1 /*
   2  * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/vmSymbols.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "memory/resourceArea.hpp"
  29 #include "oops/oop.inline.hpp"
  30 #include "os_solaris.inline.hpp"
  31 #include "runtime/handles.inline.hpp"
  32 #include "runtime/perfMemory.hpp"
  33 #include "services/memTracker.hpp"
  34 #include "utilities/exceptions.hpp"
  35 
  36 // put OS-includes here
  37 # include <sys/types.h>
  38 # include <sys/mman.h>
  39 # include <errno.h>
  40 # include <stdio.h>
  41 # include <unistd.h>
  42 # include <sys/stat.h>
  43 # include <signal.h>
  44 # include <pwd.h>
  45 # include <procfs.h>
  46 
  47 
  48 static char* backing_store_file_name = NULL;  // name of the backing store
  49                                               // file, if successfully created.
  50 
  51 // Standard Memory Implementation Details
  52 
  53 // create the PerfData memory region in standard memory.
  54 //
  55 static char* create_standard_memory(size_t size) {
  56 
  57   // allocate an aligned chuck of memory
  58   char* mapAddress = os::reserve_memory(size);
  59 
  60   if (mapAddress == NULL) {
  61     return NULL;
  62   }
  63 
  64   // commit memory
  65   if (!os::commit_memory(mapAddress, size)) {
  66     if (PrintMiscellaneous && Verbose) {
  67       warning("Could not commit PerfData memory\n");
  68     }
  69     os::release_memory(mapAddress, size);
  70     return NULL;
  71   }
  72 
  73   return mapAddress;
  74 }
  75 
  76 // delete the PerfData memory region
  77 //
  78 static void delete_standard_memory(char* addr, size_t size) {
  79 
  80   // there are no persistent external resources to cleanup for standard
  81   // memory. since DestroyJavaVM does not support unloading of the JVM,
  82   // cleanup of the memory resource is not performed. The memory will be
  83   // reclaimed by the OS upon termination of the process.
  84   //
  85   return;
  86 }
  87 
  88 // save the specified memory region to the given file
  89 //
  90 // Note: this function might be called from signal handler (by os::abort()),
  91 // don't allocate heap memory.
  92 //
  93 static void save_memory_to_file(char* addr, size_t size) {
  94 
  95   const char* destfile = PerfMemory::get_perfdata_file_path();
  96   assert(destfile[0] != '\0', "invalid PerfData file path");
  97 
  98   int result;
  99 
 100   RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
 101               result);;
 102   if (result == OS_ERR) {
 103     if (PrintMiscellaneous && Verbose) {
 104       warning("Could not create Perfdata save file: %s: %s\n",
 105               destfile, strerror(errno));
 106     }
 107   } else {
 108 
 109     int fd = result;
 110 
 111     for (size_t remaining = size; remaining > 0;) {
 112 
 113       RESTARTABLE(::write(fd, addr, remaining), result);
 114       if (result == OS_ERR) {
 115         if (PrintMiscellaneous && Verbose) {
 116           warning("Could not write Perfdata save file: %s: %s\n",
 117                   destfile, strerror(errno));
 118         }
 119         break;
 120       }
 121       remaining -= (size_t)result;
 122       addr += result;
 123     }
 124 
 125     RESTARTABLE(::close(fd), result);
 126     if (PrintMiscellaneous && Verbose) {
 127       if (result == OS_ERR) {
 128         warning("Could not close %s: %s\n", destfile, strerror(errno));
 129       }
 130     }
 131   }
 132   FREE_C_HEAP_ARRAY(char, destfile, mtInternal);
 133 }
 134 
 135 
 136 // Shared Memory Implementation Details
 137 
 138 // Note: the solaris and linux shared memory implementation uses the mmap
 139 // interface with a backing store file to implement named shared memory.
 140 // Using the file system as the name space for shared memory allows a
 141 // common name space to be supported across a variety of platforms. It
 142 // also provides a name space that Java applications can deal with through
 143 // simple file apis.
 144 //
 145 // The solaris and linux implementations store the backing store file in
 146 // a user specific temporary directory located in the /tmp file system,
 147 // which is always a local file system and is sometimes a RAM based file
 148 // system.
 149 
 150 // return the user specific temporary directory name.
 151 //
 152 // the caller is expected to free the allocated memory.
 153 //
 154 static char* get_user_tmp_dir(const char* user) {
 155 
 156   const char* tmpdir = os::get_temp_directory();
 157   const char* perfdir = PERFDATA_NAME;
 158   size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
 159   char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
 160 
 161   // construct the path name to user specific tmp directory
 162   snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
 163 
 164   return dirname;
 165 }
 166 
 167 // convert the given file name into a process id. if the file
 168 // does not meet the file naming constraints, return 0.
 169 //
 170 static pid_t filename_to_pid(const char* filename) {
 171 
 172   // a filename that doesn't begin with a digit is not a
 173   // candidate for conversion.
 174   //
 175   if (!isdigit(*filename)) {
 176     return 0;
 177   }
 178 
 179   // check if file name can be converted to an integer without
 180   // any leftover characters.
 181   //
 182   char* remainder = NULL;
 183   errno = 0;
 184   pid_t pid = (pid_t)strtol(filename, &remainder, 10);
 185 
 186   if (errno != 0) {
 187     return 0;
 188   }
 189 
 190   // check for left over characters. If any, then the filename is
 191   // not a candidate for conversion.
 192   //
 193   if (remainder != NULL && *remainder != '\0') {
 194     return 0;
 195   }
 196 
 197   // successful conversion, return the pid
 198   return pid;
 199 }
 200 
 201 
 202 // check if the given path is considered a secure directory for
 203 // the backing store files. Returns true if the directory exists
 204 // and is considered a secure location. Returns false if the path
 205 // is a symbolic link or if an error occurred.
 206 //
 207 static bool is_directory_secure(const char* path) {
 208   struct stat statbuf;
 209   int result = 0;
 210 
 211   RESTARTABLE(::lstat(path, &statbuf), result);
 212   if (result == OS_ERR) {
 213     return false;
 214   }
 215 
 216   // the path exists, now check it's mode
 217   if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {
 218     // the path represents a link or some non-directory file type,
 219     // which is not what we expected. declare it insecure.
 220     //
 221     return false;
 222   }
 223   else {
 224     // we have an existing directory, check if the permissions are safe.
 225     //
 226     if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
 227       // the directory is open for writing and could be subjected
 228       // to a symlnk attack. declare it insecure.
 229       //
 230       return false;
 231     }
 232   }
 233   return true;
 234 }
 235 
 236 
 237 // return the user name for the given user id
 238 //
 239 // the caller is expected to free the allocated memory.
 240 //
 241 static char* get_user_name(uid_t uid) {
 242 
 243   struct passwd pwent;
 244 
 245   // determine the max pwbuf size from sysconf, and hardcode
 246   // a default if this not available through sysconf.
 247   //
 248   long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
 249   if (bufsize == -1)
 250     bufsize = 1024;
 251 
 252   char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
 253 
 254 #ifdef _GNU_SOURCE
 255   struct passwd* p = NULL;
 256   int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
 257 #else  // _GNU_SOURCE
 258   struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize);
 259 #endif // _GNU_SOURCE
 260 
 261   if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
 262     if (PrintMiscellaneous && Verbose) {
 263       if (p == NULL) {
 264         warning("Could not retrieve passwd entry: %s\n",
 265                 strerror(errno));
 266       }
 267       else {
 268         warning("Could not determine user name: %s\n",
 269                 p->pw_name == NULL ? "pw_name = NULL" :
 270                                      "pw_name zero length");
 271       }
 272     }
 273     FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
 274     return NULL;
 275   }
 276 
 277   char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
 278   strcpy(user_name, p->pw_name);
 279 
 280   FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
 281   return user_name;
 282 }
 283 
 284 // return the name of the user that owns the process identified by vmid.
 285 //
 286 // This method uses a slow directory search algorithm to find the backing
 287 // store file for the specified vmid and returns the user name, as determined
 288 // by the user name suffix of the hsperfdata_<username> directory name.
 289 //
 290 // the caller is expected to free the allocated memory.
 291 //
 292 static char* get_user_name_slow(int vmid, TRAPS) {
 293 
 294   // short circuit the directory search if the process doesn't even exist.
 295   if (kill(vmid, 0) == OS_ERR) {
 296     if (errno == ESRCH) {
 297       THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
 298                   "Process not found");
 299     }
 300     else /* EPERM */ {
 301       THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
 302     }
 303   }
 304 
 305   // directory search
 306   char* oldest_user = NULL;
 307   time_t oldest_ctime = 0;
 308 
 309   const char* tmpdirname = os::get_temp_directory();
 310 
 311   DIR* tmpdirp = os::opendir(tmpdirname);
 312 
 313   if (tmpdirp == NULL) {
 314     return NULL;
 315   }
 316 
 317   // for each entry in the directory that matches the pattern hsperfdata_*,
 318   // open the directory and check if the file for the given vmid exists.
 319   // The file with the expected name and the latest creation date is used
 320   // to determine the user name for the process id.
 321   //
 322   struct dirent* dentry;
 323   char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
 324   errno = 0;
 325   while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
 326 
 327     // check if the directory entry is a hsperfdata file
 328     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
 329       continue;
 330     }
 331 
 332     char* usrdir_name = NEW_C_HEAP_ARRAY(char,
 333                   strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
 334     strcpy(usrdir_name, tmpdirname);
 335     strcat(usrdir_name, "/");
 336     strcat(usrdir_name, dentry->d_name);
 337 
 338     DIR* subdirp = os::opendir(usrdir_name);
 339 
 340     if (subdirp == NULL) {
 341       FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
 342       continue;
 343     }
 344 
 345     // Since we don't create the backing store files in directories
 346     // pointed to by symbolic links, we also don't follow them when
 347     // looking for the files. We check for a symbolic link after the
 348     // call to opendir in order to eliminate a small window where the
 349     // symlink can be exploited.
 350     //
 351     if (!is_directory_secure(usrdir_name)) {
 352       FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
 353       os::closedir(subdirp);
 354       continue;
 355     }
 356 
 357     struct dirent* udentry;
 358     char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
 359     errno = 0;
 360     while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
 361 
 362       if (filename_to_pid(udentry->d_name) == vmid) {
 363         struct stat statbuf;
 364         int result;
 365 
 366         char* filename = NEW_C_HEAP_ARRAY(char,
 367                  strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
 368 
 369         strcpy(filename, usrdir_name);
 370         strcat(filename, "/");
 371         strcat(filename, udentry->d_name);
 372 
 373         // don't follow symbolic links for the file
 374         RESTARTABLE(::lstat(filename, &statbuf), result);
 375         if (result == OS_ERR) {
 376            FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 377            continue;
 378         }
 379 
 380         // skip over files that are not regular files.
 381         if (!S_ISREG(statbuf.st_mode)) {
 382           FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 383           continue;
 384         }
 385 
 386         // compare and save filename with latest creation time
 387         if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
 388 
 389           if (statbuf.st_ctime > oldest_ctime) {
 390             char* user = strchr(dentry->d_name, '_') + 1;
 391 
 392             if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal);
 393             oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
 394 
 395             strcpy(oldest_user, user);
 396             oldest_ctime = statbuf.st_ctime;
 397           }
 398         }
 399 
 400         FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 401       }
 402     }
 403     os::closedir(subdirp);
 404     FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
 405     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
 406   }
 407   os::closedir(tmpdirp);
 408   FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 409 
 410   return(oldest_user);
 411 }
 412 
 413 // return the name of the user that owns the JVM indicated by the given vmid.
 414 //
 415 static char* get_user_name(int vmid, TRAPS) {
 416 
 417   char psinfo_name[PATH_MAX];
 418   int result;
 419 
 420   snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
 421 
 422   RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
 423 
 424   if (result != OS_ERR) {
 425     int fd = result;
 426 
 427     psinfo_t psinfo;
 428     char* addr = (char*)&psinfo;
 429 
 430     for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
 431 
 432       RESTARTABLE(::read(fd, addr, remaining), result);
 433       if (result == OS_ERR) {
 434         THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
 435       }
 436       remaining-=result;
 437       addr+=result;
 438     }
 439 
 440     RESTARTABLE(::close(fd), result);
 441 
 442     // get the user name for the effective user id of the process
 443     char* user_name = get_user_name(psinfo.pr_euid);
 444 
 445     return user_name;
 446   }
 447 
 448   if (result == OS_ERR && errno == EACCES) {
 449 
 450     // In this case, the psinfo file for the process id existed,
 451     // but we didn't have permission to access it.
 452     THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
 453                 strerror(errno));
 454   }
 455 
 456   // at this point, we don't know if the process id itself doesn't
 457   // exist or if the psinfo file doesn't exit. If the psinfo file
 458   // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
 459   // since the structured procfs and old procfs interfaces can't be
 460   // mixed, we attempt to find the file through a directory search.
 461 
 462   return get_user_name_slow(vmid, CHECK_NULL);
 463 }
 464 
 465 // return the file name of the backing store file for the named
 466 // shared memory region for the given user name and vmid.
 467 //
 468 // the caller is expected to free the allocated memory.
 469 //
 470 static char* get_sharedmem_filename(const char* dirname, int vmid) {
 471 
 472   // add 2 for the file separator and a NULL terminator.
 473   size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
 474 
 475   char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
 476   snprintf(name, nbytes, "%s/%d", dirname, vmid);
 477 
 478   return name;
 479 }
 480 
 481 
 482 // remove file
 483 //
 484 // this method removes the file specified by the given path
 485 //
 486 static void remove_file(const char* path) {
 487 
 488   int result;
 489 
 490   // if the file is a directory, the following unlink will fail. since
 491   // we don't expect to find directories in the user temp directory, we
 492   // won't try to handle this situation. even if accidentially or
 493   // maliciously planted, the directory's presence won't hurt anything.
 494   //
 495   RESTARTABLE(::unlink(path), result);
 496   if (PrintMiscellaneous && Verbose && result == OS_ERR) {
 497     if (errno != ENOENT) {
 498       warning("Could not unlink shared memory backing"
 499               " store file %s : %s\n", path, strerror(errno));
 500     }
 501   }
 502 }
 503 
 504 
 505 // remove file
 506 //
 507 // this method removes the file with the given file name in the
 508 // named directory.
 509 //
 510 static void remove_file(const char* dirname, const char* filename) {
 511 
 512   size_t nbytes = strlen(dirname) + strlen(filename) + 2;
 513   char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
 514 
 515   strcpy(path, dirname);
 516   strcat(path, "/");
 517   strcat(path, filename);
 518 
 519   remove_file(path);
 520 
 521   FREE_C_HEAP_ARRAY(char, path, mtInternal);
 522 }
 523 
 524 
 525 // cleanup stale shared memory resources
 526 //
 527 // This method attempts to remove all stale shared memory files in
 528 // the named user temporary directory. It scans the named directory
 529 // for files matching the pattern ^$[0-9]*$. For each file found, the
 530 // process id is extracted from the file name and a test is run to
 531 // determine if the process is alive. If the process is not alive,
 532 // any stale file resources are removed.
 533 //
 534 static void cleanup_sharedmem_resources(const char* dirname) {
 535 
 536   // open the user temp directory
 537   DIR* dirp = os::opendir(dirname);
 538 
 539   if (dirp == NULL) {
 540     // directory doesn't exist, so there is nothing to cleanup
 541     return;
 542   }
 543 
 544   if (!is_directory_secure(dirname)) {
 545     // the directory is not a secure directory
 546     return;
 547   }
 548 
 549   // for each entry in the directory that matches the expected file
 550   // name pattern, determine if the file resources are stale and if
 551   // so, remove the file resources. Note, instrumented HotSpot processes
 552   // for this user may start and/or terminate during this search and
 553   // remove or create new files in this directory. The behavior of this
 554   // loop under these conditions is dependent upon the implementation of
 555   // opendir/readdir.
 556   //
 557   struct dirent* entry;
 558   char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
 559   errno = 0;
 560   while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
 561 
 562     pid_t pid = filename_to_pid(entry->d_name);
 563 
 564     if (pid == 0) {
 565 
 566       if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
 567 
 568         // attempt to remove all unexpected files, except "." and ".."
 569         remove_file(dirname, entry->d_name);
 570       }
 571 
 572       errno = 0;
 573       continue;
 574     }
 575 
 576     // we now have a file name that converts to a valid integer
 577     // that could represent a process id . if this process id
 578     // matches the current process id or the process is not running,
 579     // then remove the stale file resources.
 580     //
 581     // process liveness is detected by sending signal number 0 to
 582     // the process id (see kill(2)). if kill determines that the
 583     // process does not exist, then the file resources are removed.
 584     // if kill determines that that we don't have permission to
 585     // signal the process, then the file resources are assumed to
 586     // be stale and are removed because the resources for such a
 587     // process should be in a different user specific directory.
 588     //
 589     if ((pid == os::current_process_id()) ||
 590         (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
 591 
 592         remove_file(dirname, entry->d_name);
 593     }
 594     errno = 0;
 595   }
 596   os::closedir(dirp);
 597   FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 598 }
 599 
 600 // make the user specific temporary directory. Returns true if
 601 // the directory exists and is secure upon return. Returns false
 602 // if the directory exists but is either a symlink, is otherwise
 603 // insecure, or if an error occurred.
 604 //
 605 static bool make_user_tmp_dir(const char* dirname) {
 606 
 607   // create the directory with 0755 permissions. note that the directory
 608   // will be owned by euid::egid, which may not be the same as uid::gid.
 609   //
 610   if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
 611     if (errno == EEXIST) {
 612       // The directory already exists and was probably created by another
 613       // JVM instance. However, this could also be the result of a
 614       // deliberate symlink. Verify that the existing directory is safe.
 615       //
 616       if (!is_directory_secure(dirname)) {
 617         // directory is not secure
 618         if (PrintMiscellaneous && Verbose) {
 619           warning("%s directory is insecure\n", dirname);
 620         }
 621         return false;
 622       }
 623     }
 624     else {
 625       // we encountered some other failure while attempting
 626       // to create the directory
 627       //
 628       if (PrintMiscellaneous && Verbose) {
 629         warning("could not create directory %s: %s\n",
 630                 dirname, strerror(errno));
 631       }
 632       return false;
 633     }
 634   }
 635   return true;
 636 }
 637 
 638 // create the shared memory file resources
 639 //
 640 // This method creates the shared memory file with the given size
 641 // This method also creates the user specific temporary directory, if
 642 // it does not yet exist.
 643 //
 644 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
 645 
 646   // make the user temporary directory
 647   if (!make_user_tmp_dir(dirname)) {
 648     // could not make/find the directory or the found directory
 649     // was not secure
 650     return -1;
 651   }
 652 
 653   int result;
 654 
 655   RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
 656   if (result == OS_ERR) {
 657     if (PrintMiscellaneous && Verbose) {
 658       warning("could not create file %s: %s\n", filename, strerror(errno));
 659     }
 660     return -1;
 661   }
 662 
 663   // save the file descriptor
 664   int fd = result;
 665 
 666   // set the file size
 667   RESTARTABLE(::ftruncate(fd, (off_t)size), result);
 668   if (result == OS_ERR) {
 669     if (PrintMiscellaneous && Verbose) {
 670       warning("could not set shared memory file size: %s\n", strerror(errno));
 671     }
 672     RESTARTABLE(::close(fd), result);
 673     return -1;
 674   }
 675 
 676   return fd;
 677 }
 678 
 679 // open the shared memory file for the given user and vmid. returns
 680 // the file descriptor for the open file or -1 if the file could not
 681 // be opened.
 682 //
 683 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
 684 
 685   // open the file
 686   int result;
 687   RESTARTABLE(::open(filename, oflags), result);
 688   if (result == OS_ERR) {
 689     if (errno == ENOENT) {
 690       THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
 691                   "Process not found", OS_ERR);
 692     }
 693     else if (errno == EACCES) {
 694       THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
 695                   "Permission denied", OS_ERR);
 696     }
 697     else {
 698       THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
 699     }
 700   }
 701 
 702   return result;
 703 }
 704 
 705 // create a named shared memory region. returns the address of the
 706 // memory region on success or NULL on failure. A return value of
 707 // NULL will ultimately disable the shared memory feature.
 708 //
 709 // On Solaris and Linux, the name space for shared memory objects
 710 // is the file system name space.
 711 //
 712 // A monitoring application attaching to a JVM does not need to know
 713 // the file system name of the shared memory object. However, it may
 714 // be convenient for applications to discover the existence of newly
 715 // created and terminating JVMs by watching the file system name space
 716 // for files being created or removed.
 717 //
 718 static char* mmap_create_shared(size_t size) {
 719 
 720   int result;
 721   int fd;
 722   char* mapAddress;
 723 
 724   int vmid = os::current_process_id();
 725 
 726   char* user_name = get_user_name(geteuid());
 727 
 728   if (user_name == NULL)
 729     return NULL;
 730 
 731   char* dirname = get_user_tmp_dir(user_name);
 732   char* filename = get_sharedmem_filename(dirname, vmid);
 733 
 734   // cleanup any stale shared memory files
 735   cleanup_sharedmem_resources(dirname);
 736 
 737   assert(((size > 0) && (size % os::vm_page_size() == 0)),
 738          "unexpected PerfMemory region size");
 739 
 740   fd = create_sharedmem_resources(dirname, filename, size);
 741 
 742   FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
 743   FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
 744 
 745   if (fd == -1) {
 746     FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 747     return NULL;
 748   }
 749 
 750   mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 751 
 752   // attempt to close the file - restart it if it was interrupted,
 753   // but ignore other failures
 754   RESTARTABLE(::close(fd), result);
 755   assert(result != OS_ERR, "could not close file");
 756 
 757   if (mapAddress == MAP_FAILED) {
 758     if (PrintMiscellaneous && Verbose) {
 759       warning("mmap failed -  %s\n", strerror(errno));
 760     }
 761     remove_file(filename);
 762     FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 763     return NULL;
 764   }
 765 
 766   // save the file name for use in delete_shared_memory()
 767   backing_store_file_name = filename;
 768 
 769   // clear the shared memory region
 770   (void)::memset((void*) mapAddress, 0, size);
 771 
 772   // it does not go through os api, the operation has to record from here
 773   MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC);
 774   MemTracker::record_virtual_memory_type((address)mapAddress, mtInternal);
 775 
 776   return mapAddress;
 777 }
 778 
 779 // release a named shared memory region
 780 //
 781 static void unmap_shared(char* addr, size_t bytes) {
 782   os::release_memory(addr, bytes);
 783 }
 784 
 785 // create the PerfData memory region in shared memory.
 786 //
 787 static char* create_shared_memory(size_t size) {
 788 
 789   // create the shared memory region.
 790   return mmap_create_shared(size);
 791 }
 792 
 793 // delete the shared PerfData memory region
 794 //
 795 static void delete_shared_memory(char* addr, size_t size) {
 796 
 797   // cleanup the persistent shared memory resources. since DestroyJavaVM does
 798   // not support unloading of the JVM, unmapping of the memory resource is
 799   // not performed. The memory will be reclaimed by the OS upon termination of
 800   // the process. The backing store file is deleted from the file system.
 801 
 802   assert(!PerfDisableSharedMem, "shouldn't be here");
 803 
 804   if (backing_store_file_name != NULL) {
 805     remove_file(backing_store_file_name);
 806     // Don't.. Free heap memory could deadlock os::abort() if it is called
 807     // from signal handler. OS will reclaim the heap memory.
 808     // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
 809     backing_store_file_name = NULL;
 810   }
 811 }
 812 
 813 // return the size of the file for the given file descriptor
 814 // or 0 if it is not a valid size for a shared memory file
 815 //
 816 static size_t sharedmem_filesize(int fd, TRAPS) {
 817 
 818   struct stat statbuf;
 819   int result;
 820 
 821   RESTARTABLE(::fstat(fd, &statbuf), result);
 822   if (result == OS_ERR) {
 823     if (PrintMiscellaneous && Verbose) {
 824       warning("fstat failed: %s\n", strerror(errno));
 825     }
 826     THROW_MSG_0(vmSymbols::java_io_IOException(),
 827                 "Could not determine PerfMemory size");
 828   }
 829 
 830   if ((statbuf.st_size == 0) ||
 831      ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
 832     THROW_MSG_0(vmSymbols::java_lang_Exception(),
 833                 "Invalid PerfMemory size");
 834   }
 835 
 836   return (size_t)statbuf.st_size;
 837 }
 838 
 839 // attach to a named shared memory region.
 840 //
 841 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
 842 
 843   char* mapAddress;
 844   int result;
 845   int fd;
 846   size_t size = 0;
 847   const char* luser = NULL;
 848 
 849   int mmap_prot;
 850   int file_flags;
 851 
 852   ResourceMark rm;
 853 
 854   // map the high level access mode to the appropriate permission
 855   // constructs for the file and the shared memory mapping.
 856   if (mode == PerfMemory::PERF_MODE_RO) {
 857     mmap_prot = PROT_READ;
 858     file_flags = O_RDONLY;
 859   }
 860   else if (mode == PerfMemory::PERF_MODE_RW) {
 861 #ifdef LATER
 862     mmap_prot = PROT_READ | PROT_WRITE;
 863     file_flags = O_RDWR;
 864 #else
 865     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 866               "Unsupported access mode");
 867 #endif
 868   }
 869   else {
 870     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 871               "Illegal access mode");
 872   }
 873 
 874   if (user == NULL || strlen(user) == 0) {
 875     luser = get_user_name(vmid, CHECK);
 876   }
 877   else {
 878     luser = user;
 879   }
 880 
 881   if (luser == NULL) {
 882     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 883               "Could not map vmid to user Name");
 884   }
 885 
 886   char* dirname = get_user_tmp_dir(luser);
 887 
 888   // since we don't follow symbolic links when creating the backing
 889   // store file, we don't follow them when attaching either.
 890   //
 891   if (!is_directory_secure(dirname)) {
 892     FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
 893     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 894               "Process not found");
 895   }
 896 
 897   char* filename = get_sharedmem_filename(dirname, vmid);
 898 
 899   // copy heap memory to resource memory. the open_sharedmem_file
 900   // method below need to use the filename, but could throw an
 901   // exception. using a resource array prevents the leak that
 902   // would otherwise occur.
 903   char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
 904   strcpy(rfilename, filename);
 905 
 906   // free the c heap resources that are no longer needed
 907   if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal);
 908   FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
 909   FREE_C_HEAP_ARRAY(char, filename, mtInternal);
 910 
 911   // open the shared memory file for the give vmid
 912   fd = open_sharedmem_file(rfilename, file_flags, CHECK);
 913   assert(fd != OS_ERR, "unexpected value");
 914 
 915   if (*sizep == 0) {
 916     size = sharedmem_filesize(fd, CHECK);
 917   } else {
 918     size = *sizep;
 919   }
 920 
 921   assert(size > 0, "unexpected size <= 0");
 922 
 923   mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
 924 
 925   // attempt to close the file - restart if it gets interrupted,
 926   // but ignore other failures
 927   RESTARTABLE(::close(fd), result);
 928   assert(result != OS_ERR, "could not close file");
 929 
 930   if (mapAddress == MAP_FAILED) {
 931     if (PrintMiscellaneous && Verbose) {
 932       warning("mmap failed: %s\n", strerror(errno));
 933     }
 934     THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
 935               "Could not map PerfMemory");
 936   }
 937 
 938   // it does not go through os api, the operation has to record from here
 939   MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC);
 940   MemTracker::record_virtual_memory_type((address)mapAddress, mtInternal);
 941 
 942   *addr = mapAddress;
 943   *sizep = size;
 944 
 945   if (PerfTraceMemOps) {
 946     tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
 947                INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
 948   }
 949 }
 950 
 951 
 952 
 953 
 954 // create the PerfData memory region
 955 //
 956 // This method creates the memory region used to store performance
 957 // data for the JVM. The memory may be created in standard or
 958 // shared memory.
 959 //
 960 void PerfMemory::create_memory_region(size_t size) {
 961 
 962   if (PerfDisableSharedMem) {
 963     // do not share the memory for the performance data.
 964     _start = create_standard_memory(size);
 965   }
 966   else {
 967     _start = create_shared_memory(size);
 968     if (_start == NULL) {
 969 
 970       // creation of the shared memory region failed, attempt
 971       // to create a contiguous, non-shared memory region instead.
 972       //
 973       if (PrintMiscellaneous && Verbose) {
 974         warning("Reverting to non-shared PerfMemory region.\n");
 975       }
 976       PerfDisableSharedMem = true;
 977       _start = create_standard_memory(size);
 978     }
 979   }
 980 
 981   if (_start != NULL) _capacity = size;
 982 
 983 }
 984 
 985 // delete the PerfData memory region
 986 //
 987 // This method deletes the memory region used to store performance
 988 // data for the JVM. The memory region indicated by the <address, size>
 989 // tuple will be inaccessible after a call to this method.
 990 //
 991 void PerfMemory::delete_memory_region() {
 992 
 993   assert((start() != NULL && capacity() > 0), "verify proper state");
 994 
 995   // If user specifies PerfDataSaveFile, it will save the performance data
 996   // to the specified file name no matter whether PerfDataSaveToFile is specified
 997   // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
 998   // -XX:+PerfDataSaveToFile.
 999   if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1000     save_memory_to_file(start(), capacity());
1001   }
1002 
1003   if (PerfDisableSharedMem) {
1004     delete_standard_memory(start(), capacity());
1005   }
1006   else {
1007     delete_shared_memory(start(), capacity());
1008   }
1009 }
1010 
1011 // attach to the PerfData memory region for another JVM
1012 //
1013 // This method returns an <address, size> tuple that points to
1014 // a memory buffer that is kept reasonably synchronized with
1015 // the PerfData memory region for the indicated JVM. This
1016 // buffer may be kept in synchronization via shared memory
1017 // or some other mechanism that keeps the buffer updated.
1018 //
1019 // If the JVM chooses not to support the attachability feature,
1020 // this method should throw an UnsupportedOperation exception.
1021 //
1022 // This implementation utilizes named shared memory to map
1023 // the indicated process's PerfData memory region into this JVMs
1024 // address space.
1025 //
1026 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1027 
1028   if (vmid == 0 || vmid == os::current_process_id()) {
1029      *addrp = start();
1030      *sizep = capacity();
1031      return;
1032   }
1033 
1034   mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1035 }
1036 
1037 // detach from the PerfData memory region of another JVM
1038 //
1039 // This method detaches the PerfData memory region of another
1040 // JVM, specified as an <address, size> tuple of a buffer
1041 // in this process's address space. This method may perform
1042 // arbitrary actions to accomplish the detachment. The memory
1043 // region specified by <address, size> will be inaccessible after
1044 // a call to this method.
1045 //
1046 // If the JVM chooses not to support the attachability feature,
1047 // this method should throw an UnsupportedOperation exception.
1048 //
1049 // This implementation utilizes named shared memory to detach
1050 // the indicated process's PerfData memory region from this
1051 // process's address space.
1052 //
1053 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1054 
1055   assert(addr != 0, "address sanity check");
1056   assert(bytes > 0, "capacity sanity check");
1057 
1058   if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1059     // prevent accidental detachment of this process's PerfMemory region
1060     return;
1061   }
1062 
1063   unmap_shared(addr, bytes);
1064 }
1065 
1066 char* PerfMemory::backing_store_filename() {
1067   return backing_store_file_name;
1068 }