http additions

	file system server
	add NotFound, Redirect functions
	method on a string

R=r
DELTA=212  (199 added, 4 deleted, 9 changed)
OCL=27467
CL=27471

3 files changed, 209 insertions, 13 deletions

diff --git a/src/lib/http/Makefile b/src/lib/http/Makefile
index 24553ec34..99da90816 100644
--- a/src/lib/http/Makefile
+++ b/src/lib/http/Makefile
@@ -32,8 +32,8 @@ coverage: packages
 	$(AS) $*.s
 
 O1=\
-	url.$O\
 	status.$O\
+	url.$O\
 
 O2=\
 	request.$O\
@@ -41,10 +41,13 @@ O2=\
 O3=\
 	server.$O\
 
-http.a: a1 a2 a3
+O4=\
+	fs.$O\
+
+http.a: a1 a2 a3 a4
 
 a1:	$(O1)
-	$(AR) grc http.a url.$O status.$O
+	$(AR) grc http.a status.$O url.$O
 	rm -f $(O1)
 
 a2:	$(O2)
@@ -55,12 +58,17 @@ a3:	$(O3)
 	$(AR) grc http.a server.$O
 	rm -f $(O3)
 
+a4:	$(O4)
+	$(AR) grc http.a fs.$O
+	rm -f $(O4)
+
 newpkg: clean
 	$(AR) grc http.a
 
 $(O1): newpkg
 $(O2): a1
 $(O3): a2
+$(O4): a3
 
 nuke: clean
 	rm -f $(GOROOT)/pkg/http.a
diff --git a/src/lib/http/fs.go b/src/lib/http/fs.go
new file mode 100644
index 000000000..d93859dd2
--- /dev/null
+++ b/src/lib/http/fs.go
@@ -0,0 +1,184 @@
+// Copyright 2009 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.
+
+// HTTP file system request handler
+
+package http
+
+import (
+	"fmt";
+	"http";
+	"io";
+	"os";
+	"path";
+	"strings";
+	"utf8";
+)
+
+// TODO this should be in a mime package somewhere
+var contentByExt = map[string] string {
+	".css":	"text/css",
+	".gif":	"image/gif",
+	".html":	"text/html; charset=utf-8",
+	".jpg":	"image/jpeg",
+	".js":	"application/x-javascript",
+	".png":	"image/png",
+}
+
+// Heuristic: b is text if it is valid UTF-8 and doesn't
+// contain any unprintable ASCII or Unicode characters.
+func isText(b []byte) bool {
+	for len(b) > 0 && utf8.FullRune(b) {
+		rune, size := utf8.DecodeRune(b);
+		if size == 1 && rune == utf8.RuneError {
+			// decoding error
+			return false;
+		}
+		if 0x80 <= rune && rune <= 0x9F {
+			return false;
+		}
+		if rune < ' ' {
+			switch rune {
+			case '\n', '\r', '\t':
+				// okay
+			default:
+				// binary garbage
+				return false;
+			}
+		}
+		b = b[size:len(b)];
+	}
+	return true;
+}
+
+func dirList(c *Conn, f *os.File) {
+	fmt.Fprintf(c, "<pre>\n");
+	for {
+		dirs, err := f.Readdir(100);
+		if err != nil || len(dirs) == 0 {
+			break
+		}
+		for i, d := range dirs {
+			name := d.Name;
+			if d.IsDirectory() {
+				name += "/"
+			}
+			// TODO htmlescape
+			fmt.Fprintf(c, "<a href=\"%s\">%s</a>\n", name, name);
+		}
+	}
+	fmt.Fprintf(c, "</pre>\n");
+}
+
+
+func serveFileInternal(c *Conn, r *Request, name string, redirect bool) {
+	const indexPage = "/index.html";
+
+	// redirect to strip off any index.html
+	n := len(name) - len(indexPage);
+	if n >= 0 && name[n:len(name)] == indexPage {
+		http.Redirect(c, name[0:n+1]);
+		return;
+	}
+
+	f, err := os.Open(name, os.O_RDONLY, 0);
+	if err != nil {
+		// TODO expose actual error?
+		NotFound(c, r);
+		return;
+	}
+	defer f.Close();
+
+	d, err1 := f.Stat();
+	if err1 != nil {
+		// TODO expose actual error?
+		NotFound(c, r);
+		return;
+	}
+
+	if redirect {
+		// redirect to canonical path: / at end of directory url
+		// r.Url.Path always begins with /
+		url := r.Url.Path;
+		if d.IsDirectory() {
+			if url[len(url)-1] != '/' {
+				http.Redirect(c, url + "/");
+				return;
+			}
+		} else {
+			if url[len(url)-1] == '/' {
+				http.Redirect(c, url[0:len(url)-1]);
+				return;
+			}
+		}
+	}
+
+	// use contents of index.html for directory, if present
+	if d.IsDirectory() {
+		index := name + indexPage;
+		ff, err := os.Open(index, os.O_RDONLY, 0);
+		if err == nil {
+			defer ff.Close();
+			dd, err := ff.Stat();
+			if err == nil {
+				name = index;
+				d = dd;
+				f = ff;
+			}
+		}
+	}
+
+	if d.IsDirectory() {
+		dirList(c, f);
+		return;
+	}
+
+	// serve file
+	// use extension to find content type.
+	ext := path.Ext(name);
+	if ctype, ok := contentByExt[ext]; ok {
+		c.SetHeader("Content-Type", ctype);
+	} else {
+		// read first chunk to decide between utf-8 text and binary
+		var buf [1024]byte;
+		n, err := io.Readn(f, buf);
+		b := buf[0:n];
+		if isText(b) {
+			c.SetHeader("Content-Type", "text-plain; charset=utf-8");
+		} else {
+			c.SetHeader("Content-Type", "application/octet-stream");	// generic binary
+		}
+		c.Write(b);
+	}
+	io.Copy(f, c);
+}
+
+// ServeFile replies to the request with the contents of the named file or directory.
+func ServeFile(c *Conn, r *Request, name string) {
+	serveFileInternal(c, r, name, false);
+}
+
+type fileHandler struct {
+	root string;
+	prefix string;
+}
+
+// FileServer returns a handler that serves HTTP requests
+// with the contents of the file system rooted at root.
+// It strips prefix from the incoming requests before
+// looking up the file name in the file system.
+func FileServer(root, prefix string) Handler {
+	return &fileHandler{root, prefix};
+}
+
+func (f *fileHandler) ServeHTTP(c *Conn, r *Request) {
+	path := r.Url.Path;
+	if !strings.HasPrefix(path, f.prefix) {
+		NotFound(c, r);
+		return;
+	}
+	path = path[len(f.prefix):len(path)];
+	serveFileInternal(c, r, f.root + "/" + path, true);
+}
+
diff --git a/src/lib/http/server.go b/src/lib/http/server.go
index fa29e9bc1..a8aef01f0 100644
--- a/src/lib/http/server.go
+++ b/src/lib/http/server.go
@@ -253,8 +253,8 @@ func (f HandlerFunc) ServeHTTP(c *Conn, req *Request) {
 
 // Helper handlers
 
-// 404 not found
-func notFound(c *Conn, req *Request) {
+// NotFound replies to the request with an HTTP 404 not found error.
+func NotFound(c *Conn, req *Request) {
 	c.SetHeader("Content-Type", "text/plain; charset=utf-8");
 	c.WriteHeader(StatusNotFound);
 	io.WriteString(c, "404 page not found\n");
@@ -263,22 +263,26 @@ func notFound(c *Conn, req *Request) {
 // NotFoundHandler returns a simple request handler
 // that replies to each request with a ``404 page not found'' reply.
 func NotFoundHandler() Handler {
-	return HandlerFunc(notFound)
+	return HandlerFunc(NotFound)
 }
 
-// Redirect to a fixed URL
-type redirectHandler struct {
-	to string;
-}
-func (h *redirectHandler) ServeHTTP(c *Conn, req *Request) {
-	c.SetHeader("Location", h.to);
+// Redirect replies to the request with a redirect to url,
+// which may be a path relative to the request path.
+func Redirect(c *Conn, url string) {
+	c.SetHeader("Location", url);
 	c.WriteHeader(StatusMovedPermanently);
 }
 
+// Redirect to a fixed URL
+type redirectHandler string
+func (url redirectHandler) ServeHTTP(c *Conn, req *Request) {
+	Redirect(c, url);
+}
+
 // RedirectHandler returns a request handler that redirects
 // each request it receives to the given url.
 func RedirectHandler(url string) Handler {
-	return &redirectHandler{url};
+	return redirectHandler(url);
 }
 
 // ServeMux is an HTTP request multiplexer.