src/solaris/bin/java_md.c

/*
 * Copyright (c) 1998, 2010, 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 <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 "manifest_info.h"
#include "version_comp.h"

#ifdef __linux__
#include <pthread.h>
#else
#include <thread.h>
#endif

#define JVM_DLL "libjvm.so"
#define JAVA_DLL "libjava.so"

/*
 * If a processor / os combination has the ability to run binaries of
 * two data models and cohabitation of jre/jdk bits with both data
 * models is supported, then DUAL_MODE is defined.  When DUAL_MODE is
 * defined, the architecture names for the narrow and wide version of
 * the architecture are defined in LIBARCH64NAME and LIBARCH32NAME.
 * Currently  only Solaris on sparc/sparcv9 and i586/amd64 is DUAL_MODE;
 * linux i586/amd64 could be defined as DUAL_MODE but that is not the
 * current policy.
 */

#ifdef __solaris__
#  define DUAL_MODE
#  ifndef LIBARCH32NAME
#    error "The macro LIBARCH32NAME was not defined on the compile line"
#  endif
#  ifndef LIBARCH64NAME
#    error "The macro LIBARCH64NAME was not defined on the compile line"
#  endif
#  include <sys/systeminfo.h>
#  include <sys/elf.h>
#  include <stdio.h>
#endif

/* pointer to environment */
extern char **environ;

/*
 *      A collection of useful strings. One should think of these as #define
 *      entries, but actual strings can be more efficient (with many compilers).
 */
#ifdef __linux__
static const char *system_dir   = "/usr/java";
static const char *user_dir     = "/java";
#else /* Solaris */
static const char *system_dir   = "/usr/jdk";
static const char *user_dir     = "/jdk";
#endif

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

/*
 * Flowchart of launcher execs and options processing on unix
 *
 * The selection of the proper vm shared library to open depends on
 * several classes of command line options, including vm "flavor"
 * options (-client, -server) and the data model options, -d32  and
 * -d64, as well as a version specification which may have come from
 * the command line or from the manifest of an executable jar file.
 * The vm selection options are not passed to the running
 * virtual machine; they must be screened out by the launcher.
 *
 * The version specification (if any) is processed first by the
 * platform independent routine SelectVersion.  This may result in
 * the exec of the specified launcher version.
 *
 * Previously the launcher modified the LD_LIBRARY_PATH appropriately for the
 * desired data model path, regardless if data models matched or not. The
 * launcher subsequently exec'ed the desired executable, in order to make the
 * LD_LIBRARY_PATH path available for the runtime linker. This is no longer the
 * case, the launcher dlopens the target libjvm.so. All other required
 * libraries are loaded by the runtime linker, by virtue of the $ORIGIN paths
 * baked into the shared libraries, by the build infrastructure at compile time.
 *
 *  Main
 *  (incoming argv)
 *  |
 * \|/
 * SelectVersion
 * (selects the JRE version, note: not data model)
 *  |
 * \|/
 * CreateExecutionEnvironment
 * (determines desired data model)
 *  |
 *  |
 * \|/
 *  Have Desired Model ? --> NO --> Is Dual-Mode ? --> NO --> Exit(with error)
 *  |                                          |
 *  |                                          |
 *  |                                         \|/
 *  |                                         YES
 *  |                                          |
 *  |                                          |
 *  |                                         \|/
 *  |                                CheckJvmType
 *  |                               (removes -client, -server etc.)
 *  |                                          |
 *  |                                          |
 * \|/                                        \|/
 * YES                              (find the desired executable and exec child)
 *  |                                          |
 *  |                                          |
 * \|/                                        \|/
 * CheckJvmType                                Main
 * (removes -client, -server, etc.)
 *  |
 *  |
 * \|/
 * TranslateDashJArgs...
 * (Prepare to pass args to vm)
 *  |
 *  |
 * \|/
 * ParseArguments
 * (removes -d32 and -d64 if any,
 *  processes version options,
 *  creates argument list for vm,
 *  etc.)
 *
 */

static const char * SetExecname(char **argv);
static jboolean GetJVMPath(const char *jrepath, const char *jvmtype,
                           char *jvmpath, jint jvmpathsize, const char * arch);
static jboolean GetJREPath(char *path, jint pathsize, const char * arch, jboolean speculative);


#define GetArch() GetArchPath(CURRENT_DATA_MODEL)

const char *
GetArchPath(int nbits)
{
    switch(nbits) {
#ifdef DUAL_MODE
        case 32:
            return LIBARCH32NAME;
        case 64:
            return LIBARCH64NAME;
#endif /* DUAL_MODE */
        default:
            return LIBARCHNAME;
    }
}

void
CreateExecutionEnvironment(int *pargc, char ***pargv,
                           char jrepath[], jint so_jrepath,
                           char jvmpath[], jint so_jvmpath) {
  /*
   * First, determine if we are running the desired data model.  If we
   * are running the desired data model, all the error messages
   * associated with calling GetJREPath, ReadKnownVMs, etc. should be
   * output.  However, if we are not running the desired data model,
   * some of the errors should be suppressed since it is more
   * informative to issue an error message based on whether or not the
   * os/processor combination has dual mode capabilities.
   */

    jboolean jvmpathExists;

    /* Compute/set the name of the executable */
    SetExecname(*pargv);

    /* Check data model flags, and exec process, if needed */
    {
      char *arch        = (char *)GetArch(); /* like sparc or sparcv9 */
      char * jvmtype    = NULL;
      int  argc         = *pargc;
      char **argv       = *pargv;

      int running       = CURRENT_DATA_MODEL;

      int wanted        = running;      /* What data mode is being
                                           asked for? Current model is
                                           fine unless another model
                                           is asked for */

      char** newargv    = NULL;
      int    newargc    = 0;

      /*
       * Starting in 1.5, all unix platforms accept the -d32 and -d64
       * options.  On platforms where only one data-model is supported
       * (e.g. ia-64 Linux), using the flag for the other data model is
       * an error and will terminate the program.
       */

      { /* open new scope to declare local variables */
        int i;

        newargv = (char **)JLI_MemAlloc((argc+1) * sizeof(char*));
        newargv[newargc++] = argv[0];

        /* scan for data model arguments and remove from argument list;
           last occurrence determines desired data model */
        for (i=1; i < argc; i++) {

          if (JLI_StrCmp(argv[i], "-J-d64") == 0 || JLI_StrCmp(argv[i], "-d64") == 0) {
            wanted = 64;
            continue;
          }
          if (JLI_StrCmp(argv[i], "-J-d32") == 0 || JLI_StrCmp(argv[i], "-d32") == 0) {
            wanted = 32;
            continue;
          }
          newargv[newargc++] = argv[i];

          if (IsJavaArgs()) {
            if (argv[i][0] != '-') continue;
          } else {
            if (JLI_StrCmp(argv[i], "-classpath") == 0 || JLI_StrCmp(argv[i], "-cp") == 0) {
              i++;
              if (i >= argc) break;
              newargv[newargc++] = argv[i];
              continue;
            }
            if (argv[i][0] != '-') { i++; break; }
          }
        }

        /* copy rest of args [i .. argc) */
        while (i < argc) {
          newargv[newargc++] = argv[i++];
        }
        newargv[newargc] = NULL;

        /*
         * newargv has all proper arguments here
         */

        argc = newargc;
        argv = newargv;
      }

      /* If the data model is not changing, it is an error if the
         jvmpath does not exist */
      if (wanted == running) {
        /* Find out where the JRE is that we will be using. */
        if (!GetJREPath(jrepath, so_jrepath, arch, JNI_FALSE) ) {
          JLI_ReportErrorMessage(JRE_ERROR1);
          exit(2);
        }

        /* Find the specified JVM type */
        if (ReadKnownVMs(jrepath, arch, 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(jrepath, jvmtype, jvmpath, so_jvmpath, arch )) {
          JLI_ReportErrorMessage(CFG_ERROR8, jvmtype, jvmpath);
          exit(4);
        }
        /*
         * we seem to have everything we need, so without further ado
         * we return back.
         */
        return;
      } else {  /* do the same speculatively or exit */
#ifdef DUAL_MODE
        if (running != wanted) {
          /* Find out where the JRE is that we will be using. */
          if (!GetJREPath(jrepath, so_jrepath, GetArchPath(wanted), JNI_TRUE)) {
            /* give up and let other code report error message */
            JLI_ReportErrorMessage(JRE_ERROR2, wanted);
            exit(1);
          }

          /*
           * Read in jvm.cfg for target data model and process vm
           * selection options.
           */
          if (ReadKnownVMs(jrepath, GetArchPath(wanted), JNI_TRUE) < 1) {
            /* give up and let other code report error message */
            JLI_ReportErrorMessage(JRE_ERROR2, wanted);
            exit(1);
          }
          jvmpath[0] = '\0';
          jvmtype = CheckJvmType(pargc, pargv, JNI_TRUE);
          if (JLI_StrCmp(jvmtype, "ERROR") == 0) {
            JLI_ReportErrorMessage(CFG_ERROR9);
            exit(4);
          }

          /* exec child can do error checking on the existence of the path */
          jvmpathExists = GetJVMPath(jrepath, jvmtype, jvmpath, so_jvmpath, GetArchPath(wanted));

        }
#else
        JLI_ReportErrorMessage(JRE_ERROR2, wanted);
        exit(1);
#endif
      }

      {
        char *newexec = execname;
#ifdef DUAL_MODE
        /*
         * If the data model is being changed, the path to the
         * executable must be updated accordingly; the executable name
         * and directory the executable resides in are separate.  In the
         * case of 32 => 64, the new bits are assumed to reside in, e.g.
         * "olddir/LIBARCH64NAME/execname"; in the case of 64 => 32,
         * the bits are assumed to be in "olddir/../execname".  For example,
         *
         * olddir/sparcv9/execname
         * olddir/amd64/execname
         *
         * for Solaris SPARC and Linux amd64, respectively.
         */

        if (running != wanted) {
          char *oldexec = JLI_StrCpy(JLI_MemAlloc(JLI_StrLen(execname) + 1), execname);
          char *olddir = oldexec;
          char *oldbase = JLI_StrRChr(oldexec, '/');


          newexec = JLI_MemAlloc(JLI_StrLen(execname) + 20);
          *oldbase++ = 0;
          sprintf(newexec, "%s/%s/%s", olddir,
                  ((wanted==64) ? LIBARCH64NAME : ".."), oldbase);
          argv[0] = newexec;
        }
#endif
        JLI_TraceLauncher("TRACER_MARKER:About to EXEC\n");
        (void)fflush(stdout);
        (void)fflush(stderr);
        execv(newexec, argv);
        JLI_ReportErrorMessageSys(JRE_ERROR4, newexec);

#ifdef DUAL_MODE
        if (running != wanted) {
          JLI_ReportErrorMessage(JRE_ERROR5, wanted, running);
#  ifdef __solaris__
#    ifdef __sparc
          JLI_ReportErrorMessage(JRE_ERROR6);
#    else
          JLI_ReportErrorMessage(JRE_ERROR7);
#    endif
        }
#  endif
#endif

      }
      exit(1);
    }

}

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

    if (JLI_StrChr(jvmtype, '/')) {
        JLI_Snprintf(jvmpath, jvmpathsize, "%s/" JVM_DLL, jvmtype);
    } else {
        JLI_Snprintf(jvmpath, jvmpathsize, "%s/lib/%s/%s/" JVM_DLL, jrepath, arch, jvmtype);
    }

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

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

/*
 * Find path to JRE based on .exe's location or registry settings.
 */
static jboolean
GetJREPath(char *path, jint pathsize, const char * arch, jboolean speculative)
{
    char libjava[MAXPATHLEN];

    if (GetApplicationHome(path, pathsize)) {
        /* Is JRE co-located with the application? */
        JLI_Snprintf(libjava, sizeof(libjava), "%s/lib/%s/" JAVA_DLL, path, arch);
        if (access(libjava, F_OK) == 0) {
            JLI_TraceLauncher("JRE path is %s\n", path);
            return JNI_TRUE;
        }

        /* Does the app ship a private JRE in <apphome>/jre directory? */
        JLI_Snprintf(libjava, sizeof(libjava), "%s/jre/lib/%s/" JAVA_DLL, path, arch);
        if (access(libjava, F_OK) == 0) {
            JLI_StrCat(path, "/jre");
            JLI_TraceLauncher("JRE path is %s\n", path);
            return JNI_TRUE;
        }
    }

    if (!speculative)
      JLI_ReportErrorMessage(JRE_ERROR8 JAVA_DLL);
    return JNI_FALSE;
}

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

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

    libjvm = dlopen(jvmpath, RTLD_NOW + RTLD_GLOBAL);
    if (libjvm == NULL) {
#if defined(__solaris__) && defined(__sparc) && !defined(_LP64) /* i.e. 32-bit sparc */
      FILE * fp;
      Elf32_Ehdr elf_head;
      int count;
      int location;

      fp = fopen(jvmpath, "r");
      if (fp == NULL) {
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
      }

      /* read in elf header */
      count = fread((void*)(&elf_head), sizeof(Elf32_Ehdr), 1, fp);
      fclose(fp);
      if (count < 1) {
        JLI_ReportErrorMessage(DLL_ERROR2, jvmpath, dlerror());
        return JNI_FALSE;
      }

      /*
       * Check for running a server vm (compiled with -xarch=v8plus)
       * on a stock v8 processor.  In this case, the machine type in
       * the elf header would not be included the architecture list
       * provided by the isalist command, which is turn is gotten from
       * sysinfo.  This case cannot occur on 64-bit hardware and thus
       * does not have to be checked for in binaries with an LP64 data
       * model.
       */
      if (elf_head.e_machine == EM_SPARC32PLUS) {
        char buf[257];  /* recommended buffer size from sysinfo man
                           page */
        long length;
        char* location;

        length = sysinfo(SI_ISALIST, buf, 257);
        if (length > 0) {
            location = JLI_StrStr(buf, "sparcv8plus ");
          if (location == NULL) {
            JLI_ReportErrorMessage(JVM_ERROR3);
            return JNI_FALSE;
          }
        }
      }
#endif
        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;
    }

    return JNI_TRUE;
}

/*
 * If app is "/foo/bin/javac", or "/foo/bin/sparcv9/javac" then put
 * "/foo" into buf.
 */
jboolean
GetApplicationHome(char *buf, jint bufsize)
{
    if (execname != NULL) {
        JLI_StrNCpy(buf, execname, bufsize-1);
        buf[bufsize-1] = '\0';
    } else {
        return JNI_FALSE;
    }

    if (JLI_StrRChr(buf, '/') == 0) {
        buf[0] = '\0';
        return JNI_FALSE;
    }
    *(JLI_StrRChr(buf, '/')) = '\0';    /* executable file      */
    if (JLI_StrLen(buf) < 4 || JLI_StrRChr(buf, '/') == 0) {
        buf[0] = '\0';
        return JNI_FALSE;
    }
    if (JLI_StrCmp("/bin", buf + JLI_StrLen(buf) - 4) != 0)
        *(JLI_StrRChr(buf, '/')) = '\0';        /* sparcv9 or amd64     */
    if (JLI_StrLen(buf) < 4 || JLI_StrCmp("/bin", buf + JLI_StrLen(buf) - 4) != 0) {
        buf[0] = '\0';
        return JNI_FALSE;
    }
    *(JLI_StrRChr(buf, '/')) = '\0';    /* bin                  */

    return JNI_TRUE;
}


/*
 * Return true if the named program exists
 */
static int
ProgramExists(char *name)
{
    struct stat sb;
    if (stat(name, &sb) != 0) return 0;
    if (S_ISDIR(sb.st_mode)) return 0;
    return (sb.st_mode & S_IEXEC) != 0;
}


/*
 * Find a command in a directory, returning the path.
 */
static char *
Resolve(char *indir, char *cmd)
{
    char name[PATH_MAX + 2], *real;

    if ((JLI_StrLen(indir) + JLI_StrLen(cmd) + 1)  > PATH_MAX) return 0;
    JLI_Snprintf(name, sizeof(name), "%s%c%s", indir, FILE_SEPARATOR, cmd);
    if (!ProgramExists(name)) return 0;
    real = JLI_MemAlloc(PATH_MAX + 2);
    if (!realpath(name, real))
        JLI_StrCpy(real, name);
    return real;
}


/*
 * Find a path for the executable
 */
static char *
FindExecName(char *program)
{
    char cwdbuf[PATH_MAX+2];
    char *path;
    char *tmp_path;
    char *f;
    char *result = NULL;

    /* absolute path? */
    if (*program == FILE_SEPARATOR ||
        (FILE_SEPARATOR=='\\' && JLI_StrRChr(program, ':')))
        return Resolve("", program+1);

    /* relative path? */
    if (JLI_StrRChr(program, FILE_SEPARATOR) != 0) {
        char buf[PATH_MAX+2];
        return Resolve(getcwd(cwdbuf, sizeof(cwdbuf)), program);
    }

    /* from search path? */
    path = getenv("PATH");
    if (!path || !*path) path = ".";
    tmp_path = JLI_MemAlloc(JLI_StrLen(path) + 2);
    JLI_StrCpy(tmp_path, path);

    for (f=tmp_path; *f && result==0; ) {
        char *s = f;
        while (*f && (*f != PATH_SEPARATOR)) ++f;
        if (*f) *f++ = 0;
        if (*s == FILE_SEPARATOR)
            result = Resolve(s, program);
        else {
            /* relative path element */
            char dir[2*PATH_MAX];
            JLI_Snprintf(dir, sizeof(dir), "%s%c%s", getcwd(cwdbuf, sizeof(cwdbuf)),
                    FILE_SEPARATOR, s);
            result = Resolve(dir, program);
        }
        if (result != 0) break;
    }

    JLI_MemFree(tmp_path);
    return result;
}



/*
 * 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.
 */
static const char*
SetExecname(char **argv)
{
    char* exec_path = NULL;
#if defined(__solaris__)
    {
        Dl_info dlinfo;
        int (*fptr)();

        fptr = (int (*)())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);
                }
            }
        }
    }
#elif defined(__linux__)
    {
        const char* self = "/proc/self/exe";
        char buf[PATH_MAX+1];
        int len = readlink(self, buf, PATH_MAX);
        if (len >= 0) {
            buf[len] = '\0';            /* readlink doesn't nul terminate */
            exec_path = JLI_StringDup(buf);
        }
    }
#else /* !__solaris__ && !__linux */
    {
        /* Not implemented */
    }
#endif

    if (exec_path == NULL) {
        exec_path = FindExecName(argv[0]);
    }
    execname = exec_path;
    return exec_path;
}

void JLI_ReportErrorMessage(const char* fmt, ...) {
    va_list vl;
    va_start(vl, fmt);
    vfprintf(stderr, fmt, vl);
    fprintf(stderr, "\n");
    va_end(vl);
}

void JLI_ReportErrorMessageSys(const char* fmt, ...) {
    va_list vl;
    char *emsg;

    /*
     * TODO: its safer to use strerror_r but is not available on
     * Solaris 8. Until then....
     */
    emsg = strerror(errno);
    if (emsg != NULL) {
        fprintf(stderr, "%s\n", emsg);
    }

    va_start(vl, fmt);
    vfprintf(stderr, fmt, vl);
    fprintf(stderr, "\n");
    va_end(vl);
}

void  JLI_ReportExceptionDescription(JNIEnv * env) {
  (*env)->ExceptionDescribe(env);
}

/*
 *      Since using the file system as a registry is a bit risky, perform
 *      additional sanity checks on the identified directory to validate
 *      it as a valid jre/sdk.
 *
 *      Return 0 if the tests fail; otherwise return non-zero (true).
 *
 *      Note that checking for anything more than the existence of an
 *      executable object at bin/java relative to the path being checked
 *      will break the regression tests.
 */
static int
CheckSanity(char *path, char *dir)
{
    char    buffer[PATH_MAX];

    if (JLI_StrLen(path) + JLI_StrLen(dir) + 11 > PATH_MAX)
        return (0);     /* Silently reject "impossibly" long paths */

    JLI_Snprintf(buffer, sizeof(buffer), "%s/%s/bin/java", path, dir);
    return ((access(buffer, X_OK) == 0) ? 1 : 0);
}

/*
 *      Determine if there is an acceptable JRE in the directory dirname.
 *      Upon locating the "best" one, return a fully qualified path to
 *      it. "Best" is defined as the most advanced JRE meeting the
 *      constraints contained in the manifest_info. If no JRE in this
 *      directory meets the constraints, return NULL.
 *
 *      Note that we don't check for errors in reading the directory
 *      (which would be done by checking errno).  This is because it
 *      doesn't matter if we get an error reading the directory, or
 *      we just don't find anything interesting in the directory.  We
 *      just return NULL in either case.
 *
 *      The historical names of j2sdk and j2re were changed to jdk and
 *      jre respecively as part of the 1.5 rebranding effort.  Since the
 *      former names are legacy on Linux, they must be recognized for
 *      all time.  Fortunately, this is a minor cost.
 */
static char
*ProcessDir(manifest_info *info, char *dirname)
{
    DIR     *dirp;
    struct dirent *dp;
    char    *best = NULL;
    int     offset;
    int     best_offset = 0;
    char    *ret_str = NULL;
    char    buffer[PATH_MAX];

    if ((dirp = opendir(dirname)) == NULL)
        return (NULL);

    do {
        if ((dp = readdir(dirp)) != NULL) {
            offset = 0;
            if ((JLI_StrNCmp(dp->d_name, "jre", 3) == 0) ||
                (JLI_StrNCmp(dp->d_name, "jdk", 3) == 0))
                offset = 3;
            else if (JLI_StrNCmp(dp->d_name, "j2re", 4) == 0)
                offset = 4;
            else if (JLI_StrNCmp(dp->d_name, "j2sdk", 5) == 0)
                offset = 5;
            if (offset > 0) {
                if ((JLI_AcceptableRelease(dp->d_name + offset,
                    info->jre_version)) && CheckSanity(dirname, dp->d_name))
                    if ((best == NULL) || (JLI_ExactVersionId(
                      dp->d_name + offset, best + best_offset) > 0)) {
                        if (best != NULL)
                            JLI_MemFree(best);
                        best = JLI_StringDup(dp->d_name);
                        best_offset = offset;
                    }
            }
        }
    } while (dp != NULL);
    (void) closedir(dirp);
    if (best == NULL)
        return (NULL);
    else {
        ret_str = JLI_MemAlloc(JLI_StrLen(dirname) + JLI_StrLen(best) + 2);
        sprintf(ret_str, "%s/%s", dirname, best);
        JLI_MemFree(best);
        return (ret_str);
    }
}

/*
 *      This is the global entry point. It examines the host for the optimal
 *      JRE to be used by scanning a set of directories.  The set of directories
 *      is platform dependent and can be overridden by the environment
 *      variable JAVA_VERSION_PATH.
 *
 *      This routine itself simply determines the set of appropriate
 *      directories before passing control onto ProcessDir().
 */
char*
LocateJRE(manifest_info* info)
{
    char        *path;
    char        *home;
    char        *target = NULL;
    char        *dp;
    char        *cp;

    /*
     * Start by getting JAVA_VERSION_PATH
     */
    if (info->jre_restrict_search) {
        path = JLI_StringDup(system_dir);
    } else if ((path = getenv("JAVA_VERSION_PATH")) != NULL) {
        path = JLI_StringDup(path);
    } else {
        if ((home = getenv("HOME")) != NULL) {
            path = (char *)JLI_MemAlloc(JLI_StrLen(home) + \
                        JLI_StrLen(system_dir) + JLI_StrLen(user_dir) + 2);
            sprintf(path, "%s%s:%s", home, user_dir, system_dir);
        } else {
            path = JLI_StringDup(system_dir);
        }
    }

    /*
     * Step through each directory on the path. Terminate the scan with
     * the first directory with an acceptable JRE.
     */
    cp = dp = path;
    while (dp != NULL) {
        cp = JLI_StrChr(dp, (int)':');
        if (cp != NULL)
            *cp = (char)NULL;
        if ((target = ProcessDir(info, dp)) != NULL)
            break;
        dp = cp;
        if (dp != NULL)
            dp++;
    }
    JLI_MemFree(path);
    return (target);
}

/*
 * Given a path to a jre to execute, this routine checks if this process
 * is indeed that jre.  If not, it exec's that jre.
 *
 * We want to actually check the paths rather than just the version string
 * built into the executable, so that given version specification (and
 * JAVA_VERSION_PATH) will yield the exact same Java environment, regardless
 * of the version of the arbitrary launcher we start with.
 */
void
ExecJRE(char *jre, char **argv)
{
    char    wanted[PATH_MAX];
    const char* progname = GetProgramName();

    /*
     * Resolve the real path to the directory containing the selected JRE.
     */
    if (realpath(jre, wanted) == NULL) {
        JLI_ReportErrorMessage(JRE_ERROR9, jre);
        exit(1);
    }

    /*
     * Resolve the real path to the currently running launcher.
     */
    SetExecname(argv);
    if (execname == NULL) {
        JLI_ReportErrorMessage(JRE_ERROR10);
        exit(1);
    }

    /*
     * If the path to the selected JRE directory is a match to the initial
     * portion of the path to the currently executing JRE, we have a winner!
     * If so, just return.
     */
    if (JLI_StrNCmp(wanted, execname, JLI_StrLen(wanted)) == 0)
        return;                 /* I am the droid you were looking for */


    /*
     * This should never happen (because of the selection code in SelectJRE),
     * but check for "impossibly" long path names just because buffer overruns
     * can be so deadly.
     */
    if (JLI_StrLen(wanted) + JLI_StrLen(progname) + 6 > PATH_MAX) {
        JLI_ReportErrorMessage(JRE_ERROR11);
        exit(1);
    }

    /*
     * Construct the path and exec it.
     */
    (void)JLI_StrCat(JLI_StrCat(wanted, "/bin/"), progname);
    argv[0] = JLI_StringDup(progname);
    if (JLI_IsTraceLauncher()) {
        int i;
        printf("ReExec Command: %s (%s)\n", wanted, argv[0]);
        printf("ReExec Args:");
        for (i = 1; argv[i] != NULL; i++)
            printf(" %s", argv[i]);
        printf("\n");
    }
    JLI_TraceLauncher("TRACER_MARKER:About to EXEC\n");
    (void)fflush(stdout);
    (void)fflush(stderr);
    execv(wanted, argv);
    JLI_ReportErrorMessageSys(JRE_ERROR12, wanted);
    exit(1);
}

/*
 * "Borrowed" from Solaris 10 where the unsetenv() function is being added
 * to libc thanks to SUSv3 (Standard Unix Specification, version 3). As
 * such, in the fullness of time this will appear in libc on all relevant
 * Solaris/Linux platforms and maybe even the Windows platform.  At that
 * time, this stub can be removed.
 *
 * This implementation removes the environment locking for multithreaded
 * applications.  (We don't have access to these mutexes within libc and
 * the launcher isn't multithreaded.)  Note that what remains is platform
 * independent, because it only relies on attributes that a POSIX environment
 * defines.
 *
 * Returns 0 on success, -1 on failure.
 *
 * Also removed was the setting of errno.  The only value of errno set
 * was EINVAL ("Invalid Argument").
 */

/*
 * s1(environ) is name=value
 * s2(name) is name(not the form of name=value).
 * if names match, return value of 1, else return 0
 */
static int
match_noeq(const char *s1, const char *s2)
{
        while (*s1 == *s2++) {
                if (*s1++ == '=')
                        return (1);
        }
        if (*s1 == '=' && s2[-1] == '\0')
                return (1);
        return (0);
}

/*
 * added for SUSv3 standard
 *
 * Delete entry from environ.
 * Do not free() memory!  Other threads may be using it.
 * Keep it around forever.
 */
static int
borrowed_unsetenv(const char *name)
{
        long    idx;            /* index into environ */

        if (name == NULL || *name == '\0' ||
            JLI_StrChr(name, '=') != NULL) {
                return (-1);
        }

        for (idx = 0; environ[idx] != NULL; idx++) {
                if (match_noeq(environ[idx], name))
                        break;
        }
        if (environ[idx] == NULL) {
                /* name not found but still a success */
                return (0);
        }
        /* squeeze up one entry */
        do {
                environ[idx] = environ[idx+1];
        } while (environ[++idx] != NULL);

        return (0);
}
/* --- End of "borrowed" code --- */

/*
 * Wrapper for unsetenv() function.
 */
int
UnsetEnv(char *name)
{
    return(borrowed_unsetenv(name));
}

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

static const char* SPLASHSCREEN_SO = "libsplashscreen.so";

static void* hSplashLib = NULL;

void* SplashProcAddress(const char* name) {
    if (!hSplashLib) {
        hSplashLib = dlopen(SPLASHSCREEN_SO, RTLD_LAZY | RTLD_GLOBAL);
    }
    if (hSplashLib) {
        void* sym = dlsym(hSplashLib, name);
        return sym;
    } else {
        return NULL;
    }
}

void SplashFreeLibrary() {
    if (hSplashLib) {
        dlclose(hSplashLib);
        hSplashLib = NULL;
    }
}

const char *
jlong_format_specifier() {
    return "%lld";
}



/*
 * Block current thread and continue execution in a new thread
 */
int
ContinueInNewThread0(int (JNICALL *continuation)(void *), jlong stack_size, void * args) {
    int rslt;
#ifdef __linux__
    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, stack_size);
    }

    if (pthread_create(&tid, &attr, (void *(*)(void*))continuation, (void*)args) == 0) {
      void * tmp;
      pthread_join(tid, &tmp);
      rslt = (int)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 continuation as JNI_CreateJavaVM needs to create quite a
      * few new threads, anyway, just give it a try..
      */
      rslt = continuation(args);
    }

    pthread_attr_destroy(&attr);
#else
    thread_t tid;
    long flags = 0;
    if (thr_create(NULL, stack_size, (void *(*)(void *))continuation, args, flags, &tid) == 0) {
      void * tmp;
      thr_join(tid, NULL, &tmp);
      rslt = (int)tmp;
    } else {
      /* See above. Continue in current thread if thr_create() failed */
      rslt = continuation(args);
    }
#endif
    return rslt;
}

/* Coarse estimation of number of digits assuming the worst case is a 64-bit pid. */
#define MAX_PID_STR_SZ   20

void SetJavaLauncherPlatformProps() {
   /* Linux only */
#ifdef __linux__
    const char *substr = "-Dsun.java.launcher.pid=";
    char *pid_prop_str = (char *)JLI_MemAlloc(JLI_StrLen(substr) + MAX_PID_STR_SZ + 1);
    sprintf(pid_prop_str, "%s%d", substr, getpid());
    AddOption(pid_prop_str, NULL);
#endif
}

jboolean
IsJavaw()
{
    /* noop on UNIX */
    return JNI_FALSE;
}

void
InitLauncher(jboolean javaw)
{
    JLI_SetTraceLauncher();
}

/*
 * The implementation for finding classes from the bootstrap
 * class loader, refer to java.h
 */
static FindClassFromBootLoader_t *findBootClass = NULL;

jclass
FindBootStrapClass(JNIEnv *env, const char* classname)
{
   if (findBootClass == NULL) {
       findBootClass = (FindClassFromBootLoader_t *)dlsym(RTLD_DEFAULT,
          "JVM_FindClassFromBootLoader");
       if (findBootClass == NULL) {
           JLI_ReportErrorMessage(DLL_ERROR4,
               "JVM_FindClassFromBootLoader");
           return NULL;
       }
   }
   return findBootClass(env, classname);
}