1 /*
2 * Copyright (c) 2001, 2007, 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 "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) + 3;
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 occurred.
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) + 2);
326 strcpy(usrdir_name, tmpdirname);
327 strcat(usrdir_name, "/");
328 strcat(usrdir_name, dentry->d_name);
329
330 DIR* subdirp = os::opendir(usrdir_name);
331
332 if (subdirp == NULL) {
333 FREE_C_HEAP_ARRAY(char, usrdir_name);
334 continue;
335 }
336
337 // Since we don't create the backing store files in directories
338 // pointed to by symbolic links, we also don't follow them when
339 // looking for the files. We check for a symbolic link after the
340 // call to opendir in order to eliminate a small window where the
341 // symlink can be exploited.
342 //
343 if (!is_directory_secure(usrdir_name)) {
344 FREE_C_HEAP_ARRAY(char, usrdir_name);
345 os::closedir(subdirp);
346 continue;
347 }
348
349 struct dirent* udentry;
350 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name));
351 errno = 0;
352 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
353
354 if (filename_to_pid(udentry->d_name) == vmid) {
355 struct stat statbuf;
356 int result;
357
358 char* filename = NEW_C_HEAP_ARRAY(char,
359 strlen(usrdir_name) + strlen(udentry->d_name) + 2);
360
361 strcpy(filename, usrdir_name);
362 strcat(filename, "/");
363 strcat(filename, udentry->d_name);
364
365 // don't follow symbolic links for the file
366 RESTARTABLE(::lstat(filename, &statbuf), result);
367 if (result == OS_ERR) {
368 FREE_C_HEAP_ARRAY(char, filename);
369 continue;
370 }
371
372 // skip over files that are not regular files.
373 if (!S_ISREG(statbuf.st_mode)) {
374 FREE_C_HEAP_ARRAY(char, filename);
375 continue;
376 }
377
378 // compare and save filename with latest creation time
379 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
380
381 if (statbuf.st_ctime > oldest_ctime) {
382 char* user = strchr(dentry->d_name, '_') + 1;
383
384 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
385 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1);
386
387 strcpy(oldest_user, user);
388 oldest_ctime = statbuf.st_ctime;
389 }
390 }
391
392 FREE_C_HEAP_ARRAY(char, filename);
393 }
394 }
395 os::closedir(subdirp);
396 FREE_C_HEAP_ARRAY(char, udbuf);
397 FREE_C_HEAP_ARRAY(char, usrdir_name);
398 }
399 os::closedir(tmpdirp);
400 FREE_C_HEAP_ARRAY(char, tdbuf);
401
402 return(oldest_user);
403 }
404
405 // return the name of the user that owns the JVM indicated by the given vmid.
406 //
407 static char* get_user_name(int vmid, TRAPS) {
408
409 char psinfo_name[PATH_MAX];
410 int result;
411
412 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
413
414 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
415
416 if (result != OS_ERR) {
417 int fd = result;
418
419 psinfo_t psinfo;
420 char* addr = (char*)&psinfo;
421
422 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
423
424 RESTARTABLE(::read(fd, addr, remaining), result);
425 if (result == OS_ERR) {
426 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
427 }
428 remaining-=result;
429 addr+=result;
430 }
431
432 RESTARTABLE(::close(fd), result);
433
434 // get the user name for the effective user id of the process
435 char* user_name = get_user_name(psinfo.pr_euid);
436
437 return user_name;
438 }
439
440 if (result == OS_ERR && errno == EACCES) {
441
442 // In this case, the psinfo file for the process id existed,
443 // but we didn't have permission to access it.
444 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
445 strerror(errno));
446 }
447
448 // at this point, we don't know if the process id itself doesn't
449 // exist or if the psinfo file doesn't exit. If the psinfo file
450 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
451 // since the structured procfs and old procfs interfaces can't be
452 // mixed, we attempt to find the file through a directory search.
453
454 return get_user_name_slow(vmid, CHECK_NULL);
455 }
456
457 // return the file name of the backing store file for the named
458 // shared memory region for the given user name and vmid.
459 //
460 // the caller is expected to free the allocated memory.
461 //
462 static char* get_sharedmem_filename(const char* dirname, int vmid) {
463
464 // add 2 for the file separator and a NULL terminator.
465 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
466
467 char* name = NEW_C_HEAP_ARRAY(char, nbytes);
468 snprintf(name, nbytes, "%s/%d", dirname, vmid);
469
470 return name;
471 }
472
473
474 // remove file
475 //
476 // this method removes the file specified by the given path
477 //
478 static void remove_file(const char* path) {
479
480 int result;
481
482 // if the file is a directory, the following unlink will fail. since
483 // we don't expect to find directories in the user temp directory, we
484 // won't try to handle this situation. even if accidentially or
485 // maliciously planted, the directory's presence won't hurt anything.
486 //
487 RESTARTABLE(::unlink(path), result);
488 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
489 if (errno != ENOENT) {
490 warning("Could not unlink shared memory backing"
491 " store file %s : %s\n", path, strerror(errno));
492 }
493 }
494 }
495
496
497 // remove file
498 //
499 // this method removes the file with the given file name in the
500 // named directory.
501 //
502 static void remove_file(const char* dirname, const char* filename) {
503
504 size_t nbytes = strlen(dirname) + strlen(filename) + 2;
505 char* path = NEW_C_HEAP_ARRAY(char, nbytes);
506
507 strcpy(path, dirname);
508 strcat(path, "/");
509 strcat(path, filename);
510
511 remove_file(path);
512
513 FREE_C_HEAP_ARRAY(char, path);
514 }
515
516
517 // cleanup stale shared memory resources
518 //
519 // This method attempts to remove all stale shared memory files in
520 // the named user temporary directory. It scans the named directory
521 // for files matching the pattern ^$[0-9]*$. For each file found, the
522 // process id is extracted from the file name and a test is run to
523 // determine if the process is alive. If the process is not alive,
524 // any stale file resources are removed.
525 //
526 static void cleanup_sharedmem_resources(const char* dirname) {
527
528 // open the user temp directory
529 DIR* dirp = os::opendir(dirname);
530
531 if (dirp == NULL) {
532 // directory doesn't exist, so there is nothing to cleanup
533 return;
534 }
535
536 if (!is_directory_secure(dirname)) {
537 // the directory is not a secure directory
538 return;
539 }
540
541 // for each entry in the directory that matches the expected file
542 // name pattern, determine if the file resources are stale and if
543 // so, remove the file resources. Note, instrumented HotSpot processes
544 // for this user may start and/or terminate during this search and
545 // remove or create new files in this directory. The behavior of this
546 // loop under these conditions is dependent upon the implementation of
547 // opendir/readdir.
548 //
549 struct dirent* entry;
550 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname));
551 errno = 0;
552 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
553
554 pid_t pid = filename_to_pid(entry->d_name);
555
556 if (pid == 0) {
557
558 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
559
560 // attempt to remove all unexpected files, except "." and ".."
561 remove_file(dirname, entry->d_name);
562 }
563
564 errno = 0;
565 continue;
566 }
567
568 // we now have a file name that converts to a valid integer
569 // that could represent a process id . if this process id
570 // matches the current process id or the process is not running,
571 // then remove the stale file resources.
572 //
573 // process liveness is detected by sending signal number 0 to
574 // the process id (see kill(2)). if kill determines that the
575 // process does not exist, then the file resources are removed.
576 // if kill determines that that we don't have permission to
577 // signal the process, then the file resources are assumed to
578 // be stale and are removed because the resources for such a
579 // process should be in a different user specific directory.
580 //
581 if ((pid == os::current_process_id()) ||
582 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
583
584 remove_file(dirname, entry->d_name);
585 }
586 errno = 0;
587 }
588 os::closedir(dirp);
589 FREE_C_HEAP_ARRAY(char, dbuf);
590 }
591
592 // make the user specific temporary directory. Returns true if
593 // the directory exists and is secure upon return. Returns false
594 // if the directory exists but is either a symlink, is otherwise
595 // insecure, or if an error occurred.
596 //
597 static bool make_user_tmp_dir(const char* dirname) {
598
599 // create the directory with 0755 permissions. note that the directory
600 // will be owned by euid::egid, which may not be the same as uid::gid.
601 //
602 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
603 if (errno == EEXIST) {
604 // The directory already exists and was probably created by another
605 // JVM instance. However, this could also be the result of a
606 // deliberate symlink. Verify that the existing directory is safe.
607 //
608 if (!is_directory_secure(dirname)) {
609 // directory is not secure
610 if (PrintMiscellaneous && Verbose) {
611 warning("%s directory is insecure\n", dirname);
612 }
613 return false;
614 }
615 }
616 else {
617 // we encountered some other failure while attempting
618 // to create the directory
619 //
620 if (PrintMiscellaneous && Verbose) {
621 warning("could not create directory %s: %s\n",
622 dirname, strerror(errno));
623 }
624 return false;
625 }
626 }
627 return true;
628 }
629
630 // create the shared memory file resources
631 //
632 // This method creates the shared memory file with the given size
633 // This method also creates the user specific temporary directory, if
634 // it does not yet exist.
635 //
636 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
637
638 // make the user temporary directory
639 if (!make_user_tmp_dir(dirname)) {
640 // could not make/find the directory or the found directory
641 // was not secure
642 return -1;
643 }
644
645 int result;
646
647 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
648 if (result == OS_ERR) {
649 if (PrintMiscellaneous && Verbose) {
650 warning("could not create file %s: %s\n", filename, strerror(errno));
651 }
652 return -1;
653 }
654
655 // save the file descriptor
656 int fd = result;
657
658 // set the file size
659 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
660 if (result == OS_ERR) {
661 if (PrintMiscellaneous && Verbose) {
662 warning("could not set shared memory file size: %s\n", strerror(errno));
663 }
664 RESTARTABLE(::close(fd), result);
665 return -1;
666 }
667
668 return fd;
669 }
670
671 // open the shared memory file for the given user and vmid. returns
672 // the file descriptor for the open file or -1 if the file could not
673 // be opened.
674 //
675 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
676
677 // open the file
678 int result;
679 RESTARTABLE(::open(filename, oflags), result);
680 if (result == OS_ERR) {
681 if (errno == ENOENT) {
682 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
683 "Process not found");
684 }
685 else if (errno == EACCES) {
686 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
687 "Permission denied");
688 }
689 else {
690 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
691 }
692 }
693
694 return result;
695 }
696
697 // create a named shared memory region. returns the address of the
698 // memory region on success or NULL on failure. A return value of
699 // NULL will ultimately disable the shared memory feature.
700 //
701 // On Solaris and Linux, the name space for shared memory objects
702 // is the file system name space.
703 //
704 // A monitoring application attaching to a JVM does not need to know
705 // the file system name of the shared memory object. However, it may
706 // be convenient for applications to discover the existence of newly
707 // created and terminating JVMs by watching the file system name space
708 // for files being created or removed.
709 //
710 static char* mmap_create_shared(size_t size) {
711
712 int result;
713 int fd;
714 char* mapAddress;
715
716 int vmid = os::current_process_id();
717
718 char* user_name = get_user_name(geteuid());
719
720 if (user_name == NULL)
721 return NULL;
722
723 char* dirname = get_user_tmp_dir(user_name);
724 char* filename = get_sharedmem_filename(dirname, vmid);
725
726 // cleanup any stale shared memory files
727 cleanup_sharedmem_resources(dirname);
728
729 assert(((size > 0) && (size % os::vm_page_size() == 0)),
730 "unexpected PerfMemory region size");
731
732 fd = create_sharedmem_resources(dirname, filename, size);
733
734 FREE_C_HEAP_ARRAY(char, user_name);
735 FREE_C_HEAP_ARRAY(char, dirname);
736
737 if (fd == -1) {
738 FREE_C_HEAP_ARRAY(char, filename);
739 return NULL;
740 }
741
742 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
743
744 // attempt to close the file - restart it if it was interrupted,
745 // but ignore other failures
746 RESTARTABLE(::close(fd), result);
747 assert(result != OS_ERR, "could not close file");
748
749 if (mapAddress == MAP_FAILED) {
750 if (PrintMiscellaneous && Verbose) {
751 warning("mmap failed - %s\n", strerror(errno));
752 }
753 remove_file(filename);
754 FREE_C_HEAP_ARRAY(char, filename);
755 return NULL;
756 }
757
758 // save the file name for use in delete_shared_memory()
759 backing_store_file_name = filename;
760
761 // clear the shared memory region
762 (void)::memset((void*) mapAddress, 0, size);
763
764 return mapAddress;
765 }
766
767 // release a named shared memory region
768 //
769 static void unmap_shared(char* addr, size_t bytes) {
770 os::release_memory(addr, bytes);
771 }
772
773 // create the PerfData memory region in shared memory.
774 //
775 static char* create_shared_memory(size_t size) {
776
777 // create the shared memory region.
778 return mmap_create_shared(size);
779 }
780
781 // delete the shared PerfData memory region
782 //
783 static void delete_shared_memory(char* addr, size_t size) {
784
785 // cleanup the persistent shared memory resources. since DestroyJavaVM does
786 // not support unloading of the JVM, unmapping of the memory resource is
787 // not performed. The memory will be reclaimed by the OS upon termination of
788 // the process. The backing store file is deleted from the file system.
789
790 assert(!PerfDisableSharedMem, "shouldn't be here");
791
792 if (backing_store_file_name != NULL) {
793 remove_file(backing_store_file_name);
794 // Don't.. Free heap memory could deadlock os::abort() if it is called
795 // from signal handler. OS will reclaim the heap memory.
796 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
797 backing_store_file_name = NULL;
798 }
799 }
800
801 // return the size of the file for the given file descriptor
802 // or 0 if it is not a valid size for a shared memory file
803 //
804 static size_t sharedmem_filesize(int fd, TRAPS) {
805
806 struct stat statbuf;
807 int result;
808
809 RESTARTABLE(::fstat(fd, &statbuf), result);
810 if (result == OS_ERR) {
811 if (PrintMiscellaneous && Verbose) {
812 warning("fstat failed: %s\n", strerror(errno));
813 }
814 THROW_MSG_0(vmSymbols::java_io_IOException(),
815 "Could not determine PerfMemory size");
816 }
817
818 if ((statbuf.st_size == 0) ||
819 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
820 THROW_MSG_0(vmSymbols::java_lang_Exception(),
821 "Invalid PerfMemory size");
822 }
823
824 return (size_t)statbuf.st_size;
825 }
826
827 // attach to a named shared memory region.
828 //
829 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
830
831 char* mapAddress;
832 int result;
833 int fd;
834 size_t size;
835 const char* luser = NULL;
836
837 int mmap_prot;
838 int file_flags;
839
840 ResourceMark rm;
841
842 // map the high level access mode to the appropriate permission
843 // constructs for the file and the shared memory mapping.
844 if (mode == PerfMemory::PERF_MODE_RO) {
845 mmap_prot = PROT_READ;
846 file_flags = O_RDONLY;
847 }
848 else if (mode == PerfMemory::PERF_MODE_RW) {
849 #ifdef LATER
850 mmap_prot = PROT_READ | PROT_WRITE;
851 file_flags = O_RDWR;
852 #else
853 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
854 "Unsupported access mode");
855 #endif
856 }
857 else {
858 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
859 "Illegal access mode");
860 }
861
862 if (user == NULL || strlen(user) == 0) {
863 luser = get_user_name(vmid, CHECK);
864 }
865 else {
866 luser = user;
867 }
868
869 if (luser == NULL) {
870 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
871 "Could not map vmid to user Name");
872 }
873
874 char* dirname = get_user_tmp_dir(luser);
875
876 // since we don't follow symbolic links when creating the backing
877 // store file, we don't follow them when attaching either.
878 //
879 if (!is_directory_secure(dirname)) {
880 FREE_C_HEAP_ARRAY(char, dirname);
881 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
882 "Process not found");
883 }
884
885 char* filename = get_sharedmem_filename(dirname, vmid);
886
887 // copy heap memory to resource memory. the open_sharedmem_file
888 // method below need to use the filename, but could throw an
889 // exception. using a resource array prevents the leak that
890 // would otherwise occur.
891 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
892 strcpy(rfilename, filename);
893
894 // free the c heap resources that are no longer needed
895 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
896 FREE_C_HEAP_ARRAY(char, dirname);
897 FREE_C_HEAP_ARRAY(char, filename);
898
899 // open the shared memory file for the give vmid
900 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
901 assert(fd != OS_ERR, "unexpected value");
902
903 if (*sizep == 0) {
904 size = sharedmem_filesize(fd, CHECK);
905 assert(size != 0, "unexpected size");
906 }
907
908 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
909
910 // attempt to close the file - restart if it gets interrupted,
911 // but ignore other failures
912 RESTARTABLE(::close(fd), result);
913 assert(result != OS_ERR, "could not close file");
914
915 if (mapAddress == MAP_FAILED) {
916 if (PrintMiscellaneous && Verbose) {
917 warning("mmap failed: %s\n", strerror(errno));
918 }
919 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
920 "Could not map PerfMemory");
921 }
922
923 *addr = mapAddress;
924 *sizep = size;
925
926 if (PerfTraceMemOps) {
927 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
928 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
929 }
930 }
931
932
933
934
935 // create the PerfData memory region
936 //
937 // This method creates the memory region used to store performance
938 // data for the JVM. The memory may be created in standard or
939 // shared memory.
940 //
941 void PerfMemory::create_memory_region(size_t size) {
942
943 if (PerfDisableSharedMem) {
944 // do not share the memory for the performance data.
945 _start = create_standard_memory(size);
946 }
947 else {
948 _start = create_shared_memory(size);
949 if (_start == NULL) {
950
951 // creation of the shared memory region failed, attempt
952 // to create a contiguous, non-shared memory region instead.
953 //
954 if (PrintMiscellaneous && Verbose) {
955 warning("Reverting to non-shared PerfMemory region.\n");
956 }
957 PerfDisableSharedMem = true;
958 _start = create_standard_memory(size);
959 }
960 }
961
962 if (_start != NULL) _capacity = size;
963
964 }
965
966 // delete the PerfData memory region
967 //
968 // This method deletes the memory region used to store performance
969 // data for the JVM. The memory region indicated by the <address, size>
970 // tuple will be inaccessible after a call to this method.
971 //
972 void PerfMemory::delete_memory_region() {
973
974 assert((start() != NULL && capacity() > 0), "verify proper state");
975
976 // If user specifies PerfDataSaveFile, it will save the performance data
977 // to the specified file name no matter whether PerfDataSaveToFile is specified
978 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
979 // -XX:+PerfDataSaveToFile.
980 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
981 save_memory_to_file(start(), capacity());
982 }
983
984 if (PerfDisableSharedMem) {
985 delete_standard_memory(start(), capacity());
986 }
987 else {
988 delete_shared_memory(start(), capacity());
989 }
990 }
991
992 // attach to the PerfData memory region for another JVM
993 //
994 // This method returns an <address, size> tuple that points to
995 // a memory buffer that is kept reasonably synchronized with
996 // the PerfData memory region for the indicated JVM. This
997 // buffer may be kept in synchronization via shared memory
998 // or some other mechanism that keeps the buffer updated.
999 //
1000 // If the JVM chooses not to support the attachability feature,
1001 // this method should throw an UnsupportedOperation exception.
1002 //
1003 // This implementation utilizes named shared memory to map
1004 // the indicated process's PerfData memory region into this JVMs
1005 // address space.
1006 //
1007 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1008
1009 if (vmid == 0 || vmid == os::current_process_id()) {
1010 *addrp = start();
1011 *sizep = capacity();
1012 return;
1013 }
1014
1015 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1016 }
1017
1018 // detach from the PerfData memory region of another JVM
1019 //
1020 // This method detaches the PerfData memory region of another
1021 // JVM, specified as an <address, size> tuple of a buffer
1022 // in this process's address space. This method may perform
1023 // arbitrary actions to accomplish the detachment. The memory
1024 // region specified by <address, size> will be inaccessible after
1025 // a call to this method.
1026 //
1027 // If the JVM chooses not to support the attachability feature,
1028 // this method should throw an UnsupportedOperation exception.
1029 //
1030 // This implementation utilizes named shared memory to detach
1031 // the indicated process's PerfData memory region from this
1032 // process's address space.
1033 //
1034 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1035
1036 assert(addr != 0, "address sanity check");
1037 assert(bytes > 0, "capacity sanity check");
1038
1039 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1040 // prevent accidental detachment of this process's PerfMemory region
1041 return;
1042 }
1043
1044 unmap_shared(addr, bytes);
1045 }
1046
1047 char* PerfMemory::backing_store_filename() {
1048 return backing_store_file_name;
1049 }