--- /dev/null	Wed Sep 21 11:42:03 2011
+++ new/src/os/bsd/vm/perfMemory_bsd.cpp	Wed Sep 21 11:42:32 2011
@@ -0,0 +1,1041 @@
+/*
+ * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.inline.hpp"
+#include "os_bsd.inline.hpp"
+#include "runtime/handles.inline.hpp"
+#include "runtime/perfMemory.hpp"
+#include "utilities/exceptions.hpp"
+
+// put OS-includes here
+# include <sys/types.h>
+# include <sys/mman.h>
+# include <errno.h>
+# include <stdio.h>
+# include <unistd.h>
+# include <sys/stat.h>
+# include <signal.h>
+# include <pwd.h>
+
+static char* backing_store_file_name = NULL;  // name of the backing store
+                                              // file, if successfully created.
+
+// 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
+//
+// Note: this function might be called from signal handler (by os::abort()),
+// don't allocate heap memory.
+//
+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 result;
+
+  RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
+              result);;
+  if (result == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("Could not create Perfdata save file: %s: %s\n",
+              destfile, strerror(errno));
+    }
+  } else {
+    int fd = result;
+
+    for (size_t remaining = size; remaining > 0;) {
+
+      RESTARTABLE(::write(fd, addr, remaining), result);
+      if (result == OS_ERR) {
+        if (PrintMiscellaneous && Verbose) {
+          warning("Could not write Perfdata save file: %s: %s\n",
+                  destfile, strerror(errno));
+        }
+        break;
+      }
+
+      remaining -= (size_t)result;
+      addr += result;
+    }
+
+    RESTARTABLE(::close(fd), result);
+    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 solaris and bsd shared memory implementation uses the mmap
+// interface with a backing store file to implement named shared memory.
+// Using the file system as the name space for shared memory allows a
+// common name space to be supported across a variety of platforms. It
+// also provides a name space that Java applications can deal with through
+// simple file apis.
+//
+// The solaris and bsd implementations store the backing store file in
+// a user specific temporary directory located in the /tmp file system,
+// which is always a local file system and is sometimes a RAM based file
+// system.
+
+// 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) + 3;
+  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 pid_t 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;
+  pid_t pid = (pid_t)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 occurred.
+//
+static bool is_directory_secure(const char* path) {
+  struct stat statbuf;
+  int result = 0;
+
+  RESTARTABLE(::lstat(path, &statbuf), result);
+  if (result == OS_ERR) {
+    return false;
+  }
+
+  // the path exists, now check it's mode
+  if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {
+    // the path represents a link or some non-directory file type,
+    // which is not what we expected. declare it insecure.
+    //
+    return false;
+  }
+  else {
+    // we have an existing directory, check if the permissions are safe.
+    //
+    if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
+      // the directory is open for writing and could be subjected
+      // to a symlnk attack. declare it insecure.
+      //
+      return false;
+    }
+  }
+  return true;
+}
+
+
+// return the user name for the given user id
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_name(uid_t uid) {
+
+  struct passwd pwent;
+
+  // determine the max pwbuf size from sysconf, and hardcode
+  // a default if this not available through sysconf.
+  //
+  long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
+  if (bufsize == -1)
+    bufsize = 1024;
+
+  char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize);
+
+  // POSIX interface to getpwuid_r is used on LINUX
+  struct passwd* p;
+  int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
+
+  if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
+    if (PrintMiscellaneous && Verbose) {
+      if (result != 0) {
+        warning("Could not retrieve passwd entry: %s\n",
+                strerror(result));
+      }
+      else if (p == NULL) {
+        // this check is added to protect against an observed problem
+        // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
+        // indicating success, but has p == NULL. This was observed when
+        // inserting a file descriptor exhaustion fault prior to the call
+        // getpwuid_r() call. In this case, error is set to the appropriate
+        // error condition, but this is undocumented behavior. This check
+        // is safe under any condition, but the use of errno in the output
+        // message may result in an erroneous message.
+        // Bug Id 89052 was opened with RedHat.
+        //
+        warning("Could not retrieve passwd entry: %s\n",
+                strerror(errno));
+      }
+      else {
+        warning("Could not determine user name: %s\n",
+                p->pw_name == NULL ? "pw_name = NULL" :
+                                     "pw_name zero length");
+      }
+    }
+    FREE_C_HEAP_ARRAY(char, pwbuf);
+    return NULL;
+  }
+
+  char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1);
+  strcpy(user_name, p->pw_name);
+
+  FREE_C_HEAP_ARRAY(char, pwbuf);
+  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, TRAPS) {
+
+  // short circuit the directory search if the process doesn't even exist.
+  if (kill(vmid, 0) == OS_ERR) {
+    if (errno == ESRCH) {
+      THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
+                  "Process not found");
+    }
+    else /* EPERM */ {
+      THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
+    }
+  }
+
+  // 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) + 2);
+    strcpy(usrdir_name, tmpdirname);
+    strcat(usrdir_name, "/");
+    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;
+        int result;
+
+        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);
+
+        // don't follow symbolic links for the file
+        RESTARTABLE(::lstat(filename, &statbuf), result);
+        if (result == OS_ERR) {
+           FREE_C_HEAP_ARRAY(char, filename);
+           continue;
+        }
+
+        // skip over files that are not regular files.
+        if (!S_ISREG(statbuf.st_mode)) {
+          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 JVM indicated by the given vmid.
+//
+static char* get_user_name(int vmid, TRAPS) {
+  return get_user_name_slow(vmid, CHECK_NULL);
+}
+
+// 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 specified by the given path
+//
+static void remove_file(const char* path) {
+
+  int result;
+
+  // if the file is a directory, the following unlink will fail. since
+  // we don't expect to find directories in the user temp directory, we
+  // won't try to handle this situation. even if accidentially or
+  // maliciously planted, the directory's presence won't hurt anything.
+  //
+  RESTARTABLE(::unlink(path), result);
+  if (PrintMiscellaneous && Verbose && result == OS_ERR) {
+    if (errno != ENOENT) {
+      warning("Could not unlink shared memory backing"
+              " store file %s : %s\n", path, strerror(errno));
+    }
+  }
+}
+
+
+// remove file
+//
+// this method removes the file with the given file name in the
+// named directory.
+//
+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);
+
+  remove_file(path);
+
+  FREE_C_HEAP_ARRAY(char, path);
+}
+
+
+// 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 a secure directory
+    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) {
+
+    pid_t 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 sending signal number 0 to
+    // the process id (see kill(2)). if kill determines that the
+    // process does not exist, then the file resources are removed.
+    // if kill determines that that we don't have permission to
+    // signal the process, then the file resources are assumed to
+    // be stale and are removed because the resources for such a
+    // process should be in a different user specific directory.
+    //
+    if ((pid == os::current_process_id()) ||
+        (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
+
+        remove_file(dirname, entry->d_name);
+    }
+    errno = 0;
+  }
+  os::closedir(dirp);
+  FREE_C_HEAP_ARRAY(char, dbuf);
+}
+
+// make the user specific temporary directory. Returns true if
+// the directory exists and is secure upon return. Returns false
+// if the directory exists but is either a symlink, is otherwise
+// insecure, or if an error occurred.
+//
+static bool make_user_tmp_dir(const char* dirname) {
+
+  // create the directory with 0755 permissions. note that the directory
+  // will be owned by euid::egid, which may not be the same as uid::gid.
+  //
+  if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
+    if (errno == EEXIST) {
+      // 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;
+      }
+    }
+    else {
+      // we encountered some other failure while attempting
+      // to create the directory
+      //
+      if (PrintMiscellaneous && Verbose) {
+        warning("could not create directory %s: %s\n",
+                dirname, strerror(errno));
+      }
+      return false;
+    }
+  }
+  return true;
+}
+
+// create the shared memory file resources
+//
+// This method creates the shared memory file with the given size
+// This method also creates the user specific temporary directory, if
+// it does not yet exist.
+//
+static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
+
+  // make the user temporary directory
+  if (!make_user_tmp_dir(dirname)) {
+    // could not make/find the directory or the found directory
+    // was not secure
+    return -1;
+  }
+
+  int result;
+
+  RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
+  if (result == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("could not create file %s: %s\n", filename, strerror(errno));
+    }
+    return -1;
+  }
+
+  // save the file descriptor
+  int fd = result;
+
+  // set the file size
+  RESTARTABLE(::ftruncate(fd, (off_t)size), result);
+  if (result == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("could not set shared memory file size: %s\n", strerror(errno));
+    }
+    RESTARTABLE(::close(fd), result);
+    return -1;
+  }
+
+  // Verify that we have enough disk space for this file.
+  // We'll get random SIGBUS crashes on memory accesses if
+  // we don't.
+
+  for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
+    int zero_int = 0;
+    result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
+    if (result == -1 ) break;
+    RESTARTABLE(::write(fd, &zero_int, 1), result);
+    if (result != 1) {
+      if (errno == ENOSPC) {
+        warning("Insufficient space for shared memory file:\n   %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
+      }
+      break;
+    }
+  }
+
+  if (result != -1) {
+    return fd;
+  } else {
+    RESTARTABLE(::close(fd), result);
+    return -1;
+  }
+}
+
+// open the shared memory file for the given user and vmid. returns
+// the file descriptor for the open file or -1 if the file could not
+// be opened.
+//
+static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
+
+  // open the file
+  int result;
+  RESTARTABLE(::open(filename, oflags), result);
+  if (result == OS_ERR) {
+    if (errno == ENOENT) {
+      THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
+                  "Process not found");
+    }
+    else if (errno == EACCES) {
+      THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
+                  "Permission denied");
+    }
+    else {
+      THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
+    }
+  }
+
+  return result;
+}
+
+// create a named shared memory region. returns the address of the
+// memory region on success or NULL on failure. A return value of
+// NULL will ultimately disable the shared memory feature.
+//
+// On Solaris and Bsd, the name space for shared memory objects
+// is the file system name space.
+//
+// A monitoring application attaching to a JVM does not need to know
+// the file system name of the shared memory object. However, it may
+// be convenient for applications to discover the existence of newly
+// created and terminating JVMs by watching the file system name space
+// for files being created or removed.
+//
+static char* mmap_create_shared(size_t size) {
+
+  int result;
+  int fd;
+  char* mapAddress;
+
+  int vmid = os::current_process_id();
+
+  char* user_name = get_user_name(geteuid());
+
+  if (user_name == NULL)
+    return NULL;
+
+  char* dirname = get_user_tmp_dir(user_name);
+  char* filename = get_sharedmem_filename(dirname, vmid);
+
+  // cleanup any stale shared memory files
+  cleanup_sharedmem_resources(dirname);
+
+  assert(((size > 0) && (size % os::vm_page_size() == 0)),
+         "unexpected PerfMemory region size");
+
+  fd = create_sharedmem_resources(dirname, filename, size);
+
+  FREE_C_HEAP_ARRAY(char, user_name);
+  FREE_C_HEAP_ARRAY(char, dirname);
+
+  if (fd == -1) {
+    FREE_C_HEAP_ARRAY(char, filename);
+    return NULL;
+  }
+
+  mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+
+  // attempt to close the file - restart it if it was interrupted,
+  // but ignore other failures
+  RESTARTABLE(::close(fd), result);
+  assert(result != OS_ERR, "could not close file");
+
+  if (mapAddress == MAP_FAILED) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("mmap failed -  %s\n", strerror(errno));
+    }
+    remove_file(filename);
+    FREE_C_HEAP_ARRAY(char, filename);
+    return NULL;
+  }
+
+  // save the file name for use in delete_shared_memory()
+  backing_store_file_name = filename;
+
+  // clear the shared memory region
+  (void)::memset((void*) mapAddress, 0, size);
+
+  return mapAddress;
+}
+
+// release a named shared memory region
+//
+static void unmap_shared(char* addr, size_t bytes) {
+  os::release_memory(addr, bytes);
+}
+
+// create the PerfData memory region in shared memory.
+//
+static char* create_shared_memory(size_t size) {
+
+  // create the shared memory region.
+  return mmap_create_shared(size);
+}
+
+// delete the shared PerfData memory region
+//
+static void delete_shared_memory(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
+  // the process. The backing store file is deleted from the file system.
+
+  assert(!PerfDisableSharedMem, "shouldn't be here");
+
+  if (backing_store_file_name != NULL) {
+    remove_file(backing_store_file_name);
+    // Don't.. Free heap memory could deadlock os::abort() if it is called
+    // from signal handler. OS will reclaim the heap memory.
+    // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
+    backing_store_file_name = NULL;
+  }
+}
+
+// return the size of the file for the given file descriptor
+// or 0 if it is not a valid size for a shared memory file
+//
+static size_t sharedmem_filesize(int fd, TRAPS) {
+
+  struct stat statbuf;
+  int result;
+
+  RESTARTABLE(::fstat(fd, &statbuf), result);
+  if (result == OS_ERR) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("fstat failed: %s\n", strerror(errno));
+    }
+    THROW_MSG_0(vmSymbols::java_io_IOException(),
+                "Could not determine PerfMemory size");
+  }
+
+  if ((statbuf.st_size == 0) ||
+     ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
+    THROW_MSG_0(vmSymbols::java_lang_Exception(),
+                "Invalid PerfMemory size");
+  }
+
+  return (size_t)statbuf.st_size;
+}
+
+// attach to a named shared memory region.
+//
+static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
+
+  char* mapAddress;
+  int result;
+  int fd;
+  size_t size;
+  const char* luser = NULL;
+
+  int mmap_prot;
+  int file_flags;
+
+  ResourceMark rm;
+
+  // map the high level access mode to the appropriate permission
+  // constructs for the file and the shared memory mapping.
+  if (mode == PerfMemory::PERF_MODE_RO) {
+    mmap_prot = PROT_READ;
+    file_flags = O_RDONLY;
+  }
+  else if (mode == PerfMemory::PERF_MODE_RW) {
+#ifdef LATER
+    mmap_prot = PROT_READ | PROT_WRITE;
+    file_flags = O_RDWR;
+#else
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Unsupported access mode");
+#endif
+  }
+  else {
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Illegal access mode");
+  }
+
+  if (user == NULL || strlen(user) == 0) {
+    luser = get_user_name(vmid, CHECK);
+  }
+  else {
+    luser = user;
+  }
+
+  if (luser == NULL) {
+    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+              "Could not map vmid to user Name");
+  }
+
+  char* dirname = get_user_tmp_dir(luser);
+
+  // since we don't follow symbolic links when creating the backing
+  // store file, we don't follow them when attaching either.
+  //
+  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);
+
+  // copy heap memory to resource memory. the open_sharedmem_file
+  // method below need to use the filename, but could throw an
+  // exception. using a resource array prevents the leak that
+  // would otherwise occur.
+  char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
+  strcpy(rfilename, filename);
+
+  // 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);
+
+  // open the shared memory file for the give vmid
+  fd = open_sharedmem_file(rfilename, file_flags, CHECK);
+  assert(fd != OS_ERR, "unexpected value");
+
+  if (*sizep == 0) {
+    size = sharedmem_filesize(fd, CHECK);
+    assert(size != 0, "unexpected size");
+  }
+
+  mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
+
+  // attempt to close the file - restart if it gets interrupted,
+  // but ignore other failures
+  RESTARTABLE(::close(fd), result);
+  assert(result != OS_ERR, "could not close file");
+
+  if (mapAddress == MAP_FAILED) {
+    if (PrintMiscellaneous && Verbose) {
+      warning("mmap failed: %s\n", strerror(errno));
+    }
+    THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
+              "Could not map PerfMemory");
+  }
+
+  *addr = mapAddress;
+  *sizep = size;
+
+  if (PerfTraceMemOps) {
+    tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
+               INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
+  }
+}
+
+
+
+
+// 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) {
+    // do not share the memory for the performance data.
+    _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;
+  }
+
+  mmap_attach_shared(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;
+  }
+
+  unmap_shared(addr, bytes);
+}
+
+char* PerfMemory::backing_store_filename() {
+  return backing_store_file_name;
+}