JNI Runtime.exec hangs
Hi, we're doing some java development, both standalone and used within C using jni.
The exact same application runs fine when used standalone.
But when we try to use it within C (via jni) it hangs on Runtime.exec()... (Used both with a command string and with a command string-array)
All this happens on linux, with Sun's JDK1.3.1 using the gcc-2.9.6 c-compiler and Sun's java-compiler for the java sources.
Does anyone have any clue on this?
We can't use any command using Runtime.exec via JNI (tried a really silly 'echo' command)
[589 byte] By [
arjenm] at [2007-9-26 1:40:57]
We tested now with both JDK1.4 and IBM's JDK1.3
and even with a really simple example it fails:
Test.java :
import java.lang.*;
class Test
{
public Test()
{
System.out.println("Starting program");
try
{
Process p = Runtime.getRuntime().exec("/bin/ls");
p.waitFor(); // Hangs here
}
catch (Exception e){System.out.println("Exception: " + e);}
}
}
The c-code to invoke our java:
#include <jni.h> #ifdef _WIN32
#define PATH_SEPARATOR ';'
#else /* UNIX */
#define PATH_SEPARATOR ':'
#endif
#define USER_CLASSPATH "." /* where Java2les.class is */
main()
{
JNIEnv *env;
JavaVM *jvm;
JDK1_1InitArgs vm_args;
jint res;
jclass test_class;
jobject test_object;
jmethodID mid;
jstring jstr;
jobjectArray args;
char classpath[1024];
/* IMPORTANT: specify vm_args version # if you use JDK1.1.2 and beyond */
vm_args.version = 0x00010001;
res = JNI_GetDefaultJavaVMInitArgs(&vm_args);
if(res < 0)
{
printf("VMInitArgs failed\n");
}
/* Append USER_CLASSPATH to the end of default system class path */
sprintf(classpath, "%s%c%s",
vm_args.classpath, PATH_SEPARATOR, USER_CLASSPATH);
vm_args.classpath = classpath;
/* Create the Java VM */
res = JNI_CreateJavaVM(&jvm,&env,&vm_args);
if (res < 0) {
fprintf(stderr, "Can't create Java VM\n");
exit(1);
}
res = (*env)->GetVersion(env);
printf("env : %X\n", res);
test_class = (*env)->FindClass(env, "Test");
if (test_class == 0) {
fprintf(stderr, "Can't find Test class\n");
exit(1);
}
mid = (*env)->GetMethodID(env, test_class, "<init>", "()V");
test_object = (*env)->NewObject(env, test_class, mid);
printf("Test object created\n"); /* Never reaches this place...*/
args = (*env)->NewObjectArray(env, 1,
(*env)->FindClass(env, "java/lang/String"), jstr);
if (args == 0) {
fprintf(stderr, "Out of memory\n");
exit(1);
}
(*jvm)->DestroyJavaVM(jvm);
}
The process won't get started nor finished. When supplying a non-existend executable, it gives us a IOException... (which is good)
