/*

 * Copyright 1999-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// do not include  precompiled  header file

# include "incls/_os_linux.cpp.incl"

// put OS-includes here

# include <sys/types.h>

# include <sys/mman.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>

#define MAX_PATH    (2 * K)

// for timer info max values which include all bits

#define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)

#define SEC_IN_NANOSECS  1000000000LL

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

// 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;

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

pthread_t os::Linux::_main_thread;

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

bool os::Linux::_is_floating_stack = false;

bool os::Linux::_is_NPTL = false;

bool os::Linux::_supports_fast_thread_cpu_time = false;

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

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

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;;

static pid_t _initial_pid = 0;

/* 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;

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

// utility functions

static int SR_initialize();

static int SR_finalize();

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();

}

julong os::allocatable_physical_memory(julong size) {

#ifdef _LP64

  return size;

#else

  julong result = MIN2(size, (julong)3800*M);

   if (!is_allocatable(result)) {

     // See comments under solaris for alignment considerations

     julong reasonable_size = (julong)2*G - 2 * os::vm_page_size();

     result =  MIN2(size, reasonable_size);

   }

   return result;

#endif // _LP64

}

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

// environment support

bool os::getenv(const char* name, char* buf, int len) {

  const char* val = ::getenv(name);

  if (val != NULL && strlen(val) < (size_t)len) {

    strcpy(buf, val);

    return true;

  }

  if (len > 0) buf[0] = 0;  // return a null string

  return false;

}

// 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

#elif __i386__

#define SYS_gettid 224

#elif __amd64__

#define SYS_gettid 186

#elif __sparc__

#define SYS_gettid 143

#else

#error define gettid for the arch

#endif

#endif

// Cpu architecture string

#if   defined(IA64)

static char cpu_arch[] = "ia64";

#elif defined(IA32)

static char cpu_arch[] = "i386";

#elif defined(AMD64)

static char cpu_arch[] = "amd64";

#elif defined(SPARC)

#  ifdef _LP64

static char cpu_arch[] = "sparcv9";

#  else

static char cpu_arch[] = "sparc";

#  endif

#else

#error Add appropriate cpu_arch setting

#endif

// pid_t gettid()

//

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

// thread id is used to access /proc.

//

// (Note that getpid() on LinuxThreads returns kernel thread id too; but

// on NPTL, it returns the same pid for all threads, as required by POSIX.)

//

pid_t os::Linux::gettid() {

  int rslt = syscall(SYS_gettid);

  if (rslt == -1) {

     // old kernel, no NPTL support

     return getpid();

  } else {

     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() {

  _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() {

//  char arch[12];

//  sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));

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

  //

  // Obtain the JAVA_HOME value from the location of libjvm[_g].so.

  // This library should be located at:

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

  //

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

  // assume libjvm[_g].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[_g].so" to this path so

  // it looks like libjvm[_g].so is installed there

  // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so.

  //

  // Otherwise exit.

  //

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

  // code needs to be changed accordingly.

  // The next few definitions allow the code to be verbatim:

#define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n))

#define getenv(n) ::getenv(n)

/*

 * 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.

 */

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

#define EXTENSIONS_DIR  "/lib/ext"

#define ENDORSED_DIR    "/lib/endorsed"

#define REG_DIR         "/usr/java/packages"

  {

    /* sysclasspath, java_home, dll_dir */

    {

        char *home_path;

        char *dll_path;

        char *pslash;

        char buf[MAXPATHLEN];

        os::jvm_path(buf, sizeof(buf));

        // Found the full path to libjvm.so.

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

        *(strrchr(buf, '/')) = '\0';  /* get rid of /libjvm.so */

        pslash = strrchr(buf, '/');

        if (pslash != NULL)

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

        dll_path = malloc(strlen(buf) + 1);

        if (dll_path == NULL)

            return;

        strcpy(dll_path, buf);

        Arguments::set_dll_dir(dll_path);

        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 */

            }

        }

        home_path = malloc(strlen(buf) + 1);

        if (home_path == NULL)

            return;

        strcpy(home_path, buf);

        Arguments::set_java_home(home_path);

        if (!set_boot_path('/', ':'))

            return;

    }

    /*

     * 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.

     */

    {

        char *ld_library_path;

        /*

         * Construct the invariant part of ld_library_path. Note that the

         * space for the colon and the trailing null are provided by the

         * nulls included by the sizeof operator (so actually we allocate

         * a byte more than necessary).

         */

        ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +

            strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));

        sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);

        /*

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

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

         * addressed).

         */

        char *v = getenv("LD_LIBRARY_PATH");

        if (v != NULL) {

            char *t = ld_library_path;

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

            ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);

            sprintf(ld_library_path, "%s:%s", v, t);

        }

        Arguments::set_library_path(ld_library_path);

    }

    /*

     * Extensions directories.

     *

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

     * by the nulls included by the sizeof operator (so actually one byte more

     * than necessary is allocated).

     */

    {

        char *buf = malloc(strlen(Arguments::get_java_home()) +

            sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));

        sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,

            Arguments::get_java_home());

        Arguments::set_ext_dirs(buf);

    }

    /* Endorsed standards default directory. */

    {

        char * buf;

        buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));

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

        Arguments::set_endorsed_dirs(buf);

    }

  }

#undef malloc

#undef getenv

#undef EXTENSIONS_DIR

#undef ENDORSED_DIR

  // Done

  return;

}

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

// 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);

  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. Note that _CS_GNU_LIBC_VERSION

  // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a

  // generic name for earlier versions.

  // Define macros here so we can build HotSpot on old systems.

# ifndef _CS_GNU_LIBC_VERSION