--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/os/windows/vm/perfMemory_windows.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1776 @@
+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_perfMemory_windows.cpp.incl"
+
+#include <windows.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <lmcons.h>
+
+typedef BOOL (WINAPI *SetSecurityDescriptorControlFnPtr)(
+   IN PSECURITY_DESCRIPTOR pSecurityDescriptor,
+   IN SECURITY_DESCRIPTOR_CONTROL ControlBitsOfInterest,
+   IN SECURITY_DESCRIPTOR_CONTROL ControlBitsToSet);
+
+// Standard Memory Implementation Details
+
+// create the PerfData memory region in standard memory.
+//
+static char* create_standard_memory(size_t size) {
+
+  // allocate an aligned chuck of memory
+  char* mapAddress = os::reserve_memory(size);
+
+  if (mapAddress == NULL) {
+    return NULL;
+  }
+
+  // commit memory
+  if (!os::commit_memory(mapAddress, size)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("Could not commit PerfData memory\n");
+    }
+    os::release_memory(mapAddress, size);
+    return NULL;
+  }
+
+  return mapAddress;
+}
+
+// delete the PerfData memory region
+//
+static void delete_standard_memory(char* addr, size_t size) {
+
+  // there are no persistent external resources to cleanup for standard
+  // memory. since DestroyJavaVM does not support unloading of the JVM,
+  // cleanup of the memory resource is not performed. The memory will be
+  // reclaimed by the OS upon termination of the process.
+  //
+  return;
+
+}
+
+// save the specified memory region to the given file
+//
+static void save_memory_to_file(char* addr, size_t size) {
+
+  const char* destfile = PerfMemory::get_perfdata_file_path();
+  assert(destfile[0] != '\0', "invalid Perfdata file path");
+
+  int fd = ::_open(destfile, _O_BINARY|_O_CREAT|_O_WRONLY|_O_TRUNC,
+                   _S_IREAD|_S_IWRITE);
+
+  if (fd == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("Could not create Perfdata save file: %s: %s\n",
+              destfile, strerror(errno));
+    }
+  } else {
+    for (size_t remaining = size; remaining > 0;) {
+
+      int nbytes = ::_write(fd, addr, (unsigned int)remaining);
+      if (nbytes == OS_ERR) {
+        if (PrintMiscellaneous && Verbose) {
+          warning("Could not write Perfdata save file: %s: %s\n",
+                  destfile, strerror(errno));
+        }
+        break;
+      }
+
+      remaining -= (size_t)nbytes;
+      addr += nbytes;
+    }
+
+    int result = ::_close(fd);
+    if (PrintMiscellaneous && Verbose) {
+      if (result == OS_ERR) {
+        warning("Could not close %s: %s\n", destfile, strerror(errno));
+      }
+    }
+  }
+
+  FREE_C_HEAP_ARRAY(char, destfile);
+}
+
+// Shared Memory Implementation Details
+
+// Note: the win32 shared memory implementation uses two objects to represent
+// the shared memory: a windows kernel based file mapping object and a backing
+// store file. On windows, the name space for shared memory is a kernel
+// based name space that is disjoint from other win32 name spaces. Since Java
+// is unaware of this name space, a parallel file system based name space is
+// maintained, which provides a common file system based shared memory name
+// space across the supported platforms and one that Java apps can deal with
+// through simple file apis.
+//
+// For performance and resource cleanup reasons, it is recommended that the
+// user specific directory and the backing store file be stored in either a
+// RAM based file system or a local disk based file system. Network based
+// file systems are not recommended for performance reasons. In addition,
+// use of SMB network based file systems may result in unsuccesful cleanup
+// of the disk based resource on exit of the VM. The Windows TMP and TEMP
+// environement variables, as used by the GetTempPath() Win32 API (see
+// os::get_temp_directory() in os_win32.cpp), control the location of the
+// user specific directory and the shared memory backing store file.
+
+static HANDLE sharedmem_fileMapHandle = NULL;
+static HANDLE sharedmem_fileHandle = INVALID_HANDLE_VALUE;
+static char*  sharedmem_fileName = NULL;
+
+// return the user specific temporary directory name.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_tmp_dir(const char* user) {
+
+  const char* tmpdir = os::get_temp_directory();
+  const char* perfdir = PERFDATA_NAME;
+  size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 2;
+  char* dirname = NEW_C_HEAP_ARRAY(char, nbytes);
+
+  // construct the path name to user specific tmp directory
+  _snprintf(dirname, nbytes, "%s%s_%s", tmpdir, perfdir, user);
+
+  return dirname;
+}
+
+// convert the given file name into a process id. if the file
+// does not meet the file naming constraints, return 0.
+//
+static int filename_to_pid(const char* filename) {
+
+  // a filename that doesn't begin with a digit is not a
+  // candidate for conversion.
+  //
+  if (!isdigit(*filename)) {
+    return 0;
+  }
+
+  // check if file name can be converted to an integer without
+  // any leftover characters.
+  //
+  char* remainder = NULL;
+  errno = 0;
+  int pid = (int)strtol(filename, &remainder, 10);
+
+  if (errno != 0) {
+    return 0;
+  }
+
+  // check for left over characters. If any, then the filename is
+  // not a candidate for conversion.
+  //
+  if (remainder != NULL && *remainder != '\0') {
+    return 0;
+  }
+
+  // successful conversion, return the pid
+  return pid;
+}
+
+// check if the given path is considered a secure directory for
+// the backing store files. Returns true if the directory exists
+// and is considered a secure location. Returns false if the path
+// is a symbolic link or if an error occured.
+//
+static bool is_directory_secure(const char* path) {
+
+  DWORD fa;
+
+  fa = GetFileAttributes(path);
+  if (fa == 0xFFFFFFFF) {
+    DWORD lasterror = GetLastError();
+    if (lasterror == ERROR_FILE_NOT_FOUND) {
+      return false;
+    }
+    else {
+      // unexpected error, declare the path insecure
+      if (PrintMiscellaneous && Verbose) {
+        warning("could not get attributes for file %s: ",
+                " lasterror = %d\n", path, lasterror);
+      }
+      return false;
+    }
+  }
+
+  if (fa & FILE_ATTRIBUTE_REPARSE_POINT) {
+    // we don't accept any redirection for the user specific directory
+    // so declare the path insecure. This may be too conservative,
+    // as some types of reparse points might be acceptable, but it
+    // is probably more secure to avoid these conditions.
+    //
+    if (PrintMiscellaneous && Verbose) {
+      warning("%s is a reparse point\n", path);
+    }
+    return false;
+  }
+
+  if (fa & FILE_ATTRIBUTE_DIRECTORY) {
+    // this is the expected case. Since windows supports symbolic
+    // links to directories only, not to files, there is no need
+    // to check for open write permissions on the directory. If the
+    // directory has open write permissions, any files deposited that
+    // are not expected will be removed by the cleanup code.
+    //
+    return true;
+  }
+  else {
+    // this is either a regular file or some other type of file,
+    // any of which are unexpected and therefore insecure.
+    //
+    if (PrintMiscellaneous && Verbose) {
+      warning("%s is not a directory, file attributes = "
+              INTPTR_FORMAT "\n", path, fa);
+    }
+    return false;
+  }
+}
+
+// return the user name for the owner of this process
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_name() {
+
+  /* get the user name. This code is adapted from code found in
+   * the jdk in src/windows/native/java/lang/java_props_md.c
+   * java_props_md.c  1.29 02/02/06. According to the original
+   * source, the call to GetUserName is avoided because of a resulting
+   * increase in footprint of 100K.
+   */
+  char* user = getenv("USERNAME");
+  char buf[UNLEN+1];
+  DWORD buflen = sizeof(buf);
+  if (user == NULL || strlen(user) == 0) {
+    if (GetUserName(buf, &buflen)) {
+      user = buf;
+    }
+    else {
+      return NULL;
+    }
+  }
+
+  char* user_name = NEW_C_HEAP_ARRAY(char, strlen(user)+1);
+  strcpy(user_name, user);
+
+  return user_name;
+}
+
+// return the name of the user that owns the process identified by vmid.
+//
+// This method uses a slow directory search algorithm to find the backing
+// store file for the specified vmid and returns the user name, as determined
+// by the user name suffix of the hsperfdata_<username> directory name.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_name_slow(int vmid) {
+
+  // directory search
+  char* oldest_user = NULL;
+  time_t oldest_ctime = 0;
+
+  const char* tmpdirname = os::get_temp_directory();
+
+  DIR* tmpdirp = os::opendir(tmpdirname);
+
+  if (tmpdirp == NULL) {
+    return NULL;
+  }
+
+  // for each entry in the directory that matches the pattern hsperfdata_*,
+  // open the directory and check if the file for the given vmid exists.
+  // The file with the expected name and the latest creation date is used
+  // to determine the user name for the process id.
+  //
+  struct dirent* dentry;
+  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname));
+  errno = 0;
+  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+
+    // check if the directory entry is a hsperfdata file
+    if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
+      continue;
+    }
+
+    char* usrdir_name = NEW_C_HEAP_ARRAY(char,
+                              strlen(tmpdirname) + strlen(dentry->d_name) + 1);
+    strcpy(usrdir_name, tmpdirname);
+    strcat(usrdir_name, dentry->d_name);
+
+    DIR* subdirp = os::opendir(usrdir_name);
+
+    if (subdirp == NULL) {
+      FREE_C_HEAP_ARRAY(char, usrdir_name);
+      continue;
+    }
+
+    // Since we don't create the backing store files in directories
+    // pointed to by symbolic links, we also don't follow them when
+    // looking for the files. We check for a symbolic link after the
+    // call to opendir in order to eliminate a small window where the
+    // symlink can be exploited.
+    //
+    if (!is_directory_secure(usrdir_name)) {
+      FREE_C_HEAP_ARRAY(char, usrdir_name);
+      os::closedir(subdirp);
+      continue;
+    }
+
+    struct dirent* udentry;
+    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name));
+    errno = 0;
+    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+
+      if (filename_to_pid(udentry->d_name) == vmid) {
+        struct stat statbuf;
+
+        char* filename = NEW_C_HEAP_ARRAY(char,
+                            strlen(usrdir_name) + strlen(udentry->d_name) + 2);
+
+        strcpy(filename, usrdir_name);
+        strcat(filename, "\\");
+        strcat(filename, udentry->d_name);
+
+        if (::stat(filename, &statbuf) == OS_ERR) {
+           FREE_C_HEAP_ARRAY(char, filename);
+           continue;
+        }
+
+        // skip over files that are not regular files.
+        if ((statbuf.st_mode & S_IFMT) != S_IFREG) {
+          FREE_C_HEAP_ARRAY(char, filename);
+          continue;
+        }
+
+        // compare and save filename with latest creation time
+        if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
+
+          if (statbuf.st_ctime > oldest_ctime) {
+            char* user = strchr(dentry->d_name, '_') + 1;
+
+            if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
+            oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1);
+
+            strcpy(oldest_user, user);
+            oldest_ctime = statbuf.st_ctime;
+          }
+        }
+
+        FREE_C_HEAP_ARRAY(char, filename);
+      }
+    }
+    os::closedir(subdirp);
+    FREE_C_HEAP_ARRAY(char, udbuf);
+    FREE_C_HEAP_ARRAY(char, usrdir_name);
+  }
+  os::closedir(tmpdirp);
+  FREE_C_HEAP_ARRAY(char, tdbuf);
+
+  return(oldest_user);
+}
+
+// return the name of the user that owns the process identified by vmid.
+//
+// note: this method should only be used via the Perf native methods.
+// There are various costs to this method and limiting its use to the
+// Perf native methods limits the impact to monitoring applications only.
+//
+static char* get_user_name(int vmid) {
+
+  // A fast implementation is not provided at this time. It's possible
+  // to provide a fast process id to user name mapping function using
+  // the win32 apis, but the default ACL for the process object only
+  // allows processes with the same owner SID to acquire the process
+  // handle (via OpenProcess(PROCESS_QUERY_INFORMATION)). It's possible
+  // to have the JVM change the ACL for the process object to allow arbitrary
+  // users to access the process handle and the process security token.
+  // The security ramifications need to be studied before providing this
+  // mechanism.
+  //
+  return get_user_name_slow(vmid);
+}
+
+// return the name of the shared memory file mapping object for the
+// named shared memory region for the given user name and vmid.
+//
+// The file mapping object's name is not the file name. It is a name
+// in a separate name space.
+//
+// the caller is expected to free the allocated memory.
+//
+static char *get_sharedmem_objectname(const char* user, int vmid) {
+
+  // construct file mapping object's name, add 3 for two '_' and a
+  // null terminator.
+  int nbytes = (int)strlen(PERFDATA_NAME) + (int)strlen(user) + 3;
+
+  // the id is converted to an unsigned value here because win32 allows
+  // negative process ids. However, OpenFileMapping API complains
+  // about a name containing a '-' characters.
+  //
+  nbytes += UINT_CHARS;
+  char* name = NEW_C_HEAP_ARRAY(char, nbytes);
+  _snprintf(name, nbytes, "%s_%s_%u", PERFDATA_NAME, user, vmid);
+
+  return name;
+}
+
+// return the file name of the backing store file for the named
+// shared memory region for the given user name and vmid.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_sharedmem_filename(const char* dirname, int vmid) {
+
+  // add 2 for the file separator and a null terminator.
+  size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
+
+  char* name = NEW_C_HEAP_ARRAY(char, nbytes);
+  _snprintf(name, nbytes, "%s\\%d", dirname, vmid);
+
+  return name;
+}
+
+// remove file
+//
+// this method removes the file with the given file name.
+//
+// Note: if the indicated file is on an SMB network file system, this
+// method may be unsuccessful in removing the file.
+//
+static void remove_file(const char* dirname, const char* filename) {
+
+  size_t nbytes = strlen(dirname) + strlen(filename) + 2;
+  char* path = NEW_C_HEAP_ARRAY(char, nbytes);
+
+  strcpy(path, dirname);
+  strcat(path, "\\");
+  strcat(path, filename);
+
+  if (::unlink(path) == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      if (errno != ENOENT) {
+        warning("Could not unlink shared memory backing"
+                " store file %s : %s\n", path, strerror(errno));
+      }
+    }
+  }
+
+  FREE_C_HEAP_ARRAY(char, path);
+}
+
+// returns true if the process represented by pid is alive, otherwise
+// returns false. the validity of the result is only accurate if the
+// target process is owned by the same principal that owns this process.
+// this method should not be used if to test the status of an otherwise
+// arbitrary process unless it is know that this process has the appropriate
+// privileges to guarantee a result valid.
+//
+static bool is_alive(int pid) {
+
+  HANDLE ph = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);
+  if (ph == NULL) {
+    // the process does not exist.
+    if (PrintMiscellaneous && Verbose) {
+      DWORD lastError = GetLastError();
+      if (lastError != ERROR_INVALID_PARAMETER) {
+        warning("OpenProcess failed: %d\n", GetLastError());
+      }
+    }
+    return false;
+  }
+
+  DWORD exit_status;
+  if (!GetExitCodeProcess(ph, &exit_status)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("GetExitCodeProcess failed: %d\n", GetLastError());
+    }
+    CloseHandle(ph);
+    return false;
+  }
+
+  CloseHandle(ph);
+  return (exit_status == STILL_ACTIVE) ? true : false;
+}
+
+// check if the file system is considered secure for the backing store files
+//
+static bool is_filesystem_secure(const char* path) {
+
+  char root_path[MAX_PATH];
+  char fs_type[MAX_PATH];
+
+  if (PerfBypassFileSystemCheck) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("bypassing file system criteria checks for %s\n", path);
+    }
+    return true;
+  }
+
+  char* first_colon = strchr((char *)path, ':');
+  if (first_colon == NULL) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("expected device specifier in path: %s\n", path);
+    }
+    return false;
+  }
+
+  size_t len = (size_t)(first_colon - path);
+  assert(len + 2 <= MAX_PATH, "unexpected device specifier length");
+  strncpy(root_path, path, len + 1);
+  root_path[len + 1] = '\\';
+  root_path[len + 2] = '\0';
+
+  // check that we have something like "C:\" or "AA:\"
+  assert(strlen(root_path) >= 3, "device specifier too short");
+  assert(strchr(root_path, ':') != NULL, "bad device specifier format");
+  assert(strchr(root_path, '\\') != NULL, "bad device specifier format");
+
+  DWORD maxpath;
+  DWORD flags;
+
+  if (!GetVolumeInformation(root_path, NULL, 0, NULL, &maxpath,
+                            &flags, fs_type, MAX_PATH)) {
+    // we can't get information about the volume, so assume unsafe.
+    if (PrintMiscellaneous && Verbose) {
+      warning("could not get device information for %s: "
+              " path = %s: lasterror = %d\n",
+              root_path, path, GetLastError());
+    }
+    return false;
+  }
+
+  if ((flags & FS_PERSISTENT_ACLS) == 0) {
+    // file system doesn't support ACLs, declare file system unsafe
+    if (PrintMiscellaneous && Verbose) {
+      warning("file system type %s on device %s does not support"
+              " ACLs\n", fs_type, root_path);
+    }
+    return false;
+  }
+
+  if ((flags & FS_VOL_IS_COMPRESSED) != 0) {
+    // file system is compressed, declare file system unsafe
+    if (PrintMiscellaneous && Verbose) {
+      warning("file system type %s on device %s is compressed\n",
+              fs_type, root_path);
+    }
+    return false;
+  }
+
+  return true;
+}
+
+// cleanup stale shared memory resources
+//
+// This method attempts to remove all stale shared memory files in
+// the named user temporary directory. It scans the named directory
+// for files matching the pattern ^$[0-9]*$. For each file found, the
+// process id is extracted from the file name and a test is run to
+// determine if the process is alive. If the process is not alive,
+// any stale file resources are removed.
+//
+static void cleanup_sharedmem_resources(const char* dirname) {
+
+  // open the user temp directory
+  DIR* dirp = os::opendir(dirname);
+
+  if (dirp == NULL) {
+    // directory doesn't exist, so there is nothing to cleanup
+    return;
+  }
+
+  if (!is_directory_secure(dirname)) {
+    // the directory is not secure, don't attempt any cleanup
+    return;
+  }
+
+  // for each entry in the directory that matches the expected file
+  // name pattern, determine if the file resources are stale and if
+  // so, remove the file resources. Note, instrumented HotSpot processes
+  // for this user may start and/or terminate during this search and
+  // remove or create new files in this directory. The behavior of this
+  // loop under these conditions is dependent upon the implementation of
+  // opendir/readdir.
+  //
+  struct dirent* entry;
+  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname));
+  errno = 0;
+  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+
+    int pid = filename_to_pid(entry->d_name);
+
+    if (pid == 0) {
+
+      if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
+
+        // attempt to remove all unexpected files, except "." and ".."
+        remove_file(dirname, entry->d_name);
+      }
+
+      errno = 0;
+      continue;
+    }
+
+    // we now have a file name that converts to a valid integer
+    // that could represent a process id . if this process id
+    // matches the current process id or the process is not running,
+    // then remove the stale file resources.
+    //
+    // process liveness is detected by checking the exit status
+    // of the process. if the process id is valid and the exit status
+    // indicates that it is still running, the file file resources
+    // are not removed. If the process id is invalid, or if we don't
+    // have permissions to check the process status, or if the process
+    // id is valid and the process has terminated, the the file resources
+    // are assumed to be stale and are removed.
+    //
+    if (pid == os::current_process_id() || !is_alive(pid)) {
+
+      // we can only remove the file resources. Any mapped views
+      // of the file can only be unmapped by the processes that
+      // opened those views and the file mapping object will not
+      // get removed until all views are unmapped.
+      //
+      remove_file(dirname, entry->d_name);
+    }
+    errno = 0;
+  }
+  os::closedir(dirp);
+  FREE_C_HEAP_ARRAY(char, dbuf);
+}
+
+// create a file mapping object with the requested name, and size
+// from the file represented by the given Handle object
+//
+static HANDLE create_file_mapping(const char* name, HANDLE fh, LPSECURITY_ATTRIBUTES fsa, size_t size) {
+
+  DWORD lowSize = (DWORD)size;
+  DWORD highSize = 0;
+  HANDLE fmh = NULL;
+
+  // Create a file mapping object with the given name. This function
+  // will grow the file to the specified size.
+  //
+  fmh = CreateFileMapping(
+               fh,                 /* HANDLE file handle for backing store */
+               fsa,                /* LPSECURITY_ATTRIBUTES Not inheritable */
+               PAGE_READWRITE,     /* DWORD protections */
+               highSize,           /* DWORD High word of max size */
+               lowSize,            /* DWORD Low word of max size */
+               name);              /* LPCTSTR name for object */
+
+  if (fmh == NULL) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("CreateFileMapping failed, lasterror = %d\n", GetLastError());
+    }
+    return NULL;
+  }
+
+  if (GetLastError() == ERROR_ALREADY_EXISTS) {
+
+    // a stale file mapping object was encountered. This object may be
+    // owned by this or some other user and cannot be removed until
+    // the other processes either exit or close their mapping objects
+    // and/or mapped views of this mapping object.
+    //
+    if (PrintMiscellaneous && Verbose) {
+      warning("file mapping already exists, lasterror = %d\n", GetLastError());
+    }
+
+    CloseHandle(fmh);
+    return NULL;
+  }
+
+  return fmh;
+}
+
+
+// method to free the given security descriptor and the contained
+// access control list.
+//
+static void free_security_desc(PSECURITY_DESCRIPTOR pSD) {
+
+  BOOL success, exists, isdefault;
+  PACL pACL;
+
+  if (pSD != NULL) {
+
+    // get the access control list from the security descriptor
+    success = GetSecurityDescriptorDacl(pSD, &exists, &pACL, &isdefault);
+
+    // if an ACL existed and it was not a default acl, then it must
+    // be an ACL we enlisted. free the resources.
+    //
+    if (success && exists && pACL != NULL && !isdefault) {
+      FREE_C_HEAP_ARRAY(char, pACL);
+    }
+
+    // free the security descriptor
+    FREE_C_HEAP_ARRAY(char, pSD);
+  }
+}
+
+// method to free up a security attributes structure and any
+// contained security descriptors and ACL
+//
+static void free_security_attr(LPSECURITY_ATTRIBUTES lpSA) {
+
+  if (lpSA != NULL) {
+    // free the contained security descriptor and the ACL
+    free_security_desc(lpSA->lpSecurityDescriptor);
+    lpSA->lpSecurityDescriptor = NULL;
+
+    // free the security attributes structure
+    FREE_C_HEAP_ARRAY(char, lpSA);
+  }
+}
+
+// get the user SID for the process indicated by the process handle
+//
+static PSID get_user_sid(HANDLE hProcess) {
+
+  HANDLE hAccessToken;
+  PTOKEN_USER token_buf = NULL;
+  DWORD rsize = 0;
+
+  if (hProcess == NULL) {
+    return NULL;
+  }
+
+  // get the process token
+  if (!OpenProcessToken(hProcess, TOKEN_READ, &hAccessToken)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("OpenProcessToken failure: lasterror = %d \n", GetLastError());
+    }
+    return NULL;
+  }
+
+  // determine the size of the token structured needed to retrieve
+  // the user token information from the access token.
+  //
+  if (!GetTokenInformation(hAccessToken, TokenUser, NULL, rsize, &rsize)) {
+    DWORD lasterror = GetLastError();
+    if (lasterror != ERROR_INSUFFICIENT_BUFFER) {
+      if (PrintMiscellaneous && Verbose) {
+        warning("GetTokenInformation failure: lasterror = %d,"
+                " rsize = %d\n", lasterror, rsize);
+      }
+      CloseHandle(hAccessToken);
+      return NULL;
+    }
+  }
+
+  token_buf = (PTOKEN_USER) NEW_C_HEAP_ARRAY(char, rsize);
+
+  // get the user token information
+  if (!GetTokenInformation(hAccessToken, TokenUser, token_buf, rsize, &rsize)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("GetTokenInformation failure: lasterror = %d,"
+              " rsize = %d\n", GetLastError(), rsize);
+    }
+    FREE_C_HEAP_ARRAY(char, token_buf);
+    CloseHandle(hAccessToken);
+    return NULL;
+  }
+
+  DWORD nbytes = GetLengthSid(token_buf->User.Sid);
+  PSID pSID = NEW_C_HEAP_ARRAY(char, nbytes);
+
+  if (!CopySid(nbytes, pSID, token_buf->User.Sid)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("GetTokenInformation failure: lasterror = %d,"
+              " rsize = %d\n", GetLastError(), rsize);
+    }
+    FREE_C_HEAP_ARRAY(char, token_buf);
+    FREE_C_HEAP_ARRAY(char, pSID);
+    CloseHandle(hAccessToken);
+    return NULL;
+  }
+
+  // close the access token.
+  CloseHandle(hAccessToken);
+  FREE_C_HEAP_ARRAY(char, token_buf);
+
+  return pSID;
+}
+
+// structure used to consolidate access control entry information
+//
+typedef struct ace_data {
+  PSID pSid;      // SID of the ACE
+  DWORD mask;     // mask for the ACE
+} ace_data_t;
+
+
+// method to add an allow access control entry with the access rights
+// indicated in mask for the principal indicated in SID to the given
+// security descriptor. Much of the DACL handling was adapted from
+// the example provided here:
+//      http://support.microsoft.com/kb/102102/EN-US/
+//
+
+static bool add_allow_aces(PSECURITY_DESCRIPTOR pSD,
+                           ace_data_t aces[], int ace_count) {
+  PACL newACL = NULL;
+  PACL oldACL = NULL;
+
+  if (pSD == NULL) {
+    return false;
+  }
+
+  BOOL exists, isdefault;
+
+  // retrieve any existing access control list.
+  if (!GetSecurityDescriptorDacl(pSD, &exists, &oldACL, &isdefault)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("GetSecurityDescriptor failure: lasterror = %d \n",
+              GetLastError());
+    }
+    return false;
+  }
+
+  // get the size of the DACL
+  ACL_SIZE_INFORMATION aclinfo;
+
+  // GetSecurityDescriptorDacl may return true value for exists (lpbDaclPresent)
+  // while oldACL is NULL for some case.
+  if (oldACL == NULL) {
+    exists = FALSE;
+  }
+
+  if (exists) {
+    if (!GetAclInformation(oldACL, &aclinfo,
+                           sizeof(ACL_SIZE_INFORMATION),
+                           AclSizeInformation)) {
+      if (PrintMiscellaneous && Verbose) {
+        warning("GetAclInformation failure: lasterror = %d \n", GetLastError());
+        return false;
+      }
+    }
+  } else {
+    aclinfo.AceCount = 0; // assume NULL DACL
+    aclinfo.AclBytesFree = 0;
+    aclinfo.AclBytesInUse = sizeof(ACL);
+  }
+
+  // compute the size needed for the new ACL
+  // initial size of ACL is sum of the following:
+  //   * size of ACL structure.
+  //   * size of each ACE structure that ACL is to contain minus the sid
+  //     sidStart member (DWORD) of the ACE.
+  //   * length of the SID that each ACE is to contain.
+  DWORD newACLsize = aclinfo.AclBytesInUse +
+                        (sizeof(ACCESS_ALLOWED_ACE) - sizeof(DWORD)) * ace_count;
+  for (int i = 0; i < ace_count; i++) {
+     newACLsize += GetLengthSid(aces[i].pSid);
+  }
+
+  // create the new ACL
+  newACL = (PACL) NEW_C_HEAP_ARRAY(char, newACLsize);
+
+  if (!InitializeAcl(newACL, newACLsize, ACL_REVISION)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("InitializeAcl failure: lasterror = %d \n", GetLastError());
+    }
+    FREE_C_HEAP_ARRAY(char, newACL);
+    return false;
+  }
+
+  unsigned int ace_index = 0;
+  // copy any existing ACEs from the old ACL (if any) to the new ACL.
+  if (aclinfo.AceCount != 0) {
+    while (ace_index < aclinfo.AceCount) {
+      LPVOID ace;
+      if (!GetAce(oldACL, ace_index, &ace)) {
+        if (PrintMiscellaneous && Verbose) {
+          warning("InitializeAcl failure: lasterror = %d \n", GetLastError());
+        }
+        FREE_C_HEAP_ARRAY(char, newACL);
+        return false;
+      }
+      if (((ACCESS_ALLOWED_ACE *)ace)->Header.AceFlags && INHERITED_ACE) {
+        // this is an inherited, allowed ACE; break from loop so we can
+        // add the new access allowed, non-inherited ACE in the correct
+        // position, immediately following all non-inherited ACEs.
+        break;
+      }
+
+      // determine if the SID of this ACE matches any of the SIDs
+      // for which we plan to set ACEs.
+      int matches = 0;
+      for (int i = 0; i < ace_count; i++) {
+        if (EqualSid(aces[i].pSid, &(((ACCESS_ALLOWED_ACE *)ace)->SidStart))) {
+          matches++;
+          break;
+        }
+      }
+
+      // if there are no SID matches, then add this existing ACE to the new ACL
+      if (matches == 0) {
+        if (!AddAce(newACL, ACL_REVISION, MAXDWORD, ace,
+                    ((PACE_HEADER)ace)->AceSize)) {
+          if (PrintMiscellaneous && Verbose) {
+            warning("AddAce failure: lasterror = %d \n", GetLastError());
+          }
+          FREE_C_HEAP_ARRAY(char, newACL);
+          return false;
+        }
+      }
+      ace_index++;
+    }
+  }
+
+  // add the passed-in access control entries to the new ACL
+  for (int i = 0; i < ace_count; i++) {
+    if (!AddAccessAllowedAce(newACL, ACL_REVISION,
+                             aces[i].mask, aces[i].pSid)) {
+      if (PrintMiscellaneous && Verbose) {
+        warning("AddAccessAllowedAce failure: lasterror = %d \n",
+                GetLastError());
+      }
+      FREE_C_HEAP_ARRAY(char, newACL);
+      return false;
+    }
+  }
+
+  // now copy the rest of the inherited ACEs from the old ACL
+  if (aclinfo.AceCount != 0) {
+    // picking up at ace_index, where we left off in the
+    // previous ace_index loop
+    while (ace_index < aclinfo.AceCount) {
+      LPVOID ace;
+      if (!GetAce(oldACL, ace_index, &ace)) {
+        if (PrintMiscellaneous && Verbose) {
+          warning("InitializeAcl failure: lasterror = %d \n", GetLastError());
+        }
+        FREE_C_HEAP_ARRAY(char, newACL);
+        return false;
+      }
+      if (!AddAce(newACL, ACL_REVISION, MAXDWORD, ace,
+                  ((PACE_HEADER)ace)->AceSize)) {
+        if (PrintMiscellaneous && Verbose) {
+          warning("AddAce failure: lasterror = %d \n", GetLastError());
+        }
+        FREE_C_HEAP_ARRAY(char, newACL);
+        return false;
+      }
+      ace_index++;
+    }
+  }
+
+  // add the new ACL to the security descriptor.
+  if (!SetSecurityDescriptorDacl(pSD, TRUE, newACL, FALSE)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("SetSecurityDescriptorDacl failure:"
+              " lasterror = %d \n", GetLastError());
+    }
+    FREE_C_HEAP_ARRAY(char, newACL);
+    return false;
+  }
+
+  // if running on windows 2000 or later, set the automatic inheritence
+  // control flags.
+  SetSecurityDescriptorControlFnPtr _SetSecurityDescriptorControl;
+  _SetSecurityDescriptorControl = (SetSecurityDescriptorControlFnPtr)
+       GetProcAddress(GetModuleHandle(TEXT("advapi32.dll")),
+                      "SetSecurityDescriptorControl");
+
+  if (_SetSecurityDescriptorControl != NULL) {
+    // We do not want to further propogate inherited DACLs, so making them
+    // protected prevents that.
+    if (!_SetSecurityDescriptorControl(pSD, SE_DACL_PROTECTED,
+                                            SE_DACL_PROTECTED)) {
+      if (PrintMiscellaneous && Verbose) {
+        warning("SetSecurityDescriptorControl failure:"
+                " lasterror = %d \n", GetLastError());
+      }
+      FREE_C_HEAP_ARRAY(char, newACL);
+      return false;
+    }
+  }
+   // Note, the security descriptor maintains a reference to the newACL, not
+   // a copy of it. Therefore, the newACL is not freed here. It is freed when
+   // the security descriptor containing its reference is freed.
+   //
+   return true;
+}
+
+// method to create a security attributes structure, which contains a
+// security descriptor and an access control list comprised of 0 or more
+// access control entries. The method take an array of ace_data structures
+// that indicate the ACE to be added to the security descriptor.
+//
+// the caller must free the resources associated with the security
+// attributes structure created by this method by calling the
+// free_security_attr() method.
+//
+static LPSECURITY_ATTRIBUTES make_security_attr(ace_data_t aces[], int count) {
+
+  // allocate space for a security descriptor
+  PSECURITY_DESCRIPTOR pSD = (PSECURITY_DESCRIPTOR)
+                         NEW_C_HEAP_ARRAY(char, SECURITY_DESCRIPTOR_MIN_LENGTH);
+
+  // initialize the security descriptor
+  if (!InitializeSecurityDescriptor(pSD, SECURITY_DESCRIPTOR_REVISION)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("InitializeSecurityDescriptor failure: "
+              "lasterror = %d \n", GetLastError());
+    }
+    free_security_desc(pSD);
+    return NULL;
+  }
+
+  // add the access control entries
+  if (!add_allow_aces(pSD, aces, count)) {
+    free_security_desc(pSD);
+    return NULL;
+  }
+
+  // allocate and initialize the security attributes structure and
+  // return it to the caller.
+  //
+  LPSECURITY_ATTRIBUTES lpSA = (LPSECURITY_ATTRIBUTES)
+                            NEW_C_HEAP_ARRAY(char, sizeof(SECURITY_ATTRIBUTES));
+  lpSA->nLength = sizeof(SECURITY_ATTRIBUTES);
+  lpSA->lpSecurityDescriptor = pSD;
+  lpSA->bInheritHandle = FALSE;
+
+  return(lpSA);
+}
+
+// method to create a security attributes structure with a restrictive
+// access control list that creates a set access rights for the user/owner
+// of the securable object and a separate set access rights for everyone else.
+// also provides for full access rights for the administrator group.
+//
+// the caller must free the resources associated with the security
+// attributes structure created by this method by calling the
+// free_security_attr() method.
+//
+
+static LPSECURITY_ATTRIBUTES make_user_everybody_admin_security_attr(
+                                DWORD umask, DWORD emask, DWORD amask) {
+
+  ace_data_t aces[3];
+
+  // initialize the user ace data
+  aces[0].pSid = get_user_sid(GetCurrentProcess());
+  aces[0].mask = umask;
+
+  // get the well known SID for BUILTIN\Administrators
+  PSID administratorsSid = NULL;
+  SID_IDENTIFIER_AUTHORITY SIDAuthAdministrators = SECURITY_NT_AUTHORITY;
+
+  if (!AllocateAndInitializeSid( &SIDAuthAdministrators, 2,
+           SECURITY_BUILTIN_DOMAIN_RID,
+           DOMAIN_ALIAS_RID_ADMINS,
+           0, 0, 0, 0, 0, 0, &administratorsSid)) {
+
+    if (PrintMiscellaneous && Verbose) {
+      warning("AllocateAndInitializeSid failure: "
+              "lasterror = %d \n", GetLastError());
+    }
+    return NULL;
+  }
+
+  // initialize the ace data for administrator group
+  aces[1].pSid = administratorsSid;
+  aces[1].mask = amask;
+
+  // get the well known SID for the universal Everybody
+  PSID everybodySid = NULL;
+  SID_IDENTIFIER_AUTHORITY SIDAuthEverybody = SECURITY_WORLD_SID_AUTHORITY;
+
+  if (!AllocateAndInitializeSid( &SIDAuthEverybody, 1, SECURITY_WORLD_RID,
+           0, 0, 0, 0, 0, 0, 0, &everybodySid)) {
+
+    if (PrintMiscellaneous && Verbose) {
+      warning("AllocateAndInitializeSid failure: "
+              "lasterror = %d \n", GetLastError());
+    }
+    return NULL;
+  }
+
+  // initialize the ace data for everybody else.
+  aces[2].pSid = everybodySid;
+  aces[2].mask = emask;
+
+  // create a security attributes structure with access control
+  // entries as initialized above.
+  LPSECURITY_ATTRIBUTES lpSA = make_security_attr(aces, 3);
+  FREE_C_HEAP_ARRAY(char, aces[0].pSid);
+  FreeSid(everybodySid);
+  FreeSid(administratorsSid);
+  return(lpSA);
+}
+
+
+// method to create the security attributes structure for restricting
+// access to the user temporary directory.
+//
+// the caller must free the resources associated with the security
+// attributes structure created by this method by calling the
+// free_security_attr() method.
+//
+static LPSECURITY_ATTRIBUTES make_tmpdir_security_attr() {
+
+  // create full access rights for the user/owner of the directory
+  // and read-only access rights for everybody else. This is
+  // effectively equivalent to UNIX 755 permissions on a directory.
+  //
+  DWORD umask = STANDARD_RIGHTS_REQUIRED | FILE_ALL_ACCESS;
+  DWORD emask = GENERIC_READ | FILE_LIST_DIRECTORY | FILE_TRAVERSE;
+  DWORD amask = STANDARD_RIGHTS_ALL | FILE_ALL_ACCESS;
+
+  return make_user_everybody_admin_security_attr(umask, emask, amask);
+}
+
+// method to create the security attributes structure for restricting
+// access to the shared memory backing store file.
+//
+// the caller must free the resources associated with the security
+// attributes structure created by this method by calling the
+// free_security_attr() method.
+//
+static LPSECURITY_ATTRIBUTES make_file_security_attr() {
+
+  // create extensive access rights for the user/owner of the file
+  // and attribute read-only access rights for everybody else. This
+  // is effectively equivalent to UNIX 600 permissions on a file.
+  //
+  DWORD umask = STANDARD_RIGHTS_ALL | FILE_ALL_ACCESS;
+  DWORD emask = STANDARD_RIGHTS_READ | FILE_READ_ATTRIBUTES |
+                 FILE_READ_EA | FILE_LIST_DIRECTORY | FILE_TRAVERSE;
+  DWORD amask = STANDARD_RIGHTS_ALL | FILE_ALL_ACCESS;
+
+  return make_user_everybody_admin_security_attr(umask, emask, amask);
+}
+
+// method to create the security attributes structure for restricting
+// access to the name shared memory file mapping object.
+//
+// the caller must free the resources associated with the security
+// attributes structure created by this method by calling the
+// free_security_attr() method.
+//
+static LPSECURITY_ATTRIBUTES make_smo_security_attr() {
+
+  // create extensive access rights for the user/owner of the shared
+  // memory object and attribute read-only access rights for everybody
+  // else. This is effectively equivalent to UNIX 600 permissions on
+  // on the shared memory object.
+  //
+  DWORD umask = STANDARD_RIGHTS_REQUIRED | FILE_MAP_ALL_ACCESS;
+  DWORD emask = STANDARD_RIGHTS_READ; // attributes only
+  DWORD amask = STANDARD_RIGHTS_ALL | FILE_MAP_ALL_ACCESS;
+
+  return make_user_everybody_admin_security_attr(umask, emask, amask);
+}
+
+// make the user specific temporary directory
+//
+static bool make_user_tmp_dir(const char* dirname) {
+
+
+  LPSECURITY_ATTRIBUTES pDirSA = make_tmpdir_security_attr();
+  if (pDirSA == NULL) {
+    return false;
+  }
+
+
+  // create the directory with the given security attributes
+  if (!CreateDirectory(dirname, pDirSA)) {
+    DWORD lasterror = GetLastError();
+    if (lasterror == ERROR_ALREADY_EXISTS) {
+      // The directory already exists and was probably created by another
+      // JVM instance. However, this could also be the result of a
+      // deliberate symlink. Verify that the existing directory is safe.
+      //
+      if (!is_directory_secure(dirname)) {
+        // directory is not secure
+        if (PrintMiscellaneous && Verbose) {
+          warning("%s directory is insecure\n", dirname);
+        }
+        return false;
+      }
+      // The administrator should be able to delete this directory.
+      // But the directory created by previous version of JVM may not
+      // have permission for administrators to delete this directory.
+      // So add full permission to the administrator. Also setting new
+      // DACLs might fix the corrupted the DACLs.
+      SECURITY_INFORMATION secInfo = DACL_SECURITY_INFORMATION;
+      if (!SetFileSecurity(dirname, secInfo, pDirSA->lpSecurityDescriptor)) {
+        if (PrintMiscellaneous && Verbose) {
+          lasterror = GetLastError();
+          warning("SetFileSecurity failed for %s directory.  lasterror %d \n",
+                                                        dirname, lasterror);
+        }
+      }
+    }
+    else {
+      if (PrintMiscellaneous && Verbose) {
+        warning("CreateDirectory failed: %d\n", GetLastError());
+      }
+      return false;
+    }
+  }
+
+  // free the security attributes structure
+  free_security_attr(pDirSA);
+
+  return true;
+}
+
+// create the shared memory resources
+//
+// This function creates the shared memory resources. This includes
+// the backing store file and the file mapping shared memory object.
+//
+static HANDLE create_sharedmem_resources(const char* dirname, const char* filename, const char* objectname, size_t size) {
+
+  HANDLE fh = INVALID_HANDLE_VALUE;
+  HANDLE fmh = NULL;
+
+
+  // create the security attributes for the backing store file
+  LPSECURITY_ATTRIBUTES lpFileSA = make_file_security_attr();
+  if (lpFileSA == NULL) {
+    return NULL;
+  }
+
+  // create the security attributes for the shared memory object
+  LPSECURITY_ATTRIBUTES lpSmoSA = make_smo_security_attr();
+  if (lpSmoSA == NULL) {
+    free_security_attr(lpFileSA);
+    return NULL;
+  }
+
+  // create the user temporary directory
+  if (!make_user_tmp_dir(dirname)) {
+    // could not make/find the directory or the found directory
+    // was not secure
+    return NULL;
+  }
+
+  // Create the file - the FILE_FLAG_DELETE_ON_CLOSE flag allows the
+  // file to be deleted by the last process that closes its handle to
+  // the file. This is important as the apis do not allow a terminating
+  // JVM being monitored by another process to remove the file name.
+  //
+  // the FILE_SHARE_DELETE share mode is valid only in winnt
+  //
+  fh = CreateFile(
+             filename,                   /* LPCTSTR file name */
+
+             GENERIC_READ|GENERIC_WRITE, /* DWORD desired access */
+
+             (os::win32::is_nt() ? FILE_SHARE_DELETE : 0)|
+             FILE_SHARE_READ,            /* DWORD share mode, future READONLY
+                                          * open operations allowed
+                                          */
+             lpFileSA,                   /* LPSECURITY security attributes */
+             CREATE_ALWAYS,              /* DWORD creation disposition
+                                          * create file, if it already
+                                          * exists, overwrite it.
+                                          */
+             FILE_FLAG_DELETE_ON_CLOSE,  /* DWORD flags and attributes */
+
+             NULL);                      /* HANDLE template file access */
+
+  free_security_attr(lpFileSA);
+
+  if (fh == INVALID_HANDLE_VALUE) {
+    DWORD lasterror = GetLastError();
+    if (PrintMiscellaneous && Verbose) {
+      warning("could not create file %s: %d\n", filename, lasterror);
+    }
+    return NULL;
+  }
+
+  // try to create the file mapping
+  fmh = create_file_mapping(objectname, fh, lpSmoSA, size);
+
+  free_security_attr(lpSmoSA);
+
+  if (fmh == NULL) {
+    // closing the file handle here will decrement the reference count
+    // on the file. When all processes accessing the file close their
+    // handle to it, the reference count will decrement to 0 and the
+    // OS will delete the file. These semantics are requested by the
+    // FILE_FLAG_DELETE_ON_CLOSE flag in CreateFile call above.
+    CloseHandle(fh);
+    fh = NULL;
+    return NULL;
+  }
+
+  // the file has been successfully created and the file mapping
+  // object has been created.
+  sharedmem_fileHandle = fh;
+  sharedmem_fileName = strdup(filename);
+
+  return fmh;
+}
+
+// open the shared memory object for the given vmid.
+//
+static HANDLE open_sharedmem_object(const char* objectname, DWORD ofm_access, TRAPS) {
+
+  HANDLE fmh;
+
+  // open the file mapping with the requested mode
+  fmh = OpenFileMapping(
+               ofm_access,       /* DWORD access mode */
+               FALSE,            /* BOOL inherit flag - Do not allow inherit */
+               objectname);      /* name for object */
+
+  if (fmh == NULL) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("OpenFileMapping failed for shared memory object %s:"
+              " lasterror = %d\n", objectname, GetLastError());
+    }
+    THROW_MSG_(vmSymbols::java_lang_Exception(),
+               "Could not open PerfMemory", INVALID_HANDLE_VALUE);
+  }
+
+  return fmh;;
+}
+
+// create a named shared memory region
+//
+// On Win32, a named shared memory object has a name space that
+// is independent of the file system name space. Shared memory object,
+// or more precisely, file mapping objects, provide no mechanism to
+// inquire the size of the memory region. There is also no api to
+// enumerate the memory regions for various processes.
+//
+// This implementation utilizes the shared memory name space in parallel
+// with the file system name space. This allows us to determine the
+// size of the shared memory region from the size of the file and it
+// allows us to provide a common, file system based name space for
+// shared memory across platforms.
+//
+static char* mapping_create_shared(size_t size) {
+
+  void *mapAddress;
+  int vmid = os::current_process_id();
+
+  // get the name of the user associated with this process
+  char* user = get_user_name();
+
+  if (user == NULL) {
+    return NULL;
+  }
+
+  // construct the name of the user specific temporary directory
+  char* dirname = get_user_tmp_dir(user);
+
+  // check that the file system is secure - i.e. it supports ACLs.
+  if (!is_filesystem_secure(dirname)) {
+    return NULL;
+  }
+
+  // create the names of the backing store files and for the
+  // share memory object.
+  //
+  char* filename = get_sharedmem_filename(dirname, vmid);
+  char* objectname = get_sharedmem_objectname(user, vmid);
+
+  // cleanup any stale shared memory resources
+  cleanup_sharedmem_resources(dirname);
+
+  assert(((size != 0) && (size % os::vm_page_size() == 0)),
+         "unexpected PerfMemry region size");
+
+  FREE_C_HEAP_ARRAY(char, user);
+
+  // create the shared memory resources
+  sharedmem_fileMapHandle =
+               create_sharedmem_resources(dirname, filename, objectname, size);
+
+  FREE_C_HEAP_ARRAY(char, filename);
+  FREE_C_HEAP_ARRAY(char, objectname);
+  FREE_C_HEAP_ARRAY(char, dirname);
+
+  if (sharedmem_fileMapHandle == NULL) {
+    return NULL;
+  }
+
+  // map the file into the address space
+  mapAddress = MapViewOfFile(
+                   sharedmem_fileMapHandle, /* HANDLE = file mapping object */
+                   FILE_MAP_ALL_ACCESS,     /* DWORD access flags */
+                   0,                       /* DWORD High word of offset */
+                   0,                       /* DWORD Low word of offset */
+                   (DWORD)size);            /* DWORD Number of bytes to map */
+
+  if (mapAddress == NULL) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("MapViewOfFile failed, lasterror = %d\n", GetLastError());
+    }
+    CloseHandle(sharedmem_fileMapHandle);
+    sharedmem_fileMapHandle = NULL;
+    return NULL;
+  }
+
+  // clear the shared memory region
+  (void)memset(mapAddress, '\0', size);
+
+  return (char*) mapAddress;
+}
+
+// this method deletes the file mapping object.
+//
+static void delete_file_mapping(char* addr, size_t size) {
+
+  // cleanup the persistent shared memory resources. since DestroyJavaVM does
+  // not support unloading of the JVM, unmapping of the memory resource is not
+  // performed. The memory will be reclaimed by the OS upon termination of all
+  // processes mapping the resource. The file mapping handle and the file
+  // handle are closed here to expedite the remove of the file by the OS. The
+  // file is not removed directly because it was created with
+  // FILE_FLAG_DELETE_ON_CLOSE semantics and any attempt to remove it would
+  // be unsuccessful.
+
+  // close the fileMapHandle. the file mapping will still be retained
+  // by the OS as long as any other JVM processes has an open file mapping
+  // handle or a mapped view of the file.
+  //
+  if (sharedmem_fileMapHandle != NULL) {
+    CloseHandle(sharedmem_fileMapHandle);
+    sharedmem_fileMapHandle = NULL;
+  }
+
+  // close the file handle. This will decrement the reference count on the
+  // backing store file. When the reference count decrements to 0, the OS
+  // will delete the file. These semantics apply because the file was
+  // created with the FILE_FLAG_DELETE_ON_CLOSE flag.
+  //
+  if (sharedmem_fileHandle != INVALID_HANDLE_VALUE) {
+    CloseHandle(sharedmem_fileHandle);
+    sharedmem_fileHandle = INVALID_HANDLE_VALUE;
+  }
+}
+
+// this method determines the size of the shared memory file
+//
+static size_t sharedmem_filesize(const char* filename, TRAPS) {
+
+  struct stat statbuf;
+
+  // get the file size
+  //
+  // on win95/98/me, _stat returns a file size of 0 bytes, but on
+  // winnt/2k the appropriate file size is returned. support for
+  // the sharable aspects of performance counters was abandonded
+  // on the non-nt win32 platforms due to this and other api
+  // inconsistencies
+  //
+  if (::stat(filename, &statbuf) == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("stat %s failed: %s\n", filename, strerror(errno));
+    }
+    THROW_MSG_0(vmSymbols::java_io_IOException(),
+                "Could not determine PerfMemory size");
+  }
+
+  if ((statbuf.st_size == 0) || (statbuf.st_size % os::vm_page_size() != 0)) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("unexpected file size: size = " SIZE_FORMAT "\n",
+              statbuf.st_size);
+    }
+    THROW_MSG_0(vmSymbols::java_lang_Exception(),
+                "Invalid PerfMemory size");
+  }
+
+  return statbuf.st_size;
+}
+
+// this method opens a file mapping object and maps the object
+// into the address space of the process
+//
+static void open_file_mapping(const char* user, int vmid,
+                              PerfMemory::PerfMemoryMode mode,
+                              char** addrp, size_t* sizep, TRAPS) {
+
+  ResourceMark rm;
+
+  void *mapAddress = 0;
+  size_t size;
+  HANDLE fmh;
+  DWORD ofm_access;
+  DWORD mv_access;
+  const char* luser = NULL;
+
+  if (mode == PerfMemory::PERF_MODE_RO) {
+    ofm_access = FILE_MAP_READ;
+    mv_access = FILE_MAP_READ;
+  }
+  else if (mode == PerfMemory::PERF_MODE_RW) {
+#ifdef LATER
+    ofm_access = FILE_MAP_READ | FILE_MAP_WRITE;
+    mv_access = FILE_MAP_READ | FILE_MAP_WRITE;
+#else
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Unsupported access mode");
+#endif
+  }
+  else {
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Illegal access mode");
+  }
+
+  // if a user name wasn't specified, then find the user name for
+  // the owner of the target vm.
+  if (user == NULL || strlen(user) == 0) {
+    luser = get_user_name(vmid);
+  }
+  else {
+    luser = user;
+  }
+
+  if (luser == NULL) {
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Could not map vmid to user name");
+  }
+
+  // get the names for the resources for the target vm
+  char* dirname = get_user_tmp_dir(luser);
+
+  // since we don't follow symbolic links when creating the backing
+  // store file, we also don't following them when attaching
+  //
+  if (!is_directory_secure(dirname)) {
+    FREE_C_HEAP_ARRAY(char, dirname);
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Process not found");
+  }
+
+  char* filename = get_sharedmem_filename(dirname, vmid);
+  char* objectname = get_sharedmem_objectname(luser, vmid);
+
+  // copy heap memory to resource memory. the objectname and
+  // filename are passed to methods that may throw exceptions.
+  // using resource arrays for these names prevents the leaks
+  // that would otherwise occur.
+  //
+  char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
+  char* robjectname = NEW_RESOURCE_ARRAY(char, strlen(objectname) + 1);
+  strcpy(rfilename, filename);
+  strcpy(robjectname, objectname);
+
+  // free the c heap resources that are no longer needed
+  if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
+  FREE_C_HEAP_ARRAY(char, dirname);
+  FREE_C_HEAP_ARRAY(char, filename);
+  FREE_C_HEAP_ARRAY(char, objectname);
+
+  if (*sizep == 0) {
+    size = sharedmem_filesize(rfilename, CHECK);
+    assert(size != 0, "unexpected size");
+  }
+
+  // Open the file mapping object with the given name
+  fmh = open_sharedmem_object(robjectname, ofm_access, CHECK);
+
+  assert(fmh != INVALID_HANDLE_VALUE, "unexpected handle value");
+
+  // map the entire file into the address space
+  mapAddress = MapViewOfFile(
+                 fmh,             /* HANDLE Handle of file mapping object */
+                 mv_access,       /* DWORD access flags */
+                 0,               /* DWORD High word of offset */
+                 0,               /* DWORD Low word of offset */
+                 size);           /* DWORD Number of bytes to map */
+
+  if (mapAddress == NULL) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("MapViewOfFile failed, lasterror = %d\n", GetLastError());
+    }
+    CloseHandle(fmh);
+    THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
+              "Could not map PerfMemory");
+  }
+
+  *addrp = (char*)mapAddress;
+  *sizep = size;
+
+  // File mapping object can be closed at this time without
+  // invalidating the mapped view of the file
+  CloseHandle(fmh);
+
+  if (PerfTraceMemOps) {
+    tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
+               INTPTR_FORMAT "\n", size, vmid, mapAddress);
+  }
+}
+
+// this method unmaps the the mapped view of the the
+// file mapping object.
+//
+static void remove_file_mapping(char* addr) {
+
+  // the file mapping object was closed in open_file_mapping()
+  // after the file map view was created. We only need to
+  // unmap the file view here.
+  UnmapViewOfFile(addr);
+}
+
+// create the PerfData memory region in shared memory.
+static char* create_shared_memory(size_t size) {
+
+  return mapping_create_shared(size);
+}
+
+// release a named, shared memory region
+//
+void delete_shared_memory(char* addr, size_t size) {
+
+  delete_file_mapping(addr, size);
+}
+
+
+
+
+// create the PerfData memory region
+//
+// This method creates the memory region used to store performance
+// data for the JVM. The memory may be created in standard or
+// shared memory.
+//
+void PerfMemory::create_memory_region(size_t size) {
+
+  if (PerfDisableSharedMem || !os::win32::is_nt()) {
+    // do not share the memory for the performance data.
+    PerfDisableSharedMem = true;
+    _start = create_standard_memory(size);
+  }
+  else {
+    _start = create_shared_memory(size);
+    if (_start == NULL) {
+
+      // creation of the shared memory region failed, attempt
+      // to create a contiguous, non-shared memory region instead.
+      //
+      if (PrintMiscellaneous && Verbose) {
+        warning("Reverting to non-shared PerfMemory region.\n");
+      }
+      PerfDisableSharedMem = true;
+      _start = create_standard_memory(size);
+    }
+  }
+
+  if (_start != NULL) _capacity = size;
+
+}
+
+// delete the PerfData memory region
+//
+// This method deletes the memory region used to store performance
+// data for the JVM. The memory region indicated by the <address, size>
+// tuple will be inaccessible after a call to this method.
+//
+void PerfMemory::delete_memory_region() {
+
+  assert((start() != NULL && capacity() > 0), "verify proper state");
+
+  // If user specifies PerfDataSaveFile, it will save the performance data
+  // to the specified file name no matter whether PerfDataSaveToFile is specified
+  // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
+  // -XX:+PerfDataSaveToFile.
+  if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
+    save_memory_to_file(start(), capacity());
+  }
+
+  if (PerfDisableSharedMem) {
+    delete_standard_memory(start(), capacity());
+  }
+  else {
+    delete_shared_memory(start(), capacity());
+  }
+}
+
+// attach to the PerfData memory region for another JVM
+//
+// This method returns an <address, size> tuple that points to
+// a memory buffer that is kept reasonably synchronized with
+// the PerfData memory region for the indicated JVM. This
+// buffer may be kept in synchronization via shared memory
+// or some other mechanism that keeps the buffer updated.
+//
+// If the JVM chooses not to support the attachability feature,
+// this method should throw an UnsupportedOperation exception.
+//
+// This implementation utilizes named shared memory to map
+// the indicated process's PerfData memory region into this JVMs
+// address space.
+//
+void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode,
+                        char** addrp, size_t* sizep, TRAPS) {
+
+  if (vmid == 0 || vmid == os::current_process_id()) {
+     *addrp = start();
+     *sizep = capacity();
+     return;
+  }
+
+  open_file_mapping(user, vmid, mode, addrp, sizep, CHECK);
+}
+
+// detach from the PerfData memory region of another JVM
+//
+// This method detaches the PerfData memory region of another
+// JVM, specified as an <address, size> tuple of a buffer
+// in this process's address space. This method may perform
+// arbitrary actions to accomplish the detachment. The memory
+// region specified by <address, size> will be inaccessible after
+// a call to this method.
+//
+// If the JVM chooses not to support the attachability feature,
+// this method should throw an UnsupportedOperation exception.
+//
+// This implementation utilizes named shared memory to detach
+// the indicated process's PerfData memory region from this
+// process's address space.
+//
+void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
+
+  assert(addr != 0, "address sanity check");
+  assert(bytes > 0, "capacity sanity check");
+
+  if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
+    // prevent accidental detachment of this process's PerfMemory region
+    return;
+  }
+
+  remove_file_mapping(addr);
+}
+
+char* PerfMemory::backing_store_filename() {
+  return sharedmem_fileName;
+}