--- old/src/hotspot/os/windows/os_windows.cpp	2017-10-25 11:01:40.092591235 -0700
+++ new/src/hotspot/os/windows/os_windows.cpp	2017-10-25 11:01:39.725556744 -0700
@@ -4060,15 +4060,85 @@
   }
 }
 
+// combine the high and low DWORD into a ULONGLONG
+static ULONGLONG eval_find_data(DWORD high_word, DWORD low_word) {
+  ULONGLONG value = high_word;
+  value <<= sizeof(high_word) * 8;
+  value |= low_word;
+  return value;
+}
+
+// setup the struct stat using the data from WIN32_FIND_DATAW structure
+static void setup_stat(struct stat* sbuf, WIN32_FIND_DATAW find_data) {
+  sbuf->st_size = (_off_t)eval_find_data(find_data.nFileSizeHigh, find_data.nFileSizeLow);
+  sbuf->st_mtime = eval_find_data(find_data.ftLastWriteTime.dwHighDateTime,
+                                  find_data.ftLastWriteTime.dwLowDateTime);
+  sbuf->st_ctime = eval_find_data(find_data.ftCreationTime.dwHighDateTime,
+                                  find_data.ftCreationTime.dwLowDateTime);
+  sbuf->st_atime = eval_find_data(find_data.ftLastAccessTime.dwHighDateTime,
+                                  find_data.ftLastAccessTime.dwLowDateTime);
+  if (find_data.dwFileAttributes == FILE_ATTRIBUTE_DIRECTORY) {
+    sbuf->st_mode |= S_IFDIR;
+  }
+  if (find_data.dwFileAttributes == FILE_ATTRIBUTE_NORMAL) {
+    sbuf->st_mode |= S_IFREG;
+  }
+}
+
+// The following function is adapted from java.base/windows/native/libjava/canonicalize_md.c
+// copy \\?\ or \\?\UNC\ to the front of path
+static void prefixed_path(WCHAR* wpath, size_t pathlen) {
+  if (wpath[0] == L'\\' && wpath[1] == L'\\') {
+    /* if it already has a \\?\ don't do the prefix */
+    if (!(wpath[2] == L'?' && wpath[3] == L'\\')) {
+      /* only UNC pathname includes double slashes here */
+      ::wmemmove(wpath + 7, wpath + 1, pathlen - 1);
+      ::wmemcpy_s(wpath, pathlen, L"\\\\?\\UNC", 7);
+      wpath[pathlen + 6] = L'\0';
+    }
+  }
+  else {
+    ::wmemmove(wpath + 4, wpath, pathlen);
+    ::wmemcpy_s(wpath, pathlen, L"\\\\?\\", 4);
+    wpath[pathlen + 4] = L'\0';
+  }
+}
 
 int os::stat(const char *path, struct stat *sbuf) {
-  char pathbuf[MAX_PATH];
-  if (strlen(path) > MAX_PATH - 1) {
-    errno = ENAMETOOLONG;
+  size_t path_len = strlen(path) + 1;
+  char* pathbuf = (char*)os::malloc(path_len * sizeof(char), mtInternal);
+  if (pathbuf == NULL) {
+    errno = ENOMEM;
     return -1;
   }
   os::native_path(strcpy(pathbuf, path));
-  int ret = ::stat(pathbuf, sbuf);
+  int ret;
+  if (strlen(path) < MAX_PATH) {
+    ret = ::stat(pathbuf, sbuf);
+  } else {
+    WCHAR* wpathbuf = (WCHAR*)os::malloc((path_len + 10) * sizeof (WCHAR), mtInternal);
+    if (wpathbuf == NULL) {
+      os::free(pathbuf);
+      errno = ENOMEM;
+      return -1;
+    }
+    size_t converted_chars = 0;
+    ::mbstowcs_s(&converted_chars, wpathbuf, path_len + 10, pathbuf, strlen(path));
+    prefixed_path(wpathbuf, strlen(path));
+    WIN32_FIND_DATAW find_data;
+    HANDLE h_find;
+    h_find = ::FindFirstFileW(wpathbuf, &find_data);
+    if (h_find == INVALID_HANDLE_VALUE) {
+      errno = ::GetLastError();
+      os::free(wpathbuf);
+      ret = -1;
+    } else {
+      setup_stat(sbuf, find_data);
+      ret = 0;
+      ::FindClose(h_find);
+    }
+    os::free(wpathbuf);
+  }
   if (sbuf != NULL && UseUTCFileTimestamp) {
     // Fix for 6539723.  st_mtime returned from stat() is dependent on
     // the system timezone and so can return different values for the
@@ -4092,9 +4162,10 @@
     TIME_ZONE_INFORMATION tz;
     DWORD tzid = GetTimeZoneInformation(&tz);
     int daylightBias =
-      (tzid == TIME_ZONE_ID_DAYLIGHT) ?  tz.DaylightBias : tz.StandardBias;
+      (tzid == TIME_ZONE_ID_DAYLIGHT) ? tz.DaylightBias : tz.StandardBias;
     sbuf->st_mtime += (tz.Bias + daylightBias) * 60;
   }
+  os::free(pathbuf);
   return ret;
 }
 
@@ -4207,14 +4278,34 @@
 // from src/windows/hpi/src/sys_api_md.c
 
 int os::open(const char *path, int oflag, int mode) {
-  char pathbuf[MAX_PATH];
-
-  if (strlen(path) > MAX_PATH - 1) {
-    errno = ENAMETOOLONG;
+  size_t path_len = strlen(path) + 1;
+  char* pathbuf = (char*)os::malloc(path_len * sizeof(char), mtInternal);
+  if (pathbuf == NULL) {
+    errno = ENOMEM;
     return -1;
   }
   os::native_path(strcpy(pathbuf, path));
-  return ::open(pathbuf, oflag | O_BINARY | O_NOINHERIT, mode);
+  int ret;
+  if (strlen(path) < MAX_PATH) {
+    ret = ::open(pathbuf, oflag | O_BINARY | O_NOINHERIT, mode);
+  } else {
+    WCHAR* wpathbuf = (WCHAR*)os::malloc((path_len + 10) * sizeof (WCHAR), mtInternal);
+    if (wpathbuf == NULL) {
+      os::free(pathbuf);
+      errno = ENOMEM;
+      return -1;
+    }
+    size_t converted_chars = 0;
+    ::mbstowcs_s(&converted_chars, wpathbuf, path_len + 10, pathbuf, strlen(path));
+    prefixed_path(wpathbuf, strlen(path));
+    ret = ::_wopen(wpathbuf, oflag | O_BINARY | O_NOINHERIT, mode);
+    if (ret == -1) {
+      errno = ::GetLastError();
+    }
+    os::free(wpathbuf);
+  }
+  os::free(pathbuf);
+  return ret;
 }
 
 FILE* os::open(int fd, const char* mode) {