asar: Add support in fs.realpathSync

atom/common/asar/archive.cc

@@ -206,6 +206,24 @@ bool Archive::Readdir(const base::FilePath& path,
   return true;
 }
 
+bool Archive::Realpath(const base::FilePath& path, base::FilePath* realpath) {
+  if (!header_)
+    return false;
+
+  const base::DictionaryValue* node;
+  if (!GetNodeFromPath(path.AsUTF8Unsafe(), header_.get(), &node))
+    return false;
+
+  std::string link;
+  if (node->GetString("link", &link)) {
+    *realpath = base::FilePath::FromUTF8Unsafe(link);
+    return true;
+  }
+
+  *realpath = path;
+  return true;
+}
+
 bool Archive::CopyFileOut(const base::FilePath& path, base::FilePath* out) {
   if (external_files_.contains(path)) {
     *out = external_files_.get(path)->path();

atom/common/asar/archive.h

@@ -51,6 +51,9 @@ class Archive {
   // Fs.readdir(path).
   bool Readdir(const base::FilePath& path, std::vector<base::FilePath>* files);
 
+  // Fs.realpath(path).
+  bool Realpath(const base::FilePath& path, base::FilePath* realpath);
+
   // Copy the file into a temporary file, and return the new path.
   bool CopyFileOut(const base::FilePath& path, base::FilePath* out);