1 /*
2 * Copyright (c) 2003, 2020, 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 <string.h>
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <unistd.h>
33 #include <dirent.h>
34 #include <sys/stat.h>
35 #include <fcntl.h>
36 #include <ctype.h>
37
38 #include "jni.h"
39
40 #define CHECK(X) if ((X) == 0) {printf("JNI init error line %d\n", __LINE__); _exit(1);}
41
42 /*
43 * Throws the exception of the given class name and detail message
44 */
ThrowException(JNIEnv * env,const char * name,const char * msg)45 static void ThrowException(JNIEnv *env, const char *name, const char *msg) {
46 jclass cls = (*env)->FindClass(env, name);
47 if (cls != NULL) {
48 (*env)->ThrowNew(env, cls, msg);
49 }
50 }
51
52 /*
53 * Convert a jstring to an ISO 8859_1 encoded C string
54 */
getString8859_1Chars(JNIEnv * env,jstring jstr)55 static char* getString8859_1Chars(JNIEnv *env, jstring jstr) {
56 int i;
57 char *result;
58 jint len = (*env)->GetStringLength(env, jstr);
59 const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
60 if (str == 0) {
61 return NULL;
62 }
63
64 result = (char*)malloc(len+1);
65 if (result == 0) {
66 (*env)->ReleaseStringCritical(env, jstr, str);
67 ThrowException(env, "java/lang/OutOfMemoryError", NULL);
68 return NULL;
69 }
70
71 for (i=0; i<len; i++) {
72 jchar unicode = str[i];
73 if (unicode <= 0x00ff)
74 result[i] = unicode;
75 else
76 result[i] = '?';
77 }
78
79 result[len] = 0;
80 (*env)->ReleaseStringCritical(env, jstr, str);
81 return result;
82 }
83
84 /*
85 * Class: Launcher
86 * Method: launch0
87 * Signature: ([Ljava/lang/String;I)V
88 */
Java_Launcher_launch0(JNIEnv * env,jclass cls,jobjectArray cmdarray,jint serviceFd)89 JNIEXPORT void JNICALL Java_Launcher_launch0
90 (JNIEnv *env, jclass cls, jobjectArray cmdarray, jint serviceFd)
91 {
92 pid_t pid;
93 DIR* dp;
94 struct dirent* dirp;
95 int thisFd;
96 char** cmdv;
97 int i, cmdlen;
98
99 /*
100 * Argument 0 of the command array is the program name.
101 * Here we just extract the program name and any arguments into
102 * a command array suitable for use with execvp.
103 */
104 cmdlen = (*env)->GetArrayLength(env, cmdarray);
105 if (cmdlen == 0) {
106 ThrowException(env, "java/lang/IllegalArgumentException",
107 "command array must at least include the program name");
108 return;
109 }
110 cmdv = (char **)malloc((cmdlen + 1) * sizeof(char *));
111 if (cmdv == NULL) {
112 ThrowException(env, "java/lang/OutOfMemoryError", NULL);
113 return;
114 }
115
116 for (i=0; i<cmdlen; i++) {
117 jstring str = (*env)->GetObjectArrayElement(env, cmdarray, i);
118 cmdv[i] = (char *) getString8859_1Chars(env, str);
119 if (cmdv[i] == NULL) {
120 return;
121 }
122 }
123
124 /*
125 * Command array must have NULL as the last entry
126 */
127 cmdv[cmdlen] = NULL;
128
129 /*
130 * Launch the program. As this isn't a complete inetd or Runtime.exec
131 * implementation we don't have a reaper to pick up child exit status.
132 */
133 pid = fork();
134 if (pid != 0) {
135 if (pid < 0) {
136 ThrowException(env, "java/io/IOException", "fork failed");
137 }
138 return;
139 }
140
141 /*
142 * We need to close all file descriptors except for serviceFd. To
143 * get the list of open file descriptors we read through /proc/self/fd (/dev/fd)
144 * but to open this requires a file descriptor. We could use a specific
145 * file descriptor and fdopendir but Linux doesn't seem to support
146 * fdopendir. Instead we use opendir and make an assumption on the
147 * file descriptor that is used (by opening & closing a file).
148 */
149 thisFd = open("/dev/fd", O_RDONLY);
150 if (thisFd < 0) {
151 _exit(-1);
152 }
153
154 if ((dp = fdopendir(thisFd)) == NULL) {
155 _exit(-1);
156 }
157
158 while ((dirp = readdir(dp)) != NULL) {
159 if (isdigit(dirp->d_name[0])) {
160 int fd = strtol(dirp->d_name, NULL, 10);
161 if (fd != serviceFd && fd != thisFd) {
162 close(fd);
163 }
164 }
165 }
166 closedir(dp);
167
168 /*
169 * At this point all file descriptors are closed except for
170 * serviceFd. We not dup 0,1,2 to this file descriptor and
171 * close serviceFd. This should leave us with only 0,1,2
172 * open and all connected to the same socket.
173 */
174 dup2(serviceFd, STDIN_FILENO);
175 dup2(serviceFd, STDOUT_FILENO);
176 dup2(serviceFd, STDERR_FILENO);
177 close(serviceFd);
178
179 execvp(cmdv[0], cmdv);
180 _exit(-1);
181 }
182