Java の binfmt misc/ラッパーの例
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これらは、binfmt_misc 経由で Java プログラムを実行するために使用できるラッパーと C コードの例です。
jarwrapper
#!/bin/bash
# /usr/local/bin/jarwrapper - the wrapper for binfmt_misc/jar
# set path to java using JAVA_HOME if available, otherwise assume it's on the PATH
JAVA_PATH=${JAVA_HOME:+$JAVA_HOME/jre/bin/}java
$JAVA_PATH -jar "$@"
javawrapper
#!/bin/bash
# /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java
if [ -z "$1" ]; then
exec 1>&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
# set path to java using JAVA_HOME if available, otherwise assume it's on the PATH
JAVA_PATH=${JAVA_HOME:+$JAVA_HOME/jre/bin/}java
$JAVA_PATH $FQCLASS "$@"
javaclassname (support for javawrapper)
This program is used by the javawrapper script above. Compile it with the command
$ gcc -O2 -o javaclassname javaclassname.c
and move the executable to /usr/local/bin.
/* 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 <cjw44@cam.ac.uk>.
*
* 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 <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <sys/types.h>
/* 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 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 << 8) | b2);
}
/* Reads in a value from the constant pool. */
void skip_constant(FILE *classfile, u_int16_t *cur)
{
u_int16_t len;
int seekerr = 1;
pool[*cur] = ftell(classfile);
switch(read_8(classfile))
{
case CP_UTF8:
len = read_16(classfile);
seekerr = fseek(classfile, len, SEEK_CUR);
break;
case CP_CLASS:
case CP_STRING:
seekerr = fseek(classfile, 2, SEEK_CUR);
break;
case CP_INTEGER:
case CP_FLOAT:
case CP_FIELDREF:
case CP_METHODREF:
case CP_INTERFACEMETHODREF:
case CP_NAMEANDTYPE:
seekerr = fseek(classfile, 4, SEEK_CUR);
break;
case CP_LONG:
case CP_DOUBLE:
seekerr = fseek(classfile, 8, SEEK_CUR);
++(*cur);
break;
default:
corrupt_error();
}
if(seekerr)
seek_error();
}
void error(const char *format, ...)
{
va_list ap;
va_start(ap, format);
vfprintf(stderr, format, ap);
va_end(ap);
exit(1);
}
int main(int argc, char **argv)
{
FILE *classfile;
u_int16_t cp_count, i, this_class, classinfo_ptr;
u_int8_t length;
program = argv[0];
if(!argv[1])
error("%s: Missing input file\n", program);
classfile = fopen(argv[1], "rb");
if(!classfile)
error("%s: Error opening %s\n", program, argv[1]);
if(fseek(classfile, 8, SEEK_SET)) /* skip magic and version numbers */
seek_error();
cp_count = read_16(classfile);
pool = calloc(cp_count, sizeof(long));
if(!pool)
error("%s: Out of memory for constant pool\n", program);
for(i = 1; i < cp_count; ++i)
skip_constant(classfile, &i);
if(fseek(classfile, 2, SEEK_CUR)) /* skip access flags */
seek_error();
this_class = read_16(classfile);
if(this_class < 1 || this_class >= cp_count)
corrupt_error();
if(!pool[this_class] || pool[this_class] == -1)
corrupt_error();
if(fseek(classfile, pool[this_class] + 1, SEEK_SET))
seek_error();
classinfo_ptr = read_16(classfile);
if(classinfo_ptr < 1 || classinfo_ptr >= cp_count)
corrupt_error();
if(!pool[classinfo_ptr] || pool[classinfo_ptr] == -1)
corrupt_error();
if(fseek(classfile, pool[classinfo_ptr] + 1, SEEK_SET))
seek_error();
length = read_16(classfile);
for(i = 0; i < length; ++i)
{
u_int8_t x = read_8(classfile);
if((x & 0x80) || !x)
{
if((x & 0xE0) == 0xC0)
{
u_int8_t y = read_8(classfile);
if((y & 0xC0) == 0x80)
{
int c = ((x & 0x1f) << 6) + (y & 0x3f);
if(c) putchar(c);
else utf8_error();
}
else utf8_error();
}
else utf8_error();
}
else if(x == '/') putchar('.');
else putchar(x);
}
putchar('\n');
free(pool);
fclose(classfile);
return 0;
}