (w *WriteBroadcaster) AddWriter(writer io.WriteCloser, stream string) { w.Lock() if _, ok := w.streams[stream]; !ok { w.streams[stream] = make(map[io.WriteCloser]struct{}) } w.streams[stream][writer] = struct{}{} w.Unlock() } type JSONLog struct { Log string `json:"log,omitempty"` Stream string `json:"stream,omitempty"` Created time.Time `json:"time"` } func (jl *JSONLog) Format(format string) (string, error) { if format == "" { return jl.Log, nil } if format == "json" { m, err := json.Marshal(jl) return string(m), err } return fmt.Sprintf("[%s] %s", jl.Created.Format(format), jl.Log), nil } func WriteLog(src io.Reader, dst io.WriteCloser, format string) error { dec := json.NewDecoder(src) for { l := &JSONLog{} if err := dec.Decode(l); err == io.EOF { return nil } else if err != nil { Errorf("Error streaming logs: %s", err) return err } line, err := l.Format(format) if err != nil { return err } fmt.Fprintf(dst, "%s", line) } } type LogFormatter struct { wc io.WriteCloser timeFormat string } func (w *WriteBroadcaster) Write(p []byte) (n int, err error) { created := time.Now().UTC() w.Lock() defer w.Unlock() if writers, ok := w.streams[""]; ok { for sw := range writers { if n, err := sw.Write(p); err != nil || n != len(p) { // On error, evict the writer delete(writers, sw) } } } w.buf.Write(p) lines := []string{} for { line, err := w.buf.ReadString('\n') if err != nil { w.buf.Write([]byte(line)) break } lines = append(lines, line) } if len(lines) != 0 { for stream, writers := range w.streams { if stream == "" { continue } var lp []byte for _, line := range lines { b, err := json.Marshal(&JSONLog{Log: line, Stream: stream, Created: created}) if err != nil { Errorf("Error making JSON log line: %s", err) } lp = append(lp, b...) lp = append(lp, '\n') } for sw := range writers { if _, err := sw.Write(lp); err != nil { delete(writers, sw) } } } } return len(p), nil } func (w *WriteBroadcaster) CloseWriters() error { w.Lock() defer w.Unlock() for _, writers := range w.streams { for w := range writers { w.Close() } } w.streams = make(map[string](map[io.WriteCloser]struct{})) return nil } func NewWriteBroadcaster() *WriteBroadcaster { return &WriteBroadcaster{ streams: make(map[string](map[io.WriteCloser]struct{})), 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(ids []string) (idx *TruncIndex) { idx = &TruncIndex{ ids: make(map[string]bool), bytes: []byte{' '}, } for _, id := range ids { idx.ids[id] = true idx.bytes = append(idx.bytes, []byte(id+" ")...) } idx.index = suffixarray.New(idx.bytes) return } 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] } // GenerateRandomID returns an unique id func GenerateRandomID() string { for { id := make([]byte, 32) if _, err := io.ReadFull(rand.Reader, id); err != nil { panic(err) // This shouldn't happen } value := hex.EncodeToString(id) // if we try to parse the truncated for as an int and we don't have // an error then the value is all numberic and causes issues when // used as a hostname. ref #3869 if _, err := strconv.Atoi(TruncateID(value)); err == nil { continue } return value } } func ValidateID(id string) error { if id == "" { return fmt.Errorf("Id can't be empty") } if strings.Contains(id, ":") { return fmt.Errorf("Invalid character in id: ':'") } return nil } // 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, partial 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%s", &kernel, &major, &partial) if parsed < 2 { return nil, errors.New("Can't parse kernel version " + release) } // sometimes we have 3.12.25-gentoo, but sometimes we just have 3.12-1-amd64 parsed, _ = fmt.Sscanf(partial, ".%d%s", &minor, &flavor) if parsed < 1 { flavor = partial } 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/") || strings.HasPrefix(str, "git@github.com:") || (strings.HasSuffix(str, ".git") && IsURL(str)) } // 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 { for _, line := range GetLines(resolvConf, []byte("#")) { if !bytes.Contains(line, []byte("nameserver")) { continue } for _, ip := range [][]byte{ []byte("127.0.0.1"), []byte("127.0.1.1"), } { if bytes.Contains(line, ip) { return true } } return false } return true } // GetLines parses input into lines and strips away comments. func GetLines(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]) } } return output } // 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, } } // ReplaceOrAppendValues returns the defaults with the overrides either // replaced by env key or appended to the list func ReplaceOrAppendEnvValues(defaults, overrides []string) []string { cache := make(map[string]int, len(defaults)) for i, e := range defaults { parts := strings.SplitN(e, "=", 2) cache[parts[0]] = i } for _, value := range overrides { parts := strings.SplitN(value, "=", 2) if i, exists := cache[parts[0]]; exists { defaults[i] = value } else { defaults = append(defaults, value) } } return defaults } // ReadSymlinkedDirectory returns the target directory of a symlink. // The target of the symbolic link may not be a file. func ReadSymlinkedDirectory(path string) (string, error) { var realPath string var err error if realPath, err = filepath.Abs(path); err != nil { return "", fmt.Errorf("unable to get absolute path for %s: %s", path, err) } if realPath, err = filepath.EvalSymlinks(realPath); err != nil { return "", fmt.Errorf("failed to canonicalise path for %s: %s", path, err) } realPathInfo, err := os.Stat(realPath) if err != nil { return "", fmt.Errorf("failed to stat target '%s' of '%s': %s", realPath, path, err) } if !realPathInfo.Mode().IsDir() { return "", fmt.Errorf("canonical path points to a file '%s'", realPath) } return realPath, nil } func ParseKeyValueOpt(opt string) (string, string, error) { parts := strings.SplitN(opt, "=", 2) if len(parts) != 2 { return "", "", fmt.Errorf("Unable to parse key/value option: %s", opt) } return strings.TrimSpace(parts[0]), strings.TrimSpace(parts[1]), nil }