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/*
* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* A simple launcher to launch a program as if it was launched by inetd.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include "jni.h"
/*
* Throws the exception of the given class name and detail message
*/
static void ThrowException(JNIEnv *env, const char *name, const char *msg) {
jclass cls = (*env)->FindClass(env, name);
if (cls != NULL) {
(*env)->ThrowNew(env, cls, msg);
}
}
/*
* Convert a jstring to an ISO 8859_1 encoded C string
*/
static char* getString8859_1Chars(JNIEnv *env, jstring jstr) {
int i;
char *result;
jint len = (*env)->GetStringLength(env, jstr);
const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
if (str == 0) {
return NULL;
}
result = (char*)malloc(len+1);
if (result == 0) {
(*env)->ReleaseStringCritical(env, jstr, str);
ThrowException(env, "java/lang/OutOfMemoryError", NULL);
return NULL;
}
for (i=0; i<len; i++) {
jchar unicode = str[i];
if (unicode <= 0x00ff)
result[i] = unicode;
else
result[i] = '?';
}
result[len] = 0;
(*env)->ReleaseStringCritical(env, jstr, str);
return result;
}
/*
* Class: Launcher
* Method: launch0
* Signature: ([Ljava/lang/String;I)V
*/
JNIEXPORT void JNICALL Java_Launcher_launch0
(JNIEnv *env, jclass cls, jobjectArray cmdarray, jint serviceFd)
{
pid_t pid;
DIR* dp;
struct dirent* dirp;
int thisFd;
char** cmdv;
int i, cmdlen;
/*
* Argument 0 of the command array is the program name.
* Here we just extract the program name and any arguments into
* a command array suitable for use with execvp.
*/
cmdlen = (*env)->GetArrayLength(env, cmdarray);
if (cmdlen == 0) {
ThrowException(env, "java/lang/IllegalArgumentException",
"command array must at least include the program name");
return;
}
cmdv = (char **)malloc((cmdlen + 1) * sizeof(char *));
if (cmdv == NULL) {
ThrowException(env, "java/lang/OutOfMemoryError", NULL);
return;
}
for (i=0; i<cmdlen; i++) {
jstring str = (*env)->GetObjectArrayElement(env, cmdarray, i);
cmdv[i] = (char *) getString8859_1Chars(env, str);
if (cmdv[i] == NULL) {
return;
}
}
/*
* Command array must have NULL as the last entry
*/
cmdv[cmdlen] = NULL;
/*
* Launch the program. As this isn't a complete inetd or Runtime.exec
* implementation we don't have a reaper to pick up child exit status.
*/
#ifdef __solaris__
pid = fork1();
#else
pid = fork();
#endif
if (pid != 0) {
if (pid < 0) {
ThrowException(env, "java/io/IOException", "fork failed");
}
return;
}
/*
* We need to close all file descriptors except for serviceFd. To
* get the list of open file descriptos we read through /proc/self/fd
* but to open this requires a file descriptor. We could use a specific
* file descriptor and fdopendir but Linux doesn't seem to support
* fdopendir. Instead we use opendir and make an assumption on the
* file descriptor that is used (by opening & closing a file).
*/
thisFd = open("/dev/null", O_RDONLY);
if (thisFd < 0) {
_exit(-1);
}
close(thisFd);
if ((dp = opendir("/proc/self/fd")) == NULL) {
_exit(-1);
}
while ((dirp = readdir(dp)) != NULL) {
if (isdigit(dirp->d_name[0])) {
int fd = strtol(dirp->d_name, NULL, 10);
if (fd != serviceFd && fd != thisFd) {
close(fd);
}
}
}
closedir(dp);
/*
* At this point all file descriptors are closed except for
* serviceFd. We not dup 0,1,2 to this file descriptor and
* close serviceFd. This should leave us with only 0,1,2
* open and all connected to the same socket.
*/
dup2(serviceFd, STDIN_FILENO);
dup2(serviceFd, STDOUT_FILENO);
dup2(serviceFd, STDERR_FILENO);
close(serviceFd);
execvp(cmdv[0], cmdv);
_exit(-1);
}
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