src/java.base/share/native/libjava/System.c - toolchain/jdk/jdk21 - Git at Google

 /*
  * Copyright (c) 1994, 2022, 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.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * 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.
  */

 #include <string.h>

 #include "jni.h"
 #include "jni_util.h"
 #include "jvm.h"
 #include "java_props.h"

 #include "java_lang_System.h"
 #include "jdk_internal_util_SystemProps_Raw.h"

 #define OBJ "Ljava/lang/Object;"

 /* Only register the performance-critical methods */
 static JNINativeMethod methods[] = {
     {"currentTimeMillis", "()J",              (void *)&JVM_CurrentTimeMillis},
     {"nanoTime",          "()J",              (void *)&JVM_NanoTime},
     {"arraycopy",     "(" OBJ "I" OBJ "II)V", (void *)&JVM_ArrayCopy},
 };

 #undef OBJ

 JNIEXPORT void JNICALL
 Java_java_lang_System_registerNatives(JNIEnv *env, jclass cls)
 {
     (*env)->RegisterNatives(env, cls,
                             methods, sizeof(methods)/sizeof(methods[0]));
 }

 JNIEXPORT jint JNICALL
 Java_java_lang_System_identityHashCode(JNIEnv *env, jobject this, jobject x)
 {
     return JVM_IHashCode(env, x);
 }

 /* VENDOR, VENDOR_URL, VENDOR_URL_BUG are set in VersionProps.java.template. */

 /*
  * Store the UTF-8 string encoding of the value in the array
  * at the index if the value is non-null.  Store nothing if the value is null.
  * On any error, return from Java_jdk_internal_util_SystemProps_00024Raw_platformProperties.
  */
 #define PUTPROP(array, prop_index, val)                    \
     if (val != NULL) {                                     \
         jstring jval = (*env)->NewStringUTF(env, val);     \
         if (jval == NULL)                                  \
             return NULL;                                   \
         (*env)->SetObjectArrayElement(env, array, jdk_internal_util_SystemProps_Raw_##prop_index, jval); \
         if ((*env)->ExceptionOccurred(env))                \
             return NULL;                                   \
         (*env)->DeleteLocalRef(env, jval);                 \
     }

 /*
  * Store the Platform string encoding of the value in the array
  * at the index if the value is non-null.  Store nothing if the value is null.
  * On any error, return from Java_jdk_internal_util_SystemProps_00024Raw_platformProperties.
  */
 #define PUTPROP_PlatformString(array, prop_index, val)     \
     if (val != NULL) {                                     \
         jstring jval = GetStringPlatform(env, val);        \
         if (jval == NULL)                                  \
             return NULL;                                   \
         (*env)->SetObjectArrayElement(env, array, jdk_internal_util_SystemProps_Raw_##prop_index, jval); \
         if ((*env)->ExceptionOccurred(env))                \
             return NULL;                                   \
         (*env)->DeleteLocalRef(env, jval);                 \
     }

 /*
  * Gather the system properties and return as a String[].
  * The first FIXED_LENGTH entries are the platform defined property values, no names.
  * The remaining array indices are alternating key/value pairs
  * supplied by the VM including those defined on the command line
  * using -Dkey=value that may override the platform defined value.
  * The caller is responsible for replacing platform provided values as needed.
  *
  * Class:     jdk_internal_util_SystemProps_Raw
  * Method:    platformProperties
  * Signature: ()[Ljava/lang/String;
  */
 JNIEXPORT jobjectArray JNICALL
 Java_jdk_internal_util_SystemProps_00024Raw_platformProperties(JNIEnv *env, jclass cla)
 {
     java_props_t *sprops;
     jobject propArray = NULL;
     jclass classString;
     int nstrings = jdk_internal_util_SystemProps_Raw_FIXED_LENGTH;

     // Get the platform specific values
     sprops = GetJavaProperties(env);
     CHECK_NULL_RETURN(sprops, NULL);

     /*
      * !!! DO NOT call PUTPROP_PlatformString (NewStringPlatform) before this line !!!
      */
     InitializeEncoding(env, sprops->sun_jnu_encoding);

     // Ensure capacity for the array and for a string for each fixed length element
     if ((*env)->EnsureLocalCapacity(env, nstrings + 2) < 0) {
         return NULL;
     }

     // Allocate an array of String for all the well known props
     classString = JNU_ClassString(env);
     CHECK_NULL_RETURN(classString, NULL);

     propArray = (*env)->NewObjectArray(env, nstrings, classString, NULL);
     CHECK_NULL_RETURN(propArray, NULL);

     /* os properties */
     PUTPROP(propArray, _os_name_NDX, sprops->os_name);
     PUTPROP(propArray, _os_version_NDX, sprops->os_version);
     PUTPROP(propArray, _os_arch_NDX, sprops->os_arch);

 #ifdef JDK_ARCH_ABI_PROP_NAME
     PUTPROP(propArray, _sun_arch_abi_NDX, sprops->sun_arch_abi);
 #endif

     /* file system properties */
     PUTPROP(propArray, _file_separator_NDX, sprops->file_separator);
     PUTPROP(propArray, _path_separator_NDX, sprops->path_separator);
     PUTPROP(propArray, _line_separator_NDX, sprops->line_separator);

 #ifdef MACOSX
     /*
      * Since sun_jnu_encoding is now hard-coded to UTF-8 on Mac, we don't
      * want to use it to overwrite file.encoding
      */
     PUTPROP(propArray, _file_encoding_NDX, sprops->encoding);
 #else
     PUTPROP(propArray, _file_encoding_NDX, sprops->sun_jnu_encoding);
 #endif
     PUTPROP(propArray, _sun_jnu_encoding_NDX, sprops->sun_jnu_encoding);

     /*
      * file encoding for stdout and stderr
      */
     PUTPROP(propArray, _stdout_encoding_NDX, sprops->stdout_encoding);
     PUTPROP(propArray, _stderr_encoding_NDX, sprops->stderr_encoding);

     /* unicode_encoding specifies the default endianness */
     PUTPROP(propArray, _sun_io_unicode_encoding_NDX, sprops->unicode_encoding);
     PUTPROP(propArray, _sun_cpu_endian_NDX, sprops->cpu_endian);
     PUTPROP(propArray, _sun_cpu_isalist_NDX, sprops->cpu_isalist);

 #ifdef MACOSX
     /* Proxy setting properties */
     if (sprops->httpProxyEnabled) {
         PUTPROP(propArray, _http_proxyHost_NDX, sprops->httpHost);
         PUTPROP(propArray, _http_proxyPort_NDX, sprops->httpPort);
     }

     if (sprops->httpsProxyEnabled) {
         PUTPROP(propArray, _https_proxyHost_NDX, sprops->httpsHost);
         PUTPROP(propArray, _https_proxyPort_NDX, sprops->httpsPort);
     }

     if (sprops->ftpProxyEnabled) {
         PUTPROP(propArray, _ftp_proxyHost_NDX, sprops->ftpHost);
         PUTPROP(propArray, _ftp_proxyPort_NDX, sprops->ftpPort);
     }

     if (sprops->socksProxyEnabled) {
         PUTPROP(propArray, _socksProxyHost_NDX, sprops->socksHost);
         PUTPROP(propArray, _socksProxyPort_NDX, sprops->socksPort);
     }

     // Mac OS X only has a single proxy exception list which applies
     // to all protocols
     if (sprops->exceptionList) {
         PUTPROP(propArray, _http_nonProxyHosts_NDX, sprops->exceptionList);
         PUTPROP(propArray, _ftp_nonProxyHosts_NDX, sprops->exceptionList);
         PUTPROP(propArray, _socksNonProxyHosts_NDX, sprops->exceptionList);
     }
 #endif

     /* data model */
     if (sizeof(sprops) == 4) {
         sprops->data_model = "32";
     } else if (sizeof(sprops) == 8) {
         sprops->data_model = "64";
     } else {
         sprops->data_model = "unknown";
     }
     PUTPROP(propArray, _sun_arch_data_model_NDX, sprops->data_model);

     /* patch level */
     PUTPROP(propArray, _sun_os_patch_level_NDX, sprops->patch_level);

     PUTPROP_PlatformString(propArray, _java_io_tmpdir_NDX, sprops->tmp_dir);

     PUTPROP_PlatformString(propArray, _user_name_NDX, sprops->user_name);
     PUTPROP_PlatformString(propArray, _user_home_NDX, sprops->user_home);
     PUTPROP_PlatformString(propArray, _user_dir_NDX, sprops->user_dir);

    /*
     * Set i18n related property fields from platform.
     */
    PUTPROP(propArray, _display_language_NDX, sprops->display_language);
    PUTPROP(propArray, _display_script_NDX, sprops->display_script);
    PUTPROP(propArray, _display_country_NDX, sprops->display_country);
    PUTPROP(propArray, _display_variant_NDX, sprops->display_variant);

    PUTPROP(propArray, _format_language_NDX, sprops->format_language);
    PUTPROP(propArray, _format_script_NDX, sprops->format_script);
    PUTPROP(propArray, _format_country_NDX, sprops->format_country);
    PUTPROP(propArray, _format_variant_NDX, sprops->format_variant);

    return propArray;
 }

 /*
  * Gather the VM and command line properties and return as a String[].
  * The array indices are alternating key/value pairs
  * supplied by the VM including those defined on the command line
  * using -Dkey=value that may override the platform defined value.
  *
  * Note: The platform encoding must have been set.
  *
  * Class:     jdk_internal_util_SystemProps_Raw
  * Method:    vmProperties
  * Signature: ()[Ljava/lang/String;
  */
 JNIEXPORT jobjectArray JNICALL
 Java_jdk_internal_util_SystemProps_00024Raw_vmProperties(JNIEnv *env, jclass cla)
 {
     jobjectArray cmdProps = JVM_GetProperties(env);
     return cmdProps;
 }

 /*
  * The following three functions implement setter methods for
  * java.lang.System.{in, out, err}. They are natively implemented
  * because they violate the semantics of the language (i.e. set final
  * variable).
  */
 JNIEXPORT void JNICALL
 Java_java_lang_System_setIn0(JNIEnv *env, jclass cla, jobject stream)
 {
     jfieldID fid =
         (*env)->GetStaticFieldID(env,cla,"in","Ljava/io/InputStream;");
     if (fid == 0)
         return;
     (*env)->SetStaticObjectField(env,cla,fid,stream);
 }

 JNIEXPORT void JNICALL
 Java_java_lang_System_setOut0(JNIEnv *env, jclass cla, jobject stream)
 {
     jfieldID fid =
         (*env)->GetStaticFieldID(env,cla,"out","Ljava/io/PrintStream;");
     if (fid == 0)
         return;
     (*env)->SetStaticObjectField(env,cla,fid,stream);
 }

 JNIEXPORT void JNICALL
 Java_java_lang_System_setErr0(JNIEnv *env, jclass cla, jobject stream)
 {
     jfieldID fid =
         (*env)->GetStaticFieldID(env,cla,"err","Ljava/io/PrintStream;");
     if (fid == 0)
         return;
     (*env)->SetStaticObjectField(env,cla,fid,stream);
 }

 static void cpchars(jchar *dst, char *src, int n)
 {
     int i;
     for (i = 0; i < n; i++) {
         dst[i] = src[i];
     }
 }

 JNIEXPORT jstring JNICALL
 Java_java_lang_System_mapLibraryName(JNIEnv *env, jclass ign, jstring libname)
 {
     int len;
     int prefix_len = (int) strlen(JNI_LIB_PREFIX);
     int suffix_len = (int) strlen(JNI_LIB_SUFFIX);

     jchar chars[256];
     if (libname == NULL) {
         JNU_ThrowNullPointerException(env, 0);
         return NULL;
     }
     len = (*env)->GetStringLength(env, libname);
     if (len > 240) {
         JNU_ThrowIllegalArgumentException(env, "name too long");
         return NULL;
     }
     cpchars(chars, JNI_LIB_PREFIX, prefix_len);
     (*env)->GetStringRegion(env, libname, 0, len, chars + prefix_len);
     len += prefix_len;
     cpchars(chars + len, JNI_LIB_SUFFIX, suffix_len);
     len += suffix_len;

     return (*env)->NewString(env, chars, len);
 }
	/*
	* Copyright (c) 1994, 2022, 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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.
	*/

	#include <string.h>

	#include "jni.h"
	#include "jni_util.h"
	#include "jvm.h"
	#include "java_props.h"

	#include "java_lang_System.h"
	#include "jdk_internal_util_SystemProps_Raw.h"

	#define OBJ "Ljava/lang/Object;"

	/* Only register the performance-critical methods */
	static JNINativeMethod methods[] = {
	{"currentTimeMillis", "()J", (void *)&JVM_CurrentTimeMillis},
	{"nanoTime", "()J", (void *)&JVM_NanoTime},
	{"arraycopy", "(" OBJ "I" OBJ "II)V", (void *)&JVM_ArrayCopy},
	};

	#undef OBJ

	JNIEXPORT void JNICALL
	Java_java_lang_System_registerNatives(JNIEnv *env, jclass cls)
	{
	(*env)->RegisterNatives(env, cls,
	methods, sizeof(methods)/sizeof(methods[0]));
	}

	JNIEXPORT jint JNICALL
	Java_java_lang_System_identityHashCode(JNIEnv *env, jobject this, jobject x)
	{
	return JVM_IHashCode(env, x);
	}

	/* VENDOR, VENDOR_URL, VENDOR_URL_BUG are set in VersionProps.java.template. */

	/*
	* Store the UTF-8 string encoding of the value in the array
	* at the index if the value is non-null. Store nothing if the value is null.
	* On any error, return from Java_jdk_internal_util_SystemProps_00024Raw_platformProperties.
	*/
	#define PUTPROP(array, prop_index, val) \
	if (val != NULL) { \
	jstring jval = (*env)->NewStringUTF(env, val); \
	if (jval == NULL) \
	return NULL; \
	(*env)->SetObjectArrayElement(env, array, jdk_internal_util_SystemProps_Raw_##prop_index, jval); \
	if ((*env)->ExceptionOccurred(env)) \
	return NULL; \
	(*env)->DeleteLocalRef(env, jval); \
	}

	/*
	* Store the Platform string encoding of the value in the array
	* at the index if the value is non-null. Store nothing if the value is null.
	* On any error, return from Java_jdk_internal_util_SystemProps_00024Raw_platformProperties.
	*/
	#define PUTPROP_PlatformString(array, prop_index, val) \
	if (val != NULL) { \
	jstring jval = GetStringPlatform(env, val); \
	if (jval == NULL) \
	return NULL; \
	(*env)->SetObjectArrayElement(env, array, jdk_internal_util_SystemProps_Raw_##prop_index, jval); \
	if ((*env)->ExceptionOccurred(env)) \
	return NULL; \
	(*env)->DeleteLocalRef(env, jval); \
	}

	/*
	* Gather the system properties and return as a String[].
	* The first FIXED_LENGTH entries are the platform defined property values, no names.
	* The remaining array indices are alternating key/value pairs
	* supplied by the VM including those defined on the command line
	* using -Dkey=value that may override the platform defined value.
	* The caller is responsible for replacing platform provided values as needed.
	*
	* Class: jdk_internal_util_SystemProps_Raw
	* Method: platformProperties
	* Signature: ()[Ljava/lang/String;
	*/
	JNIEXPORT jobjectArray JNICALL
	Java_jdk_internal_util_SystemProps_00024Raw_platformProperties(JNIEnv *env, jclass cla)
	{
	java_props_t *sprops;
	jobject propArray = NULL;
	jclass classString;
	int nstrings = jdk_internal_util_SystemProps_Raw_FIXED_LENGTH;

	// Get the platform specific values
	sprops = GetJavaProperties(env);
	CHECK_NULL_RETURN(sprops, NULL);

	/*
	* !!! DO NOT call PUTPROP_PlatformString (NewStringPlatform) before this line !!!
	*/
	InitializeEncoding(env, sprops->sun_jnu_encoding);

	// Ensure capacity for the array and for a string for each fixed length element
	if ((*env)->EnsureLocalCapacity(env, nstrings + 2) < 0) {
	return NULL;
	}

	// Allocate an array of String for all the well known props
	classString = JNU_ClassString(env);
	CHECK_NULL_RETURN(classString, NULL);

	propArray = (*env)->NewObjectArray(env, nstrings, classString, NULL);
	CHECK_NULL_RETURN(propArray, NULL);

	/* os properties */
	PUTPROP(propArray, _os_name_NDX, sprops->os_name);
	PUTPROP(propArray, _os_version_NDX, sprops->os_version);
	PUTPROP(propArray, _os_arch_NDX, sprops->os_arch);

	#ifdef JDK_ARCH_ABI_PROP_NAME
	PUTPROP(propArray, _sun_arch_abi_NDX, sprops->sun_arch_abi);
	#endif

	/* file system properties */
	PUTPROP(propArray, _file_separator_NDX, sprops->file_separator);
	PUTPROP(propArray, _path_separator_NDX, sprops->path_separator);
	PUTPROP(propArray, _line_separator_NDX, sprops->line_separator);

	#ifdef MACOSX
	/*
	* Since sun_jnu_encoding is now hard-coded to UTF-8 on Mac, we don't
	* want to use it to overwrite file.encoding
	*/
	PUTPROP(propArray, _file_encoding_NDX, sprops->encoding);
	#else
	PUTPROP(propArray, _file_encoding_NDX, sprops->sun_jnu_encoding);
	#endif
	PUTPROP(propArray, _sun_jnu_encoding_NDX, sprops->sun_jnu_encoding);

	/*
	* file encoding for stdout and stderr
	*/
	PUTPROP(propArray, _stdout_encoding_NDX, sprops->stdout_encoding);
	PUTPROP(propArray, _stderr_encoding_NDX, sprops->stderr_encoding);

	/* unicode_encoding specifies the default endianness */
	PUTPROP(propArray, _sun_io_unicode_encoding_NDX, sprops->unicode_encoding);
	PUTPROP(propArray, _sun_cpu_endian_NDX, sprops->cpu_endian);
	PUTPROP(propArray, _sun_cpu_isalist_NDX, sprops->cpu_isalist);

	#ifdef MACOSX
	/* Proxy setting properties */
	if (sprops->httpProxyEnabled) {
	PUTPROP(propArray, _http_proxyHost_NDX, sprops->httpHost);
	PUTPROP(propArray, _http_proxyPort_NDX, sprops->httpPort);
	}

	if (sprops->httpsProxyEnabled) {
	PUTPROP(propArray, _https_proxyHost_NDX, sprops->httpsHost);
	PUTPROP(propArray, _https_proxyPort_NDX, sprops->httpsPort);
	}

	if (sprops->ftpProxyEnabled) {
	PUTPROP(propArray, _ftp_proxyHost_NDX, sprops->ftpHost);
	PUTPROP(propArray, _ftp_proxyPort_NDX, sprops->ftpPort);
	}

	if (sprops->socksProxyEnabled) {
	PUTPROP(propArray, _socksProxyHost_NDX, sprops->socksHost);
	PUTPROP(propArray, _socksProxyPort_NDX, sprops->socksPort);
	}

	// Mac OS X only has a single proxy exception list which applies
	// to all protocols
	if (sprops->exceptionList) {
	PUTPROP(propArray, _http_nonProxyHosts_NDX, sprops->exceptionList);
	PUTPROP(propArray, _ftp_nonProxyHosts_NDX, sprops->exceptionList);
	PUTPROP(propArray, _socksNonProxyHosts_NDX, sprops->exceptionList);
	}
	#endif

	/* data model */
	if (sizeof(sprops) == 4) {
	sprops->data_model = "32";
	} else if (sizeof(sprops) == 8) {
	sprops->data_model = "64";
	} else {
	sprops->data_model = "unknown";
	}
	PUTPROP(propArray, _sun_arch_data_model_NDX, sprops->data_model);

	/* patch level */
	PUTPROP(propArray, _sun_os_patch_level_NDX, sprops->patch_level);

	PUTPROP_PlatformString(propArray, _java_io_tmpdir_NDX, sprops->tmp_dir);

	PUTPROP_PlatformString(propArray, _user_name_NDX, sprops->user_name);
	PUTPROP_PlatformString(propArray, _user_home_NDX, sprops->user_home);
	PUTPROP_PlatformString(propArray, _user_dir_NDX, sprops->user_dir);

	/*
	* Set i18n related property fields from platform.
	*/
	PUTPROP(propArray, _display_language_NDX, sprops->display_language);
	PUTPROP(propArray, _display_script_NDX, sprops->display_script);
	PUTPROP(propArray, _display_country_NDX, sprops->display_country);
	PUTPROP(propArray, _display_variant_NDX, sprops->display_variant);

	PUTPROP(propArray, _format_language_NDX, sprops->format_language);
	PUTPROP(propArray, _format_script_NDX, sprops->format_script);
	PUTPROP(propArray, _format_country_NDX, sprops->format_country);
	PUTPROP(propArray, _format_variant_NDX, sprops->format_variant);

	return propArray;
	}

	/*
	* Gather the VM and command line properties and return as a String[].
	* The array indices are alternating key/value pairs
	* supplied by the VM including those defined on the command line
	* using -Dkey=value that may override the platform defined value.
	*
	* Note: The platform encoding must have been set.
	*
	* Class: jdk_internal_util_SystemProps_Raw
	* Method: vmProperties
	* Signature: ()[Ljava/lang/String;
	*/
	JNIEXPORT jobjectArray JNICALL
	Java_jdk_internal_util_SystemProps_00024Raw_vmProperties(JNIEnv *env, jclass cla)
	{
	jobjectArray cmdProps = JVM_GetProperties(env);
	return cmdProps;
	}

	/*
	* The following three functions implement setter methods for
	* java.lang.System.{in, out, err}. They are natively implemented
	* because they violate the semantics of the language (i.e. set final
	* variable).
	*/
	JNIEXPORT void JNICALL
	Java_java_lang_System_setIn0(JNIEnv *env, jclass cla, jobject stream)
	{
	jfieldID fid =
	(*env)->GetStaticFieldID(env,cla,"in","Ljava/io/InputStream;");
	if (fid == 0)
	return;
	(*env)->SetStaticObjectField(env,cla,fid,stream);
	}

	JNIEXPORT void JNICALL
	Java_java_lang_System_setOut0(JNIEnv *env, jclass cla, jobject stream)
	{
	jfieldID fid =
	(*env)->GetStaticFieldID(env,cla,"out","Ljava/io/PrintStream;");
	if (fid == 0)
	return;
	(*env)->SetStaticObjectField(env,cla,fid,stream);
	}

	JNIEXPORT void JNICALL
	Java_java_lang_System_setErr0(JNIEnv *env, jclass cla, jobject stream)
	{
	jfieldID fid =
	(*env)->GetStaticFieldID(env,cla,"err","Ljava/io/PrintStream;");
	if (fid == 0)
	return;
	(*env)->SetStaticObjectField(env,cla,fid,stream);
	}

	static void cpchars(jchar dst, char src, int n)
	{
	int i;
	for (i = 0; i < n; i++) {
	dst[i] = src[i];
	}
	}

	JNIEXPORT jstring JNICALL
	Java_java_lang_System_mapLibraryName(JNIEnv *env, jclass ign, jstring libname)
	{
	int len;
	int prefix_len = (int) strlen(JNI_LIB_PREFIX);
	int suffix_len = (int) strlen(JNI_LIB_SUFFIX);

	jchar chars[256];
	if (libname == NULL) {
	JNU_ThrowNullPointerException(env, 0);
	return NULL;
	}
	len = (*env)->GetStringLength(env, libname);
	if (len > 240) {
	JNU_ThrowIllegalArgumentException(env, "name too long");
	return NULL;
	}
	cpchars(chars, JNI_LIB_PREFIX, prefix_len);
	(*env)->GetStringRegion(env, libname, 0, len, chars + prefix_len);
	len += prefix_len;
	cpchars(chars + len, JNI_LIB_SUFFIX, suffix_len);
	len += suffix_len;

	return (*env)->NewString(env, chars, len);
	}