1 /*
2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * jexec for J2SE
28 *
29 * jexec is used by the system to allow execution of JAR files.
30 * Essentially jexec needs to run java and
31 * needs to be a native ISA executable (not a shell script), although
32 * this native ISA executable requirement was a mistake that will be fixed.
33 * (<ISA> is sparc or i386 or amd64).
34 *
35 * When you execute a jar file, jexec is executed by the system as follows:
36 * /usr/java/jre/lib/<ISA>/jexec -jar JARFILENAME
37 * so this just needs to be turned into:
38 * /usr/java/jre/bin/java -jar JARFILENAME
39 *
40 * Solaris systems (new 7's and all 8's) will be looking for jexec at:
41 * /usr/java/jre/lib/<ISA>/jexec
42 * Older systems may need to add this to their /etc/system file:
43 * set javaexec:jexec="/usr/java/jre/lib/<ISA>/jexec"
44 * and reboot the machine for this to work.
45 *
46 * This source should be compiled as:
47 * cc -o jexec jexec.c
48 *
49 * And jexec should be placed at the following location of the installation:
50 * <INSTALLATIONDIR>/jre/lib/<ISA>/jexec (for Solaris)
51 * <INSTALLATIONDIR>/lib/jexec (for Linux)
52 *
53 * NOTE: Unless <INSTALLATIONDIR> is the "default" JDK on the system
54 * (i.e. /usr/java -> <INSTALLATIONDIR>), this jexec will not be
55 * found. The 1.2 java is only the default on Solaris 8 and
56 * on systems where the 1.2 packages were installed and no 1.1
57 * java was found.
58 *
59 * NOTE: You must use 1.2 jar to build your jar files. The system
60 * doesn't seem to pick up 1.1 jar files.
61 *
62 * NOTE: We don't need to set LD_LIBRARY_PATH here, even though we
63 * are running the actual java binary because the java binary will
64 * look for it's libraries through it's own runpath, which uses
65 * $ORIGIN.
66 *
67 * NOTE: This jexec should NOT have any special .so library needs because
68 * it appears that this executable will NOT get the $ORIGIN of jexec
69 * but the $ORIGIN of the jar file being executed. Be careful to keep
70 * this program simple and with no .so dependencies.
71 */
72
73 #include <stdlib.h>
74 #include <stdio.h>
75 #include <unistd.h>
76 #include <string.h>
77 #include <limits.h>
78 #include <errno.h>
79 #ifdef __linux__
80 # include <sys/types.h>
81 # include <sys/stat.h>
82 # include <fcntl.h>
83 # include "manifest_info.h"
84 #endif
85
86 static const int CRAZY_EXEC = ENOEXEC;
87 static const int BAD_MAGIC = ENOEXEC;
88
89 static const char * BAD_EXEC_MSG = "jexec failed";
90 static const char * CRAZY_EXEC_MSG = "missing args";
91 static const char * MISSING_JAVA_MSG = "can't locate java";
92 #ifdef __linux__
93 static const char * BAD_PATHNAME_MSG = "invalid path";
94 static const char * BAD_FILE_MSG = "invalid file";
95 static const char * BAD_MAGIC_MSG = "invalid file (bad magic number)";
96 #endif
97 static const char * UNKNOWN_ERROR = "unknown error";
98
99 /* Define a constant that represents the number of directories to pop off the
100 * current location to find the java binary */
101 #ifdef __linux__
102 static const int RELATIVE_DEPTH = 2;
103 #else /* Solaris */
104 static const int RELATIVE_DEPTH = 3;
105 #endif
106
107 /* path to java after popping */
108 static const char * BIN_PATH = "/bin/java";
109
110 /* flag used when running JAR files */
111 static const char * JAR_FLAG = "-jar";
112
113
114 #ifdef __linux__
115 /* largest possible size for a local file header */
116 static const size_t CHUNK_SIZE = 65535;
117
118 /* smallest possible size for a local file header */
119 static const ssize_t MIN_SIZE = LOCHDR + 1 + 4;
120 #endif
121
122
123 int main(int argc, const char * argv[]);
124 void errorExit(int error, const char * message);
125 int getJavaPath(const char * path, char * buf, int depth);
126 #ifdef __linux__
127 const char * isJar(const char * path);
128 #endif
129
130
131 /*
132 * This is the main entry point. This program (jexec) will attempt to execute
133 * a JAR file by finding the Java program (java), relative to its own location.
134 * The exact location of the Java program depends on the platform, i.e.
135 *
136 * <INSTALLATIONDIR>/jre/lib/<ISA>/jexec (for Solaris)
137 * <INSTALLATIONDIR>/lib/jexec (for Linux JDK)
138 *
139 * Once the Java program is found, this program copies any remaining arguments
140 * into another array, which is then used to exec the Java program.
141 *
142 * On Linux this program does some additional steps. When copying the array of
143 * args, it is necessary to insert the "-jar" flag between arg[0], the program
144 * name, and the original arg[1], which is presumed to be a path to a JAR file.
145 * It is also necessary to verify that the original arg[1] really is a JAR file.
146 * (These steps are unnecessary on Solaris because they are taken care of by
147 * the kernel.)
148 */
149 int main(int argc, const char * argv[]) {
150 /* We need to exec the original arguments using java, instead of jexec.
151 * Also, for Linux, it is necessary to add the "-jar" argument between
152 * the new arg[0], and the old arg[1]. To do this we will create a new
153 * args array. */
154 char java[PATH_MAX + 1]; /* path to java binary */
155 const char ** nargv = NULL; /* new args array */
156 int nargc = 0; /* new args array count */
157 int argi = 0; /* index into old array */
158
159 /* Make sure we have something to work with */
160 if ((argc < 1) || (argv == NULL)) {
161 /* Shouldn't happen... */
162 errorExit(CRAZY_EXEC, CRAZY_EXEC_MSG);
163 }
164
165 /* Get the path to the java binary, which is in a known position relative
166 * to our current position, which is in argv[0]. */
167 if (getJavaPath(argv[argi++], java, RELATIVE_DEPTH) != 0) {
168 errorExit(errno, MISSING_JAVA_MSG);
169 }
170
171 nargv = (const char **) malloc((argc + 2) * (sizeof (const char *)));
172 nargv[nargc++] = java;
173
174 #ifdef __linux__
175 /* The "-jar" flag is already in the original args list on Solaris,
176 * so it only needs to be added on Linux. */
177 nargv[nargc++] = JAR_FLAG;
178 #endif
179
180 if (argc >= 2) {
181 const char * jarfile = argv[argi++];
182 const char * message = NULL;
183
184 #ifdef __linux__
185 /* On Linux we also need to make sure argv[1] is really a JAR
186 * file (this will also resolve any symlinks, which helps). */
187 char jarPath[PATH_MAX + 1];
188
189 if (realpath(jarfile, jarPath) == NULL) {
190 errorExit(errno, BAD_PATHNAME_MSG);
191 }
192
193 message = isJar(jarPath);
194 if (message != NULL) {
195 errorExit(errno, message);
196 }
197
198 jarfile = jarPath;
199 #endif
200 /* the next argument is the path to the JAR file */
201 nargv[nargc++] = jarfile;
202 }
203
204 /* finally copy any remaining arguments */
205 while (argi < argc) {
206 nargv[nargc++] = argv[argi++];
207 }
208
209 /* finally add one last terminating null */
210 nargv[nargc++] = NULL;
211
212 /* It's time to exec the java binary with the new arguments. It
213 * is possible that we've reached this point without actually
214 * having a JAR file argument (i.e. if argc < 2), but we still
215 * want to exec the java binary, since that will take care of
216 * displaying the correct usage. */
217 execv(java, (char * const *) nargv);
218
219 /* If the exec worked, this process would have been replaced
220 * by the new process. So any code reached beyond this point
221 * implies an error in the exec. */
222 free(nargv);
223 errorExit(errno, BAD_EXEC_MSG);
224 return 0; // keep the compiler happy
225 }
226
227
228 /*
229 * Exit the application by setting errno, and writing a message.
230 *
231 * Parameters:
232 * error - errno is set to this value, and it is used to exit.
233 * message - the message to write.
234 */
235 void errorExit(int error, const char * message) {
236 if (error != 0) {
237 errno = error;
238 perror((message != NULL) ? message : UNKNOWN_ERROR);
239 }
240
241 exit((error == 0) ? 0 : 1);
242 }
243
244
245 /*
246 * Get the path to the java binary that should be relative to the current path.
247 *
248 * Parameters:
249 * path - the input path that the java binary that should be relative to.
250 * buf - a buffer of size PATH_MAX or greater that the java path is
251 * copied to.
252 * depth - the number of names to trim off the current path, including the
253 * name of this program.
254 *
255 * Returns:
256 * This function returns 0 on success; otherwise it returns the value of
257 * errno.
258 */
259 int getJavaPath(const char * path, char * buf, int depth) {
260 int result = 0;
261
262 /* Get the full path to this program. Depending on whether this is Solaris
263 * or Linux, this will be something like,
264 *
265 * <FOO>/jre/lib/<ISA>/jexec (for Solaris)
266 * <FOO>/lib/jexec (for Linux)
267 */
268 if (realpath(path, buf) != NULL) {
269 int count = 0;
270
271 /* Pop off the filename, and then subdirectories for each level of
272 * depth */
273 for (count = 0; count < depth; count++) {
274 *(strrchr(buf, '/')) = '\0';
275 }
276
277 /* Append the relative location of java, creating something like,
278 *
279 * <FOO>/jre/bin/java (for Solaris)
280 * <FOO>/bin/java (for Linux)
281 */
282 strcat(buf, BIN_PATH);
283 }
284 else {
285 /* Failed to get the path */
286 result = errno;
287 }
288
289 return (result);
290 }
291
292
293 #ifdef __linux__
294 /*
295 * Check if the given file is a JAR file.
296 *
297 * Parameters:
298 * path - the path to the file to check for JAR magic.
299 *
300 * Returns:
301 * This function return NULL on success. Otherwise, errno is set, and it
302 * returns a message that indicates what caused the failure.
303 */
304 const char * isJar(const char * path) {
305 const char * result = BAD_FILE_MSG;
306
307 int fd = open(path, O_RDONLY);
308 if (fd != -1) {
309 unsigned char buf[CHUNK_SIZE];
310
311 ssize_t count = read(fd, buf, CHUNK_SIZE);
312 if (count >= MIN_SIZE) {
313 result = BAD_MAGIC_MSG;
314
315 // be sure the file is at least a ZIP file
316 if (GETSIG(buf) == LOCSIG) {
317
318 off_t flen = LOCNAM(buf);
319 off_t xlen = LOCEXT(buf);
320 off_t start = LOCHDR + flen;
321 off_t end = start + xlen;
322
323 if (end <= count) {
324 while (start < end) {
325 off_t xhid = SH(buf, start);
326 off_t xdlen = SH(buf, start + 2);
327
328 start += 4 + xdlen;
329 if (xhid == 0xcafe) {
330 // found the JAR magic
331 result = NULL;
332 break;
333 }
334 }
335 }
336 }
337 }
338
339 if (result != NULL) {
340 errno = BAD_MAGIC;
341 }
342
343 close (fd);
344 }
345
346 return (result);
347 }
348 #endif