fix dev-server for file embedding

Change-Id: I23254930eaedf11a87389d85f54f86bafac20866

dev-server

@@ -14,6 +14,7 @@ my $opt_wipe;
 my $opt_tls;
 my $opt_nobuild;
 my $opt_all;  # listen on all interfaces
+my $opt_staticres; # use static resources, not those on disk
 
 # keep indexes in memory only. often used with --wipe, but not
 # necessarily. if --wipe isn't used, all blobs are re-indexed
@@ -28,6 +29,7 @@ GetOptions("wipe" => \$opt_wipe,
            "memory" => \$opt_memory,
            "mongo" => \$opt_mongo,
            "mysql" => \$opt_mysql,
+           "staticres" => \$opt_staticres,
     )
     or usage();
 
@@ -125,7 +127,9 @@ $ENV{CAMLI_DBNAME} = $DBNAME;
 
 # To use resources from disk, instead of the copies linked into the
 # binary:
-$ENV{CAMLI_DEV_UI_FILES} = "$FindBin::Bin/server/go/camlistored/ui"; # set in server/go/camlistored/ui/fileembed.go
+unless ($opt_staticres) {
+    $ENV{CAMLI_DEV_UI_FILES} = "$FindBin::Bin/server/camlistored/ui"; # set in server/camlistored/ui/fileembed.go
+}
 
 exec("./gopath/bin/camlistored",
      "-configfile=$Bin/config/dev-server-config.json",

pkg/fileembed/fileembed.go

@@ -23,6 +23,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 )
@@ -67,9 +68,15 @@ func (f *Files) add(filename string, sf *staticFile) {
 	f.file[filename] = sf
 }
 
-func (f *Files) Open(filename string) (http.File, error) {
+var _ http.FileSystem = (*Files)(nil)
+
+func (f *Files) Open(filename string) (hf http.File, err error) {
+	if strings.HasPrefix(filename, "/") {
+		filename = filename[1:]
+	}
 	if e := f.OverrideEnv; e != "" && os.Getenv(e) != "" {
-		return os.Open(filepath.Join(os.Getenv(e), filename))
+		diskPath := filepath.Join(os.Getenv(e), filename)
+		return os.Open(diskPath)
 	}
 	f.lk.Lock()
 	defer f.lk.Unlock()