jdk8-mips64-public/hotspot: src/os/linux/vm/perfMemory

src/os/linux/vm/perfMemory_linux.cpp@0f2fe7d37d8c (annotated)

src/os/linux/vm/perfMemory_linux.cpp

Mon, 17 Jun 2019 16:41:38 +0100

author: andrew
date: Mon, 17 Jun 2019 16:41:38 +0100
changeset 9711: 0f2fe7d37d8c
parent 9507: 7e72702243a4
child 9756: 2be326848943
child 9858: b985cbb00e68
permissions: -rw-r--r--

8202353: os::readdir should use readdir instead of readdir_r
Summary: Summary: os::readdir uses POSIX readdir, drop buffer arg, fix JFR uses.
Reviewed-by: coleenp, tschatzl, bsrbnd, shade, phh

 /*
  * Copyright (c) 2001, 2018, 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 "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/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, 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, 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, strerror(errno));
       }
     }
   }
   FREE_C_HEAP_ARRAY(char, destfile, mtInternal);
 }
 // 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, 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, 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",
                 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",
                 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, mtInternal);
     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, mtInternal);
   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(), 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;
   errno = 0;
   while ((dentry = os::readdir(tmpdirp)) != 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, mtInternal);
       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, mtInternal);
       os::closedir(subdirp);
       continue;
     }
     struct dirent* udentry;
     errno = 0;
     while ((udentry = os::readdir(subdirp)) != 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, mtInternal);
            continue;
         }
         // skip over files that are not regular files.
         if (!S_ISREG(statbuf.st_mode)) {
           FREE_C_HEAP_ARRAY(char, filename, mtInternal);
           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, mtInternal);
             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, mtInternal);
       }
     }
     os::closedir(subdirp);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
   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, 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;
   errno = 0;
   while ((entry = os::readdir(dirp)) != 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);
 }
 // 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, 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, 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", 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", 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(), 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 Solaris and 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, mtInternal);
   FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
   if (fd == -1) {
     FREE_C_HEAP_ARRAY(char, filename, mtInternal);
     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", strerror(errno));
     }
     remove_file(filename);
     FREE_C_HEAP_ARRAY(char, filename, mtInternal);
     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", 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, mtInternal);
     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, mtInternal);
   FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
   FREE_C_HEAP_ARRAY(char, filename, mtInternal);
   // 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", 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;
   if (PerfTraceMemOps) {
     tty->print("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);
 }
 char* PerfMemory::backing_store_filename() {
   return backing_store_file_name;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/os/linux/vm/perfMemory_linux.cpp@0f2fe7d37d8c (annotated)

src/os/linux/vm/perfMemory_linux.cpp