530 lines
13 KiB
Go
530 lines
13 KiB
Go
package fs
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import (
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"sort"
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"strings"
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"sync"
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"syscall"
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)
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type realFS struct {
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// Stores the file entries for directories we've listed before
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entriesMutex sync.Mutex
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entries map[string]entriesOrErr
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// If true, do not use the "entries" cache
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doNotCacheEntries bool
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// This stores data that will end up being returned by "WatchData()"
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watchMutex sync.Mutex
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watchData map[string]privateWatchData
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// When building with WebAssembly, the Go compiler doesn't correctly handle
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// platform-specific path behavior. Hack around these bugs by compiling
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// support for both Unix and Windows paths into all executables and switch
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// between them at run-time instead.
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fp goFilepath
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}
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type entriesOrErr struct {
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entries DirEntries
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canonicalError error
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originalError error
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}
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type watchState uint8
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const (
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stateNone watchState = iota
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stateDirHasAccessedEntries // Compare "accessedEntries"
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stateDirMissing // Compare directory presence
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stateFileHasModKey // Compare "modKey"
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stateFileNeedModKey // Need to transition to "stateFileHasModKey" or "stateFileUnusableModKey" before "WatchData()" returns
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stateFileMissing // Compare file presence
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stateFileUnusableModKey // Compare "fileContents"
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)
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type privateWatchData struct {
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accessedEntries *accessedEntries
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fileContents string
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modKey ModKey
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state watchState
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}
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type RealFSOptions struct {
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WantWatchData bool
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AbsWorkingDir string
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DoNotCache bool
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}
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func RealFS(options RealFSOptions) (FS, error) {
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var fp goFilepath
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if CheckIfWindows() {
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fp.isWindows = true
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fp.pathSeparator = '\\'
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} else {
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fp.isWindows = false
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fp.pathSeparator = '/'
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}
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// Come up with a default working directory if one was not specified
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fp.cwd = options.AbsWorkingDir
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if fp.cwd == "" {
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if cwd, err := os.Getwd(); err == nil {
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fp.cwd = cwd
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} else if fp.isWindows {
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fp.cwd = "C:\\"
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} else {
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fp.cwd = "/"
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}
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} else if !fp.isAbs(fp.cwd) {
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return nil, fmt.Errorf("The working directory %q is not an absolute path", fp.cwd)
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}
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// Resolve symlinks in the current working directory. Symlinks are resolved
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// when input file paths are converted to absolute paths because we need to
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// recognize an input file as unique even if it has multiple symlinks
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// pointing to it. The build will generate relative paths from the current
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// working directory to the absolute input file paths for error messages,
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// so the current working directory should be processed the same way. Not
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// doing this causes test failures with esbuild when run from inside a
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// symlinked directory.
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//
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// This deliberately ignores errors due to e.g. infinite loops. If there is
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// an error, we will just use the original working directory and likely
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// encounter an error later anyway. And if we don't encounter an error
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// later, then the current working directory didn't even matter and the
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// error is unimportant.
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if path, err := fp.evalSymlinks(fp.cwd); err == nil {
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fp.cwd = path
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}
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// Only allocate memory for watch data if necessary
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var watchData map[string]privateWatchData
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if options.WantWatchData {
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watchData = make(map[string]privateWatchData)
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}
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return &realFS{
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entries: make(map[string]entriesOrErr),
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fp: fp,
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watchData: watchData,
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doNotCacheEntries: options.DoNotCache,
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}, nil
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}
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func (fs *realFS) ReadDirectory(dir string) (entries DirEntries, canonicalError error, originalError error) {
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if !fs.doNotCacheEntries {
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// First, check the cache
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cached, ok := func() (cached entriesOrErr, ok bool) {
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fs.entriesMutex.Lock()
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defer fs.entriesMutex.Unlock()
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cached, ok = fs.entries[dir]
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return
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}()
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if ok {
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// Cache hit: stop now
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return cached.entries, cached.canonicalError, cached.originalError
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}
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}
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// Cache miss: read the directory entries
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names, canonicalError, originalError := fs.readdir(dir)
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entries = DirEntries{dir, make(map[string]*Entry), nil}
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// Unwrap to get the underlying error
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if pathErr, ok := canonicalError.(*os.PathError); ok {
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canonicalError = pathErr.Unwrap()
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}
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if canonicalError == nil {
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for _, name := range names {
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// Call "stat" lazily for performance. The "@material-ui/icons" package
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// contains a directory with over 11,000 entries in it and running "stat"
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// for each entry was a big performance issue for that package.
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entries.data[strings.ToLower(name)] = &Entry{
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dir: dir,
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base: name,
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needStat: true,
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}
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}
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}
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// Store data for watch mode
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if fs.watchData != nil {
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defer fs.watchMutex.Unlock()
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fs.watchMutex.Lock()
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state := stateDirHasAccessedEntries
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if canonicalError != nil {
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state = stateDirMissing
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}
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entries.accessedEntries = &accessedEntries{wasPresent: make(map[string]bool)}
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fs.watchData[dir] = privateWatchData{
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accessedEntries: entries.accessedEntries,
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state: state,
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}
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}
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// Update the cache unconditionally. Even if the read failed, we don't want to
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// retry again later. The directory is inaccessible so trying again is wasted.
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if canonicalError != nil {
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entries.data = nil
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}
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if !fs.doNotCacheEntries {
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fs.entriesMutex.Lock()
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defer fs.entriesMutex.Unlock()
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fs.entries[dir] = entriesOrErr{
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entries: entries,
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canonicalError: canonicalError,
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originalError: originalError,
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}
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}
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return entries, canonicalError, originalError
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}
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func (fs *realFS) ReadFile(path string) (contents string, canonicalError error, originalError error) {
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BeforeFileOpen()
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defer AfterFileClose()
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buffer, originalError := ioutil.ReadFile(path)
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canonicalError = fs.canonicalizeError(originalError)
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// Allocate the string once
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fileContents := string(buffer)
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// Store data for watch mode
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if fs.watchData != nil {
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defer fs.watchMutex.Unlock()
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fs.watchMutex.Lock()
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data, ok := fs.watchData[path]
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if canonicalError != nil {
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data.state = stateFileMissing
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} else if !ok {
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data.state = stateFileNeedModKey
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}
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data.fileContents = fileContents
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fs.watchData[path] = data
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}
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return fileContents, canonicalError, originalError
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}
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type realOpenedFile struct {
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handle *os.File
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len int
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}
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func (f *realOpenedFile) Len() int {
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return f.len
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}
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func (f *realOpenedFile) Read(start int, end int) ([]byte, error) {
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bytes := make([]byte, end-start)
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remaining := bytes
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_, err := f.handle.Seek(int64(start), io.SeekStart)
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if err != nil {
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return nil, err
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}
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for len(remaining) > 0 {
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n, err := f.handle.Read(remaining)
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if err != nil && n <= 0 {
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return nil, err
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}
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remaining = remaining[n:]
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}
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return bytes, nil
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}
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func (f *realOpenedFile) Close() error {
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return f.handle.Close()
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}
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func (fs *realFS) OpenFile(path string) (OpenedFile, error, error) {
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BeforeFileOpen()
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defer AfterFileClose()
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f, err := os.Open(path)
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if err != nil {
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return nil, fs.canonicalizeError(err), err
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}
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info, err := f.Stat()
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if err != nil {
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f.Close()
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return nil, fs.canonicalizeError(err), err
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}
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return &realOpenedFile{f, int(info.Size())}, nil, nil
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}
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func (fs *realFS) ModKey(path string) (ModKey, error) {
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BeforeFileOpen()
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defer AfterFileClose()
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key, err := modKey(path)
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// Store data for watch mode
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if fs.watchData != nil {
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defer fs.watchMutex.Unlock()
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fs.watchMutex.Lock()
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data, ok := fs.watchData[path]
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if !ok {
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if err == modKeyUnusable {
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data.state = stateFileUnusableModKey
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} else if err != nil {
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data.state = stateFileMissing
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} else {
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data.state = stateFileHasModKey
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}
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} else if data.state == stateFileNeedModKey {
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data.state = stateFileHasModKey
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}
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data.modKey = key
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fs.watchData[path] = data
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}
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return key, err
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}
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func (fs *realFS) IsAbs(p string) bool {
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return fs.fp.isAbs(p)
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}
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func (fs *realFS) Abs(p string) (string, bool) {
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abs, err := fs.fp.abs(p)
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return abs, err == nil
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}
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func (fs *realFS) Dir(p string) string {
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return fs.fp.dir(p)
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}
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func (fs *realFS) Base(p string) string {
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return fs.fp.base(p)
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}
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func (fs *realFS) Ext(p string) string {
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return fs.fp.ext(p)
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}
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func (fs *realFS) Join(parts ...string) string {
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return fs.fp.clean(fs.fp.join(parts))
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}
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func (fs *realFS) Cwd() string {
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return fs.fp.cwd
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}
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func (fs *realFS) Rel(base string, target string) (string, bool) {
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if rel, err := fs.fp.rel(base, target); err == nil {
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return rel, true
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}
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return "", false
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}
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func (fs *realFS) readdir(dirname string) (entries []string, canonicalError error, originalError error) {
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BeforeFileOpen()
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defer AfterFileClose()
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f, originalError := os.Open(dirname)
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canonicalError = fs.canonicalizeError(originalError)
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// Stop now if there was an error
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if canonicalError != nil {
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return nil, canonicalError, originalError
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}
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defer f.Close()
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entries, err := f.Readdirnames(-1)
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// Unwrap to get the underlying error
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if syscallErr, ok := err.(*os.SyscallError); ok {
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err = syscallErr.Unwrap()
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}
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// Don't convert ENOTDIR to ENOENT here. ENOTDIR is a legitimate error
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// condition for Readdirnames() on non-Windows platforms.
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return entries, canonicalError, originalError
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}
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func (fs *realFS) canonicalizeError(err error) error {
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// Unwrap to get the underlying error
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if pathErr, ok := err.(*os.PathError); ok {
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err = pathErr.Unwrap()
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}
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// This has been copied from golang.org/x/sys/windows
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const ERROR_INVALID_NAME syscall.Errno = 123
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// Windows is much more restrictive than Unix about file names. If a file name
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// is invalid, it will return ERROR_INVALID_NAME. Treat this as ENOENT (i.e.
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// "the file does not exist") so that the resolver continues trying to resolve
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// the path on this failure instead of aborting with an error.
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if fs.fp.isWindows && err == ERROR_INVALID_NAME {
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err = syscall.ENOENT
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}
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// Windows returns ENOTDIR here even though nothing we've done yet has asked
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// for a directory. This really means ENOENT on Windows. Return ENOENT here
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// so callers that check for ENOENT will successfully detect this file as
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// missing.
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if err == syscall.ENOTDIR {
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err = syscall.ENOENT
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}
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return err
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}
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func (fs *realFS) kind(dir string, base string) (symlink string, kind EntryKind) {
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entryPath := fs.fp.join([]string{dir, base})
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// Use "lstat" since we want information about symbolic links
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BeforeFileOpen()
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defer AfterFileClose()
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stat, err := os.Lstat(entryPath)
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if err != nil {
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return
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}
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mode := stat.Mode()
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// Follow symlinks now so the cache contains the translation
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if (mode & os.ModeSymlink) != 0 {
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symlink = entryPath
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linksWalked := 0
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for {
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linksWalked++
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if linksWalked > 255 {
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return // Error: too many links
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}
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link, err := os.Readlink(symlink)
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if err != nil {
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return // Skip over this entry
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}
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if !fs.fp.isAbs(link) {
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link = fs.fp.join([]string{dir, link})
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}
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symlink = fs.fp.clean(link)
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// Re-run "lstat" on the symlink target
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stat2, err2 := os.Lstat(symlink)
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if err2 != nil {
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return // Skip over this entry
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}
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mode = stat2.Mode()
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if (mode & os.ModeSymlink) == 0 {
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break
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}
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dir = fs.fp.dir(symlink)
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}
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}
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// We consider the entry either a directory or a file
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if (mode & os.ModeDir) != 0 {
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kind = DirEntry
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} else {
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kind = FileEntry
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}
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return
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}
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func (fs *realFS) WatchData() WatchData {
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paths := make(map[string]func() string)
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for path, data := range fs.watchData {
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// Each closure below needs its own copy of these loop variables
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path := path
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data := data
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// Each function should return true if the state has been changed
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if data.state == stateFileNeedModKey {
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key, err := modKey(path)
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if err == modKeyUnusable {
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data.state = stateFileUnusableModKey
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} else if err != nil {
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data.state = stateFileMissing
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} else {
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data.state = stateFileHasModKey
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data.modKey = key
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}
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}
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switch data.state {
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case stateDirMissing:
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paths[path] = func() string {
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info, err := os.Stat(path)
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if err == nil && info.IsDir() {
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return path
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}
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return ""
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}
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case stateDirHasAccessedEntries:
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paths[path] = func() string {
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names, err, _ := fs.readdir(path)
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if err != nil {
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return path
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}
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data.accessedEntries.mutex.Lock()
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defer data.accessedEntries.mutex.Unlock()
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if allEntries := data.accessedEntries.allEntries; allEntries != nil {
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// Check all entries
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if len(names) != len(allEntries) {
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return path
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}
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sort.Strings(names)
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for i, s := range names {
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if s != allEntries[i] {
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return path
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}
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}
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} else {
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// Check individual entries
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isPresent := make(map[string]bool, len(names))
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for _, name := range names {
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isPresent[strings.ToLower(name)] = true
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}
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for name, wasPresent := range data.accessedEntries.wasPresent {
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if wasPresent != isPresent[name] {
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return fs.Join(path, name)
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}
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}
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}
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return ""
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}
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case stateFileMissing:
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paths[path] = func() string {
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if info, err := os.Stat(path); err == nil && !info.IsDir() {
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return path
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}
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return ""
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}
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case stateFileHasModKey:
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paths[path] = func() string {
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if key, err := modKey(path); err != nil || key != data.modKey {
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return path
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}
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return ""
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}
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case stateFileUnusableModKey:
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paths[path] = func() string {
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if buffer, err := ioutil.ReadFile(path); err != nil || string(buffer) != data.fileContents {
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return path
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}
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return ""
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}
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}
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}
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return WatchData{
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Paths: paths,
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}
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}
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