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503c5bf9 MCC |
1 | Java(tm) Binary Kernel Support for Linux v1.03 |
2 | ---------------------------------------------- | |
1da177e4 LT |
3 | |
4 | Linux beats them ALL! While all other OS's are TALKING about direct | |
5 | support of Java Binaries in the OS, Linux is doing it! | |
6 | ||
7 | You can execute Java applications and Java Applets just like any | |
8 | other program after you have done the following: | |
9 | ||
10 | 1) You MUST FIRST install the Java Developers Kit for Linux. | |
11 | The Java on Linux HOWTO gives the details on getting and | |
12 | installing this. This HOWTO can be found at: | |
13 | ||
14 | ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO | |
15 | ||
16 | You should also set up a reasonable CLASSPATH environment | |
17 | variable to use Java applications that make use of any | |
18 | nonstandard classes (not included in the same directory | |
19 | as the application itself). | |
20 | ||
21 | 2) You have to compile BINFMT_MISC either as a module or into | |
503c5bf9 | 22 | the kernel (``CONFIG_BINFMT_MISC``) and set it up properly. |
1da177e4 LT |
23 | If you choose to compile it as a module, you will have |
24 | to insert it manually with modprobe/insmod, as kmod | |
503c5bf9 | 25 | cannot easily be supported with binfmt_misc. |
1da177e4 LT |
26 | Read the file 'binfmt_misc.txt' in this directory to know |
27 | more about the configuration process. | |
28 | ||
29 | 3) Add the following configuration items to binfmt_misc | |
503c5bf9 MCC |
30 | (you should really have read ``binfmt_misc.txt`` now): |
31 | support for Java applications:: | |
32 | ||
1da177e4 | 33 | ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:' |
503c5bf9 MCC |
34 | |
35 | support for executable Jar files:: | |
36 | ||
1da177e4 | 37 | ':ExecutableJAR:E::jar::/usr/local/bin/jarwrapper:' |
503c5bf9 MCC |
38 | |
39 | support for Java Applets:: | |
40 | ||
1da177e4 | 41 | ':Applet:E::html::/usr/bin/appletviewer:' |
503c5bf9 MCC |
42 | |
43 | or the following, if you want to be more selective:: | |
44 | ||
1da177e4 LT |
45 | ':Applet:M::<!--applet::/usr/bin/appletviewer:' |
46 | ||
59dd24d3 | 47 | Of course you have to fix the path names. The path/file names given in this |
503c5bf9 MCC |
48 | document match the Debian 2.1 system. (i.e. jdk installed in ``/usr``, |
49 | custom wrappers from this document in ``/usr/local``) | |
1da177e4 LT |
50 | |
51 | Note, that for the more selective applet support you have to modify | |
503c5bf9 MCC |
52 | existing html-files to contain ``<!--applet-->`` in the first line |
53 | (``<`` has to be the first character!) to let this work! | |
1da177e4 LT |
54 | |
55 | For the compiled Java programs you need a wrapper script like the | |
56 | following (this is because Java is broken in case of the filename | |
57 | handling), again fix the path names, both in the script and in the | |
58 | above given configuration string. | |
59 | ||
503c5bf9 MCC |
60 | You, too, need the little program after the script. Compile like:: |
61 | ||
62 | gcc -O2 -o javaclassname javaclassname.c | |
63 | ||
64 | and stick it to ``/usr/local/bin``. | |
1da177e4 LT |
65 | |
66 | Both the javawrapper shellscript and the javaclassname program | |
67 | were supplied by Colin J. Watson <cjw44@cam.ac.uk>. | |
68 | ||
07a37ba5 JN |
69 | Javawrapper shell script: |
70 | ||
71 | .. code-block:: sh | |
503c5bf9 MCC |
72 | |
73 | #!/bin/bash | |
74 | # /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java | |
1da177e4 | 75 | |
503c5bf9 | 76 | if [ -z "$1" ]; then |
1da177e4 LT |
77 | exec 1>&2 |
78 | echo Usage: $0 class-file | |
79 | exit 1 | |
503c5bf9 | 80 | fi |
1da177e4 | 81 | |
503c5bf9 MCC |
82 | CLASS=$1 |
83 | FQCLASS=`/usr/local/bin/javaclassname $1` | |
84 | FQCLASSN=`echo $FQCLASS | sed -e 's/^.*\.\([^.]*\)$/\1/'` | |
85 | FQCLASSP=`echo $FQCLASS | sed -e 's-\.-/-g' -e 's-^[^/]*$--' -e 's-/[^/]*$--'` | |
1da177e4 | 86 | |
503c5bf9 MCC |
87 | # for example: |
88 | # CLASS=Test.class | |
89 | # FQCLASS=foo.bar.Test | |
90 | # FQCLASSN=Test | |
91 | # FQCLASSP=foo/bar | |
1da177e4 | 92 | |
503c5bf9 | 93 | unset CLASSBASE |
1da177e4 | 94 | |
503c5bf9 | 95 | declare -i LINKLEVEL=0 |
1da177e4 | 96 | |
503c5bf9 | 97 | while :; do |
1da177e4 LT |
98 | if [ "`basename $CLASS .class`" == "$FQCLASSN" ]; then |
99 | # See if this directory works straight off | |
100 | cd -L `dirname $CLASS` | |
101 | CLASSDIR=$PWD | |
102 | cd $OLDPWD | |
103 | if echo $CLASSDIR | grep -q "$FQCLASSP$"; then | |
104 | CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` | |
105 | break; | |
106 | fi | |
107 | # Try dereferencing the directory name | |
108 | cd -P `dirname $CLASS` | |
109 | CLASSDIR=$PWD | |
110 | cd $OLDPWD | |
111 | if echo $CLASSDIR | grep -q "$FQCLASSP$"; then | |
112 | CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` | |
113 | break; | |
114 | fi | |
115 | # If no other possible filename exists | |
116 | if [ ! -L $CLASS ]; then | |
117 | exec 1>&2 | |
118 | echo $0: | |
119 | echo " $CLASS should be in a" \ | |
120 | "directory tree called $FQCLASSP" | |
121 | exit 1 | |
122 | fi | |
123 | fi | |
124 | if [ ! -L $CLASS ]; then break; fi | |
125 | # Go down one more level of symbolic links | |
126 | let LINKLEVEL+=1 | |
127 | if [ $LINKLEVEL -gt 5 ]; then | |
128 | exec 1>&2 | |
129 | echo $0: | |
130 | echo " Too many symbolic links encountered" | |
131 | exit 1 | |
132 | fi | |
133 | CLASS=`ls --color=no -l $CLASS | sed -e 's/^.* \([^ ]*\)$/\1/'` | |
503c5bf9 | 134 | done |
1da177e4 | 135 | |
503c5bf9 | 136 | if [ -z "$CLASSBASE" ]; then |
1da177e4 LT |
137 | if [ -z "$FQCLASSP" ]; then |
138 | GOODNAME=$FQCLASSN.class | |
139 | else | |
140 | GOODNAME=$FQCLASSP/$FQCLASSN.class | |
141 | fi | |
142 | exec 1>&2 | |
143 | echo $0: | |
144 | echo " $FQCLASS should be in a file called $GOODNAME" | |
145 | exit 1 | |
503c5bf9 | 146 | fi |
1da177e4 | 147 | |
503c5bf9 | 148 | if ! echo $CLASSPATH | grep -q "^\(.*:\)*$CLASSBASE\(:.*\)*"; then |
1da177e4 LT |
149 | # class is not in CLASSPATH, so prepend dir of class to CLASSPATH |
150 | if [ -z "${CLASSPATH}" ] ; then | |
151 | export CLASSPATH=$CLASSBASE | |
152 | else | |
153 | export CLASSPATH=$CLASSBASE:$CLASSPATH | |
154 | fi | |
503c5bf9 | 155 | fi |
1da177e4 | 156 | |
503c5bf9 MCC |
157 | shift |
158 | /usr/bin/java $FQCLASS "$@" | |
1da177e4 | 159 | |
07a37ba5 JN |
160 | javaclassname.c: |
161 | ||
162 | .. code-block:: c | |
1da177e4 | 163 | |
503c5bf9 | 164 | /* javaclassname.c |
07a37ba5 JN |
165 | * |
166 | * Extracts the class name from a Java class file; intended for use in a Java | |
167 | * wrapper of the type supported by the binfmt_misc option in the Linux kernel. | |
168 | * | |
169 | * Copyright (C) 1999 Colin J. Watson <cjw44@cam.ac.uk>. | |
170 | * | |
171 | * This program is free software; you can redistribute it and/or modify | |
172 | * it under the terms of the GNU General Public License as published by | |
173 | * the Free Software Foundation; either version 2 of the License, or | |
174 | * (at your option) any later version. | |
175 | * | |
176 | * This program is distributed in the hope that it will be useful, | |
177 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
178 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
179 | * GNU General Public License for more details. | |
180 | * | |
181 | * You should have received a copy of the GNU General Public License | |
182 | * along with this program; if not, write to the Free Software | |
183 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
184 | */ | |
1da177e4 | 185 | |
503c5bf9 MCC |
186 | #include <stdlib.h> |
187 | #include <stdio.h> | |
188 | #include <stdarg.h> | |
189 | #include <sys/types.h> | |
190 | ||
191 | /* From Sun's Java VM Specification, as tag entries in the constant pool. */ | |
192 | ||
193 | #define CP_UTF8 1 | |
194 | #define CP_INTEGER 3 | |
195 | #define CP_FLOAT 4 | |
196 | #define CP_LONG 5 | |
197 | #define CP_DOUBLE 6 | |
198 | #define CP_CLASS 7 | |
199 | #define CP_STRING 8 | |
200 | #define CP_FIELDREF 9 | |
201 | #define CP_METHODREF 10 | |
202 | #define CP_INTERFACEMETHODREF 11 | |
203 | #define CP_NAMEANDTYPE 12 | |
204 | #define CP_METHODHANDLE 15 | |
205 | #define CP_METHODTYPE 16 | |
206 | #define CP_INVOKEDYNAMIC 18 | |
207 | ||
208 | /* Define some commonly used error messages */ | |
209 | ||
210 | #define seek_error() error("%s: Cannot seek\n", program) | |
211 | #define corrupt_error() error("%s: Class file corrupt\n", program) | |
212 | #define eof_error() error("%s: Unexpected end of file\n", program) | |
213 | #define utf8_error() error("%s: Only ASCII 1-255 supported\n", program); | |
214 | ||
215 | char *program; | |
216 | ||
217 | long *pool; | |
218 | ||
219 | u_int8_t read_8(FILE *classfile); | |
220 | u_int16_t read_16(FILE *classfile); | |
221 | void skip_constant(FILE *classfile, u_int16_t *cur); | |
222 | void error(const char *format, ...); | |
223 | int main(int argc, char **argv); | |
224 | ||
225 | /* Reads in an unsigned 8-bit integer. */ | |
226 | u_int8_t read_8(FILE *classfile) | |
227 | { | |
1da177e4 LT |
228 | int b = fgetc(classfile); |
229 | if(b == EOF) | |
230 | eof_error(); | |
231 | return (u_int8_t)b; | |
503c5bf9 | 232 | } |
1da177e4 | 233 | |
503c5bf9 MCC |
234 | /* Reads in an unsigned 16-bit integer. */ |
235 | u_int16_t read_16(FILE *classfile) | |
236 | { | |
1da177e4 LT |
237 | int b1, b2; |
238 | b1 = fgetc(classfile); | |
239 | if(b1 == EOF) | |
240 | eof_error(); | |
241 | b2 = fgetc(classfile); | |
242 | if(b2 == EOF) | |
243 | eof_error(); | |
244 | return (u_int16_t)((b1 << 8) | b2); | |
503c5bf9 | 245 | } |
1da177e4 | 246 | |
503c5bf9 MCC |
247 | /* Reads in a value from the constant pool. */ |
248 | void skip_constant(FILE *classfile, u_int16_t *cur) | |
249 | { | |
1da177e4 LT |
250 | u_int16_t len; |
251 | int seekerr = 1; | |
252 | pool[*cur] = ftell(classfile); | |
253 | switch(read_8(classfile)) | |
254 | { | |
255 | case CP_UTF8: | |
256 | len = read_16(classfile); | |
257 | seekerr = fseek(classfile, len, SEEK_CUR); | |
258 | break; | |
259 | case CP_CLASS: | |
260 | case CP_STRING: | |
f76f133b | 261 | case CP_METHODTYPE: |
1da177e4 LT |
262 | seekerr = fseek(classfile, 2, SEEK_CUR); |
263 | break; | |
f76f133b JC |
264 | case CP_METHODHANDLE: |
265 | seekerr = fseek(classfile, 3, SEEK_CUR); | |
266 | break; | |
1da177e4 LT |
267 | case CP_INTEGER: |
268 | case CP_FLOAT: | |
269 | case CP_FIELDREF: | |
270 | case CP_METHODREF: | |
271 | case CP_INTERFACEMETHODREF: | |
272 | case CP_NAMEANDTYPE: | |
f76f133b | 273 | case CP_INVOKEDYNAMIC: |
1da177e4 LT |
274 | seekerr = fseek(classfile, 4, SEEK_CUR); |
275 | break; | |
276 | case CP_LONG: | |
277 | case CP_DOUBLE: | |
278 | seekerr = fseek(classfile, 8, SEEK_CUR); | |
279 | ++(*cur); | |
280 | break; | |
281 | default: | |
282 | corrupt_error(); | |
283 | } | |
284 | if(seekerr) | |
285 | seek_error(); | |
503c5bf9 | 286 | } |
1da177e4 | 287 | |
503c5bf9 MCC |
288 | void error(const char *format, ...) |
289 | { | |
1da177e4 LT |
290 | va_list ap; |
291 | va_start(ap, format); | |
292 | vfprintf(stderr, format, ap); | |
293 | va_end(ap); | |
294 | exit(1); | |
503c5bf9 | 295 | } |
1da177e4 | 296 | |
503c5bf9 MCC |
297 | int main(int argc, char **argv) |
298 | { | |
1da177e4 LT |
299 | FILE *classfile; |
300 | u_int16_t cp_count, i, this_class, classinfo_ptr; | |
301 | u_int8_t length; | |
302 | ||
303 | program = argv[0]; | |
304 | ||
305 | if(!argv[1]) | |
306 | error("%s: Missing input file\n", program); | |
307 | classfile = fopen(argv[1], "rb"); | |
308 | if(!classfile) | |
309 | error("%s: Error opening %s\n", program, argv[1]); | |
310 | ||
311 | if(fseek(classfile, 8, SEEK_SET)) /* skip magic and version numbers */ | |
312 | seek_error(); | |
313 | cp_count = read_16(classfile); | |
314 | pool = calloc(cp_count, sizeof(long)); | |
315 | if(!pool) | |
316 | error("%s: Out of memory for constant pool\n", program); | |
317 | ||
318 | for(i = 1; i < cp_count; ++i) | |
319 | skip_constant(classfile, &i); | |
320 | if(fseek(classfile, 2, SEEK_CUR)) /* skip access flags */ | |
321 | seek_error(); | |
322 | ||
323 | this_class = read_16(classfile); | |
324 | if(this_class < 1 || this_class >= cp_count) | |
325 | corrupt_error(); | |
326 | if(!pool[this_class] || pool[this_class] == -1) | |
327 | corrupt_error(); | |
328 | if(fseek(classfile, pool[this_class] + 1, SEEK_SET)) | |
329 | seek_error(); | |
330 | ||
331 | classinfo_ptr = read_16(classfile); | |
332 | if(classinfo_ptr < 1 || classinfo_ptr >= cp_count) | |
333 | corrupt_error(); | |
334 | if(!pool[classinfo_ptr] || pool[classinfo_ptr] == -1) | |
335 | corrupt_error(); | |
336 | if(fseek(classfile, pool[classinfo_ptr] + 1, SEEK_SET)) | |
337 | seek_error(); | |
338 | ||
339 | length = read_16(classfile); | |
340 | for(i = 0; i < length; ++i) | |
341 | { | |
342 | u_int8_t x = read_8(classfile); | |
343 | if((x & 0x80) || !x) | |
344 | { | |
345 | if((x & 0xE0) == 0xC0) | |
346 | { | |
347 | u_int8_t y = read_8(classfile); | |
348 | if((y & 0xC0) == 0x80) | |
349 | { | |
350 | int c = ((x & 0x1f) << 6) + (y & 0x3f); | |
351 | if(c) putchar(c); | |
352 | else utf8_error(); | |
353 | } | |
354 | else utf8_error(); | |
355 | } | |
356 | else utf8_error(); | |
357 | } | |
358 | else if(x == '/') putchar('.'); | |
359 | else putchar(x); | |
360 | } | |
361 | putchar('\n'); | |
362 | free(pool); | |
363 | fclose(classfile); | |
364 | return 0; | |
503c5bf9 | 365 | } |
1da177e4 | 366 | |
503c5bf9 | 367 | jarwrapper:: |
1da177e4 | 368 | |
503c5bf9 MCC |
369 | #!/bin/bash |
370 | # /usr/local/java/bin/jarwrapper - the wrapper for binfmt_misc/jar | |
1da177e4 | 371 | |
503c5bf9 | 372 | java -jar $1 |
1da177e4 LT |
373 | |
374 | ||
503c5bf9 MCC |
375 | Now simply ``chmod +x`` the ``.class``, ``.jar`` and/or ``.html`` files you |
376 | want to execute. | |
377 | ||
1da177e4 LT |
378 | To add a Java program to your path best put a symbolic link to the main |
379 | .class file into /usr/bin (or another place you like) omitting the .class | |
380 | extension. The directory containing the original .class file will be | |
381 | added to your CLASSPATH during execution. | |
382 | ||
383 | ||
384 | To test your new setup, enter in the following simple Java app, and name | |
07a37ba5 JN |
385 | it "HelloWorld.java": |
386 | ||
387 | .. code-block:: java | |
1da177e4 LT |
388 | |
389 | class HelloWorld { | |
390 | public static void main(String args[]) { | |
391 | System.out.println("Hello World!"); | |
392 | } | |
393 | } | |
394 | ||
503c5bf9 MCC |
395 | Now compile the application with:: |
396 | ||
1da177e4 LT |
397 | javac HelloWorld.java |
398 | ||
503c5bf9 MCC |
399 | Set the executable permissions of the binary file, with:: |
400 | ||
1da177e4 LT |
401 | chmod 755 HelloWorld.class |
402 | ||
503c5bf9 MCC |
403 | And then execute it:: |
404 | ||
1da177e4 LT |
405 | ./HelloWorld.class |
406 | ||
407 | ||
503c5bf9 MCC |
408 | To execute Java Jar files, simple chmod the ``*.jar`` files to include |
409 | the execution bit, then just do:: | |
410 | ||
1da177e4 LT |
411 | ./Application.jar |
412 | ||
413 | ||
503c5bf9 MCC |
414 | To execute Java Applets, simple chmod the ``*.html`` files to include |
415 | the execution bit, then just do:: | |
416 | ||
1da177e4 LT |
417 | ./Applet.html |
418 | ||
419 | ||
420 | originally by Brian A. Lantz, brian@lantz.com | |
be2a608b | 421 | heavily edited for binfmt_misc by Richard Günther |
1da177e4 LT |
422 | new scripts by Colin J. Watson <cjw44@cam.ac.uk> |
423 | added executable Jar file support by Kurt Huwig <kurt@iku-netz.de> |