src/java.base/macosx/native/libjli/java_md_macosx.m

/*
 * Copyright (c) 2012, 2024, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 "java.h"
#include "jvm_md.h"
#include <dirent.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>

#include "manifest_info.h"

/* Support Cocoa event loop on the main thread */
#include <Cocoa/Cocoa.h>
#include <objc/objc-runtime.h>
#include <objc/objc-auto.h>

#include <errno.h>
#include <spawn.h>
#include <unistd.h>

struct NSAppArgs {
    int argc;
    char **argv;
};

#define JVM_DLL "libjvm.dylib"
#define JAVA_DLL "libjava.dylib"
/* FALLBACK avoids naming conflicts with system libraries
 * (eg, ImageIO's libJPEG.dylib) */
#define LD_LIBRARY_PATH "DYLD_FALLBACK_LIBRARY_PATH"

/*
 * Following is the high level flow of the launcher
 * code residing in the common java.c and this
 * macosx specific java_md_macosx file:
 *
 *  - JLI_Launch function, which is the entry point
 *    to the launcher, calls CreateExecutionEnvironment.
 *
 *  - CreateExecutionEnvironment does the following
 *    (not necessarily in this order):
 *      - determines the relevant JVM type that needs
 *        to be ultimately created
 *      - determines the path and asserts the presence
 *        of libjava and relevant libjvm library
 *      - removes any JVM selection options from the
 *        arguments that were passed to the launcher
 *
 *  - CreateExecutionEnvironment then creates a new
 *    thread, within the same process, to launch the
 *    application's main() Java method and parks the
 *    current thread, on which CreateExecutionEnvironment
 *    was invoked, in Apple's Cocoa event loop. Before
 *    doing so, CreateExecutionEnvironment maintains a
 *    state flag to keep note that a new thread has
 *    been spawned.
 *
 *  - The newly created thread (in which the application's
 *    main() method will ultimately run) starts right from
 *    the beginning of the current process' main function,
 *    which effectively means that JLI_Launch is re-invoked
 *    on this new thread and the same above sequence of code
 *    flow repeats again. During this "recursive" call, when
 *    at the point of creating a new thread in
 *    CreateExecutionEnvironment, the CreateExecutionEnvironment
 *    will check for the state flag to see if a new thread
 *    has already been spawned and upon noticing that it
 *    has, it will skip spawning any more threads and will
 *    return back from CreateExecutionEnvironment.
 *
 *  - The control returns back from CreateExecutionEnvironment
 *    to JLI_Launch, and the thread on which the control
 *    returns is the thread on which the application's main()
 *    Java method will be invoked.
 *
 *  - JLI_Launch then invokes LoadJavaVM which dlopen()s the
 *    JVM library and asserts the presence of JNI Invocation
 *    Functions "JNI_CreateJavaVM", "JNI_GetDefaultJavaVMInitArgs"
 *    and "JNI_GetCreatedJavaVMs" in that library. It then sets
 *    internal function pointers in the launcher to point to
 *    those functions.
 *
 *  - JLI_Launch then translates any -J options by invoking
 *    TranslateApplicationArgs.
 *
 *  - JLI_Launch then invokes ParseArguments to parse/process
 *    the launcher arguments.
 *
 *  - JLI_Launch then ultimately calls JVMInit.
 *
 *  - JVMInit then invokes JavaMain.
 *
 *  - JavaMain, before launching the application, invokes
 *    PostJVMInit.
 *
 *  - PostJVMInit invokes ShowSplashScreen which displays
 *    a splash screen for the application, if applicable.
 *
 *  - Control then returns back from PostJVMInit into
 *    JavaMain, which then loads the application's main
 *    class and invokes the relevant main() Java method.
 *
 *  - JavaMain then returns back an integer result which
 *    then gets propagated as a return value all the way
 *    out of the JLI_Launch function.
 */

/* Store the name of the executable once computed */
static char *execname = NULL;

/*
 * execname accessor from other parts of platform dependent logic
 */
const char *
GetExecName() {
    return execname;
}

/*
 * Exports the JNI interface from libjli
 *
 * This allows client code to link against the JDK bundles,
 * and not worry about trying to pick a HotSpot to link against.
 *
 * Switching architectures is unsupported, since client code has
 * made that choice before the JVM was requested.
 */

static InvocationFunctions *sExportedJNIFunctions = NULL;
static char *sPreferredJVMType = NULL;

static InvocationFunctions *GetExportedJNIFunctions() {
    if (sExportedJNIFunctions != NULL) return sExportedJNIFunctions;

    char jdkRoot[PATH_MAX];
    jboolean got = GetJDKInstallRoot(jdkRoot, sizeof(jdkRoot), JNI_FALSE);
    if (!got) {
        JLI_ReportErrorMessage("Failed to determine JDK installation root");
        return NULL;
    }

    char *preferredJVM = sPreferredJVMType;
    if (preferredJVM == NULL) {
#if defined(__i386__)
        preferredJVM = "client";
#elif defined(__x86_64__)
        preferredJVM = "server";
#elif defined(__aarch64__)
        preferredJVM = "server";
#else
#error "Unknown architecture - needs definition"
#endif
    }

    char jvmPath[PATH_MAX];
    jboolean gotJVMPath = GetJVMPath(jdkRoot, preferredJVM, jvmPath, sizeof(jvmPath));
    if (!gotJVMPath) {
        JLI_ReportErrorMessage("Failed to GetJVMPath()");
        return NULL;
    }

    InvocationFunctions *fxns = malloc(sizeof(InvocationFunctions));
    jboolean vmLoaded = LoadJavaVM(jvmPath, fxns);
    if (!vmLoaded) {
        JLI_ReportErrorMessage("Failed to LoadJavaVM()");
        return NULL;
    }

    return sExportedJNIFunctions = fxns;
}

#ifndef STATIC_BUILD

JNIEXPORT jint JNICALL
JNI_GetDefaultJavaVMInitArgs(void *args) {
    InvocationFunctions *ifn = GetExportedJNIFunctions();
    if (ifn == NULL) return JNI_ERR;
    return ifn->GetDefaultJavaVMInitArgs(args);
}

JNIEXPORT jint JNICALL
JNI_CreateJavaVM(JavaVM **pvm, void **penv, void *args) {
    InvocationFunctions *ifn = GetExportedJNIFunctions();
    if (ifn == NULL) return JNI_ERR;
    return ifn->CreateJavaVM(pvm, penv, args);
}

JNIEXPORT jint JNICALL
JNI_GetCreatedJavaVMs(JavaVM **vmBuf, jsize bufLen, jsize *nVMs) {
    InvocationFunctions *ifn = GetExportedJNIFunctions();
    if (ifn == NULL) return JNI_ERR;
    return ifn->GetCreatedJavaVMs(vmBuf, bufLen, nVMs);
}
#endif

/*
 * Allow JLI-aware launchers to specify a client/server preference
 */
JNIEXPORT void JNICALL
JLI_SetPreferredJVM(const char *prefJVM) {
    if (sPreferredJVMType != NULL) {
        free(sPreferredJVMType);
        sPreferredJVMType = NULL;
    }

    if (prefJVM == NULL) return;
    sPreferredJVMType = strdup(prefJVM);
}

static BOOL awtLoaded = NO;
static pthread_mutex_t awtLoaded_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  awtLoaded_cv = PTHREAD_COND_INITIALIZER;

JNIEXPORT void JNICALL
JLI_NotifyAWTLoaded()
{
    pthread_mutex_lock(&awtLoaded_mutex);
    awtLoaded = YES;
    pthread_cond_signal(&awtLoaded_cv);
    pthread_mutex_unlock(&awtLoaded_mutex);
}

static int (*main_fptr)(int argc, char **argv) = NULL;

/*
 * Unwrap the arguments and re-run main()
 */
static void *apple_main (void *arg)
{
    if (main_fptr == NULL) {
#ifdef STATIC_BUILD
        extern int main(int argc, char **argv);
        main_fptr = &main;
#else
        main_fptr = (int (*)())dlsym(RTLD_DEFAULT, "main");
#endif
        if (main_fptr == NULL) {
            JLI_ReportErrorMessageSys("error locating main entrypoint\n");
            exit(1);
        }
    }

    struct NSAppArgs *args = (struct NSAppArgs *) arg;
    exit(main_fptr(args->argc, args->argv));
}

static void dummyTimer(CFRunLoopTimerRef timer, void *info) {}

static void ParkEventLoop() {
    // RunLoop needs at least one source, and 1e20 is pretty far into the future
    CFRunLoopTimerRef t = CFRunLoopTimerCreate(kCFAllocatorDefault, 1.0e20, 0.0, 0, 0, dummyTimer, NULL);
    CFRunLoopAddTimer(CFRunLoopGetCurrent(), t, kCFRunLoopDefaultMode);
    CFRelease(t);

    // Park this thread in the main run loop.
    int32_t result;
    do {
        result = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 1.0e20, false);
    } while (result != kCFRunLoopRunFinished);
}

/*
 * Mac OS X mandates that the GUI event loop run on very first thread of
 * an application. This requires that we re-call Java's main() on a new
 * thread, reserving the 'main' thread for Cocoa.
 */
static void MacOSXStartup(int argc, char *argv[]) {
    // Thread already started?
    static jboolean started = false;
    int rc;
    if (started) {
        return;
    }
    started = true;

    // Hand off arguments
    struct NSAppArgs args;
    args.argc = argc;
    args.argv = argv;

    // Fire up the main thread
    pthread_t main_thr;
    rc = pthread_create(&main_thr, NULL, &apple_main, &args);
    if (rc != 0) {
        JLI_ReportErrorMessageSys("Could not create main thread, return code: %d\n", rc);
        exit(1);
    }
    rc = pthread_detach(main_thr);
    if (rc != 0) {
        JLI_ReportErrorMessage("pthread_detach() failed, return code: %d\n", rc);
        exit(1);
    }

    ParkEventLoop();
}

void
CreateExecutionEnvironment(int *pargc, char ***pargv,
                           char jdkroot[], jint so_jdkroot,
                           char jvmpath[], jint so_jvmpath,
                           char jvmcfg[], jint so_jvmcfg) {
    /* Compute/set the name of the executable */
    SetExecname(*pargv);

    char * jvmtype    = NULL;
    int  argc         = *pargc;
    char **argv       = *pargv;

    if (!JLI_IsStaticallyLinked()) {
        /* Find out where the JDK is that we will be using. */
        if (!GetJDKInstallRoot(jdkroot, so_jdkroot, JNI_FALSE) ) {
            JLI_ReportErrorMessage(LAUNCHER_ERROR1);
            exit(2);
        }
        JLI_Snprintf(jvmcfg, so_jvmcfg, "%s%slib%sjvm.cfg",
                     jdkroot, FILESEP, FILESEP);
        /* Find the specified JVM type */
        if (ReadKnownVMs(jvmcfg, JNI_FALSE) < 1) {
            JLI_ReportErrorMessage(CFG_ERROR7);
            exit(1);
        }

        jvmpath[0] = '\0';
        jvmtype = CheckJvmType(pargc, pargv, JNI_FALSE);
        if (JLI_StrCmp(jvmtype, "ERROR") == 0) {
            JLI_ReportErrorMessage(CFG_ERROR9);
            exit(4);
        }

        if (!GetJVMPath(jdkroot, jvmtype, jvmpath, so_jvmpath)) {
            JLI_ReportErrorMessage(CFG_ERROR8, jvmtype, jvmpath);
            exit(4);
        }
    }

    /*
     * Mac OS X requires the Cocoa event loop to be run on the "main"
     * thread. Spawn off a new thread to run main() and pass
     * this thread off to the Cocoa event loop.
     */
    MacOSXStartup(argc, argv);

    /*
     * we seem to have everything we need
     */
    return;
}

/*
 * VM choosing is done by the launcher (java.c).
 */
static jboolean
GetJVMPath(const char *jdkroot, const char *jvmtype,
           char *jvmpath, jint jvmpathsize)
{
    struct stat s;

    if (JLI_StrChr(jvmtype, '/')) {
        JLI_Snprintf(jvmpath, jvmpathsize, "%s/" JVM_DLL, jvmtype);
    } else {
        /*
         * macosx client library is built thin, i386 only.
         * 64 bit client requests must load server library
         */
        JLI_Snprintf(jvmpath, jvmpathsize, "%s/lib/%s/" JVM_DLL, jdkroot, jvmtype);
    }

    JLI_TraceLauncher("Does `%s' exist ... ", jvmpath);

    if (JLI_IsStaticallyLinked()) {
        return JNI_TRUE;
    }
    if (stat(jvmpath, &s) == 0) {
        JLI_TraceLauncher("yes.\n");
        return JNI_TRUE;
    } else {
        JLI_TraceLauncher("no.\n");
        return JNI_FALSE;
    }
}

/*
 * Find path to the JDK installation root
 */
static jboolean
GetJDKInstallRoot(char *path, jint pathsize, jboolean speculative)
{
    char libjava[MAXPATHLEN];

    JLI_TraceLauncher("Attempt to get JDK installation root from launcher executable path\n");

    if (GetApplicationHome(path, pathsize)) {
        /* Is the JDK co-located with the application? */
        if (JLI_IsStaticallyLinked()) {
            char jvm_cfg[MAXPATHLEN];
            JLI_Snprintf(jvm_cfg, sizeof(jvm_cfg), "%s/lib/jvm.cfg", path);
            if (access(jvm_cfg, F_OK) == 0) {
                return JNI_TRUE;
            }
        } else {
            JLI_Snprintf(libjava, sizeof(libjava), "%s/lib/" JAVA_DLL, path);
            if (access(libjava, F_OK) == 0) {
                return JNI_TRUE;
            }
        }
    }

    /* try to find ourselves instead */
    Dl_info selfInfo;
    dladdr(&GetJDKInstallRoot, &selfInfo);

    if (JLI_IsStaticallyLinked()) {
        char jvm_cfg[MAXPATHLEN];
        char *p = NULL;
        strncpy(jvm_cfg, selfInfo.dli_fname, MAXPATHLEN);
        p = strrchr(jvm_cfg, '/'); *p = '\0';
        p = strrchr(jvm_cfg, '/');
        if (strcmp(p, "/.") == 0) {
            *p = '\0';
            p = strrchr(jvm_cfg, '/'); *p = '\0';
        } else {
          *p = '\0';
        }
        strncpy(path, jvm_cfg, pathsize);
        strncat(jvm_cfg, "/lib/jvm.cfg", MAXPATHLEN);
        if (access(jvm_cfg, F_OK) == 0) {
           return JNI_TRUE;
        }
    }

    char *realPathToSelf = realpath(selfInfo.dli_fname, path);
    if (realPathToSelf != path) {
        return JNI_FALSE;
    }

    size_t pathLen = strlen(realPathToSelf);
    if (pathLen == 0) {
        return JNI_FALSE;
    }

    const char lastPathComponent[] = "/lib/libjli.dylib";
    size_t sizeOfLastPathComponent = sizeof(lastPathComponent) - 1;
    if (pathLen < sizeOfLastPathComponent) {
        return JNI_FALSE;
    }

    size_t indexOfLastPathComponent = pathLen - sizeOfLastPathComponent;
    if (0 == strncmp(realPathToSelf + indexOfLastPathComponent, lastPathComponent, sizeOfLastPathComponent)) {
        realPathToSelf[indexOfLastPathComponent + 1] = '\0';
        return JNI_TRUE;
    }

    // If libjli.dylib is loaded from a macos bundle MacOS dir, find the JDK
    // install root at ../Home.
    const char altLastPathComponent[] = "/MacOS/libjli.dylib";
    size_t sizeOfAltLastPathComponent = sizeof(altLastPathComponent) - 1;
    if (pathLen < sizeOfLastPathComponent) {
        return JNI_FALSE;
    }

    size_t indexOfAltLastPathComponent = pathLen - sizeOfAltLastPathComponent;
    if (0 == strncmp(realPathToSelf + indexOfAltLastPathComponent, altLastPathComponent, sizeOfAltLastPathComponent)) {
        JLI_Snprintf(realPathToSelf + indexOfAltLastPathComponent, sizeOfAltLastPathComponent, "%s", "/Home");
        if (access(realPathToSelf, F_OK) == 0) {
            return JNI_TRUE;
        }
    }

    if (!speculative)
      JLI_ReportErrorMessage(LAUNCHER_ERROR2 JAVA_DLL);
    return JNI_FALSE;
}

jboolean
LoadJavaVM(const char *jvmpath, InvocationFunctions *ifn)
{
    void *libjvm;

    JLI_TraceLauncher("JVM path is %s\n", jvmpath);

    if (!JLI_IsStaticallyLinked()) {
        libjvm = dlopen(jvmpath, RTLD_NOW + RTLD_GLOBAL);
    } else {
        libjvm = dlopen(NULL, RTLD_FIRST);
    }

    if (libjvm == NULL) {
        JLI_ReportErrorMessage(DLL_ERROR1, __LINE__);
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
    }

    ifn->CreateJavaVM = (CreateJavaVM_t)
        dlsym(libjvm, "JNI_CreateJavaVM");
    if (ifn->CreateJavaVM == NULL) {
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
    }

    ifn->GetDefaultJavaVMInitArgs = (GetDefaultJavaVMInitArgs_t)
        dlsym(libjvm, "JNI_GetDefaultJavaVMInitArgs");
    if (ifn->GetDefaultJavaVMInitArgs == NULL) {
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
    }

    ifn->GetCreatedJavaVMs = (GetCreatedJavaVMs_t)
    dlsym(libjvm, "JNI_GetCreatedJavaVMs");
    if (ifn->GetCreatedJavaVMs == NULL) {
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
    }

    return JNI_TRUE;
}

/*
 * Compute the name of the executable
 *
 * In order to re-exec securely we need the absolute path of the
 * executable. On Solaris getexecname(3c) may not return an absolute
 * path so we use dladdr to get the filename of the executable and
 * then use realpath to derive an absolute path. From Solaris 9
 * onwards the filename returned in DL_info structure from dladdr is
 * an absolute pathname so technically realpath isn't required.
 * On Linux we read the executable name from /proc/self/exe.
 * As a fallback, and for platforms other than Solaris and Linux,
 * we use FindExecName to compute the executable name.
 */
const char*
SetExecname(char **argv)
{
    char* exec_path = NULL;
    {
        Dl_info dlinfo;
        void *fptr;

        if (JLI_IsStaticallyLinked()) {
            fptr = (void *)&SetExecname;
        } else {
            fptr = dlsym(RTLD_DEFAULT, "main");
        }
        if (fptr == NULL) {
            JLI_ReportErrorMessage(DLL_ERROR3, dlerror());
            return JNI_FALSE;
        }

        if (dladdr((void*)fptr, &dlinfo)) {
            char *resolved = (char*)JLI_MemAlloc(PATH_MAX+1);
            if (resolved != NULL) {
                exec_path = realpath(dlinfo.dli_fname, resolved);
                if (exec_path == NULL) {
                    JLI_MemFree(resolved);
                }
            }
        }
    }
    if (exec_path == NULL) {
        exec_path = FindExecName(argv[0]);
    }
    execname = exec_path;
    return exec_path;
}

/* --- Splash Screen shared library support --- */

static JavaVM* SetJavaVMValue()
{
    JavaVM * jvm = NULL;

    // The handle is good for both the launcher and the libosxapp.dylib
    void * handle = dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL);
    if (handle) {
        typedef JavaVM* (*JLI_GetJavaVMInstance_t)();

        JLI_GetJavaVMInstance_t JLI_GetJavaVMInstance =
            (JLI_GetJavaVMInstance_t)dlsym(handle,
                    "JLI_GetJavaVMInstance");
        if (JLI_GetJavaVMInstance) {
            jvm = JLI_GetJavaVMInstance();
        }

        if (jvm) {
            typedef void (*OSXAPP_SetJavaVM_t)(JavaVM*);

            OSXAPP_SetJavaVM_t OSXAPP_SetJavaVM =
                (OSXAPP_SetJavaVM_t)dlsym(handle, "OSXAPP_SetJavaVM");
            if (OSXAPP_SetJavaVM) {
                OSXAPP_SetJavaVM(jvm);
            } else {
                jvm = NULL;
            }
        }

        dlclose(handle);
    }

    return jvm;
}

static const char* SPLASHSCREEN_SO = JNI_LIB_NAME("splashscreen");

static void* hSplashLib = NULL;

void* SplashProcAddress(const char* name) {
    if (!hSplashLib) {
        char jdkRoot[PATH_MAX];
        if (!GetJDKInstallRoot(jdkRoot, sizeof(jdkRoot), JNI_FALSE)) {
            JLI_ReportErrorMessage(LAUNCHER_ERROR1);
            return NULL;
        }

        char splashPath[PATH_MAX];
        const int ret = JLI_Snprintf(splashPath, sizeof(splashPath),
                                     "%s/lib/%s", jdkRoot, SPLASHSCREEN_SO);
        if (ret >= (int)sizeof(splashPath)) {
            JLI_ReportErrorMessage(LAUNCHER_ERROR3);
            return NULL;
        }
        if (ret < 0) {
            JLI_ReportErrorMessage(LAUNCHER_ERROR5);
            return NULL;
        }

        hSplashLib = dlopen(splashPath, RTLD_LAZY | RTLD_GLOBAL);
        // It's OK if dlopen() fails. The splash screen library binary file
        // might have been stripped out from the JDK image to reduce its size
        // (e.g. on embedded platforms).

        if (hSplashLib) {
            if (!SetJavaVMValue()) {
                dlclose(hSplashLib);
                hSplashLib = NULL;
            }
        }
    }
    if (hSplashLib) {
        void* sym = dlsym(hSplashLib, name);
        return sym;
    } else {
        return NULL;
    }
}

/*
 * Signature adapter for pthread_create().
 */
static void* ThreadJavaMain(void* args) {
    return (void*)(intptr_t)JavaMain(args);
}

static size_t adjustStackSize(size_t stack_size) {
    long page_size = getpagesize();
    if (stack_size % page_size == 0) {
        return stack_size;
    } else {
        long pages = stack_size / page_size;
        // Ensure we don't go over limit
        if (stack_size <= SIZE_MAX - page_size) {
            pages++;
        }
        return page_size * pages;
    }
}

/*
 * Block current thread and continue execution in a new thread.
 */
int
CallJavaMainInNewThread(jlong stack_size, void* args) {
    int rslt;
    pthread_t tid;
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);

    if (stack_size > 0) {
        pthread_attr_setstacksize(&attr, adjustStackSize(stack_size));
    }
    pthread_attr_setguardsize(&attr, 0); // no pthread guard page on java threads

    if (pthread_create(&tid, &attr, ThreadJavaMain, args) == 0) {
        void* tmp;
        pthread_join(tid, &tmp);
        rslt = (int)(intptr_t)tmp;
    } else {
       /*
        * Continue execution in current thread if for some reason (e.g. out of
        * memory/LWP)  a new thread can't be created. This will likely fail
        * later in JavaMain as JNI_CreateJavaVM needs to create quite a
        * few new threads, anyway, just give it a try..
        */
        rslt = JavaMain(args);
    }

    pthread_attr_destroy(&attr);
    return rslt;
}

static JavaVM* jvmInstance = NULL;
static jboolean sameThread = JNI_FALSE; /* start VM in current thread */

/*
 * Note there is a callback on this function from the splashscreen logic,
 * this as well SetJavaVMValue() needs to be simplified.
 */
JNIEXPORT JavaVM* JNICALL
JLI_GetJavaVMInstance()
{
    return jvmInstance;
}

void
RegisterThread()
{
    // stubbed out for windows and *nixes.
}

static void
SetXDockArgForAWT(const char *arg)
{
    char envVar[80];
    if (strstr(arg, "-Xdock:name=") == arg) {
        /*
         * The APP_NAME_<pid> environment variable is used to pass
         * an application name as specified with the -Xdock:name command
         * line option from Java launcher code to the AWT code in order
         * to assign this name to the app's dock tile on the Mac.
         * The _<pid> part is added to avoid collisions with child processes.
         *
         * WARNING: This environment variable is an implementation detail and
         * isn't meant for use outside of the core platform. The mechanism for
         * passing this information from Java launcher to other modules may
         * change drastically between update release, and it may even be
         * removed or replaced with another mechanism.
         *
         * NOTE: It is used by SWT
         */
        snprintf(envVar, sizeof(envVar), "APP_NAME_%d", getpid());
        setenv(envVar, (arg + 12), 1);
    }

    if (strstr(arg, "-Xdock:icon=") == arg) {
        /*
         * The APP_ICON_<pid> environment variable is used to pass
         * an application icon as specified with the -Xdock:icon command
         * line option from Java launcher code to the AWT code in order
         * to assign this icon to the app's dock tile on the Mac.
         * The _<pid> part is added to avoid collisions with child processes.
         *
         * WARNING: This environment variable is an implementation detail and
         * isn't meant for use outside of the core platform. The mechanism for
         * passing this information from Java launcher to other modules may
         * change drastically between update release, and it may even be
         * removed or replaced with another mechanism.
         *
         * NOTE: It is used by SWT, and JavaFX.
         */
        snprintf(envVar, sizeof(envVar), "APP_ICON_%d", getpid());
        setenv(envVar, (arg + 12), 1);
    }
}

static void
SetMainClassForAWT(JNIEnv *env, jclass mainClass) {
    jclass classClass = NULL;
    NULL_CHECK(classClass = FindBootStrapClass(env, "java/lang/Class"));

    jmethodID getCanonicalNameMID = NULL;
    NULL_CHECK(getCanonicalNameMID = (*env)->GetMethodID(env, classClass, "getCanonicalName", "()Ljava/lang/String;"));

    jclass strClass = NULL;
    NULL_CHECK(strClass = (*env)->FindClass(env, "java/lang/String"));

    jmethodID lastIndexMID = NULL;
    NULL_CHECK(lastIndexMID = (*env)->GetMethodID(env, strClass, "lastIndexOf", "(I)I"));

    jmethodID subStringMID = NULL;
    NULL_CHECK(subStringMID = (*env)->GetMethodID(env, strClass, "substring", "(I)Ljava/lang/String;"));

    jstring mainClassString = (*env)->CallObjectMethod(env, mainClass, getCanonicalNameMID);
    if ((*env)->ExceptionCheck(env) || NULL == mainClassString) {
        (*env)->ExceptionClear(env);
        return;
    }

    jint lastPeriod = (*env)->CallIntMethod(env, mainClassString, lastIndexMID, (jint)'.');
    if ((*env)->ExceptionCheck(env)) {
        (*env)->ExceptionClear(env);
        return;
    }

    if (lastPeriod != -1) {
        mainClassString = (*env)->CallObjectMethod(env, mainClassString, subStringMID, lastPeriod+1);
        if ((*env)->ExceptionCheck(env)) {
            (*env)->ExceptionClear(env);
            return;
        }
    }

    /* There are multiple apple.awt.*" system properties that AWT(the desktop module)
     * references that are inherited from Apple JDK.
     * This inherited AWT code looks for this property and uses it for the name
     * of the app as it appears in the system menu bar.
     *
     * No idea if how much external code ever sets it, but use it if set, else
     * if not set (the high probability event) set it to the application class name.
     */
    const char* propName = "apple.awt.application.name";
    jstring jKey = NULL;
    NULL_CHECK(jKey = (*env)->NewStringUTF(env, propName));

    jclass sysClass = NULL;
    NULL_CHECK(sysClass = (*env)->FindClass(env, "java/lang/System"));

    jmethodID getPropertyMID = NULL;
    NULL_CHECK(getPropertyMID = (*env)->GetStaticMethodID(env, sysClass,
               "getProperty", "(Ljava/lang/String;)Ljava/lang/String;"));

    jmethodID setPropertyMID = NULL;
    NULL_CHECK(setPropertyMID = (*env)->GetStaticMethodID(env, sysClass,
               "setProperty",
               "(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;"));

    jstring jValue = (*env)->CallStaticObjectMethod(env, sysClass, getPropertyMID, jKey);
    if ((*env)->ExceptionCheck(env)) {
        (*env)->ExceptionClear(env);
        (*env)->DeleteLocalRef(env, jKey);
        return;
    }
    if (jValue == NULL) {
        (*env)->CallStaticObjectMethod(env, sysClass, setPropertyMID,
                                       jKey, mainClassString);
        if ((*env)->ExceptionCheck(env)) {
            (*env)->ExceptionClear(env);
            (*env)->DeleteLocalRef(env, jKey);
            return;
        }
    } else {
        (*env)->DeleteLocalRef(env, jValue);
    }

    (*env)->DeleteLocalRef(env, jKey);
}

void
SetXStartOnFirstThreadArg()
{
    // XXX: BEGIN HACK
    // short circuit hack for <https://bugs.eclipse.org/bugs/show_bug.cgi?id=211625>
    // need a way to get AWT/Swing apps launched when spawned from Eclipse,
    // which currently has no UI to not pass the -XstartOnFirstThread option
    if (getenv("HACK_IGNORE_START_ON_FIRST_THREAD") != NULL) return;
    // XXX: END HACK

    sameThread = JNI_TRUE;
    // Set a variable that tells us we started on the main thread.
    // This is used by the AWT during startup. (See LWCToolkit.m)
    char envVar[80];
    snprintf(envVar, sizeof(envVar), "JAVA_STARTED_ON_FIRST_THREAD_%d", getpid());
    setenv(envVar, "1", 1);
}

// MacOSX we may continue in the same thread
int
JVMInit(InvocationFunctions* ifn, jlong threadStackSize,
                 int argc, char **argv,
                 int mode, char *what, int ret) {
    if (sameThread) {
        JLI_TraceLauncher("In same thread\n");
        // need to block this thread against the main thread
        // so signals get caught correctly
        __block int rslt = 0;
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
        {
            NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock: ^{
                JavaMainArgs args;
                args.argc = argc;
                args.argv = argv;
                args.mode = mode;
                args.what = what;
                args.ifn  = *ifn;
                rslt = JavaMain(&args);
            }];

            /*
             * We cannot use dispatch_sync here, because it blocks the main dispatch queue.
             * Using the main NSRunLoop allows the dispatch queue to run properly once
             * SWT (or whatever toolkit this is needed for) kicks off it's own NSRunLoop
             * and starts running.
             */
            [op performSelectorOnMainThread:@selector(start) withObject:nil waitUntilDone:YES];
        }
        [pool drain];
        return rslt;
    } else {
        return ContinueInNewThread(ifn, threadStackSize, argc, argv, mode, what, ret);
    }
}

/*
 * Note the jvmInstance must be initialized first before entering into
 * ShowSplashScreen, as there is a callback into the JLI_GetJavaVMInstance.
 */
void PostJVMInit(JNIEnv *env, jclass mainClass, JavaVM *vm) {
    jvmInstance = vm;
    SetMainClassForAWT(env, mainClass);
    CHECK_EXCEPTION_RETURN();
    ShowSplashScreen();
}

jboolean
ProcessPlatformOption(const char* arg)
{
    if (JLI_StrCmp(arg, "-XstartOnFirstThread") == 0) {
       SetXStartOnFirstThreadArg();
       return JNI_TRUE;
    } else if (JLI_StrCCmp(arg, "-Xdock:") == 0) {
       SetXDockArgForAWT(arg);
       return JNI_TRUE;
    }
    // arguments we know not
    return JNI_FALSE;
}