《jdk8u源码分析》12.ParseArguments

src/share/bin/java.c::ParseArguments

/*
 * Parses command line arguments.  Returns JNI_FALSE if launcher
 * should exit without starting vm, returns JNI_TRUE if vm needs
 * to be started to process given options.  *pret (the launcher
 * process return value) is set to 0 for a normal exit.
 */
static jboolean
ParseArguments(int *pargc, char ***pargv,
               int *pmode, char **pwhat,
               int *pret, const char *jrepath)
{
    int argc = *pargc;
    char **argv = *pargv;
    int mode = LM_UNKNOWN;
    char *arg;

    *pret = 0;
	
	//将以'-'开始的命令行参数转换为JVM可选参数
    while ((arg = *argv) != 0 && *arg == '-') {
        argv++; --argc;
        if (JLI_StrCmp(arg, "-classpath") == 0 || JLI_StrCmp(arg, "-cp") == 0) {
        	//"Error: %s requires class path specification"
            ARG_CHECK (argc, ARG_ERROR1, arg);
            //@see: 11.SetClassPath
            SetClassPath(*argv);
            mode = LM_CLASS;
            argv++; --argc;
        } else if (JLI_StrCmp(arg, "-jar") == 0) {
        	//"Error: %s requires jar file specification"
            ARG_CHECK (argc, ARG_ERROR2, arg);
            mode = LM_JAR;
        } else if (JLI_StrCmp(arg, "-help") == 0 ||
                   JLI_StrCmp(arg, "-h") == 0 ||
                   JLI_StrCmp(arg, "-?") == 0) {
            printUsage = JNI_TRUE;
            return JNI_TRUE;
        } else if (JLI_StrCmp(arg, "-version") == 0) {
            printVersion = JNI_TRUE;
            return JNI_TRUE;
        } else if (JLI_StrCmp(arg, "-showversion") == 0) {
            showVersion = JNI_TRUE;
        } else if (JLI_StrCmp(arg, "-X") == 0) {
            printXUsage = JNI_TRUE;
            return JNI_TRUE;
/*
 * The following case checks for -XshowSettings OR -XshowSetting:SUBOPT.
 * In the latter case, any SUBOPT value not recognized will default to "all"
 */
        } else if (JLI_StrCmp(arg, "-XshowSettings") == 0 ||
                JLI_StrCCmp(arg, "-XshowSettings:") == 0) {
            showSettings = arg;
        } else if (JLI_StrCmp(arg, "-Xdiag") == 0) {
        	//@see: 10.AddApplicationOptions
            AddOption("-Dsun.java.launcher.diag=true", NULL);
/*
 * The following case provide backward compatibility with old-style
 * command line options.
 */
        } else if (JLI_StrCmp(arg, "-fullversion") == 0) {
            JLI_ReportMessage("%s full version \"%s\"", _launcher_name, GetFullVersion());
            return JNI_FALSE;
        } else if (JLI_StrCmp(arg, "-verbosegc") == 0) {
            AddOption("-verbose:gc", NULL);
        } else if (JLI_StrCmp(arg, "-t") == 0) {
            AddOption("-Xt", NULL);
        } else if (JLI_StrCmp(arg, "-tm") == 0) {
            AddOption("-Xtm", NULL);
        } else if (JLI_StrCmp(arg, "-debug") == 0) {
            AddOption("-Xdebug", NULL);
        } else if (JLI_StrCmp(arg, "-noclassgc") == 0) {
            AddOption("-Xnoclassgc", NULL);
        } else if (JLI_StrCmp(arg, "-Xfuture") == 0) {
            AddOption("-Xverify:all", NULL);
        } else if (JLI_StrCmp(arg, "-verify") == 0) {
            AddOption("-Xverify:all", NULL);
        } else if (JLI_StrCmp(arg, "-verifyremote") == 0) {
            AddOption("-Xverify:remote", NULL);
        } else if (JLI_StrCmp(arg, "-noverify") == 0) {
            AddOption("-Xverify:none", NULL);
        } else if (JLI_StrCCmp(arg, "-prof") == 0) {
            char *p = arg + 5;
            char *tmp = JLI_MemAlloc(JLI_StrLen(arg) + 50);
            if (*p) {
                sprintf(tmp, "-Xrunhprof:cpu=old,file=%s", p + 1);
            } else {
                sprintf(tmp, "-Xrunhprof:cpu=old,file=java.prof");
            }
            AddOption(tmp, NULL);
        } else if (JLI_StrCCmp(arg, "-ss") == 0 ||
                   JLI_StrCCmp(arg, "-oss") == 0 ||
                   JLI_StrCCmp(arg, "-ms") == 0 ||
                   JLI_StrCCmp(arg, "-mx") == 0) {
            char *tmp = JLI_MemAlloc(JLI_StrLen(arg) + 6);
            sprintf(tmp, "-X%s", arg + 1); /* skip '-' */
            AddOption(tmp, NULL);
        } else if (JLI_StrCmp(arg, "-checksource") == 0 ||
                   JLI_StrCmp(arg, "-cs") == 0 ||
                   JLI_StrCmp(arg, "-noasyncgc") == 0) {
            /* No longer supported */
            //"Warning: %s option is no longer supported."
            JLI_ReportErrorMessage(ARG_WARN, arg);
        } else if (JLI_StrCCmp(arg, "-version:") == 0 ||
                   JLI_StrCmp(arg, "-no-jre-restrict-search") == 0 ||
                   JLI_StrCmp(arg, "-jre-restrict-search") == 0 ||
                   JLI_StrCCmp(arg, "-splash:") == 0) {
            ; /* Ignore machine independent options already handled */
        } else if (ProcessPlatformOption(arg)) {
            ; /* Processing of platform dependent options */
        } else if (RemovableOption(arg)) {
            ; /* Do not pass option to vm. */
        } else {
            AddOption(arg, NULL);
        }
    }

	//命令行参数过滤掉所有以'-'开始后，将剩余的参数赋值给pwhat指针（用户参数）
    if (--argc >= 0) {
        *pwhat = *argv++;
    }

    if (*pwhat == NULL) {
        *pret = 1;
    } else if (mode == LM_UNKNOWN) {
        /* default to LM_CLASS if -jar and -cp option are
         * not specified */
        //设置默认启动模式：LM_CLASS
        mode = LM_CLASS;
    }

	//将剩余的参数重新赋值给pagrv指针（外部调用）
    if (argc >= 0) {
        *pargc = argc;
        *pargv = argv;
    }
	
	//设置启动模式（外部调用）
    *pmode = mode;

    return JNI_TRUE;
}

src/share/bin/java.h::LaunchMode

enum LaunchMode {               // cf. sun.launcher.LauncherHelper
    LM_UNKNOWN = 0,				//未知
    LM_CLASS,					//Class启动
    LM_JAR						//jar包启动
};

src/share/bin/java.c::ARG_CHECK

//剩余参数数量少于1，表示无启动主程序，打印异常
#define ARG_CHECK(AC_arg_count, AC_failure_message, AC_questionable_arg) \
    do { \
        if (AC_arg_count < 1) { \
            JLI_ReportErrorMessage(AC_failure_message, AC_questionable_arg); \
            printUsage = JNI_TRUE; \
            *pret = 1; \
            return JNI_TRUE; \
        } \
    } while (JNI_FALSE)

src/solaris/bin/java_md_solinux.c::ProcessPlatformOption(linux)

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

src/macosx/bin/java_md_macosx.c::ProcessPlatformOption(mac)

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;
}

src/windows/bin/java_md.c::ProcessPlatformOption(windows)

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

src/share/bin/java.c::RemovableOption

/*
 * Return JNI_TRUE for an option string that has no effect but should
 * _not_ be passed on to the vm; return JNI_FALSE otherwise.  On
 * Solaris SPARC, this screening needs to be done if:
 *    -d32 or -d64 is passed to a binary with an unmatched data model
 *    (the exec in CreateExecutionEnvironment removes -d<n> options and points the
 *    exec to the proper binary).  In the case of when the data model and the
 *    requested version is matched, an exec would not occur, and these options
 *    were erroneously passed to the vm.
 */
jboolean
RemovableOption(char * option)
{
  /*
   * Unconditionally remove both -d32 and -d64 options since only
   * the last such options has an effect; e.g.
   * java -d32 -d64 -d32 -version
   * is equivalent to
   * java -d32 -version
   */
  //@see：6.CreateExecutionEnvironment 用于判断jvm运行环境：64bit | 32bit
  if( (JLI_StrCCmp(option, "-d32")  == 0 ) ||
      (JLI_StrCCmp(option, "-d64")  == 0 ) )
    return JNI_TRUE;
  else
    return JNI_FALSE;
}