src: adjust THP sysfs config token retrieval and file closure

PR-URL: #37187
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: jayaddison

src/large_pages/node_large_page.cc

@@ -258,23 +258,21 @@ struct text_region FindNodeTextRegion() {
 
 #if defined(__linux__)
 bool IsTransparentHugePagesEnabled() {
-  std::ifstream ifs;
-
   // File format reference:
   // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/huge_memory.c?id=13391c60da3308ed9980de0168f74cce6c62ac1d#n163
-  ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
-  if (!ifs) {
+  const char* filename = "/sys/kernel/mm/transparent_hugepage/enabled";
+  std::ifstream config_stream(filename, std::ios::in);
+  if (!config_stream.good()) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");
     return false;
   }
 
-  std::string always, madvise;
-  if (ifs.is_open()) {
-    ifs >> always >> madvise;
-  }
-  ifs.close();
-
-  return always == "[always]" || madvise == "[madvise]";
+  std::string token;
+  config_stream >> token;
+  if ("[always]" == token) return true;
+  config_stream >> token;
+  if ("[madvise]" == token) return true;
+  return false;
 }
 #elif defined(__FreeBSD__)
 bool IsSuperPagesEnabled() {