1 /*

     2  * Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 # include "incls/_precompiled.incl"

    26 # include "incls/_perfMemory_solaris.cpp.incl"

    27 

    28 // put OS-includes here

    29 # include <sys/types.h>

    30 # include <sys/mman.h>

    31 # include <errno.h>

    32 # include <stdio.h>

    33 # include <unistd.h>

    34 # include <sys/stat.h>

    35 # include <signal.h>

    36 # include <pwd.h>

    37 # include <procfs.h>

    38 

    39 

    40 static char* backing_store_file_name = NULL;  // name of the backing store

    41                                               // file, if successfully created.

    42 

    43 // Standard Memory Implementation Details

    44 

    45 // create the PerfData memory region in standard memory.

    46 //

    47 static char* create_standard_memory(size_t size) {

    48 

    49   // allocate an aligned chuck of memory

    50   char* mapAddress = os::reserve_memory(size);

    51 

    52   if (mapAddress == NULL) {

    53     return NULL;

    54   }

    55 

    56   // commit memory

    57   if (!os::commit_memory(mapAddress, size)) {

    58     if (PrintMiscellaneous && Verbose) {

    59       warning("Could not commit PerfData memory\n");

    60     }

    61     os::release_memory(mapAddress, size);

    62     return NULL;

    63   }

    64 

    65   return mapAddress;

    66 }

    67 

    68 // delete the PerfData memory region

    69 //

    70 static void delete_standard_memory(char* addr, size_t size) {

    71 

    72   // there are no persistent external resources to cleanup for standard

    73   // memory. since DestroyJavaVM does not support unloading of the JVM,

    74   // cleanup of the memory resource is not performed. The memory will be

    75   // reclaimed by the OS upon termination of the process.

    76   //

    77   return;

    78 }

    79 

    80 // save the specified memory region to the given file

    81 //

    82 // Note: this function might be called from signal handler (by os::abort()),

    83 // don't allocate heap memory.

    84 //

    85 static void save_memory_to_file(char* addr, size_t size) {

    86 

    87   const char* destfile = PerfMemory::get_perfdata_file_path();

    88   assert(destfile[0] != '\0', "invalid PerfData file path");

    89 

    90   int result;

    91 

    92   RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),

    93               result);;

    94   if (result == OS_ERR) {

    95     if (PrintMiscellaneous && Verbose) {

    96       warning("Could not create Perfdata save file: %s: %s\n",

    97               destfile, strerror(errno));

    98     }

    99   } else {

   100 

   101     int fd = result;

   102 

   103     for (size_t remaining = size; remaining > 0;) {

   104 

   105       RESTARTABLE(::write(fd, addr, remaining), result);

   106       if (result == OS_ERR) {

   107         if (PrintMiscellaneous && Verbose) {

   108           warning("Could not write Perfdata save file: %s: %s\n",

   109                   destfile, strerror(errno));

   110         }

   111         break;

   112       }

   113       remaining -= (size_t)result;

   114       addr += result;

   115     }

   116 

   117     RESTARTABLE(::close(fd), result);

   118     if (PrintMiscellaneous && Verbose) {

   119       if (result == OS_ERR) {

   120         warning("Could not close %s: %s\n", destfile, strerror(errno));

   121       }

   122     }

   123   }

   124   FREE_C_HEAP_ARRAY(char, destfile);

   125 }

   126 

   127 

   128 // Shared Memory Implementation Details

   129 

   130 // Note: the solaris and linux shared memory implementation uses the mmap

   131 // interface with a backing store file to implement named shared memory.

   132 // Using the file system as the name space for shared memory allows a

   133 // common name space to be supported across a variety of platforms. It

   134 // also provides a name space that Java applications can deal with through

   135 // simple file apis.

   136 //

   137 // The solaris and linux implementations store the backing store file in

   138 // a user specific temporary directory located in the /tmp file system,

   139 // which is always a local file system and is sometimes a RAM based file

   140 // system.

   141 

   142 // return the user specific temporary directory name.

   143 //

   144 // the caller is expected to free the allocated memory.

   145 //

   146 static char* get_user_tmp_dir(const char* user) {

   147 

   148   const char* tmpdir = os::get_temp_directory();

   149   const char* perfdir = PERFDATA_NAME;

   150   size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 2;

   151   char* dirname = NEW_C_HEAP_ARRAY(char, nbytes);

   152 

   153   // construct the path name to user specific tmp directory

   154   snprintf(dirname, nbytes, "%s%s_%s", tmpdir, perfdir, user);

   155 

   156   return dirname;

   157 }

   158 

   159 // convert the given file name into a process id. if the file

   160 // does not meet the file naming constraints, return 0.

   161 //

   162 static pid_t filename_to_pid(const char* filename) {

   163 

   164   // a filename that doesn't begin with a digit is not a

   165   // candidate for conversion.

   166   //

   167   if (!isdigit(*filename)) {

   168     return 0;

   169   }

   170 

   171   // check if file name can be converted to an integer without

   172   // any leftover characters.

   173   //

   174   char* remainder = NULL;

   175   errno = 0;

   176   pid_t pid = (pid_t)strtol(filename, &remainder, 10);

   177 

   178   if (errno != 0) {

   179     return 0;

   180   }

   181 

   182   // check for left over characters. If any, then the filename is

   183   // not a candidate for conversion.

   184   //

   185   if (remainder != NULL && *remainder != '\0') {

   186     return 0;

   187   }

   188 

   189   // successful conversion, return the pid

   190   return pid;

   191 }

   192 

   193 

   194 // check if the given path is considered a secure directory for

   195 // the backing store files. Returns true if the directory exists

   196 // and is considered a secure location. Returns false if the path

   197 // is a symbolic link or if an error occured.

   198 //

   199 static bool is_directory_secure(const char* path) {

   200   struct stat statbuf;

   201   int result = 0;

   202 

   203   RESTARTABLE(::lstat(path, &statbuf), result);

   204   if (result == OS_ERR) {

   205     return false;

   206   }

   207 

   208   // the path exists, now check it's mode

   209   if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {

   210     // the path represents a link or some non-directory file type,

   211     // which is not what we expected. declare it insecure.

   212     //

   213     return false;

   214   }

   215   else {

   216     // we have an existing directory, check if the permissions are safe.

   217     //

   218     if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {

   219       // the directory is open for writing and could be subjected

   220       // to a symlnk attack. declare it insecure.

   221       //

   222       return false;

   223     }

   224   }

   225   return true;

   226 }

   227 

   228 

   229 // return the user name for the given user id

   230 //

   231 // the caller is expected to free the allocated memory.

   232 //

   233 static char* get_user_name(uid_t uid) {

   234 

   235   struct passwd pwent;

   236 

   237   // determine the max pwbuf size from sysconf, and hardcode

   238   // a default if this not available through sysconf.

   239   //

   240   long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);

   241   if (bufsize == -1)

   242     bufsize = 1024;

   243 

   244   char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize);

   245 

   246 #ifdef _GNU_SOURCE

   247   struct passwd* p = NULL;

   248   int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);

   249 #else  // _GNU_SOURCE

   250   struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize);

   251 #endif // _GNU_SOURCE

   252 

   253   if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {

   254     if (PrintMiscellaneous && Verbose) {

   255       if (p == NULL) {

   256         warning("Could not retrieve passwd entry: %s\n",

   257                 strerror(errno));

   258       }

   259       else {

   260         warning("Could not determine user name: %s\n",

   261                 p->pw_name == NULL ? "pw_name = NULL" :

   262                                      "pw_name zero length");

   263       }

   264     }

   265     FREE_C_HEAP_ARRAY(char, pwbuf);

   266     return NULL;

   267   }

   268 

   269   char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1);

   270   strcpy(user_name, p->pw_name);

   271 

   272   FREE_C_HEAP_ARRAY(char, pwbuf);

   273   return user_name;

   274 }

   275 

   276 // return the name of the user that owns the process identified by vmid.

   277 //

   278 // This method uses a slow directory search algorithm to find the backing

   279 // store file for the specified vmid and returns the user name, as determined

   280 // by the user name suffix of the hsperfdata_<username> directory name.

   281 //

   282 // the caller is expected to free the allocated memory.

   283 //

   284 static char* get_user_name_slow(int vmid, TRAPS) {

   285 

   286   // short circuit the directory search if the process doesn't even exist.

   287   if (kill(vmid, 0) == OS_ERR) {

   288     if (errno == ESRCH) {

   289       THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),

   290                   "Process not found");

   291     }

   292     else /* EPERM */ {

   293       THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));

   294     }

   295   }

   296 

   297   // directory search

   298   char* oldest_user = NULL;

   299   time_t oldest_ctime = 0;

   300 

   301   const char* tmpdirname = os::get_temp_directory();

   302 

   303   DIR* tmpdirp = os::opendir(tmpdirname);

   304 

   305   if (tmpdirp == NULL) {

   306     return NULL;

   307   }

   308 

   309   // for each entry in the directory that matches the pattern hsperfdata_*,

   310   // open the directory and check if the file for the given vmid exists.

   311   // The file with the expected name and the latest creation date is used

   312   // to determine the user name for the process id.

   313   //

   314   struct dirent* dentry;

   315   char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname));

   316   errno = 0;

   317   while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {

   318 

   319     // check if the directory entry is a hsperfdata file

   320     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {

   321       continue;

   322     }

   323 

   324     char* usrdir_name = NEW_C_HEAP_ARRAY(char,

   325                               strlen(tmpdirname) + strlen(dentry->d_name) + 1);

   326     strcpy(usrdir_name, tmpdirname);

   327     strcat(usrdir_name, dentry->d_name);

   328 

   329     DIR* subdirp = os::opendir(usrdir_name);

   330 

   331     if (subdirp == NULL) {

   332       FREE_C_HEAP_ARRAY(char, usrdir_name);

   333       continue;

   334     }

   335 

   336     // Since we don't create the backing store files in directories

   337     // pointed to by symbolic links, we also don't follow them when

   338     // looking for the files. We check for a symbolic link after the

   339     // call to opendir in order to eliminate a small window where the

   340     // symlink can be exploited.

   341     //

   342     if (!is_directory_secure(usrdir_name)) {

   343       FREE_C_HEAP_ARRAY(char, usrdir_name);

   344       os::closedir(subdirp);

   345       continue;

   346     }

   347 

   348     struct dirent* udentry;

   349     char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name));

   350     errno = 0;

   351     while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {

   352 

   353       if (filename_to_pid(udentry->d_name) == vmid) {

   354         struct stat statbuf;

   355         int result;

   356 

   357         char* filename = NEW_C_HEAP_ARRAY(char,

   358                             strlen(usrdir_name) + strlen(udentry->d_name) + 2);

   359 

   360         strcpy(filename, usrdir_name);

   361         strcat(filename, "/");

   362         strcat(filename, udentry->d_name);

   363 

   364         // don't follow symbolic links for the file

   365         RESTARTABLE(::lstat(filename, &statbuf), result);

   366         if (result == OS_ERR) {

   367            FREE_C_HEAP_ARRAY(char, filename);

   368            continue;

   369         }

   370 

   371         // skip over files that are not regular files.

   372         if (!S_ISREG(statbuf.st_mode)) {

   373           FREE_C_HEAP_ARRAY(char, filename);

   374           continue;

   375         }

   376 

   377         // compare and save filename with latest creation time

   378         if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {

   379 

   380           if (statbuf.st_ctime > oldest_ctime) {

   381             char* user = strchr(dentry->d_name, '_') + 1;

   382 

   383             if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);

   384             oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1);

   385 

   386             strcpy(oldest_user, user);

   387             oldest_ctime = statbuf.st_ctime;

   388           }

   389         }

   390 

   391         FREE_C_HEAP_ARRAY(char, filename);

   392       }

   393     }

   394     os::closedir(subdirp);

   395     FREE_C_HEAP_ARRAY(char, udbuf);

   396     FREE_C_HEAP_ARRAY(char, usrdir_name);

   397   }

   398   os::closedir(tmpdirp);

   399   FREE_C_HEAP_ARRAY(char, tdbuf);

   400 

   401   return(oldest_user);

   402 }

   403 

   404 // return the name of the user that owns the JVM indicated by the given vmid.

   405 //

   406 static char* get_user_name(int vmid, TRAPS) {

   407 

   408   char psinfo_name[PATH_MAX];

   409   int result;

   410 

   411   snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);

   412 

   413   RESTARTABLE(::open(psinfo_name, O_RDONLY), result);

   414 

   415   if (result != OS_ERR) {

   416     int fd = result;

   417 

   418     psinfo_t psinfo;

   419     char* addr = (char*)&psinfo;

   420 

   421     for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {

   422 

   423       RESTARTABLE(::read(fd, addr, remaining), result);

   424       if (result == OS_ERR) {

   425         THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");

   426       }

   427       remaining-=result;

   428       addr+=result;

   429     }

   430 

   431     RESTARTABLE(::close(fd), result);

   432 

   433     // get the user name for the effective user id of the process

   434     char* user_name = get_user_name(psinfo.pr_euid);

   435 

   436     return user_name;

   437   }

   438 

   439   if (result == OS_ERR && errno == EACCES) {

   440 

   441     // In this case, the psinfo file for the process id existed,

   442     // but we didn't have permission to access it.

   443     THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),

   444                 strerror(errno));

   445   }

   446 

   447   // at this point, we don't know if the process id itself doesn't

   448   // exist or if the psinfo file doesn't exit. If the psinfo file

   449   // doesn't exist, then we are running on Solaris 2.5.1 or earlier.

   450   // since the structured procfs and old procfs interfaces can't be

   451   // mixed, we attempt to find the file through a directory search.

   452 

   453   return get_user_name_slow(vmid, CHECK_NULL);

   454 }

   455 

   456 // return the file name of the backing store file for the named

   457 // shared memory region for the given user name and vmid.

   458 //

   459 // the caller is expected to free the allocated memory.

   460 //

   461 static char* get_sharedmem_filename(const char* dirname, int vmid) {

   462 

   463   // add 2 for the file separator and a NULL terminator.

   464   size_t nbytes = strlen(dirname) + UINT_CHARS + 2;

   465 

   466   char* name = NEW_C_HEAP_ARRAY(char, nbytes);

   467   snprintf(name, nbytes, "%s/%d", dirname, vmid);

   468 

   469   return name;

   470 }

   471 

   472 

   473 // remove file

   474 //

   475 // this method removes the file specified by the given path

   476 //

   477 static void remove_file(const char* path) {

   478 

   479   int result;

   480 

   481   // if the file is a directory, the following unlink will fail. since

   482   // we don't expect to find directories in the user temp directory, we

   483   // won't try to handle this situation. even if accidentially or

   484   // maliciously planted, the directory's presence won't hurt anything.

   485   //

   486   RESTARTABLE(::unlink(path), result);

   487   if (PrintMiscellaneous && Verbose && result == OS_ERR) {

   488     if (errno != ENOENT) {

   489       warning("Could not unlink shared memory backing"

   490               " store file %s : %s\n", path, strerror(errno));

   491     }

   492   }

   493 }

   494 

   495 

   496 // remove file

   497 //

   498 // this method removes the file with the given file name in the

   499 // named directory.

   500 //

   501 static void remove_file(const char* dirname, const char* filename) {

   502 

   503   size_t nbytes = strlen(dirname) + strlen(filename) + 2;

   504   char* path = NEW_C_HEAP_ARRAY(char, nbytes);

   505 

   506   strcpy(path, dirname);

   507   strcat(path, "/");

   508   strcat(path, filename);

   509 

   510   remove_file(path);

   511 

   512   FREE_C_HEAP_ARRAY(char, path);

   513 }

   514 

   515 

   516 // cleanup stale shared memory resources

   517 //

   518 // This method attempts to remove all stale shared memory files in

   519 // the named user temporary directory. It scans the named directory

   520 // for files matching the pattern ^$[0-9]*$. For each file found, the

   521 // process id is extracted from the file name and a test is run to

   522 // determine if the process is alive. If the process is not alive,

   523 // any stale file resources are removed.

   524 //

   525 static void cleanup_sharedmem_resources(const char* dirname) {

   526 

   527   // open the user temp directory

   528   DIR* dirp = os::opendir(dirname);

   529 

   530   if (dirp == NULL) {

   531     // directory doesn't exist, so there is nothing to cleanup

   532     return;

   533   }

   534 

   535   if (!is_directory_secure(dirname)) {

   536     // the directory is not a secure directory

   537     return;

   538   }

   539 

   540   // for each entry in the directory that matches the expected file

   541   // name pattern, determine if the file resources are stale and if

   542   // so, remove the file resources. Note, instrumented HotSpot processes

   543   // for this user may start and/or terminate during this search and

   544   // remove or create new files in this directory. The behavior of this

   545   // loop under these conditions is dependent upon the implementation of

   546   // opendir/readdir.

   547   //

   548   struct dirent* entry;

   549   char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname));

   550   errno = 0;

   551   while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {

   552 

   553     pid_t pid = filename_to_pid(entry->d_name);

   554 

   555     if (pid == 0) {

   556 

   557       if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {

   558 

   559         // attempt to remove all unexpected files, except "." and ".."

   560         remove_file(dirname, entry->d_name);

   561       }

   562 

   563       errno = 0;

   564       continue;

   565     }

   566 

   567     // we now have a file name that converts to a valid integer

   568     // that could represent a process id . if this process id

   569     // matches the current process id or the process is not running,

   570     // then remove the stale file resources.

   571     //

   572     // process liveness is detected by sending signal number 0 to

   573     // the process id (see kill(2)). if kill determines that the

   574     // process does not exist, then the file resources are removed.

   575     // if kill determines that that we don't have permission to

   576     // signal the process, then the file resources are assumed to

   577     // be stale and are removed because the resources for such a

   578     // process should be in a different user specific directory.

   579     //

   580     if ((pid == os::current_process_id()) ||

   581         (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {

   582 

   583         remove_file(dirname, entry->d_name);

   584     }

   585     errno = 0;

   586   }

   587   os::closedir(dirp);

   588   FREE_C_HEAP_ARRAY(char, dbuf);

   589 }

   590 

   591 // make the user specific temporary directory. Returns true if

   592 // the directory exists and is secure upon return. Returns false

   593 // if the directory exists but is either a symlink, is otherwise

   594 // insecure, or if an error occurred.

   595 //

   596 static bool make_user_tmp_dir(const char* dirname) {

   597 

   598   // create the directory with 0755 permissions. note that the directory

   599   // will be owned by euid::egid, which may not be the same as uid::gid.

   600   //

   601   if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {

   602     if (errno == EEXIST) {

   603       // The directory already exists and was probably created by another

   604       // JVM instance. However, this could also be the result of a

   605       // deliberate symlink. Verify that the existing directory is safe.

   606       //

   607       if (!is_directory_secure(dirname)) {

   608         // directory is not secure

   609         if (PrintMiscellaneous && Verbose) {

   610           warning("%s directory is insecure\n", dirname);

   611         }

   612         return false;

   613       }

   614     }

   615     else {

   616       // we encountered some other failure while attempting

   617       // to create the directory

   618       //

   619       if (PrintMiscellaneous && Verbose) {

   620         warning("could not create directory %s: %s\n",

   621                 dirname, strerror(errno));

   622       }

   623       return false;

   624     }

   625   }

   626   return true;

   627 }

   628 

   629 // create the shared memory file resources

   630 //

   631 // This method creates the shared memory file with the given size

   632 // This method also creates the user specific temporary directory, if

   633 // it does not yet exist.

   634 //

   635 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {

   636 

   637   // make the user temporary directory

   638   if (!make_user_tmp_dir(dirname)) {

   639     // could not make/find the directory or the found directory

   640     // was not secure

   641     return -1;

   642   }

   643 

   644   int result;

   645 

   646   RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);

   647   if (result == OS_ERR) {

   648     if (PrintMiscellaneous && Verbose) {

   649       warning("could not create file %s: %s\n", filename, strerror(errno));

   650     }

   651     return -1;

   652   }

   653 

   654   // save the file descriptor

   655   int fd = result;

   656 

   657   // set the file size

   658   RESTARTABLE(::ftruncate(fd, (off_t)size), result);

   659   if (result == OS_ERR) {

   660     if (PrintMiscellaneous && Verbose) {

   661       warning("could not set shared memory file size: %s\n", strerror(errno));

   662     }

   663     RESTARTABLE(::close(fd), result);

   664     return -1;

   665   }

   666 

   667   return fd;

   668 }

   669 

   670 // open the shared memory file for the given user and vmid. returns

   671 // the file descriptor for the open file or -1 if the file could not

   672 // be opened.

   673 //

   674 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {

   675 

   676   // open the file

   677   int result;

   678   RESTARTABLE(::open(filename, oflags), result);

   679   if (result == OS_ERR) {

   680     if (errno == ENOENT) {

   681       THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),

   682                   "Process not found");

   683     }

   684     else if (errno == EACCES) {

   685       THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),

   686                   "Permission denied");

   687     }

   688     else {

   689       THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));

   690     }

   691   }

   692 

   693   return result;

   694 }

   695 

   696 // create a named shared memory region. returns the address of the

   697 // memory region on success or NULL on failure. A return value of

   698 // NULL will ultimately disable the shared memory feature.

   699 //

   700 // On Solaris and Linux, the name space for shared memory objects

   701 // is the file system name space.

   702 //

   703 // A monitoring application attaching to a JVM does not need to know

   704 // the file system name of the shared memory object. However, it may

   705 // be convenient for applications to discover the existence of newly

   706 // created and terminating JVMs by watching the file system name space

   707 // for files being created or removed.

   708 //

   709 static char* mmap_create_shared(size_t size) {

   710 

   711   int result;

   712   int fd;

   713   char* mapAddress;

   714 

   715   int vmid = os::current_process_id();

   716 

   717   char* user_name = get_user_name(geteuid());

   718 

   719   if (user_name == NULL)

   720     return NULL;

   721 

   722   char* dirname = get_user_tmp_dir(user_name);

   723   char* filename = get_sharedmem_filename(dirname, vmid);

   724 

   725   // cleanup any stale shared memory files

   726   cleanup_sharedmem_resources(dirname);

   727 

   728   assert(((size > 0) && (size % os::vm_page_size() == 0)),

   729          "unexpected PerfMemory region size");

   730 

   731   fd = create_sharedmem_resources(dirname, filename, size);

   732 

   733   FREE_C_HEAP_ARRAY(char, user_name);

   734   FREE_C_HEAP_ARRAY(char, dirname);

   735 

   736   if (fd == -1) {

   737     FREE_C_HEAP_ARRAY(char, filename);

   738     return NULL;

   739   }

   740 

   741   mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

   742 

   743   // attempt to close the file - restart it if it was interrupted,

   744   // but ignore other failures

   745   RESTARTABLE(::close(fd), result);

   746   assert(result != OS_ERR, "could not close file");

   747 

   748   if (mapAddress == MAP_FAILED) {

   749     if (PrintMiscellaneous && Verbose) {

   750       warning("mmap failed -  %s\n", strerror(errno));

   751     }

   752     remove_file(filename);

   753     FREE_C_HEAP_ARRAY(char, filename);

   754     return NULL;

   755   }

   756 

   757   // save the file name for use in delete_shared_memory()

   758   backing_store_file_name = filename;

   759 

   760   // clear the shared memory region

   761   (void)::memset((void*) mapAddress, 0, size);

   762 

   763   return mapAddress;

   764 }

   765 

   766 // release a named shared memory region

   767 //

   768 static void unmap_shared(char* addr, size_t bytes) {

   769   os::release_memory(addr, bytes);

   770 }

   771 

   772 // create the PerfData memory region in shared memory.

   773 //

   774 static char* create_shared_memory(size_t size) {

   775 

   776   // create the shared memory region.

   777   return mmap_create_shared(size);

   778 }

   779 

   780 // delete the shared PerfData memory region

   781 //

   782 static void delete_shared_memory(char* addr, size_t size) {

   783 

   784   // cleanup the persistent shared memory resources. since DestroyJavaVM does

   785   // not support unloading of the JVM, unmapping of the memory resource is

   786   // not performed. The memory will be reclaimed by the OS upon termination of

   787   // the process. The backing store file is deleted from the file system.

   788 

   789   assert(!PerfDisableSharedMem, "shouldn't be here");

   790 

   791   if (backing_store_file_name != NULL) {

   792     remove_file(backing_store_file_name);

   793     // Don't.. Free heap memory could deadlock os::abort() if it is called

   794     // from signal handler. OS will reclaim the heap memory.

   795     // FREE_C_HEAP_ARRAY(char, backing_store_file_name);

   796     backing_store_file_name = NULL;

   797   }

   798 }

   799 

   800 // return the size of the file for the given file descriptor

   801 // or 0 if it is not a valid size for a shared memory file

   802 //

   803 static size_t sharedmem_filesize(int fd, TRAPS) {

   804 

   805   struct stat statbuf;

   806   int result;

   807 

   808   RESTARTABLE(::fstat(fd, &statbuf), result);

   809   if (result == OS_ERR) {

   810     if (PrintMiscellaneous && Verbose) {

   811       warning("fstat failed: %s\n", strerror(errno));

   812     }

   813     THROW_MSG_0(vmSymbols::java_io_IOException(),

   814                 "Could not determine PerfMemory size");

   815   }

   816 

   817   if ((statbuf.st_size == 0) ||

   818      ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {

   819     THROW_MSG_0(vmSymbols::java_lang_Exception(),

   820                 "Invalid PerfMemory size");

   821   }

   822 

   823   return (size_t)statbuf.st_size;

   824 }

   825 

   826 // attach to a named shared memory region.

   827 //

   828 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {

   829 

   830   char* mapAddress;

   831   int result;

   832   int fd;

   833   size_t size;

   834   const char* luser = NULL;

   835 

   836   int mmap_prot;

   837   int file_flags;

   838 

   839   ResourceMark rm;

   840 

   841   // map the high level access mode to the appropriate permission

   842   // constructs for the file and the shared memory mapping.

   843   if (mode == PerfMemory::PERF_MODE_RO) {

   844     mmap_prot = PROT_READ;

   845     file_flags = O_RDONLY;

   846   }

   847   else if (mode == PerfMemory::PERF_MODE_RW) {

   848 #ifdef LATER

   849     mmap_prot = PROT_READ | PROT_WRITE;

   850     file_flags = O_RDWR;

   851 #else

   852     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),

   853               "Unsupported access mode");

   854 #endif

   855   }

   856   else {

   857     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),

   858               "Illegal access mode");

   859   }

   860 

   861   if (user == NULL || strlen(user) == 0) {

   862     luser = get_user_name(vmid, CHECK);

   863   }

   864   else {

   865     luser = user;

   866   }

   867 

   868   if (luser == NULL) {

   869     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),

   870               "Could not map vmid to user Name");

   871   }

   872 

   873   char* dirname = get_user_tmp_dir(luser);

   874 

   875   // since we don't follow symbolic links when creating the backing

   876   // store file, we don't follow them when attaching either.

   877   //

   878   if (!is_directory_secure(dirname)) {

   879     FREE_C_HEAP_ARRAY(char, dirname);

   880     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),

   881               "Process not found");

   882   }

   883 

   884   char* filename = get_sharedmem_filename(dirname, vmid);

   885 

   886   // copy heap memory to resource memory. the open_sharedmem_file

   887   // method below need to use the filename, but could throw an

   888   // exception. using a resource array prevents the leak that

   889   // would otherwise occur.

   890   char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);

   891   strcpy(rfilename, filename);

   892 

   893   // free the c heap resources that are no longer needed

   894   if (luser != user) FREE_C_HEAP_ARRAY(char, luser);

   895   FREE_C_HEAP_ARRAY(char, dirname);

   896   FREE_C_HEAP_ARRAY(char, filename);

   897 

   898   // open the shared memory file for the give vmid

   899   fd = open_sharedmem_file(rfilename, file_flags, CHECK);

   900   assert(fd != OS_ERR, "unexpected value");

   901 

   902   if (*sizep == 0) {

   903     size = sharedmem_filesize(fd, CHECK);

   904     assert(size != 0, "unexpected size");

   905   }

   906 

   907   mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);

   908 

   909   // attempt to close the file - restart if it gets interrupted,

   910   // but ignore other failures

   911   RESTARTABLE(::close(fd), result);

   912   assert(result != OS_ERR, "could not close file");

   913 

   914   if (mapAddress == MAP_FAILED) {

   915     if (PrintMiscellaneous && Verbose) {

   916       warning("mmap failed: %s\n", strerror(errno));

   917     }

   918     THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),

   919               "Could not map PerfMemory");

   920   }

   921 

   922   *addr = mapAddress;

   923   *sizep = size;

   924 

   925   if (PerfTraceMemOps) {

   926     tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "

   927                INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);

   928   }

   929 }

   930 

   931 

   932 

   933 

   934 // create the PerfData memory region

   935 //

   936 // This method creates the memory region used to store performance

   937 // data for the JVM. The memory may be created in standard or

   938 // shared memory.

   939 //

   940 void PerfMemory::create_memory_region(size_t size) {

   941 

   942   if (PerfDisableSharedMem) {

   943     // do not share the memory for the performance data.

   944     _start = create_standard_memory(size);

   945   }

   946   else {

   947     _start = create_shared_memory(size);

   948     if (_start == NULL) {

   949 

   950       // creation of the shared memory region failed, attempt

   951       // to create a contiguous, non-shared memory region instead.

   952       //

   953       if (PrintMiscellaneous && Verbose) {

   954         warning("Reverting to non-shared PerfMemory region.\n");

   955       }

   956       PerfDisableSharedMem = true;

   957       _start = create_standard_memory(size);

   958     }

   959   }

   960 

   961   if (_start != NULL) _capacity = size;

   962 

   963 }

   964 

   965 // delete the PerfData memory region

   966 //

   967 // This method deletes the memory region used to store performance

   968 // data for the JVM. The memory region indicated by the <address, size>

   969 // tuple will be inaccessible after a call to this method.

   970 //

   971 void PerfMemory::delete_memory_region() {

   972 

   973   assert((start() != NULL && capacity() > 0), "verify proper state");

   974 

   975   // If user specifies PerfDataSaveFile, it will save the performance data

   976   // to the specified file name no matter whether PerfDataSaveToFile is specified

   977   // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag

   978   // -XX:+PerfDataSaveToFile.

   979   if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {

   980     save_memory_to_file(start(), capacity());

   981   }

   982 

   983   if (PerfDisableSharedMem) {

   984     delete_standard_memory(start(), capacity());

   985   }

   986   else {

   987     delete_shared_memory(start(), capacity());

   988   }

   989 }

   990 

   991 // attach to the PerfData memory region for another JVM

   992 //

   993 // This method returns an <address, size> tuple that points to

   994 // a memory buffer that is kept reasonably synchronized with

   995 // the PerfData memory region for the indicated JVM. This

   996 // buffer may be kept in synchronization via shared memory

   997 // or some other mechanism that keeps the buffer updated.

   998 //

   999 // If the JVM chooses not to support the attachability feature,

  1000 // this method should throw an UnsupportedOperation exception.

  1001 //

  1002 // This implementation utilizes named shared memory to map

  1003 // the indicated process's PerfData memory region into this JVMs

  1004 // address space.

  1005 //

  1006 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {

  1007 

  1008   if (vmid == 0 || vmid == os::current_process_id()) {

  1009      *addrp = start();

  1010      *sizep = capacity();

  1011      return;

  1012   }

  1013 

  1014   mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);

  1015 }

  1016 

  1017 // detach from the PerfData memory region of another JVM

  1018 //

  1019 // This method detaches the PerfData memory region of another

  1020 // JVM, specified as an <address, size> tuple of a buffer

  1021 // in this process's address space. This method may perform

  1022 // arbitrary actions to accomplish the detachment. The memory

  1023 // region specified by <address, size> will be inaccessible after

  1024 // a call to this method.

  1025 //

  1026 // If the JVM chooses not to support the attachability feature,

  1027 // this method should throw an UnsupportedOperation exception.

  1028 //

  1029 // This implementation utilizes named shared memory to detach

  1030 // the indicated process's PerfData memory region from this

  1031 // process's address space.

  1032 //

  1033 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {

  1034 

  1035   assert(addr != 0, "address sanity check");

  1036   assert(bytes > 0, "capacity sanity check");

  1037 

  1038   if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {

  1039     // prevent accidental detachment of this process's PerfMemory region

  1040     return;

  1041   }

  1042 

  1043   unmap_shared(addr, bytes);

  1044 }

  1045 

  1046 char* PerfMemory::backing_store_filename() {

  1047   return backing_store_file_name;

  1048 }