1 /*
2 * Copyright (c) 2003, 2018, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * A simple launcher to launch a program as if it was launched by inetd.
26 */
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <sys/types.h>
30 #include <sys/socket.h>
31 #include <unistd.h>
32 #include <dirent.h>
33 #include <sys/stat.h>
34 #include <fcntl.h>
35 #include <ctype.h>
36
37 #include "jni.h"
38
39 /*
40 * Throws the exception of the given class name and detail message
41 */
42 static void ThrowException(JNIEnv *env, const char *name, const char *msg) {
43 jclass cls = (*env)->FindClass(env, name);
44 if (cls != NULL) {
45 (*env)->ThrowNew(env, cls, msg);
46 }
47 }
48
49 /*
50 * Convert a jstring to an ISO 8859_1 encoded C string
51 */
52 static char* getString8859_1Chars(JNIEnv *env, jstring jstr) {
53 int i;
54 char *result;
55 jint len = (*env)->GetStringLength(env, jstr);
56 const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
57 if (str == 0) {
58 return NULL;
59 }
60
61 result = (char*)malloc(len+1);
62 if (result == 0) {
63 (*env)->ReleaseStringCritical(env, jstr, str);
64 ThrowException(env, "java/lang/OutOfMemoryError", NULL);
65 return NULL;
66 }
67
68 for (i=0; i<len; i++) {
69 jchar unicode = str[i];
70 if (unicode <= 0x00ff)
71 result[i] = unicode;
72 else
73 result[i] = '?';
74 }
75
76 result[len] = 0;
77 (*env)->ReleaseStringCritical(env, jstr, str);
78 return result;
79 }
80
81
82 /*
83 * Class: Launcher
84 * Method: launch0
85 * Signature: ([Ljava/lang/String;I)V
86 */
87 JNIEXPORT void JNICALL Java_Launcher_launch0
88 (JNIEnv *env, jclass cls, jobjectArray cmdarray, jint serviceFd)
89 {
90 pid_t pid;
91 DIR* dp;
92 struct dirent* dirp;
93 int thisFd;
94 char** cmdv;
95 int i, cmdlen;
96
97 /*
98 * Argument 0 of the command array is the program name.
99 * Here we just extract the program name and any arguments into
100 * a command array suitable for use with execvp.
101 */
102 cmdlen = (*env)->GetArrayLength(env, cmdarray);
103 if (cmdlen == 0) {
104 ThrowException(env, "java/lang/IllegalArgumentException",
105 "command array must at least include the program name");
106 return;
107 }
108 cmdv = (char **)malloc((cmdlen + 1) * sizeof(char *));
109 if (cmdv == NULL) {
110 ThrowException(env, "java/lang/OutOfMemoryError", NULL);
111 return;
112 }
113
114 for (i=0; i<cmdlen; i++) {
115 jstring str = (*env)->GetObjectArrayElement(env, cmdarray, i);
116 cmdv[i] = (char *) getString8859_1Chars(env, str);
117 if (cmdv[i] == NULL) {
118 return;
119 }
120 }
121
122 /*
123 * Command array must have NULL as the last entry
124 */
125 cmdv[cmdlen] = NULL;
126
127 /*
128 * Launch the program. As this isn't a complete inetd or Runtime.exec
129 * implementation we don't have a reaper to pick up child exit status.
130 */
131 #ifdef __solaris__
132 pid = fork1();
133 #else
134 pid = fork();
135 #endif
136 if (pid != 0) {
137 if (pid < 0) {
138 ThrowException(env, "java/io/IOException", "fork failed");
139 }
140 return;
141 }
142
143 /*
144 * We need to close all file descriptors except for serviceFd. To
145 * get the list of open file descriptos we read through /proc/self/fd
146 * but to open this requires a file descriptor. We could use a specific
147 * file descriptor and fdopendir but Linux doesn't seem to support
148 * fdopendir. Instead we use opendir and make an assumption on the
149 * file descriptor that is used (by opening & closing a file).
150 */
151 thisFd = open("/dev/null", O_RDONLY);
152 if (thisFd < 0) {
153 _exit(-1);
154 }
155 close(thisFd);
156
157 if ((dp = opendir("/proc/self/fd")) == NULL) {
158 _exit(-1);
159 }
160
161 while ((dirp = readdir(dp)) != NULL) {
162 if (isdigit(dirp->d_name[0])) {
163 int fd = strtol(dirp->d_name, NULL, 10);
164 if (fd != serviceFd && fd != thisFd) {
165 close(fd);
166 }
167 }
168 }
169 closedir(dp);
170
171 /*
172 * At this point all file descriptors are closed except for
173 * serviceFd. We not dup 0,1,2 to this file descriptor and
174 * close serviceFd. This should leave us with only 0,1,2
175 * open and all connected to the same socket.
176 */
177 dup2(serviceFd, STDIN_FILENO);
178 dup2(serviceFd, STDOUT_FILENO);
179 dup2(serviceFd, STDERR_FILENO);
180 close(serviceFd);
181
182 execvp(cmdv[0], cmdv);
183 _exit(-1);
184 }