godoc: report Status 404 if a pkg or file is not found

Fixes #1005.

R=rsc, r
CC=golang-dev
https://golang.org/cl/1935041

src/cmd/godoc/codewalk.go

@@ -218,6 +218,7 @@ func codewalkFileprint(c *http.Conn, r *http.Request, f string) {
 	abspath := absolutePath(f, *goroot)
 	data, err := ioutil.ReadFile(abspath)
 	if err != nil {
+		log.Stderr(err)
 		serveError(c, r, f, err)
 		return
 	}

src/cmd/godoc/godoc.go

@@ -1186,7 +1186,6 @@ type PageInfoMode uint
 const (
 	exportsOnly PageInfoMode = 1 << iota // only keep exported stuff
 	genDoc                               // generate documentation
-	tryMode                              // don't log errors
 )
 
 
@@ -1197,6 +1196,7 @@ type PageInfo struct {
 	PDoc    *doc.PackageDoc // nil if no single package documentation
 	Dirs    *DirList        // nil if no directory information
 	IsPkg   bool            // false if this is not documenting a real package
+	Err     os.Error        // directory read error or nil
 }
 
 
@@ -1210,10 +1210,10 @@ type httpHandler struct {
 // getPageInfo returns the PageInfo for a package directory abspath. If the
 // parameter genAST is set, an AST containing only the package exports is
 // computed (PageInfo.PAst), otherwise package documentation (PageInfo.Doc)
-// is extracted from the AST. If the parameter try is set, no errors are
-// logged if getPageInfo fails. If there is no corresponding package in the
-// directory, PageInfo.PDoc and PageInfo.PExp are nil. If there are no sub-
-// directories, PageInfo.Dirs is nil.
+// is extracted from the AST. If there is no corresponding package in the
+// directory, PageInfo.PAst and PageInfo.PDoc are nil. If there are no sub-
+// directories, PageInfo.Dirs is nil. If a directory read error occured,
+// PageInfo.Err is set to the respective error but the error is not logged.
 //
 func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInfoMode) PageInfo {
 	// filter function to select the desired .go files
@@ -1225,9 +1225,10 @@ func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInf
 
 	// get package ASTs
 	pkgs, err := parser.ParseDir(abspath, filter, parser.ParseComments)
-	if err != nil && mode&tryMode != 0 {
-		// TODO: errors should be shown instead of an empty directory
-		log.Stderrf("parser.parseDir: %s", err)
+	if err != nil && pkgs == nil {
+		// only report directory read errors, ignore parse errors
+		// (may be able to extract partial package information)
+		return PageInfo{Dirname: abspath, Err: err}
 	}
 
 	// select package
@@ -1314,7 +1315,7 @@ func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInf
 		dir = newDirectory(abspath, 1)
 	}
 
-	return PageInfo{abspath, plist, past, pdoc, dir.listing(true), h.isPkg}
+	return PageInfo{abspath, plist, past, pdoc, dir.listing(true), h.isPkg, nil}
 }
 
 
@@ -1330,6 +1331,11 @@ func (h *httpHandler) ServeHTTP(c *http.Conn, r *http.Request) {
 		mode |= genDoc
 	}
 	info := h.getPageInfo(abspath, relpath, r.FormValue("p"), mode)
+	if info.Err != nil {
+		log.Stderr(info.Err)
+		serveError(c, r, relpath, info.Err)
+		return
+	}
 
 	if r.FormValue("f") == "text" {
 		contents := applyTemplate(packageText, "packageText", info)

src/cmd/godoc/main.go

@@ -66,6 +66,7 @@ var (
 
 func serveError(c *http.Conn, r *http.Request, relpath string, err os.Error) {
 	contents := applyTemplate(errorHTML, "errorHTML", err) // err may contain an absolute path!
+	c.WriteHeader(http.StatusNotFound)
 	servePage(c, "File "+relpath, "", "", contents)
 }
 
@@ -333,15 +334,18 @@ func main() {
 	}
 	// TODO(gri): Provide a mechanism (flag?) to select a package
 	//            if there are multiple packages in a directory.
-	info := pkgHandler.getPageInfo(abspath, relpath, "", mode|tryMode)
+	info := pkgHandler.getPageInfo(abspath, relpath, "", mode)
 
-	if info.PAst == nil && info.PDoc == nil && info.Dirs == nil {
+	if info.Err != nil || info.PAst == nil && info.PDoc == nil && info.Dirs == nil {
 		// try again, this time assume it's a command
 		if len(path) > 0 && path[0] != '/' {
 			abspath = absolutePath(path, cmdHandler.fsRoot)
 		}
 		info = cmdHandler.getPageInfo(abspath, relpath, "", mode)
 	}
+	if info.Err != nil {
+		log.Exitf("%v", info.Err)
+	}
 
 	// If we have more than one argument, use the remaining arguments for filtering
 	if flag.NArg() > 1 {