/*

 * Copyright (c) 1999, 2015, 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.

 *

 */

// no precompiled headers

#include "classfile/classLoader.hpp"

#include "classfile/systemDictionary.hpp"

#include "classfile/vmSymbols.hpp"

#include "code/icBuffer.hpp"

#include "code/vtableStubs.hpp"

#include "compiler/compileBroker.hpp"

#include "compiler/disassembler.hpp"

#include "interpreter/interpreter.hpp"

#include "jvm_linux.h"

#include "memory/allocation.inline.hpp"

#include "memory/filemap.hpp"

#include "mutex_linux.inline.hpp"

#include "oops/oop.inline.hpp"

#include "os_linux.inline.hpp"

#include "os_share_linux.hpp"

#include "prims/jniFastGetField.hpp"

#include "prims/jvm.h"

#include "prims/jvm_misc.hpp"

#include "runtime/arguments.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/extendedPC.hpp"

#include "runtime/globals.hpp"

#include "runtime/interfaceSupport.hpp"

#include "runtime/init.hpp"

#include "runtime/java.hpp"

#include "runtime/javaCalls.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/objectMonitor.hpp"

#include "runtime/orderAccess.inline.hpp"

#include "runtime/osThread.hpp"

#include "runtime/perfMemory.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/statSampler.hpp"

#include "runtime/stubRoutines.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/threadCritical.hpp"

#include "runtime/timer.hpp"

#include "semaphore_posix.hpp"

#include "services/attachListener.hpp"

#include "services/memTracker.hpp"

#include "services/runtimeService.hpp"

#include "utilities/decoder.hpp"

#include "utilities/defaultStream.hpp"

#include "utilities/events.hpp"

#include "utilities/elfFile.hpp"

#include "utilities/growableArray.hpp"

#include "utilities/macros.hpp"

#include "utilities/vmError.hpp"

// put OS-includes here

# include <sys/types.h>

# include <sys/mman.h>

# include <sys/stat.h>

# include <sys/select.h>

# include <pthread.h>

# include <signal.h>

# include <errno.h>

# include <dlfcn.h>

# include <stdio.h>

# include <unistd.h>

# include <sys/resource.h>

# include <pthread.h>

# include <sys/stat.h>

# include <sys/time.h>

# include <sys/times.h>

# include <sys/utsname.h>

# include <sys/socket.h>

# include <sys/wait.h>

# include <pwd.h>

# include <poll.h>

# include <semaphore.h>

# include <fcntl.h>

# include <string.h>

# include <syscall.h>

# include <sys/sysinfo.h>

# include <gnu/libc-version.h>

# include <sys/ipc.h>

# include <sys/shm.h>

# include <link.h>

# include <stdint.h>

# include <inttypes.h>

# include <sys/ioctl.h>

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

// if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling

// getrusage() is prepared to handle the associated failure.

#ifndef RUSAGE_THREAD

  #define RUSAGE_THREAD   (1)               /* only the calling thread */

#endif

#define MAX_PATH    (2 * K)

#define MAX_SECS 100000000

// for timer info max values which include all bits

#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)

#define LARGEPAGES_BIT (1 << 6)

////////////////////////////////////////////////////////////////////////////////

// global variables

julong os::Linux::_physical_memory = 0;

address   os::Linux::_initial_thread_stack_bottom = NULL;

uintptr_t os::Linux::_initial_thread_stack_size   = 0;

int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;

int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;

int (*os::Linux::_pthread_setname_np)(pthread_t, const char*) = NULL;

Mutex* os::Linux::_createThread_lock = NULL;

pthread_t os::Linux::_main_thread;

int os::Linux::_page_size = -1;

const int os::Linux::_vm_default_page_size = (8 * K);

bool os::Linux::_supports_fast_thread_cpu_time = false;

const char * os::Linux::_glibc_version = NULL;

const char * os::Linux::_libpthread_version = NULL;

pthread_condattr_t os::Linux::_condattr[1];

static jlong initial_time_count=0;

static int clock_tics_per_sec = 100;

// For diagnostics to print a message once. see run_periodic_checks

static sigset_t check_signal_done;

static bool check_signals = true;

// Signal number used to suspend/resume a thread

// do not use any signal number less than SIGSEGV, see 4355769

static int SR_signum = SIGUSR2;

sigset_t SR_sigset;

// Declarations

static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);

// utility functions

static int SR_initialize();

julong os::available_memory() {

  return Linux::available_memory();

}

julong os::Linux::available_memory() {

  // values in struct sysinfo are "unsigned long"

  struct sysinfo si;

  sysinfo(&si);

  return (julong)si.freeram * si.mem_unit;

}

julong os::physical_memory() {

  return Linux::physical_memory();

}

// Return true if user is running as root.

bool os::have_special_privileges() {

  static bool init = false;

  static bool privileges = false;

  if (!init) {

    privileges = (getuid() != geteuid()) || (getgid() != getegid());

    init = true;

  }

  return privileges;

}

#ifndef SYS_gettid

// i386: 224, ia64: 1105, amd64: 186, sparc 143

  #ifdef __ia64__

    #define SYS_gettid 1105

  #else

    #ifdef __i386__

      #define SYS_gettid 224

    #else

      #ifdef __amd64__

        #define SYS_gettid 186

      #else

        #ifdef __sparc__

          #define SYS_gettid 143

        #else

          #error define gettid for the arch

        #endif

      #endif

    #endif

  #endif

#endif

// Cpu architecture string

static char cpu_arch[] = HOTSPOT_LIB_ARCH;

// pid_t gettid()

//

// Returns the kernel thread id of the currently running thread. Kernel

// thread id is used to access /proc.

pid_t os::Linux::gettid() {

  int rslt = syscall(SYS_gettid);

  assert(rslt != -1, "must be."); // old linuxthreads implementation?

  return (pid_t)rslt;

}

// Most versions of linux have a bug where the number of processors are

// determined by looking at the /proc file system.  In a chroot environment,

// the system call returns 1.  This causes the VM to act as if it is

// a single processor and elide locking (see is_MP() call).

static bool unsafe_chroot_detected = false;

static const char *unstable_chroot_error = "/proc file system not found.\n"

                     "Java may be unstable running multithreaded in a chroot "

                     "environment on Linux when /proc filesystem is not mounted.";

void os::Linux::initialize_system_info() {

  set_processor_count(sysconf(_SC_NPROCESSORS_CONF));

  if (processor_count() == 1) {

    pid_t pid = os::Linux::gettid();

    char fname[32];

    jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);

    FILE *fp = fopen(fname, "r");

    if (fp == NULL) {

      unsafe_chroot_detected = true;

    } else {

      fclose(fp);

    }

  }

  _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);

  assert(processor_count() > 0, "linux error");

}

void os::init_system_properties_values() {

  // The next steps are taken in the product version:

  //

  // Obtain the JAVA_HOME value from the location of libjvm.so.

  // This library should be located at:

  // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.

  //

  // If "/jre/lib/" appears at the right place in the path, then we

  // assume libjvm.so is installed in a JDK and we use this path.

  //

  // Otherwise exit with message: "Could not create the Java virtual machine."

  //

  // The following extra steps are taken in the debugging version:

  //

  // If "/jre/lib/" does NOT appear at the right place in the path

  // instead of exit check for $JAVA_HOME environment variable.

  //

  // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,

  // then we append a fake suffix "hotspot/libjvm.so" to this path so

  // it looks like libjvm.so is installed there

  // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.

  //

  // Otherwise exit.

  //

  // Important note: if the location of libjvm.so changes this

  // code needs to be changed accordingly.

  // See ld(1):

  //      The linker uses the following search paths to locate required

  //      shared libraries:

  //        1: ...

  //        ...

  //        7: The default directories, normally /lib and /usr/lib.

#if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))

  #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"

#else

  #define DEFAULT_LIBPATH "/lib:/usr/lib"

#endif

// Base path of extensions installed on the system.

#define SYS_EXT_DIR     "/usr/java/packages"

#define EXTENSIONS_DIR  "/lib/ext"

  // Buffer that fits several sprintfs.

  // Note that the space for the colon and the trailing null are provided

  // by the nulls included by the sizeof operator.

  const size_t bufsize =

    MAX2((size_t)MAXPATHLEN,  // For dll_dir & friends.

         (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir

  char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);

  // sysclasspath, java_home, dll_dir

  {

    char *pslash;

    os::jvm_path(buf, bufsize);

    // Found the full path to libjvm.so.

    // Now cut the path to <java_home>/jre if we can.

    pslash = strrchr(buf, '/');

    if (pslash != NULL) {

      *pslash = '\0';            // Get rid of /libjvm.so.

    }

    pslash = strrchr(buf, '/');

    if (pslash != NULL) {

      *pslash = '\0';            // Get rid of /{client|server|hotspot}.

    }

    Arguments::set_dll_dir(buf);

    if (pslash != NULL) {

      pslash = strrchr(buf, '/');

      if (pslash != NULL) {

        *pslash = '\0';          // Get rid of /<arch>.

        pslash = strrchr(buf, '/');

        if (pslash != NULL) {

          *pslash = '\0';        // Get rid of /lib.

        }

      }

    }

    Arguments::set_java_home(buf);

    set_boot_path('/', ':');

  }

  // Where to look for native libraries.

  //

  // Note: Due to a legacy implementation, most of the library path

  // is set in the launcher. This was to accomodate linking restrictions

  // on legacy Linux implementations (which are no longer supported).

  // Eventually, all the library path setting will be done here.

  //

  // However, to prevent the proliferation of improperly built native

  // libraries, the new path component /usr/java/packages is added here.

  // Eventually, all the library path setting will be done here.

  {

    // Get the user setting of LD_LIBRARY_PATH, and prepended it. It

    // should always exist (until the legacy problem cited above is

    // addressed).

    const char *v = ::getenv("LD_LIBRARY_PATH");

    const char *v_colon = ":";

    if (v == NULL) { v = ""; v_colon = ""; }

    // That's +1 for the colon and +1 for the trailing '\0'.

    char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,

                                                     strlen(v) + 1 +

                                                     sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,

                                                     mtInternal);

    sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);

    Arguments::set_library_path(ld_library_path);

    FREE_C_HEAP_ARRAY(char, ld_library_path);

  }

  // Extensions directories.

  sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());

  Arguments::set_ext_dirs(buf);

  FREE_C_HEAP_ARRAY(char, buf);

#undef DEFAULT_LIBPATH

#undef SYS_EXT_DIR

#undef EXTENSIONS_DIR

}

////////////////////////////////////////////////////////////////////////////////

// breakpoint support

void os::breakpoint() {

  BREAKPOINT;

}

extern "C" void breakpoint() {

  // use debugger to set breakpoint here

}

////////////////////////////////////////////////////////////////////////////////

// signal support

debug_only(static bool signal_sets_initialized = false);

static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;

bool os::Linux::is_sig_ignored(int sig) {

  struct sigaction oact;

  sigaction(sig, (struct sigaction*)NULL, &oact);

  void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*,  oact.sa_sigaction)

                                 : CAST_FROM_FN_PTR(void*,  oact.sa_handler);

  if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {

    return true;

  } else {

    return false;

  }

}

void os::Linux::signal_sets_init() {

  // Should also have an assertion stating we are still single-threaded.

  assert(!signal_sets_initialized, "Already initialized");

  // Fill in signals that are necessarily unblocked for all threads in

  // the VM. Currently, we unblock the following signals:

  // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden

  //                         by -Xrs (=ReduceSignalUsage));

  // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all

  // other threads. The "ReduceSignalUsage" boolean tells us not to alter

  // the dispositions or masks wrt these signals.

  // Programs embedding the VM that want to use the above signals for their

  // own purposes must, at this time, use the "-Xrs" option to prevent

  // interference with shutdown hooks and BREAK_SIGNAL thread dumping.

  // (See bug 4345157, and other related bugs).

  // In reality, though, unblocking these signals is really a nop, since

  // these signals are not blocked by default.

  sigemptyset(&unblocked_sigs);

  sigemptyset(&allowdebug_blocked_sigs);

  sigaddset(&unblocked_sigs, SIGILL);

  sigaddset(&unblocked_sigs, SIGSEGV);

  sigaddset(&unblocked_sigs, SIGBUS);

  sigaddset(&unblocked_sigs, SIGFPE);

#if defined(PPC64)

  sigaddset(&unblocked_sigs, SIGTRAP);

#endif

  sigaddset(&unblocked_sigs, SR_signum);

  if (!ReduceSignalUsage) {

    if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {

      sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);

      sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);

    }

    if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {

      sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);

      sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);

    }

    if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {

      sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);

      sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);

    }

  }

  // Fill in signals that are blocked by all but the VM thread.

  sigemptyset(&vm_sigs);

  if (!ReduceSignalUsage) {

    sigaddset(&vm_sigs, BREAK_SIGNAL);

  }

  debug_only(signal_sets_initialized = true);

}

// These are signals that are unblocked while a thread is running Java.

// (For some reason, they get blocked by default.)

sigset_t* os::Linux::unblocked_signals() {

  assert(signal_sets_initialized, "Not initialized");

  return &unblocked_sigs;

}

// These are the signals that are blocked while a (non-VM) thread is

// running Java. Only the VM thread handles these signals.

sigset_t* os::Linux::vm_signals() {

  assert(signal_sets_initialized, "Not initialized");

  return &vm_sigs;

}

// These are signals that are blocked during cond_wait to allow debugger in

sigset_t* os::Linux::allowdebug_blocked_signals() {

  assert(signal_sets_initialized, "Not initialized");

  return &allowdebug_blocked_sigs;

}

void os::Linux::hotspot_sigmask(Thread* thread) {

  //Save caller's signal mask before setting VM signal mask

  sigset_t caller_sigmask;

  pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);

  OSThread* osthread = thread->osthread();

  osthread->set_caller_sigmask(caller_sigmask);

  pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);

  if (!ReduceSignalUsage) {

    if (thread->is_VM_thread()) {

      // Only the VM thread handles BREAK_SIGNAL ...

      pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);

    } else {

      // ... all other threads block BREAK_SIGNAL

      pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);

    }

  }

}

//////////////////////////////////////////////////////////////////////////////

// detecting pthread library

void os::Linux::libpthread_init() {

  // Save glibc and pthread version strings.

#if !defined(_CS_GNU_LIBC_VERSION) || \

    !defined(_CS_GNU_LIBPTHREAD_VERSION)

  #error "glibc too old (< 2.3.2)"

#endif