--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/perfMemory_linux.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1284 @@
+/*
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "logging/log.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.inline.hpp"
+#include "os_linux.inline.hpp"
+#include "runtime/handles.inline.hpp"
+#include "runtime/os.hpp"
+#include "runtime/perfMemory.hpp"
+#include "services/memTracker.hpp"
+#include "utilities/exceptions.hpp"
+
+// put OS-includes here
+# include <sys/types.h>
+# include <sys/mman.h>
+# include <errno.h>
+# include <stdio.h>
+# include <unistd.h>
+# include <sys/stat.h>
+# include <signal.h>
+# include <pwd.h>
+
+static char* backing_store_file_name = NULL; // name of the backing store
+ // file, if successfully created.
+
+// Standard Memory Implementation Details
+
+// create the PerfData memory region in standard memory.
+//
+static char* create_standard_memory(size_t size) {
+
+ // allocate an aligned chuck of memory
+ char* mapAddress = os::reserve_memory(size);
+
+ if (mapAddress == NULL) {
+ return NULL;
+ }
+
+ // commit memory
+ if (!os::commit_memory(mapAddress, size, !ExecMem)) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("Could not commit PerfData memory\n");
+ }
+ os::release_memory(mapAddress, size);
+ return NULL;
+ }
+
+ return mapAddress;
+}
+
+// delete the PerfData memory region
+//
+static void delete_standard_memory(char* addr, size_t size) {
+
+ // there are no persistent external resources to cleanup for standard
+ // memory. since DestroyJavaVM does not support unloading of the JVM,
+ // cleanup of the memory resource is not performed. The memory will be
+ // reclaimed by the OS upon termination of the process.
+ //
+ return;
+}
+
+// save the specified memory region to the given file
+//
+// Note: this function might be called from signal handler (by os::abort()),
+// don't allocate heap memory.
+//
+static void save_memory_to_file(char* addr, size_t size) {
+
+ const char* destfile = PerfMemory::get_perfdata_file_path();
+ assert(destfile[0] != '\0', "invalid PerfData file path");
+
+ int result;
+
+ RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
+ result);;
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("Could not create Perfdata save file: %s: %s\n",
+ destfile, os::strerror(errno));
+ }
+ } else {
+ int fd = result;
+
+ for (size_t remaining = size; remaining > 0;) {
+
+ RESTARTABLE(::write(fd, addr, remaining), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("Could not write Perfdata save file: %s: %s\n",
+ destfile, os::strerror(errno));
+ }
+ break;
+ }
+
+ remaining -= (size_t)result;
+ addr += result;
+ }
+
+ result = ::close(fd);
+ if (PrintMiscellaneous && Verbose) {
+ if (result == OS_ERR) {
+ warning("Could not close %s: %s\n", destfile, os::strerror(errno));
+ }
+ }
+ }
+ FREE_C_HEAP_ARRAY(char, destfile);
+}
+
+
+// Shared Memory Implementation Details
+
+// Note: the solaris and linux shared memory implementation uses the mmap
+// interface with a backing store file to implement named shared memory.
+// Using the file system as the name space for shared memory allows a
+// common name space to be supported across a variety of platforms. It
+// also provides a name space that Java applications can deal with through
+// simple file apis.
+//
+// The solaris and linux implementations store the backing store file in
+// a user specific temporary directory located in the /tmp file system,
+// which is always a local file system and is sometimes a RAM based file
+// system.
+
+// return the user specific temporary directory name.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_tmp_dir(const char* user) {
+
+ const char* tmpdir = os::get_temp_directory();
+ const char* perfdir = PERFDATA_NAME;
+ size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
+ char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
+
+ // construct the path name to user specific tmp directory
+ snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
+
+ return dirname;
+}
+
+// convert the given file name into a process id. if the file
+// does not meet the file naming constraints, return 0.
+//
+static pid_t filename_to_pid(const char* filename) {
+
+ // a filename that doesn't begin with a digit is not a
+ // candidate for conversion.
+ //
+ if (!isdigit(*filename)) {
+ return 0;
+ }
+
+ // check if file name can be converted to an integer without
+ // any leftover characters.
+ //
+ char* remainder = NULL;
+ errno = 0;
+ pid_t pid = (pid_t)strtol(filename, &remainder, 10);
+
+ if (errno != 0) {
+ return 0;
+ }
+
+ // check for left over characters. If any, then the filename is
+ // not a candidate for conversion.
+ //
+ if (remainder != NULL && *remainder != '\0') {
+ return 0;
+ }
+
+ // successful conversion, return the pid
+ return pid;
+}
+
+
+// Check if the given statbuf is considered a secure directory for
+// the backing store files. Returns true if the directory is considered
+// a secure location. Returns false if the statbuf is a symbolic link or
+// if an error occurred.
+//
+static bool is_statbuf_secure(struct stat *statp) {
+ if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
+ // The path represents a link or some non-directory file type,
+ // which is not what we expected. Declare it insecure.
+ //
+ return false;
+ }
+ // We have an existing directory, check if the permissions are safe.
+ //
+ if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
+ // The directory is open for writing and could be subjected
+ // to a symlink or a hard link attack. Declare it insecure.
+ //
+ return false;
+ }
+ // If user is not root then see if the uid of the directory matches the effective uid of the process.
+ uid_t euid = geteuid();
+ if ((euid != 0) && (statp->st_uid != euid)) {
+ // The directory was not created by this user, declare it insecure.
+ //
+ return false;
+ }
+ return true;
+}
+
+
+// Check if the given path is considered a secure directory for
+// the backing store files. Returns true if the directory exists
+// and is considered a secure location. Returns false if the path
+// is a symbolic link or if an error occurred.
+//
+static bool is_directory_secure(const char* path) {
+ struct stat statbuf;
+ int result = 0;
+
+ RESTARTABLE(::lstat(path, &statbuf), result);
+ if (result == OS_ERR) {
+ return false;
+ }
+
+ // The path exists, see if it is secure.
+ return is_statbuf_secure(&statbuf);
+}
+
+
+// Check if the given directory file descriptor is considered a secure
+// directory for the backing store files. Returns true if the directory
+// exists and is considered a secure location. Returns false if the path
+// is a symbolic link or if an error occurred.
+//
+static bool is_dirfd_secure(int dir_fd) {
+ struct stat statbuf;
+ int result = 0;
+
+ RESTARTABLE(::fstat(dir_fd, &statbuf), result);
+ if (result == OS_ERR) {
+ return false;
+ }
+
+ // The path exists, now check its mode.
+ return is_statbuf_secure(&statbuf);
+}
+
+
+// Check to make sure fd1 and fd2 are referencing the same file system object.
+//
+static bool is_same_fsobject(int fd1, int fd2) {
+ struct stat statbuf1;
+ struct stat statbuf2;
+ int result = 0;
+
+ RESTARTABLE(::fstat(fd1, &statbuf1), result);
+ if (result == OS_ERR) {
+ return false;
+ }
+ RESTARTABLE(::fstat(fd2, &statbuf2), result);
+ if (result == OS_ERR) {
+ return false;
+ }
+
+ if ((statbuf1.st_ino == statbuf2.st_ino) &&
+ (statbuf1.st_dev == statbuf2.st_dev)) {
+ return true;
+ } else {
+ return false;
+ }
+}
+
+
+// Open the directory of the given path and validate it.
+// Return a DIR * of the open directory.
+//
+static DIR *open_directory_secure(const char* dirname) {
+ // Open the directory using open() so that it can be verified
+ // to be secure by calling is_dirfd_secure(), opendir() and then check
+ // to see if they are the same file system object. This method does not
+ // introduce a window of opportunity for the directory to be attacked that
+ // calling opendir() and is_directory_secure() does.
+ int result;
+ DIR *dirp = NULL;
+ RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ if (errno == ELOOP) {
+ warning("directory %s is a symlink and is not secure\n", dirname);
+ } else {
+ warning("could not open directory %s: %s\n", dirname, os::strerror(errno));
+ }
+ }
+ return dirp;
+ }
+ int fd = result;
+
+ // Determine if the open directory is secure.
+ if (!is_dirfd_secure(fd)) {
+ // The directory is not a secure directory.
+ os::close(fd);
+ return dirp;
+ }
+
+ // Open the directory.
+ dirp = ::opendir(dirname);
+ if (dirp == NULL) {
+ // The directory doesn't exist, close fd and return.
+ os::close(fd);
+ return dirp;
+ }
+
+ // Check to make sure fd and dirp are referencing the same file system object.
+ if (!is_same_fsobject(fd, dirfd(dirp))) {
+ // The directory is not secure.
+ os::close(fd);
+ os::closedir(dirp);
+ dirp = NULL;
+ return dirp;
+ }
+
+ // Close initial open now that we know directory is secure
+ os::close(fd);
+
+ return dirp;
+}
+
+// NOTE: The code below uses fchdir(), open() and unlink() because
+// fdopendir(), openat() and unlinkat() are not supported on all
+// versions. Once the support for fdopendir(), openat() and unlinkat()
+// is available on all supported versions the code can be changed
+// to use these functions.
+
+// Open the directory of the given path, validate it and set the
+// current working directory to it.
+// Return a DIR * of the open directory and the saved cwd fd.
+//
+static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
+
+ // Open the directory.
+ DIR* dirp = open_directory_secure(dirname);
+ if (dirp == NULL) {
+ // Directory doesn't exist or is insecure, so there is nothing to cleanup.
+ return dirp;
+ }
+ int fd = dirfd(dirp);
+
+ // Open a fd to the cwd and save it off.
+ int result;
+ RESTARTABLE(::open(".", O_RDONLY), result);
+ if (result == OS_ERR) {
+ *saved_cwd_fd = -1;
+ } else {
+ *saved_cwd_fd = result;
+ }
+
+ // Set the current directory to dirname by using the fd of the directory and
+ // handle errors, otherwise shared memory files will be created in cwd.
+ result = fchdir(fd);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("could not change to directory %s", dirname);
+ }
+ if (*saved_cwd_fd != -1) {
+ ::close(*saved_cwd_fd);
+ *saved_cwd_fd = -1;
+ }
+ // Close the directory.
+ os::closedir(dirp);
+ return NULL;
+ } else {
+ return dirp;
+ }
+}
+
+// Close the directory and restore the current working directory.
+//
+static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
+
+ int result;
+ // If we have a saved cwd change back to it and close the fd.
+ if (saved_cwd_fd != -1) {
+ result = fchdir(saved_cwd_fd);
+ ::close(saved_cwd_fd);
+ }
+
+ // Close the directory.
+ os::closedir(dirp);
+}
+
+// Check if the given file descriptor is considered a secure.
+//
+static bool is_file_secure(int fd, const char *filename) {
+
+ int result;
+ struct stat statbuf;
+
+ // Determine if the file is secure.
+ RESTARTABLE(::fstat(fd, &statbuf), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("fstat failed on %s: %s\n", filename, os::strerror(errno));
+ }
+ return false;
+ }
+ if (statbuf.st_nlink > 1) {
+ // A file with multiple links is not expected.
+ if (PrintMiscellaneous && Verbose) {
+ warning("file %s has multiple links\n", filename);
+ }
+ return false;
+ }
+ return true;
+}
+
+
+// return the user name for the given user id
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_name(uid_t uid) {
+
+ struct passwd pwent;
+
+ // determine the max pwbuf size from sysconf, and hardcode
+ // a default if this not available through sysconf.
+ //
+ long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
+ if (bufsize == -1)
+ bufsize = 1024;
+
+ char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
+
+ // POSIX interface to getpwuid_r is used on LINUX
+ struct passwd* p;
+ int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
+
+ if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
+ if (PrintMiscellaneous && Verbose) {
+ if (result != 0) {
+ warning("Could not retrieve passwd entry: %s\n",
+ os::strerror(result));
+ }
+ else if (p == NULL) {
+ // this check is added to protect against an observed problem
+ // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
+ // indicating success, but has p == NULL. This was observed when
+ // inserting a file descriptor exhaustion fault prior to the call
+ // getpwuid_r() call. In this case, error is set to the appropriate
+ // error condition, but this is undocumented behavior. This check
+ // is safe under any condition, but the use of errno in the output
+ // message may result in an erroneous message.
+ // Bug Id 89052 was opened with RedHat.
+ //
+ warning("Could not retrieve passwd entry: %s\n",
+ os::strerror(errno));
+ }
+ else {
+ warning("Could not determine user name: %s\n",
+ p->pw_name == NULL ? "pw_name = NULL" :
+ "pw_name zero length");
+ }
+ }
+ FREE_C_HEAP_ARRAY(char, pwbuf);
+ return NULL;
+ }
+
+ char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
+ strcpy(user_name, p->pw_name);
+
+ FREE_C_HEAP_ARRAY(char, pwbuf);
+ return user_name;
+}
+
+// return the name of the user that owns the process identified by vmid.
+//
+// This method uses a slow directory search algorithm to find the backing
+// store file for the specified vmid and returns the user name, as determined
+// by the user name suffix of the hsperfdata_<username> directory name.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_user_name_slow(int vmid, TRAPS) {
+
+ // short circuit the directory search if the process doesn't even exist.
+ if (kill(vmid, 0) == OS_ERR) {
+ if (errno == ESRCH) {
+ THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
+ "Process not found");
+ }
+ else /* EPERM */ {
+ THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno));
+ }
+ }
+
+ // directory search
+ char* oldest_user = NULL;
+ time_t oldest_ctime = 0;
+
+ const char* tmpdirname = os::get_temp_directory();
+
+ // open the temp directory
+ DIR* tmpdirp = os::opendir(tmpdirname);
+
+ if (tmpdirp == NULL) {
+ // Cannot open the directory to get the user name, return.
+ return NULL;
+ }
+
+ // for each entry in the directory that matches the pattern hsperfdata_*,
+ // open the directory and check if the file for the given vmid exists.
+ // The file with the expected name and the latest creation date is used
+ // to determine the user name for the process id.
+ //
+ struct dirent* dentry;
+ char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
+ errno = 0;
+ while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+
+ // check if the directory entry is a hsperfdata file
+ if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
+ continue;
+ }
+
+ char* usrdir_name = NEW_C_HEAP_ARRAY(char,
+ strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
+ strcpy(usrdir_name, tmpdirname);
+ strcat(usrdir_name, "/");
+ strcat(usrdir_name, dentry->d_name);
+
+ // open the user directory
+ DIR* subdirp = open_directory_secure(usrdir_name);
+
+ if (subdirp == NULL) {
+ FREE_C_HEAP_ARRAY(char, usrdir_name);
+ continue;
+ }
+
+ // Since we don't create the backing store files in directories
+ // pointed to by symbolic links, we also don't follow them when
+ // looking for the files. We check for a symbolic link after the
+ // call to opendir in order to eliminate a small window where the
+ // symlink can be exploited.
+ //
+ if (!is_directory_secure(usrdir_name)) {
+ FREE_C_HEAP_ARRAY(char, usrdir_name);
+ os::closedir(subdirp);
+ continue;
+ }
+
+ struct dirent* udentry;
+ char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
+ errno = 0;
+ while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+
+ if (filename_to_pid(udentry->d_name) == vmid) {
+ struct stat statbuf;
+ int result;
+
+ char* filename = NEW_C_HEAP_ARRAY(char,
+ strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
+
+ strcpy(filename, usrdir_name);
+ strcat(filename, "/");
+ strcat(filename, udentry->d_name);
+
+ // don't follow symbolic links for the file
+ RESTARTABLE(::lstat(filename, &statbuf), result);
+ if (result == OS_ERR) {
+ FREE_C_HEAP_ARRAY(char, filename);
+ continue;
+ }
+
+ // skip over files that are not regular files.
+ if (!S_ISREG(statbuf.st_mode)) {
+ FREE_C_HEAP_ARRAY(char, filename);
+ continue;
+ }
+
+ // compare and save filename with latest creation time
+ if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
+
+ if (statbuf.st_ctime > oldest_ctime) {
+ char* user = strchr(dentry->d_name, '_') + 1;
+
+ if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
+ oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
+
+ strcpy(oldest_user, user);
+ oldest_ctime = statbuf.st_ctime;
+ }
+ }
+
+ FREE_C_HEAP_ARRAY(char, filename);
+ }
+ }
+ os::closedir(subdirp);
+ FREE_C_HEAP_ARRAY(char, udbuf);
+ FREE_C_HEAP_ARRAY(char, usrdir_name);
+ }
+ os::closedir(tmpdirp);
+ FREE_C_HEAP_ARRAY(char, tdbuf);
+
+ return(oldest_user);
+}
+
+// return the name of the user that owns the JVM indicated by the given vmid.
+//
+static char* get_user_name(int vmid, TRAPS) {
+ return get_user_name_slow(vmid, THREAD);
+}
+
+// return the file name of the backing store file for the named
+// shared memory region for the given user name and vmid.
+//
+// the caller is expected to free the allocated memory.
+//
+static char* get_sharedmem_filename(const char* dirname, int vmid) {
+
+ // add 2 for the file separator and a null terminator.
+ size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
+
+ char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
+ snprintf(name, nbytes, "%s/%d", dirname, vmid);
+
+ return name;
+}
+
+
+// remove file
+//
+// this method removes the file specified by the given path
+//
+static void remove_file(const char* path) {
+
+ int result;
+
+ // if the file is a directory, the following unlink will fail. since
+ // we don't expect to find directories in the user temp directory, we
+ // won't try to handle this situation. even if accidentially or
+ // maliciously planted, the directory's presence won't hurt anything.
+ //
+ RESTARTABLE(::unlink(path), result);
+ if (PrintMiscellaneous && Verbose && result == OS_ERR) {
+ if (errno != ENOENT) {
+ warning("Could not unlink shared memory backing"
+ " store file %s : %s\n", path, os::strerror(errno));
+ }
+ }
+}
+
+
+// cleanup stale shared memory resources
+//
+// This method attempts to remove all stale shared memory files in
+// the named user temporary directory. It scans the named directory
+// for files matching the pattern ^$[0-9]*$. For each file found, the
+// process id is extracted from the file name and a test is run to
+// determine if the process is alive. If the process is not alive,
+// any stale file resources are removed.
+//
+static void cleanup_sharedmem_resources(const char* dirname) {
+
+ int saved_cwd_fd;
+ // open the directory
+ DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
+ if (dirp == NULL) {
+ // directory doesn't exist or is insecure, so there is nothing to cleanup
+ return;
+ }
+
+ // for each entry in the directory that matches the expected file
+ // name pattern, determine if the file resources are stale and if
+ // so, remove the file resources. Note, instrumented HotSpot processes
+ // for this user may start and/or terminate during this search and
+ // remove or create new files in this directory. The behavior of this
+ // loop under these conditions is dependent upon the implementation of
+ // opendir/readdir.
+ //
+ struct dirent* entry;
+ char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
+
+ errno = 0;
+ while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+
+ pid_t pid = filename_to_pid(entry->d_name);
+
+ if (pid == 0) {
+
+ if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
+ // attempt to remove all unexpected files, except "." and ".."
+ unlink(entry->d_name);
+ }
+
+ errno = 0;
+ continue;
+ }
+
+ // we now have a file name that converts to a valid integer
+ // that could represent a process id . if this process id
+ // matches the current process id or the process is not running,
+ // then remove the stale file resources.
+ //
+ // process liveness is detected by sending signal number 0 to
+ // the process id (see kill(2)). if kill determines that the
+ // process does not exist, then the file resources are removed.
+ // if kill determines that that we don't have permission to
+ // signal the process, then the file resources are assumed to
+ // be stale and are removed because the resources for such a
+ // process should be in a different user specific directory.
+ //
+ if ((pid == os::current_process_id()) ||
+ (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
+ unlink(entry->d_name);
+ }
+ errno = 0;
+ }
+
+ // close the directory and reset the current working directory
+ close_directory_secure_cwd(dirp, saved_cwd_fd);
+
+ FREE_C_HEAP_ARRAY(char, dbuf);
+}
+
+// make the user specific temporary directory. Returns true if
+// the directory exists and is secure upon return. Returns false
+// if the directory exists but is either a symlink, is otherwise
+// insecure, or if an error occurred.
+//
+static bool make_user_tmp_dir(const char* dirname) {
+
+ // create the directory with 0755 permissions. note that the directory
+ // will be owned by euid::egid, which may not be the same as uid::gid.
+ //
+ if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
+ if (errno == EEXIST) {
+ // The directory already exists and was probably created by another
+ // JVM instance. However, this could also be the result of a
+ // deliberate symlink. Verify that the existing directory is safe.
+ //
+ if (!is_directory_secure(dirname)) {
+ // directory is not secure
+ if (PrintMiscellaneous && Verbose) {
+ warning("%s directory is insecure\n", dirname);
+ }
+ return false;
+ }
+ }
+ else {
+ // we encountered some other failure while attempting
+ // to create the directory
+ //
+ if (PrintMiscellaneous && Verbose) {
+ warning("could not create directory %s: %s\n",
+ dirname, os::strerror(errno));
+ }
+ return false;
+ }
+ }
+ return true;
+}
+
+// create the shared memory file resources
+//
+// This method creates the shared memory file with the given size
+// This method also creates the user specific temporary directory, if
+// it does not yet exist.
+//
+static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
+
+ // make the user temporary directory
+ if (!make_user_tmp_dir(dirname)) {
+ // could not make/find the directory or the found directory
+ // was not secure
+ return -1;
+ }
+
+ int saved_cwd_fd;
+ // open the directory and set the current working directory to it
+ DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
+ if (dirp == NULL) {
+ // Directory doesn't exist or is insecure, so cannot create shared
+ // memory file.
+ return -1;
+ }
+
+ // Open the filename in the current directory.
+ // Cannot use O_TRUNC here; truncation of an existing file has to happen
+ // after the is_file_secure() check below.
+ int result;
+ RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ if (errno == ELOOP) {
+ warning("file %s is a symlink and is not secure\n", filename);
+ } else {
+ warning("could not create file %s: %s\n", filename, os::strerror(errno));
+ }
+ }
+ // close the directory and reset the current working directory
+ close_directory_secure_cwd(dirp, saved_cwd_fd);
+
+ return -1;
+ }
+ // close the directory and reset the current working directory
+ close_directory_secure_cwd(dirp, saved_cwd_fd);
+
+ // save the file descriptor
+ int fd = result;
+
+ // check to see if the file is secure
+ if (!is_file_secure(fd, filename)) {
+ ::close(fd);
+ return -1;
+ }
+
+ // truncate the file to get rid of any existing data
+ RESTARTABLE(::ftruncate(fd, (off_t)0), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("could not truncate shared memory file: %s\n", os::strerror(errno));
+ }
+ ::close(fd);
+ return -1;
+ }
+ // set the file size
+ RESTARTABLE(::ftruncate(fd, (off_t)size), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("could not set shared memory file size: %s\n", os::strerror(errno));
+ }
+ ::close(fd);
+ return -1;
+ }
+
+ // Verify that we have enough disk space for this file.
+ // We'll get random SIGBUS crashes on memory accesses if
+ // we don't.
+
+ for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
+ int zero_int = 0;
+ result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
+ if (result == -1 ) break;
+ RESTARTABLE(::write(fd, &zero_int, 1), result);
+ if (result != 1) {
+ if (errno == ENOSPC) {
+ warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
+ }
+ break;
+ }
+ }
+
+ if (result != -1) {
+ return fd;
+ } else {
+ ::close(fd);
+ return -1;
+ }
+}
+
+// open the shared memory file for the given user and vmid. returns
+// the file descriptor for the open file or -1 if the file could not
+// be opened.
+//
+static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
+
+ // open the file
+ int result;
+ RESTARTABLE(::open(filename, oflags), result);
+ if (result == OS_ERR) {
+ if (errno == ENOENT) {
+ THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
+ "Process not found", OS_ERR);
+ }
+ else if (errno == EACCES) {
+ THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
+ "Permission denied", OS_ERR);
+ }
+ else {
+ THROW_MSG_(vmSymbols::java_io_IOException(),
+ os::strerror(errno), OS_ERR);
+ }
+ }
+ int fd = result;
+
+ // check to see if the file is secure
+ if (!is_file_secure(fd, filename)) {
+ ::close(fd);
+ return -1;
+ }
+
+ return fd;
+}
+
+// create a named shared memory region. returns the address of the
+// memory region on success or NULL on failure. A return value of
+// NULL will ultimately disable the shared memory feature.
+//
+// On Linux, the name space for shared memory objects
+// is the file system name space.
+//
+// A monitoring application attaching to a JVM does not need to know
+// the file system name of the shared memory object. However, it may
+// be convenient for applications to discover the existence of newly
+// created and terminating JVMs by watching the file system name space
+// for files being created or removed.
+//
+static char* mmap_create_shared(size_t size) {
+
+ int result;
+ int fd;
+ char* mapAddress;
+
+ int vmid = os::current_process_id();
+
+ char* user_name = get_user_name(geteuid());
+
+ if (user_name == NULL)
+ return NULL;
+
+ char* dirname = get_user_tmp_dir(user_name);
+ char* filename = get_sharedmem_filename(dirname, vmid);
+
+ // get the short filename
+ char* short_filename = strrchr(filename, '/');
+ if (short_filename == NULL) {
+ short_filename = filename;
+ } else {
+ short_filename++;
+ }
+
+ // cleanup any stale shared memory files
+ cleanup_sharedmem_resources(dirname);
+
+ assert(((size > 0) && (size % os::vm_page_size() == 0)),
+ "unexpected PerfMemory region size");
+
+ fd = create_sharedmem_resources(dirname, short_filename, size);
+
+ FREE_C_HEAP_ARRAY(char, user_name);
+ FREE_C_HEAP_ARRAY(char, dirname);
+
+ if (fd == -1) {
+ FREE_C_HEAP_ARRAY(char, filename);
+ return NULL;
+ }
+
+ mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+
+ result = ::close(fd);
+ assert(result != OS_ERR, "could not close file");
+
+ if (mapAddress == MAP_FAILED) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("mmap failed - %s\n", os::strerror(errno));
+ }
+ remove_file(filename);
+ FREE_C_HEAP_ARRAY(char, filename);
+ return NULL;
+ }
+
+ // save the file name for use in delete_shared_memory()
+ backing_store_file_name = filename;
+
+ // clear the shared memory region
+ (void)::memset((void*) mapAddress, 0, size);
+
+ // it does not go through os api, the operation has to record from here
+ MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
+
+ return mapAddress;
+}
+
+// release a named shared memory region
+//
+static void unmap_shared(char* addr, size_t bytes) {
+ os::release_memory(addr, bytes);
+}
+
+// create the PerfData memory region in shared memory.
+//
+static char* create_shared_memory(size_t size) {
+
+ // create the shared memory region.
+ return mmap_create_shared(size);
+}
+
+// delete the shared PerfData memory region
+//
+static void delete_shared_memory(char* addr, size_t size) {
+
+ // cleanup the persistent shared memory resources. since DestroyJavaVM does
+ // not support unloading of the JVM, unmapping of the memory resource is
+ // not performed. The memory will be reclaimed by the OS upon termination of
+ // the process. The backing store file is deleted from the file system.
+
+ assert(!PerfDisableSharedMem, "shouldn't be here");
+
+ if (backing_store_file_name != NULL) {
+ remove_file(backing_store_file_name);
+ // Don't.. Free heap memory could deadlock os::abort() if it is called
+ // from signal handler. OS will reclaim the heap memory.
+ // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
+ backing_store_file_name = NULL;
+ }
+}
+
+// return the size of the file for the given file descriptor
+// or 0 if it is not a valid size for a shared memory file
+//
+static size_t sharedmem_filesize(int fd, TRAPS) {
+
+ struct stat statbuf;
+ int result;
+
+ RESTARTABLE(::fstat(fd, &statbuf), result);
+ if (result == OS_ERR) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("fstat failed: %s\n", os::strerror(errno));
+ }
+ THROW_MSG_0(vmSymbols::java_io_IOException(),
+ "Could not determine PerfMemory size");
+ }
+
+ if ((statbuf.st_size == 0) ||
+ ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
+ THROW_MSG_0(vmSymbols::java_lang_Exception(),
+ "Invalid PerfMemory size");
+ }
+
+ return (size_t)statbuf.st_size;
+}
+
+// attach to a named shared memory region.
+//
+static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
+
+ char* mapAddress;
+ int result;
+ int fd;
+ size_t size = 0;
+ const char* luser = NULL;
+
+ int mmap_prot;
+ int file_flags;
+
+ ResourceMark rm;
+
+ // map the high level access mode to the appropriate permission
+ // constructs for the file and the shared memory mapping.
+ if (mode == PerfMemory::PERF_MODE_RO) {
+ mmap_prot = PROT_READ;
+ file_flags = O_RDONLY | O_NOFOLLOW;
+ }
+ else if (mode == PerfMemory::PERF_MODE_RW) {
+#ifdef LATER
+ mmap_prot = PROT_READ | PROT_WRITE;
+ file_flags = O_RDWR | O_NOFOLLOW;
+#else
+ THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+ "Unsupported access mode");
+#endif
+ }
+ else {
+ THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+ "Illegal access mode");
+ }
+
+ if (user == NULL || strlen(user) == 0) {
+ luser = get_user_name(vmid, CHECK);
+ }
+ else {
+ luser = user;
+ }
+
+ if (luser == NULL) {
+ THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+ "Could not map vmid to user Name");
+ }
+
+ char* dirname = get_user_tmp_dir(luser);
+
+ // since we don't follow symbolic links when creating the backing
+ // store file, we don't follow them when attaching either.
+ //
+ if (!is_directory_secure(dirname)) {
+ FREE_C_HEAP_ARRAY(char, dirname);
+ if (luser != user) {
+ FREE_C_HEAP_ARRAY(char, luser);
+ }
+ THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+ "Process not found");
+ }
+
+ char* filename = get_sharedmem_filename(dirname, vmid);
+
+ // copy heap memory to resource memory. the open_sharedmem_file
+ // method below need to use the filename, but could throw an
+ // exception. using a resource array prevents the leak that
+ // would otherwise occur.
+ char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
+ strcpy(rfilename, filename);
+
+ // free the c heap resources that are no longer needed
+ if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
+ FREE_C_HEAP_ARRAY(char, dirname);
+ FREE_C_HEAP_ARRAY(char, filename);
+
+ // open the shared memory file for the give vmid
+ fd = open_sharedmem_file(rfilename, file_flags, THREAD);
+
+ if (fd == OS_ERR) {
+ return;
+ }
+
+ if (HAS_PENDING_EXCEPTION) {
+ ::close(fd);
+ return;
+ }
+
+ if (*sizep == 0) {
+ size = sharedmem_filesize(fd, CHECK);
+ } else {
+ size = *sizep;
+ }
+
+ assert(size > 0, "unexpected size <= 0");
+
+ mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
+
+ result = ::close(fd);
+ assert(result != OS_ERR, "could not close file");
+
+ if (mapAddress == MAP_FAILED) {
+ if (PrintMiscellaneous && Verbose) {
+ warning("mmap failed: %s\n", os::strerror(errno));
+ }
+ THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
+ "Could not map PerfMemory");
+ }
+
+ // it does not go through os api, the operation has to record from here
+ MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
+
+ *addr = mapAddress;
+ *sizep = size;
+
+ log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at "
+ INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress));
+}
+
+// create the PerfData memory region
+//
+// This method creates the memory region used to store performance
+// data for the JVM. The memory may be created in standard or
+// shared memory.
+//
+void PerfMemory::create_memory_region(size_t size) {
+
+ if (PerfDisableSharedMem) {
+ // do not share the memory for the performance data.
+ _start = create_standard_memory(size);
+ }
+ else {
+ _start = create_shared_memory(size);
+ if (_start == NULL) {
+
+ // creation of the shared memory region failed, attempt
+ // to create a contiguous, non-shared memory region instead.
+ //
+ if (PrintMiscellaneous && Verbose) {
+ warning("Reverting to non-shared PerfMemory region.\n");
+ }
+ PerfDisableSharedMem = true;
+ _start = create_standard_memory(size);
+ }
+ }
+
+ if (_start != NULL) _capacity = size;
+
+}
+
+// delete the PerfData memory region
+//
+// This method deletes the memory region used to store performance
+// data for the JVM. The memory region indicated by the <address, size>
+// tuple will be inaccessible after a call to this method.
+//
+void PerfMemory::delete_memory_region() {
+
+ assert((start() != NULL && capacity() > 0), "verify proper state");
+
+ // If user specifies PerfDataSaveFile, it will save the performance data
+ // to the specified file name no matter whether PerfDataSaveToFile is specified
+ // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
+ // -XX:+PerfDataSaveToFile.
+ if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
+ save_memory_to_file(start(), capacity());
+ }
+
+ if (PerfDisableSharedMem) {
+ delete_standard_memory(start(), capacity());
+ }
+ else {
+ delete_shared_memory(start(), capacity());
+ }
+}
+
+// attach to the PerfData memory region for another JVM
+//
+// This method returns an <address, size> tuple that points to
+// a memory buffer that is kept reasonably synchronized with
+// the PerfData memory region for the indicated JVM. This
+// buffer may be kept in synchronization via shared memory
+// or some other mechanism that keeps the buffer updated.
+//
+// If the JVM chooses not to support the attachability feature,
+// this method should throw an UnsupportedOperation exception.
+//
+// This implementation utilizes named shared memory to map
+// the indicated process's PerfData memory region into this JVMs
+// address space.
+//
+void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
+
+ if (vmid == 0 || vmid == os::current_process_id()) {
+ *addrp = start();
+ *sizep = capacity();
+ return;
+ }
+
+ mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
+}
+
+// detach from the PerfData memory region of another JVM
+//
+// This method detaches the PerfData memory region of another
+// JVM, specified as an <address, size> tuple of a buffer
+// in this process's address space. This method may perform
+// arbitrary actions to accomplish the detachment. The memory
+// region specified by <address, size> will be inaccessible after
+// a call to this method.
+//
+// If the JVM chooses not to support the attachability feature,
+// this method should throw an UnsupportedOperation exception.
+//
+// This implementation utilizes named shared memory to detach
+// the indicated process's PerfData memory region from this
+// process's address space.
+//
+void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
+
+ assert(addr != 0, "address sanity check");
+ assert(bytes > 0, "capacity sanity check");
+
+ if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
+ // prevent accidental detachment of this process's PerfMemory region
+ return;
+ }
+
+ unmap_shared(addr, bytes);
+}