Java(tm) Binary Kernel Support for Linux v1.03 |
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Java(tm) Binary Kernel Support for Linux v1.03¶
Linux beats them ALL! While all other OS’s are TALKING about direct support of Java Binaries in the OS, Linux is doing it! You can execute Java applications and Java Applets just like any other program after you have done the following: You MUST FIRST install the Java Developers Kit for Linux. The Java on Linux HOWTO gives the details on getting and installing this. This HOWTO can be found at: ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO You should also set up a reasonable CLASSPATH environment variable to use Java applications that make use of any nonstandard classes (not included in the same directory as the application itself). You have to compile BINFMT_MISC either as a module or into the kernel (CONFIG_BINFMT_MISC) and set it up properly. If you choose to compile it as a module, you will have to insert it manually with modprobe/insmod, as kmod cannot easily be supported with binfmt_misc. Read the file ‘binfmt_misc.txt’ in this directory to know more about the configuration process. Add the following configuration items to binfmt_misc (you should really have read binfmt_misc.txt now): support for Java applications: ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:'support for executable Jar files: ':ExecutableJAR:E::jar::/usr/local/bin/jarwrapper:'support for Java Applets: ':Applet:E::html::/usr/bin/appletviewer:'or the following, if you want to be more selective: ':Applet:M:: in the first line (&2 echo Usage: $0 class-file exit 1 fi CLASS=$1 FQCLASS=`/usr/local/bin/javaclassname $1` FQCLASSN=`echo $FQCLASS | sed -e 's/^.*\.\([^.]*\)$/\1/'` FQCLASSP=`echo $FQCLASS | sed -e 's-\.-/-g' -e 's-^[^/]*$--' -e 's-/[^/]*$--'` # for example: # CLASS=Test.class # FQCLASS=foo.bar.Test # FQCLASSN=Test # FQCLASSP=foo/bar unset CLASSBASE declare -i LINKLEVEL=0 while :; do if [ "`basename $CLASS .class`" == "$FQCLASSN" ]; then # See if this directory works straight off cd -L `dirname $CLASS` CLASSDIR=$PWD cd $OLDPWD if echo $CLASSDIR | grep -q "$FQCLASSP$"; then CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` break; fi # Try dereferencing the directory name cd -P `dirname $CLASS` CLASSDIR=$PWD cd $OLDPWD if echo $CLASSDIR | grep -q "$FQCLASSP$"; then CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` break; fi # If no other possible filename exists if [ ! -L $CLASS ]; then exec 1>&2 echo $0: echo " $CLASS should be in a" \ "directory tree called $FQCLASSP" exit 1 fi fi if [ ! -L $CLASS ]; then break; fi # Go down one more level of symbolic links let LINKLEVEL+=1 if [ $LINKLEVEL -gt 5 ]; then exec 1>&2 echo $0: echo " Too many symbolic links encountered" exit 1 fi CLASS=`ls --color=no -l $CLASS | sed -e 's/^.* \([^ ]*\)$/\1/'` done if [ -z "$CLASSBASE" ]; then if [ -z "$FQCLASSP" ]; then GOODNAME=$FQCLASSN.class else GOODNAME=$FQCLASSP/$FQCLASSN.class fi exec 1>&2 echo $0: echo " $FQCLASS should be in a file called $GOODNAME" exit 1 fi if ! echo $CLASSPATH | grep -q "^\(.*:\)*$CLASSBASE\(:.*\)*"; then # class is not in CLASSPATH, so prepend dir of class to CLASSPATH if [ -z "${CLASSPATH}" ] ; then export CLASSPATH=$CLASSBASE else export CLASSPATH=$CLASSBASE:$CLASSPATH fi fi shift /usr/bin/java $FQCLASS "$@"javaclassname.c: /* javaclassname.c * * Extracts the class name from a Java class file; intended for use in a Java * wrapper of the type supported by the binfmt_misc option in the Linux kernel. * * Copyright (C) 1999 Colin J. Watson . * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program 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 for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include /* From Sun's Java VM Specification, as tag entries in the constant pool. */ #define CP_UTF8 1 #define CP_INTEGER 3 #define CP_FLOAT 4 #define CP_LONG 5 #define CP_DOUBLE 6 #define CP_CLASS 7 #define CP_STRING 8 #define CP_FIELDREF 9 #define CP_METHODREF 10 #define CP_INTERFACEMETHODREF 11 #define CP_NAMEANDTYPE 12 #define CP_METHODHANDLE 15 #define CP_METHODTYPE 16 #define CP_INVOKEDYNAMIC 18 /* Define some commonly used error messages */ #define seek_error() error("%s: Cannot seek\n", program) #define corrupt_error() error("%s: Class file corrupt\n", program) #define eof_error() error("%s: Unexpected end of file\n", program) #define utf8_error() error("%s: Only ASCII 1-255 supported\n", program); char *program; long *pool; u_int8_t read_8(FILE *classfile); u_int16_t read_16(FILE *classfile); void skip_constant(FILE *classfile, u_int16_t *cur); void error(const char *format, ...); int main(int argc, char **argv); /* Reads in an unsigned 8-bit integer. */ u_int8_t read_8(FILE *classfile) { int b = fgetc(classfile); if(b == EOF) eof_error(); return (u_int8_t)b; } /* Reads in an unsigned 16-bit integer. */ u_int16_t read_16(FILE *classfile) { int b1, b2; b1 = fgetc(classfile); if(b1 == EOF) eof_error(); b2 = fgetc(classfile); if(b2 == EOF) eof_error(); return (u_int16_t)((b1 |
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