1 files changed, 168 insertions, 0 deletions
diff --git a/src/cmd/godoc/utils.go b/src/cmd/godoc/utils.go
new file mode 100644
index 000000000..11e46aee5
--- /dev/null
+++ b/src/cmd/godoc/utils.go
@@ -0,0 +1,168 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains support functionality for godoc.
+
+package main
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+	"utf8"
+)
+
+// An RWValue wraps a value and permits mutually exclusive
+// access to it and records the time the value was last set.
+//
+type RWValue struct {
+	mutex     sync.RWMutex
+	value     interface{}
+	timestamp int64 // time of last set(), in seconds since epoch
+}
+
+func (v *RWValue) set(value interface{}) {
+	v.mutex.Lock()
+	v.value = value
+	v.timestamp = time.Seconds()
+	v.mutex.Unlock()
+}
+
+func (v *RWValue) get() (interface{}, int64) {
+	v.mutex.RLock()
+	defer v.mutex.RUnlock()
+	return v.value, v.timestamp
+}
+
+// TODO(gri) For now, using os.Getwd() is ok here since the functionality
+//           based on this code is not invoked for the appengine version,
+//           but this is fragile. Determine what the right thing to do is,
+//           here (possibly have some Getwd-equivalent in FileSystem).
+var cwd, _ = os.Getwd() // ignore errors
+
+// canonicalizePaths takes a list of (directory/file) paths and returns
+// the list of corresponding absolute paths in sorted (increasing) order.
+// Relative paths are assumed to be relative to the current directory,
+// empty and duplicate paths as well as paths for which filter(path) is
+// false are discarded. filter may be nil in which case it is not used.
+//
+func canonicalizePaths(list []string, filter func(path string) bool) []string {
+	i := 0
+	for _, path := range list {
+		path = strings.TrimSpace(path)
+		if len(path) == 0 {
+			continue // ignore empty paths (don't assume ".")
+		}
+		// len(path) > 0: normalize path
+		if filepath.IsAbs(path) {
+			path = filepath.Clean(path)
+		} else {
+			path = filepath.Join(cwd, path)
+		}
+		// we have a non-empty absolute path
+		if filter != nil && !filter(path) {
+			continue
+		}
+		// keep the path
+		list[i] = path
+		i++
+	}
+	list = list[0:i]
+
+	// sort the list and remove duplicate entries
+	sort.Strings(list)
+	i = 0
+	prev := ""
+	for _, path := range list {
+		if path != prev {
+			list[i] = path
+			i++
+			prev = path
+		}
+	}
+
+	return list[0:i]
+}
+
+// writeFileAtomically writes data to a temporary file and then
+// atomically renames that file to the file named by filename.
+//
+func writeFileAtomically(filename string, data []byte) os.Error {
+	// TODO(gri) this won't work on appengine
+	f, err := ioutil.TempFile(filepath.Split(filename))
+	if err != nil {
+		return err
+	}
+	n, err := f.Write(data)
+	f.Close()
+	if err != nil {
+		return err
+	}
+	if n < len(data) {
+		return io.ErrShortWrite
+	}
+	return os.Rename(f.Name(), filename)
+}
+
+// isText returns true if a significant prefix of s looks like correct UTF-8;
+// that is, if it is likely that s is human-readable text.
+//
+func isText(s []byte) bool {
+	const max = 1024 // at least utf8.UTFMax
+	if len(s) > max {
+		s = s[0:max]
+	}
+	for i, c := range string(s) {
+		if i+utf8.UTFMax > len(s) {
+			// last char may be incomplete - ignore
+			break
+		}
+		if c == 0xFFFD || c < ' ' && c != '\n' && c != '\t' && c != '\f' {
+			// decoding error or control character - not a text file
+			return false
+		}
+	}
+	return true
+}
+
+// TODO(gri): Should have a mapping from extension to handler, eventually.
+
+// textExt[x] is true if the extension x indicates a text file, and false otherwise.
+var textExt = map[string]bool{
+	".css": false, // must be served raw
+	".js":  false, // must be served raw
+}
+
+// isTextFile returns true if the file has a known extension indicating
+// a text file, or if a significant chunk of the specified file looks like
+// correct UTF-8; that is, if it is likely that the file contains human-
+// readable text.
+//
+func isTextFile(filename string) bool {
+	// if the extension is known, use it for decision making
+	if isText, found := textExt[filepath.Ext(filename)]; found {
+		return isText
+	}
+
+	// the extension is not known; read an initial chunk
+	// of the file and check if it looks like text
+	f, err := fs.Open(filename)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	var buf [1024]byte
+	n, err := f.Read(buf[0:])
+	if err != nil {
+		return false
+	}
+
+	return isText(buf[0:n])
+}