jdk8-mips64-public/hotspot: src/os/windows/vm/perfMemory

src/os/windows/vm/perfMemory_windows.cpp@98cb887364d3 (annotated)

src/os/windows/vm/perfMemory_windows.cpp

Fri, 27 Feb 2009 13:27:09 -0800

author: twisti
date: Fri, 27 Feb 2009 13:27:09 -0800
changeset 1040: 98cb887364d3
parent 435: a61af66fc99e
child 1788: a2ea687fdc7c
permissions: -rw-r--r--

6810672: Comment typos
Summary: I have collected some typos I have found while looking at the code.
Reviewed-by: kvn, never

 /*
  * 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 occurred.
 //
 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 inheritance
   // control flags.
   SetSecurityDescriptorControlFnPtr _SetSecurityDescriptorControl;
   _SetSecurityDescriptorControl = (SetSecurityDescriptorControlFnPtr)
        GetProcAddress(GetModuleHandle(TEXT("advapi32.dll")),
                       "SetSecurityDescriptorControl");
   if (_SetSecurityDescriptorControl != NULL) {
     // We do not want to further propagate 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, &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, &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 */
 ,                       /* DWORD High word of offset */
 ,                       /* 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 */
 ,               /* DWORD High word of offset */
 ,               /* 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;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/os/windows/vm/perfMemory_windows.cpp@98cb887364d3 (annotated)

src/os/windows/vm/perfMemory_windows.cpp