patch-2.3.10 linux/Documentation/java.txt

• Lines: 366
• Date: Thu Jul 1 10:47:08 1999
• Orig file: v2.3.9/linux/Documentation/java.txt
• Orig date: Tue Apr 28 14:22:04 1998

diff -u --recursive --new-file v2.3.9/linux/Documentation/java.txt linux/Documentation/java.txt
@@ -21,7 +21,7 @@
 2) 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 kerneld
+   to insert it manually with modprobe/insmod, as kmod
    can not easy be supported with binfmt_misc. 
    Read the file 'binfmt_misc.txt' in this directory to know
    more about the configuration process.
@@ -29,14 +29,15 @@
 3) 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/java/bin/javawrapper:'
+     ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:'
    support for Java Applets:
-     ':Applet:E::html::/usr/local/java/bin/appletviewer:'
+     ':Applet:E::html::/usr/bin/appletviewer:'
    or the following, if you want to be more selective:
-     ':Applet:M::<!--applet::/usr/local/java/bin/appletviewer:'
+     ':Applet:M::<!--applet::/usr/bin/appletviewer:'
 
-   Of cause you have to fix the path names, if you installed the JDK
-   at another place than /usr/local/java.
+   Of cause you have to fix the path names. Given path/file names in this
+   document match the Debian 2.1 system. (i.e. jdk installed in /usr,
+   custom wrappers from this document in /usr/local)
 
    Note, that for the more selective applet support you have to modify
    existing html-files to contain <!--applet--> in the first line
@@ -45,42 +46,300 @@
    For the compiled Java programs you need a wrapper script like the
    following (this is because Java is broken in case of the filename
    handling), again fix the path names, both in the script and in the
-   above given configuration string:
+   above given configuration string.
+
+   You, too, need the little program after the script. Compile like
+   gcc -O2 -o javaclassname javaclassname.c
+   and stick it to /usr/local/bin.
+
+   Both the javawrapper shellscript and the javaclassname program
+   were supplied by Colin J. Watson <cjw44@cam.ac.uk>.
 
 ====================== Cut here ===================
 #!/bin/bash
-# /usr/local/java/bin/javawrapper - the wrapper for binfmt_misc/java
-CLASS=$1
+# /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java
 
-# if classname is a link, we follow it (this could be done easier - how?)
-if [ -L "$1" ] ; then
-        CLASS=`ls --color=no -l $1 | tr -s '\t ' '  ' | cut -d ' ' -f 11`
+if [ -z "$1" ]; then
+	exec 1>&2
+	echo Usage: $0 class-file
+	exit 1
 fi
-CLASSN=`basename $CLASS .class`
-CLASSP=`dirname $CLASS`
 
-FOO=$PATH
-PATH=$CLASSPATH
-if [ -z "`type -p -a $CLASSN.class`" ] ; then
-        # class is not in CLASSPATH
-        if [ -e "$CLASSP/$CLASSN.class" ] ; then
-                # append dir of class to CLASSPATH
-                if [ -z "${CLASSPATH}" ] ; then
-                        export CLASSPATH=$CLASSP
-                else
-                        export CLASSPATH=$CLASSP:$CLASSPATH
-                fi
-        else
-                # uh! now we would have to create a symbolic link - really
-                # ugly, i.e. print a message that one has to change the setup
-                echo "Hey! This is not a good setup to run $1 !"
-                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
-PATH=$FOO
 
 shift
-/usr/local/java/bin/java $CLASSN "$@"
+/usr/bin/java $FQCLASS "$@"
+====================== Cut here ===================
+
+
+====================== Cut here ===================
+/* 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;
+}
 ====================== Cut here ===================
 
 
@@ -116,4 +375,6 @@
 
 
 originally by Brian A. Lantz, brian@lantz.com
-heavily edited for binfmt_misc by Richard Günther.
+heavily edited for binfmt_misc by Richard Günther
+new scripts by Colin J. Watson <cjw44@cam.ac.uk>.
+