alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (java_md_solinux.c)

This example Java source code file (java_md_solinux.c) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

dual_mode, filesep, getarchpath, jli_memfree, jli_reporterrormessage, jli_snprintf, jli_strcmp, jli_strlen, jli_tracelauncher, jni_false, jni_true, ld_library_path, null, setenv_required

The java_md_solinux.c Java example source code

/*
 * Copyright (c) 1998, 2013, 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 "manifest_info.h"
#include "version_comp.h"


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

/* help jettison the LD_LIBRARY_PATH settings in the future */
#ifndef SETENV_REQUIRED
#define SETENV_REQUIRED
#endif
/*
 * 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__
#  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

/*
 * 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.
 *
 * Now, in most cases,the launcher will dlopen the target libjvm.so. All
 * required libraries are loaded by the runtime linker, using the
 * $RPATH/$ORIGIN baked into the shared libraries at compile time. Therefore,
 * in most cases, the launcher will only exec, if the data models are
 * mismatched, and will not set any environment variables, regardless of the
 * data models.
 *
 * However, if the environment contains a LD_LIBRARY_PATH, this will cause the
 * launcher to inspect the LD_LIBRARY_PATH. The launcher will check
 *  a. if the LD_LIBRARY_PATH's first component is the the path to the desired
 *     libjvm.so
 *  b. if any other libjvm.so is found in any of the paths.
 * If case b is true, then the launcher will set the LD_LIBRARY_PATH to the
 * desired JRE and reexec, in order to propagate the environment.
 *
 *  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/library
 *  |                                          |
 *  |                                          |
 * \|/                                        \|/
 * CheckJvmType                          RequiresSetenv
 * (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.)
 *   |
 *   |
 *  \|/
 * RequiresSetenv
 * Is LD_LIBRARY_PATH
 * and friends set ? --> NO --> Have Desired Model ? NO --> Re-exec --> Main
 *  YES                              YES --> Continue
 *   |
 *   |
 *  \|/
 * Path is desired JRE ? YES --> Have Desired Model ? NO --> Re-exec --> Main
 *  NO                               YES --> Continue
 *   |
 *   |
 *  \|/
 * Paths have well known
 * jvm paths ?       --> NO --> Have Desired Model ? NO --> Re-exec --> Main
 *  YES                              YES --> Continue
 *   |
 *   |
 *  \|/
 *  Does libjvm.so exit
 *  in any of them ? --> NO --> Have Desired Model ? NO --> Re-exec --> Main
 *   YES                             YES --> Continue
 *   |
 *   |
 *  \|/
 *  Set the LD_LIBRARY_PATH
 *   |
 *   |
 *  \|/
 * Re-exec
 *   |
 *   |
 *  \|/
 * Main
 */

#define GetArch() GetArchPath(CURRENT_DATA_MODEL)

/* 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;
}

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

#ifdef SETENV_REQUIRED
static jboolean
JvmExists(const char *path) {
    char tmp[PATH_MAX + 1];
    struct stat statbuf;
    JLI_Snprintf(tmp, PATH_MAX, "%s/%s", path, JVM_DLL);
    if (stat(tmp, &statbuf) == 0) {
        return JNI_TRUE;
    }
    return JNI_FALSE;
}
/*
 * contains a lib/$LIBARCH/{server,client}/libjvm.so ?
 */
static jboolean
ContainsLibJVM(int wanted, const char *env) {
    char clientPattern[PATH_MAX + 1];
    char serverPattern[PATH_MAX + 1];
    char *envpath;
    char *path;
    jboolean clientPatternFound;
    jboolean serverPatternFound;

    /* fastest path */
    if (env == NULL) {
        return JNI_FALSE;
    }

    /* the usual suspects */
    JLI_Snprintf(clientPattern, PATH_MAX, "lib/%s/client", GetArchPath(wanted));
    JLI_Snprintf(serverPattern, PATH_MAX, "lib/%s/server", GetArchPath(wanted));

    /* to optimize for time, test if any of our usual suspects are present. */
    clientPatternFound = JLI_StrStr(env, clientPattern) != NULL;
    serverPatternFound = JLI_StrStr(env, serverPattern) != NULL;
    if (clientPatternFound == JNI_FALSE && serverPatternFound == JNI_FALSE) {
        return JNI_FALSE;
    }

    /*
     * we have a suspicious path component, check if it contains a libjvm.so
     */
    envpath = JLI_StringDup(env);
    for (path = JLI_StrTok(envpath, ":"); path != NULL; path = JLI_StrTok(NULL, ":")) {
        if (clientPatternFound && JLI_StrStr(path, clientPattern) != NULL) {
            if (JvmExists(path)) {
                JLI_MemFree(envpath);
                return JNI_TRUE;
            }
        }
        if (serverPatternFound && JLI_StrStr(path, serverPattern)  != NULL) {
            if (JvmExists(path)) {
                JLI_MemFree(envpath);
                return JNI_TRUE;
            }
        }
    }
    JLI_MemFree(envpath);
    return JNI_FALSE;
}

/*
 * Test whether the environment variable needs to be set, see flowchart.
 */
static jboolean
RequiresSetenv(int wanted, const char *jvmpath) {
    char jpath[PATH_MAX + 1];
    char *llp;
    char *dmllp = NULL;
    char *p; /* a utility pointer */

    llp = getenv("LD_LIBRARY_PATH");
#ifdef __solaris__
    dmllp = (CURRENT_DATA_MODEL == 32)
            ? getenv("LD_LIBRARY_PATH_32")
            : getenv("LD_LIBRARY_PATH_64");
#endif /* __solaris__ */
    /* no environment variable is a good environment variable */
    if (llp == NULL && dmllp == NULL) {
        return JNI_FALSE;
    }
#ifdef __linux
    /*
     * On linux, if a binary is running as sgid or suid, glibc sets
     * LD_LIBRARY_PATH to the empty string for security purposes. (In contrast,
     * on Solaris the LD_LIBRARY_PATH variable for a privileged binary does not
     * lose its settings; but the dynamic linker does apply more scrutiny to the
     * path.) The launcher uses the value of LD_LIBRARY_PATH to prevent an exec
     * loop, here and further downstream. Therefore, if we are running sgid or
     * suid, this function's setting of LD_LIBRARY_PATH will be ineffective and
     * we should case a return from the calling function.  Getting the right
     * libraries will be handled by the RPATH. In reality, this check is
     * redundant, as the previous check for a non-null LD_LIBRARY_PATH will
     * return back to the calling function forthwith, it is left here to safe
     * guard against any changes, in the glibc's existing security policy.
     */
    if ((getgid() != getegid()) || (getuid() != geteuid())) {
        return JNI_FALSE;
    }
#endif /* __linux */

    /*
     * Prevent recursions. Since LD_LIBRARY_PATH is the one which will be set by
     * previous versions of the JRE, thus it is the only path that matters here.
     * So we check to see if the desired JRE is set.
     */
    JLI_StrNCpy(jpath, jvmpath, PATH_MAX);
    p = JLI_StrRChr(jpath, '/');
    *p = '\0';
    if (llp != NULL && JLI_StrNCmp(llp, jpath, JLI_StrLen(jpath)) == 0) {
        return JNI_FALSE;
    }

    /* scrutinize all the paths further */
    if (llp != NULL &&  ContainsLibJVM(wanted, llp)) {
        return JNI_TRUE;
    }
    if (dmllp != NULL && ContainsLibJVM(wanted, dmllp)) {
        return JNI_TRUE;
    }
    return JNI_FALSE;
}
#endif /* SETENV_REQUIRED */

void
CreateExecutionEnvironment(int *pargc, char ***pargv,
                           char jrepath[], jint so_jrepath,
                           char jvmpath[], jint so_jvmpath,
                           char jvmcfg[],  jint so_jvmcfg) {
  /*
   * 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 */
#ifdef SETENV_REQUIRED
      jboolean mustsetenv = JNI_FALSE;
      char *runpath     = NULL; /* existing effective LD_LIBRARY_PATH setting */
      char* new_runpath = NULL; /* desired new LD_LIBRARY_PATH string */
      char* newpath     = NULL; /* path on new LD_LIBRARY_PATH */
      char* lastslash   = NULL;
      char** newenvp    = NULL; /* current environment */
#ifdef __solaris__
      char*  dmpath     = NULL;  /* data model specific LD_LIBRARY_PATH,
                                    Solaris only */
#endif /* __solaris__ */
#endif  /* SETENV_REQUIRED */

      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);
        }
        JLI_Snprintf(jvmcfg, so_jvmcfg, "%s%slib%s%s%sjvm.cfg",
                     jrepath, FILESEP, FILESEP,  arch, 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(jrepath, jvmtype, jvmpath, so_jvmpath, arch, 0 )) {
          JLI_ReportErrorMessage(CFG_ERROR8, jvmtype, jvmpath);
          exit(4);
        }
        /*
         * we seem to have everything we need, so without further ado
         * we return back, otherwise proceed to set the environment.
         */
#ifdef SETENV_REQUIRED
        mustsetenv = RequiresSetenv(wanted, jvmpath);
        JLI_TraceLauncher("mustsetenv: %s\n", mustsetenv ? "TRUE" : "FALSE");

        if (mustsetenv == JNI_FALSE) {
            JLI_MemFree(newargv);
            return;
        }
#else
        JLI_MemFree(newargv);
        return;
#endif /* SETENV_REQUIRED */
      } 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);
          }
          JLI_Snprintf(jvmcfg, so_jvmcfg, "%s%slib%s%s%sjvm.cfg",
                       jrepath, FILESEP, FILESEP, GetArchPath(wanted), FILESEP);
          /*
           * Read in jvm.cfg for target data model and process vm
           * selection options.
           */
          if (ReadKnownVMs(jvmcfg, 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), 0);
#ifdef SETENV_REQUIRED
          mustsetenv = RequiresSetenv(wanted, jvmpath);
#endif /* SETENV_REQUIRED */
        }
#else /* ! DUALMODE */
        JLI_ReportErrorMessage(JRE_ERROR2, wanted);
        exit(1);
#endif /* DUAL_MODE */
        }
#ifdef SETENV_REQUIRED
        if (mustsetenv) {
            /*
             * We will set the LD_LIBRARY_PATH as follows:
             *
             *     o          $JVMPATH (directory portion only)
             *     o          $JRE/lib/$LIBARCHNAME
             *     o          $JRE/../lib/$LIBARCHNAME
             *
             * followed by the user's previous effective LD_LIBRARY_PATH, if
             * any.
             */

#ifdef __solaris__
            /*
             * Starting in Solaris 7, ld.so.1 supports three LD_LIBRARY_PATH
             * variables:
             *
             * 1. LD_LIBRARY_PATH -- used for 32 and 64 bit searches if
             * data-model specific variables are not set.
             *
             * 2. LD_LIBRARY_PATH_64 -- overrides and replaces LD_LIBRARY_PATH
             * for 64-bit binaries.
             *
             * 3. LD_LIBRARY_PATH_32 -- overrides and replaces LD_LIBRARY_PATH
             * for 32-bit binaries.
             *
             * The vm uses LD_LIBRARY_PATH to set the java.library.path system
             * property.  To shield the vm from the complication of multiple
             * LD_LIBRARY_PATH variables, if the appropriate data model
             * specific variable is set, we will act as if LD_LIBRARY_PATH had
             * the value of the data model specific variant and the data model
             * specific variant will be unset.  Note that the variable for the
             * *wanted* data model must be used (if it is set), not simply the
             * current running data model.
             */

            switch (wanted) {
                case 0:
                    if (running == 32) {
                        dmpath = getenv("LD_LIBRARY_PATH_32");
                        wanted = 32;
                    } else {
                        dmpath = getenv("LD_LIBRARY_PATH_64");
                        wanted = 64;
                    }
                    break;

                case 32:
                    dmpath = getenv("LD_LIBRARY_PATH_32");
                    break;

                case 64:
                    dmpath = getenv("LD_LIBRARY_PATH_64");
                    break;

                default:
                    JLI_ReportErrorMessage(JRE_ERROR3, __LINE__);
                    exit(1); /* unknown value in wanted */
                    break;
            }

            /*
             * If dmpath is NULL, the relevant data model specific variable is
             * not set and normal LD_LIBRARY_PATH should be used.
             */
            if (dmpath == NULL) {
                runpath = getenv("LD_LIBRARY_PATH");
            } else {
                runpath = dmpath;
            }
#else /* ! __solaris__ */
            /*
             * If not on Solaris, assume only a single LD_LIBRARY_PATH
             * variable.
             */
            runpath = getenv("LD_LIBRARY_PATH");
#endif /* __solaris__ */

            /* runpath contains current effective LD_LIBRARY_PATH setting */

            jvmpath = JLI_StringDup(jvmpath);
            new_runpath = JLI_MemAlloc(((runpath != NULL) ? JLI_StrLen(runpath) : 0) +
                    2 * JLI_StrLen(jrepath) + 2 * JLI_StrLen(arch) +
                    JLI_StrLen(jvmpath) + 52);
            newpath = new_runpath + JLI_StrLen("LD_LIBRARY_PATH=");


            /*
             * Create desired LD_LIBRARY_PATH value for target data model.
             */
            {
                /* remove the name of the .so from the JVM path */
                lastslash = JLI_StrRChr(jvmpath, '/');
                if (lastslash)
                    *lastslash = '\0';

                sprintf(new_runpath, "LD_LIBRARY_PATH="
                        "%s:"
                        "%s/lib/%s:"
                        "%s/../lib/%s",
                        jvmpath,
#ifdef DUAL_MODE
                        jrepath, GetArchPath(wanted),
                        jrepath, GetArchPath(wanted)
#else /* !DUAL_MODE */
                        jrepath, arch,
                        jrepath, arch
#endif /* DUAL_MODE */
                        );


                /*
                 * Check to make sure that the prefix of the current path is the
                 * desired environment variable setting, though the RequiresSetenv
                 * checks if the desired runpath exists, this logic does a more
                 * comprehensive check.
                 */
                if (runpath != NULL &&
                        JLI_StrNCmp(newpath, runpath, JLI_StrLen(newpath)) == 0 &&
                        (runpath[JLI_StrLen(newpath)] == 0 || runpath[JLI_StrLen(newpath)] == ':') &&
                        (running == wanted) /* data model does not have to be changed */
#ifdef __solaris__
                        && (dmpath == NULL) /* data model specific variables not set  */
#endif /* __solaris__ */
                        ) {
                    JLI_MemFree(newargv);
                    JLI_MemFree(new_runpath);
                    return;
                }
            }

            /*
             * Place the desired environment setting onto the prefix of
             * LD_LIBRARY_PATH.  Note that this prevents any possible infinite
             * loop of execv() because we test for the prefix, above.
             */
            if (runpath != 0) {
                JLI_StrCat(new_runpath, ":");
                JLI_StrCat(new_runpath, runpath);
            }

            if (putenv(new_runpath) != 0) {
                exit(1); /* problem allocating memory; LD_LIBRARY_PATH not set
                    properly */
            }

            /*
             * Unix systems document that they look at LD_LIBRARY_PATH only
             * once at startup, so we have to re-exec the current executable
             * to get the changed environment variable to have an effect.
             */

#ifdef __solaris__
            /*
             * If dmpath is not NULL, remove the data model specific string
             * in the environment for the exec'ed child.
             */
            if (dmpath != NULL)
                (void)UnsetEnv((wanted == 32) ? "LD_LIBRARY_PATH_32" : "LD_LIBRARY_PATH_64");
#endif /* __solaris */

            newenvp = environ;
        }
#endif /* SETENV_REQUIRED */
        {
            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 /* DUAL_MODE */
            JLI_TraceLauncher("TRACER_MARKER:About to EXEC\n");
            (void) fflush(stdout);
            (void) fflush(stderr);
#ifdef SETENV_REQUIRED
            if (mustsetenv) {
                execve(newexec, argv, newenvp);
            } else {
                execv(newexec, argv);
            }
#else /* !SETENV_REQUIRED */
            execv(newexec, argv);
#endif /* SETENV_REQUIRED */
            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  /* ! __sparc__ */
                JLI_ReportErrorMessage(JRE_ERROR7);
#endif  /* __sparc */
#endif /* __solaris__ */
            }
#endif /* DUAL_MODE */

        }
        exit(1);
    }
}

/*
 * On Solaris VM choosing is done by the launcher (java.c),
 * bitsWanted is used by MacOSX,  on Solaris and Linux this.
 * parameter is unused.
 */
static jboolean
GetJVMPath(const char *jrepath, const char *jvmtype,
           char *jvmpath, jint jvmpathsize, const char * arch, int bitsWanted)
{
    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)
{
    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;
    }

    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;
#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(2) 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;
}

/* --- Splash Screen shared library support --- */
static const char* SPLASHSCREEN_SO = JNI_LIB_NAME("splashscreen");
static void* hSplashLib = NULL;

void* SplashProcAddress(const char* name) {
    if (!hSplashLib) {
        int ret;
        char jrePath[MAXPATHLEN];
        char splashPath[MAXPATHLEN];

        if (!GetJREPath(jrePath, sizeof(jrePath), GetArch(), JNI_FALSE)) {
            JLI_ReportErrorMessage(JRE_ERROR1);
            return NULL;
        }
        ret = JLI_Snprintf(splashPath, sizeof(splashPath), "%s/lib/%s/%s",
                     jrePath, GetArch(), SPLASHSCREEN_SO);

        if (ret >= (int) sizeof(splashPath)) {
            JLI_ReportErrorMessage(JRE_ERROR11);
            return NULL;
        }
        if (ret < 0) {
            JLI_ReportErrorMessage(JRE_ERROR13);
            return NULL;
        }
        hSplashLib = dlopen(splashPath, RTLD_LAZY | RTLD_GLOBAL);
        JLI_TraceLauncher("Info: loaded %s\n", splashPath);
    }
    if (hSplashLib) {
        void* sym = dlsym(hSplashLib, name);
        return sym;
    } else {
        return NULL;
    }
}

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

/*
 * 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 /* ! __linux__ */
    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 /* __linux__ */
    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 /* __linux__ */
}

int
JVMInit(InvocationFunctions* ifn, jlong threadStackSize,
        int argc, char **argv,
        int mode, char *what, int ret)
{
    ShowSplashScreen();
    return ContinueInNewThread(ifn, threadStackSize, argc, argv, mode, what, ret);
}

void
PostJVMInit(JNIEnv *env, jstring mainClass, JavaVM *vm)
{
    // stubbed out for windows and *nixes.
}

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

/*
 * on unix, we return a false to indicate this option is not applicable
 */
jboolean
ProcessPlatformOption(const char *arg)
{
    return JNI_FALSE;
}

Other Java examples (source code examples)

Here is a short list of links related to this Java java_md_solinux.c source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.