1 | /* |
2 | * Copyright (c) 1999, 2017, 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 "jni.h" |
84 | # include "manifest_info.h" |
85 | #endif |
86 | |
87 | static const int CRAZY_EXEC = ENOEXEC; |
88 | static const int BAD_MAGIC = ENOEXEC; |
89 | |
90 | static const char * BAD_EXEC_MSG = "jexec failed" ; |
91 | static const char * CRAZY_EXEC_MSG = "missing args" ; |
92 | static const char * MISSING_JAVA_MSG = "can't locate java" ; |
93 | static const char * BAD_ARG_MSG = "incorrect number of arguments" ; |
94 | static const char * MEM_FAILED_MSG = "memory allocation failed" ; |
95 | #ifdef __linux__ |
96 | static const char * BAD_PATHNAME_MSG = "invalid path" ; |
97 | static const char * BAD_FILE_MSG = "invalid file" ; |
98 | static const char * BAD_MAGIC_MSG = "invalid file (bad magic number)" ; |
99 | #endif |
100 | static const char * UNKNOWN_ERROR = "unknown error" ; |
101 | |
102 | /* Define a constant that represents the number of directories to pop off the |
103 | * current location to find the java binary */ |
104 | #ifdef __linux__ |
105 | static const int RELATIVE_DEPTH = 2; |
106 | #else /* Solaris */ |
107 | static const int RELATIVE_DEPTH = 3; |
108 | #endif |
109 | |
110 | /* path to java after popping */ |
111 | static const char * BIN_PATH = "/bin/java" ; |
112 | |
113 | /* flag used when running JAR files */ |
114 | static const char * JAR_FLAG = "-jar" ; |
115 | |
116 | |
117 | #ifdef __linux__ |
118 | /* largest possible size for a local file header */ |
119 | static const size_t CHUNK_SIZE = 65535; |
120 | |
121 | /* smallest possible size for a local file header */ |
122 | static const ssize_t MIN_SIZE = LOCHDR + 1 + 4; |
123 | #endif |
124 | |
125 | |
126 | int main(int argc, const char * argv[]); |
127 | void errorExit(int error, const char * message); |
128 | int getJavaPath(const char * path, char * buf, int depth); |
129 | #ifdef __linux__ |
130 | const char * isJar(const char * path); |
131 | #endif |
132 | |
133 | |
134 | /* |
135 | * This is the main entry point. This program (jexec) will attempt to execute |
136 | * a JAR file by finding the Java program (java), relative to its own location. |
137 | * The exact location of the Java program depends on the platform, i.e. |
138 | * |
139 | * <INSTALLATIONDIR>/jre/lib/<ISA>/jexec (for Solaris) |
140 | * <INSTALLATIONDIR>/lib/jexec (for Linux JDK) |
141 | * |
142 | * Once the Java program is found, this program copies any remaining arguments |
143 | * into another array, which is then used to exec the Java program. |
144 | * |
145 | * On Linux this program does some additional steps. When copying the array of |
146 | * args, it is necessary to insert the "-jar" flag between arg[0], the program |
147 | * name, and the original arg[1], which is presumed to be a path to a JAR file. |
148 | * It is also necessary to verify that the original arg[1] really is a JAR file. |
149 | * (These steps are unnecessary on Solaris because they are taken care of by |
150 | * the kernel.) |
151 | */ |
152 | int main(int argc, const char * argv[]) { |
153 | /* We need to exec the original arguments using java, instead of jexec. |
154 | * Also, for Linux, it is necessary to add the "-jar" argument between |
155 | * the new arg[0], and the old arg[1]. To do this we will create a new |
156 | * args array. */ |
157 | char java[PATH_MAX + 1]; /* path to java binary */ |
158 | const char ** nargv = NULL; /* new args array */ |
159 | int nargc = 0; /* new args array count */ |
160 | int argi = 0; /* index into old array */ |
161 | size_t alen = 0; /* length of new array */ |
162 | |
163 | /* Make sure we have something to work with */ |
164 | if ((argc < 1) || (argv == NULL)) { |
165 | /* Shouldn't happen... */ |
166 | errorExit(CRAZY_EXEC, CRAZY_EXEC_MSG); |
167 | } |
168 | |
169 | /* Get the path to the java binary, which is in a known position relative |
170 | * to our current position, which is in argv[0]. */ |
171 | if (getJavaPath(argv[argi++], java, RELATIVE_DEPTH) != 0) { |
172 | errorExit(errno, MISSING_JAVA_MSG); |
173 | } |
174 | alen = (argc + 2) * (sizeof (const char *)); |
175 | if (alen <= 0 || alen > INT_MAX / sizeof(char *)) { |
176 | errorExit(errno, BAD_ARG_MSG); |
177 | } |
178 | nargv = (const char **) malloc(alen); |
179 | if (nargv == NULL) { |
180 | errorExit(errno, MEM_FAILED_MSG); |
181 | } |
182 | nargv[nargc++] = java; |
183 | |
184 | #ifdef __linux__ |
185 | /* The "-jar" flag is already in the original args list on Solaris, |
186 | * so it only needs to be added on Linux. */ |
187 | nargv[nargc++] = JAR_FLAG; |
188 | #endif |
189 | |
190 | if (argc >= 2) { |
191 | const char * jarfile = argv[argi++]; |
192 | const char * message = NULL; |
193 | |
194 | #ifdef __linux__ |
195 | /* On Linux we also need to make sure argv[1] is really a JAR |
196 | * file (this will also resolve any symlinks, which helps). */ |
197 | char jarPath[PATH_MAX + 1]; |
198 | |
199 | if (realpath(jarfile, jarPath) == NULL) { |
200 | errorExit(errno, BAD_PATHNAME_MSG); |
201 | } |
202 | |
203 | message = isJar(jarPath); |
204 | if (message != NULL) { |
205 | errorExit(errno, message); |
206 | } |
207 | |
208 | jarfile = jarPath; |
209 | #endif |
210 | /* the next argument is the path to the JAR file */ |
211 | nargv[nargc++] = jarfile; |
212 | } |
213 | |
214 | /* finally copy any remaining arguments */ |
215 | while (argi < argc) { |
216 | nargv[nargc++] = argv[argi++]; |
217 | } |
218 | |
219 | /* finally add one last terminating null */ |
220 | nargv[nargc++] = NULL; |
221 | |
222 | /* It's time to exec the java binary with the new arguments. It |
223 | * is possible that we've reached this point without actually |
224 | * having a JAR file argument (i.e. if argc < 2), but we still |
225 | * want to exec the java binary, since that will take care of |
226 | * displaying the correct usage. */ |
227 | execv(java, (char * const *) nargv); |
228 | |
229 | /* If the exec worked, this process would have been replaced |
230 | * by the new process. So any code reached beyond this point |
231 | * implies an error in the exec. */ |
232 | free(nargv); |
233 | errorExit(errno, BAD_EXEC_MSG); |
234 | return 0; // keep the compiler happy |
235 | } |
236 | |
237 | |
238 | /* |
239 | * Exit the application by setting errno, and writing a message. |
240 | * |
241 | * Parameters: |
242 | * error - errno is set to this value, and it is used to exit. |
243 | * message - the message to write. |
244 | */ |
245 | void errorExit(int error, const char * message) { |
246 | if (error != 0) { |
247 | errno = error; |
248 | perror((message != NULL) ? message : UNKNOWN_ERROR); |
249 | } |
250 | |
251 | exit((error == 0) ? 0 : 1); |
252 | } |
253 | |
254 | |
255 | /* |
256 | * Get the path to the java binary that should be relative to the current path. |
257 | * |
258 | * Parameters: |
259 | * path - the input path that the java binary that should be relative to. |
260 | * buf - a buffer of size PATH_MAX or greater that the java path is |
261 | * copied to. |
262 | * depth - the number of names to trim off the current path, including the |
263 | * name of this program. |
264 | * |
265 | * Returns: |
266 | * This function returns 0 on success; otherwise it returns the value of |
267 | * errno. |
268 | */ |
269 | int getJavaPath(const char * path, char * buf, int depth) { |
270 | int result = 0; |
271 | |
272 | /* Get the full path to this program. Depending on whether this is Solaris |
273 | * or Linux, this will be something like, |
274 | * |
275 | * <FOO>/jre/lib/<ISA>/jexec (for Solaris) |
276 | * <FOO>/lib/jexec (for Linux) |
277 | */ |
278 | if (realpath(path, buf) != NULL) { |
279 | int count = 0; |
280 | |
281 | /* Pop off the filename, and then subdirectories for each level of |
282 | * depth */ |
283 | for (count = 0; count < depth; count++) { |
284 | *(strrchr(buf, '/')) = '\0'; |
285 | } |
286 | |
287 | /* Append the relative location of java, creating something like, |
288 | * |
289 | * <FOO>/jre/bin/java (for Solaris) |
290 | * <FOO>/bin/java (for Linux) |
291 | */ |
292 | strcat(buf, BIN_PATH); |
293 | } |
294 | else { |
295 | /* Failed to get the path */ |
296 | result = errno; |
297 | } |
298 | |
299 | return (result); |
300 | } |
301 | |
302 | |
303 | #ifdef __linux__ |
304 | /* |
305 | * Check if the given file is a JAR file. |
306 | * |
307 | * Parameters: |
308 | * path - the path to the file to check for JAR magic. |
309 | * |
310 | * Returns: |
311 | * This function return NULL on success. Otherwise, errno is set, and it |
312 | * returns a message that indicates what caused the failure. |
313 | */ |
314 | const char * isJar(const char * path) { |
315 | const char * result = BAD_FILE_MSG; |
316 | |
317 | int fd = open(path, O_RDONLY); |
318 | if (fd != -1) { |
319 | unsigned char buf[CHUNK_SIZE]; |
320 | |
321 | ssize_t count = read(fd, buf, CHUNK_SIZE); |
322 | if (count >= MIN_SIZE) { |
323 | result = BAD_MAGIC_MSG; |
324 | |
325 | // be sure the file is at least a ZIP file |
326 | if (LOCSIG_AT(buf)) { |
327 | |
328 | off_t flen = LOCNAM(buf); |
329 | off_t xlen = LOCEXT(buf); |
330 | off_t start = LOCHDR + flen; |
331 | off_t end = start + xlen; |
332 | |
333 | if (end <= count) { |
334 | end -= 4; // make sure there are 4 bytes to read at start |
335 | while (start <= end) { |
336 | off_t xhid = SH(buf, start); |
337 | off_t xdlen = SH(buf, start + 2); |
338 | |
339 | start += 4 + xdlen; |
340 | if (xhid == 0xcafe) { |
341 | // found the JAR magic |
342 | result = NULL; |
343 | break; |
344 | } |
345 | } |
346 | } |
347 | } |
348 | } |
349 | |
350 | if (result != NULL) { |
351 | errno = BAD_MAGIC; |
352 | } |
353 | |
354 | close (fd); |
355 | } |
356 | |
357 | return (result); |
358 | } |
359 | #endif |
360 | |