Thu, 04 Apr 2013 10:01:26 -0700
8003310: Enable -Wunused-function when compiling with gcc
Summary: Add the -Wunused-function flag and remove a number of unused functions.
Reviewed-by: dholmes, coleenp, kvn
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 */
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"
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>
48 static char* backing_store_file_name = NULL; // name of the backing store
49 // file, if successfully created.
51 // Standard Memory Implementation Details
53 // create the PerfData memory region in standard memory.
54 //
55 static char* create_standard_memory(size_t size) {
57 // allocate an aligned chuck of memory
58 char* mapAddress = os::reserve_memory(size);
60 if (mapAddress == NULL) {
61 return NULL;
62 }
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 }
73 return mapAddress;
74 }
76 // delete the PerfData memory region
77 //
78 static void delete_standard_memory(char* addr, size_t size) {
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 }
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) {
95 const char* destfile = PerfMemory::get_perfdata_file_path();
96 assert(destfile[0] != '\0', "invalid PerfData file path");
98 int result;
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 {
109 int fd = result;
111 for (size_t remaining = size; remaining > 0;) {
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 }
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 }
136 // Shared Memory Implementation Details
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.
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) {
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);
161 // construct the path name to user specific tmp directory
162 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
164 return dirname;
165 }
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) {
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 }
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);
186 if (errno != 0) {
187 return 0;
188 }
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 }
197 // successful conversion, return the pid
198 return pid;
199 }
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;
211 RESTARTABLE(::lstat(path, &statbuf), result);
212 if (result == OS_ERR) {
213 return false;
214 }
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 }
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) {
243 struct passwd pwent;
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;
252 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
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
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 }
277 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
278 strcpy(user_name, p->pw_name);
280 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
281 return user_name;
282 }
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) {
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 }
305 // directory search
306 char* oldest_user = NULL;
307 time_t oldest_ctime = 0;
309 const char* tmpdirname = os::get_temp_directory();
311 DIR* tmpdirp = os::opendir(tmpdirname);
313 if (tmpdirp == NULL) {
314 return NULL;
315 }
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) {
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 }
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);
338 DIR* subdirp = os::opendir(usrdir_name);
340 if (subdirp == NULL) {
341 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
342 continue;
343 }
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 }
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) {
362 if (filename_to_pid(udentry->d_name) == vmid) {
363 struct stat statbuf;
364 int result;
366 char* filename = NEW_C_HEAP_ARRAY(char,
367 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
369 strcpy(filename, usrdir_name);
370 strcat(filename, "/");
371 strcat(filename, udentry->d_name);
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 }
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 }
386 // compare and save filename with latest creation time
387 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
389 if (statbuf.st_ctime > oldest_ctime) {
390 char* user = strchr(dentry->d_name, '_') + 1;
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);
395 strcpy(oldest_user, user);
396 oldest_ctime = statbuf.st_ctime;
397 }
398 }
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);
410 return(oldest_user);
411 }
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) {
417 char psinfo_name[PATH_MAX];
418 int result;
420 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
422 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
424 if (result != OS_ERR) {
425 int fd = result;
427 psinfo_t psinfo;
428 char* addr = (char*)&psinfo;
430 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
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 }
440 RESTARTABLE(::close(fd), result);
442 // get the user name for the effective user id of the process
443 char* user_name = get_user_name(psinfo.pr_euid);
445 return user_name;
446 }
448 if (result == OS_ERR && errno == EACCES) {
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 }
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.
462 return get_user_name_slow(vmid, CHECK_NULL);
463 }
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) {
472 // add 2 for the file separator and a NULL terminator.
473 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
475 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
476 snprintf(name, nbytes, "%s/%d", dirname, vmid);
478 return name;
479 }
482 // remove file
483 //
484 // this method removes the file specified by the given path
485 //
486 static void remove_file(const char* path) {
488 int result;
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 }
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) {
512 size_t nbytes = strlen(dirname) + strlen(filename) + 2;
513 char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
515 strcpy(path, dirname);
516 strcat(path, "/");
517 strcat(path, filename);
519 remove_file(path);
521 FREE_C_HEAP_ARRAY(char, path, mtInternal);
522 }
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) {
536 // open the user temp directory
537 DIR* dirp = os::opendir(dirname);
539 if (dirp == NULL) {
540 // directory doesn't exist, so there is nothing to cleanup
541 return;
542 }
544 if (!is_directory_secure(dirname)) {
545 // the directory is not a secure directory
546 return;
547 }
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) {
562 pid_t pid = filename_to_pid(entry->d_name);
564 if (pid == 0) {
566 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
568 // attempt to remove all unexpected files, except "." and ".."
569 remove_file(dirname, entry->d_name);
570 }
572 errno = 0;
573 continue;
574 }
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))) {
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 }
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) {
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 }
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) {
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 }
653 int result;
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 }
663 // save the file descriptor
664 int fd = result;
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 }
676 return fd;
677 }
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) {
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_0(vmSymbols::java_lang_IllegalArgumentException(),
691 "Process not found");
692 }
693 else if (errno == EACCES) {
694 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
695 "Permission denied");
696 }
697 else {
698 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
699 }
700 }
702 return result;
703 }
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) {
720 int result;
721 int fd;
722 char* mapAddress;
724 int vmid = os::current_process_id();
726 char* user_name = get_user_name(geteuid());
728 if (user_name == NULL)
729 return NULL;
731 char* dirname = get_user_tmp_dir(user_name);
732 char* filename = get_sharedmem_filename(dirname, vmid);
734 // cleanup any stale shared memory files
735 cleanup_sharedmem_resources(dirname);
737 assert(((size > 0) && (size % os::vm_page_size() == 0)),
738 "unexpected PerfMemory region size");
740 fd = create_sharedmem_resources(dirname, filename, size);
742 FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
743 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
745 if (fd == -1) {
746 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
747 return NULL;
748 }
750 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
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");
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 }
766 // save the file name for use in delete_shared_memory()
767 backing_store_file_name = filename;
769 // clear the shared memory region
770 (void)::memset((void*) mapAddress, 0, size);
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);
776 return mapAddress;
777 }
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 }
785 // create the PerfData memory region in shared memory.
786 //
787 static char* create_shared_memory(size_t size) {
789 // create the shared memory region.
790 return mmap_create_shared(size);
791 }
793 // delete the shared PerfData memory region
794 //
795 static void delete_shared_memory(char* addr, size_t size) {
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.
802 assert(!PerfDisableSharedMem, "shouldn't be here");
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 }
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) {
818 struct stat statbuf;
819 int result;
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 }
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 }
836 return (size_t)statbuf.st_size;
837 }
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) {
843 char* mapAddress;
844 int result;
845 int fd;
846 size_t size;
847 const char* luser = NULL;
849 int mmap_prot;
850 int file_flags;
852 ResourceMark rm;
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 }
874 if (user == NULL || strlen(user) == 0) {
875 luser = get_user_name(vmid, CHECK);
876 }
877 else {
878 luser = user;
879 }
881 if (luser == NULL) {
882 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
883 "Could not map vmid to user Name");
884 }
886 char* dirname = get_user_tmp_dir(luser);
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 }
897 char* filename = get_sharedmem_filename(dirname, vmid);
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);
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);
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");
915 if (*sizep == 0) {
916 size = sharedmem_filesize(fd, CHECK);
917 assert(size != 0, "unexpected size");
918 }
920 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
922 // attempt to close the file - restart if it gets interrupted,
923 // but ignore other failures
924 RESTARTABLE(::close(fd), result);
925 assert(result != OS_ERR, "could not close file");
927 if (mapAddress == MAP_FAILED) {
928 if (PrintMiscellaneous && Verbose) {
929 warning("mmap failed: %s\n", strerror(errno));
930 }
931 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
932 "Could not map PerfMemory");
933 }
935 // it does not go through os api, the operation has to record from here
936 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC);
937 MemTracker::record_virtual_memory_type((address)mapAddress, mtInternal);
939 *addr = mapAddress;
940 *sizep = size;
942 if (PerfTraceMemOps) {
943 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
944 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
945 }
946 }
951 // create the PerfData memory region
952 //
953 // This method creates the memory region used to store performance
954 // data for the JVM. The memory may be created in standard or
955 // shared memory.
956 //
957 void PerfMemory::create_memory_region(size_t size) {
959 if (PerfDisableSharedMem) {
960 // do not share the memory for the performance data.
961 _start = create_standard_memory(size);
962 }
963 else {
964 _start = create_shared_memory(size);
965 if (_start == NULL) {
967 // creation of the shared memory region failed, attempt
968 // to create a contiguous, non-shared memory region instead.
969 //
970 if (PrintMiscellaneous && Verbose) {
971 warning("Reverting to non-shared PerfMemory region.\n");
972 }
973 PerfDisableSharedMem = true;
974 _start = create_standard_memory(size);
975 }
976 }
978 if (_start != NULL) _capacity = size;
980 }
982 // delete the PerfData memory region
983 //
984 // This method deletes the memory region used to store performance
985 // data for the JVM. The memory region indicated by the <address, size>
986 // tuple will be inaccessible after a call to this method.
987 //
988 void PerfMemory::delete_memory_region() {
990 assert((start() != NULL && capacity() > 0), "verify proper state");
992 // If user specifies PerfDataSaveFile, it will save the performance data
993 // to the specified file name no matter whether PerfDataSaveToFile is specified
994 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
995 // -XX:+PerfDataSaveToFile.
996 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
997 save_memory_to_file(start(), capacity());
998 }
1000 if (PerfDisableSharedMem) {
1001 delete_standard_memory(start(), capacity());
1002 }
1003 else {
1004 delete_shared_memory(start(), capacity());
1005 }
1006 }
1008 // attach to the PerfData memory region for another JVM
1009 //
1010 // This method returns an <address, size> tuple that points to
1011 // a memory buffer that is kept reasonably synchronized with
1012 // the PerfData memory region for the indicated JVM. This
1013 // buffer may be kept in synchronization via shared memory
1014 // or some other mechanism that keeps the buffer updated.
1015 //
1016 // If the JVM chooses not to support the attachability feature,
1017 // this method should throw an UnsupportedOperation exception.
1018 //
1019 // This implementation utilizes named shared memory to map
1020 // the indicated process's PerfData memory region into this JVMs
1021 // address space.
1022 //
1023 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1025 if (vmid == 0 || vmid == os::current_process_id()) {
1026 *addrp = start();
1027 *sizep = capacity();
1028 return;
1029 }
1031 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1032 }
1034 // detach from the PerfData memory region of another JVM
1035 //
1036 // This method detaches the PerfData memory region of another
1037 // JVM, specified as an <address, size> tuple of a buffer
1038 // in this process's address space. This method may perform
1039 // arbitrary actions to accomplish the detachment. The memory
1040 // region specified by <address, size> will be inaccessible after
1041 // a call to this method.
1042 //
1043 // If the JVM chooses not to support the attachability feature,
1044 // this method should throw an UnsupportedOperation exception.
1045 //
1046 // This implementation utilizes named shared memory to detach
1047 // the indicated process's PerfData memory region from this
1048 // process's address space.
1049 //
1050 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1052 assert(addr != 0, "address sanity check");
1053 assert(bytes > 0, "capacity sanity check");
1055 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1056 // prevent accidental detachment of this process's PerfMemory region
1057 return;
1058 }
1060 unmap_shared(addr, bytes);
1061 }
1063 char* PerfMemory::backing_store_filename() {
1064 return backing_store_file_name;
1065 }