src/java.base/share/native/libjava/jni_util.c - master - niceSOFT/openjdk21

src/java.base/share/native/libjava/jni_util.c
1 253 строки36 KB
Rudi Horn
8308748: JNU_GetStringPlatformChars may write to String's internal memory array
06 июн 2023, 15:58
06 июн 2023, 15:588f0839b
/*
 * Copyright (c) 1997, 2023, 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 <stdlib.h>
#include <string.h>

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

/* Due to a bug in the win32 C runtime library strings
 * such as "z:" need to be appended with a "." so we
 * must allocate at least 4 bytes to allow room for
 * this expansion. See 4235353 for details.
 * This macro returns NULL if the requested size is
 * negative, or the size is INT_MAX as the macro adds 1
 * that overflows into negative value.
 */
#define MALLOC_MIN4(len) ((len) >= INT_MAX || (len) < 0 ? \
    NULL : \
    ((char *)malloc((len) + 1 < 4 ? 4 : (len) + 1)))

/**
 * Throw a Java exception by name. Similar to SignalError.
 */
JNIEXPORT void JNICALL
JNU_ThrowByName(JNIEnv *env, const char *name, const char *msg)
{
    jclass cls = (*env)->FindClass(env, name);

    if (cls != 0) /* Otherwise an exception has already been thrown */
        (*env)->ThrowNew(env, cls, msg);
}

/* JNU_Throw common exceptions */

JNIEXPORT void JNICALL
JNU_ThrowNullPointerException(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/NullPointerException", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowArrayIndexOutOfBoundsException(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/ArrayIndexOutOfBoundsException", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowOutOfMemoryError(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/OutOfMemoryError", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowIllegalArgumentException(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/IllegalArgumentException", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowInternalError(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/InternalError", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowClassNotFoundException(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/lang/ClassNotFoundException", msg);
}

JNIEXPORT void JNICALL
JNU_ThrowIOException(JNIEnv *env, const char *msg)
{
    JNU_ThrowByName(env, "java/io/IOException", msg);
}

/*
 * Throw an exception by name, using the string returned by
 * getLastErrorString for the detail string. If the last-error
 * string is NULL, use the given default detail string.
 */
JNIEXPORT void JNICALL
JNU_ThrowByNameWithLastError(JNIEnv *env, const char *name,
                             const char *defaultDetail)
{
    jstring s = getLastErrorString(env);

    if (s != NULL) {
        jobject x = JNU_NewObjectByName(env, name,
                                        "(Ljava/lang/String;)V", s);
        if (x != NULL) {
            (*env)->Throw(env, x);
        }
    }
    if (!(*env)->ExceptionOccurred(env)) {
        JNU_ThrowByName(env, name, defaultDetail);
    }
}

/*
 * Throw an exception by name, using a given message and the string
 * returned by getLastErrorString to construct the detail string.
 */
JNIEXPORT void JNICALL
JNU_ThrowByNameWithMessageAndLastError
  (JNIEnv *env, const char *name, const char *message)
{
    size_t messagelen = message == NULL ? 0 : strlen(message);

    jstring s = getLastErrorString(env);
    if (s != NULL) {
        jobject x = NULL;
        if (messagelen > 0) {
            jstring s2 = NULL;
            size_t messageextlen = messagelen + 4;
            char *str1 = (char *)malloc((messageextlen) * sizeof(char));
            if (str1 == NULL) {
                JNU_ThrowOutOfMemoryError(env, 0);
                return;
            }
            jio_snprintf(str1, messageextlen, " (%s)", message);
            s2 = (*env)->NewStringUTF(env, str1);
            free(str1);
            JNU_CHECK_EXCEPTION(env);
            if (s2 != NULL) {
                jstring s3 = JNU_CallMethodByName(
                                 env, NULL, s, "concat",
                                 "(Ljava/lang/String;)Ljava/lang/String;",
                                 s2).l;
                (*env)->DeleteLocalRef(env, s2);
                JNU_CHECK_EXCEPTION(env);
                if (s3 != NULL) {
                    (*env)->DeleteLocalRef(env, s);
                    s = s3;
                }
            }
        }
        x = JNU_NewObjectByName(env, name, "(Ljava/lang/String;)V", s);
        if (x != NULL) {
            (*env)->Throw(env, x);
        }
    }

    if (!(*env)->ExceptionOccurred(env)) {
        if (messagelen > 0) {
            JNU_ThrowByName(env, name, message);
        } else {
            JNU_ThrowByName(env, name, "no further information");
        }
    }
}

/*
 * Convenience function.
 * Call JNU_ThrowByNameWithLastError for java.io.IOException.
 */
JNIEXPORT void JNICALL
JNU_ThrowIOExceptionWithLastError(JNIEnv *env, const char *defaultDetail)
{
    JNU_ThrowByNameWithLastError(env, "java/io/IOException", defaultDetail);
}

/*
 * Throw java.io.IOException using a given message and the string
 * returned by getLastErrorString to construct the detail string.
 */
JNIEXPORT void JNICALL
JNU_ThrowIOExceptionWithMessageAndLastError(JNIEnv *env, const char *message)
{
    JNU_ThrowByNameWithMessageAndLastError(env, "java/io/IOException", message);
}


JNIEXPORT jvalue JNICALL
JNU_CallStaticMethodByName(JNIEnv *env,
                           jboolean *hasException,
                           const char *class_name,
                           const char *name,
                           const char *signature,
                           ...)
{
    jclass clazz;
    jmethodID mid;
    va_list args;
    jvalue result;
    const char *p = signature;

    /* find out the return type */
    while (*p && *p != ')')
        p++;
    p++;

    result.i = 0;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        goto done2;

    clazz = (*env)->FindClass(env, class_name);
    if (clazz == 0)
        goto done2;
    mid = (*env)->GetStaticMethodID(env, clazz, name, signature);
    if (mid == 0)
        goto done1;
    va_start(args, signature);
    switch (*p) {
    case 'V':
        (*env)->CallStaticVoidMethodV(env, clazz, mid, args);
        break;
    case '[':
    case 'L':
        result.l = (*env)->CallStaticObjectMethodV(env, clazz, mid, args);
        break;
    case 'Z':
        result.z = (*env)->CallStaticBooleanMethodV(env, clazz, mid, args);
        break;
    case 'B':
        result.b = (*env)->CallStaticByteMethodV(env, clazz, mid, args);
        break;
    case 'C':
        result.c = (*env)->CallStaticCharMethodV(env, clazz, mid, args);
        break;
    case 'S':
        result.s = (*env)->CallStaticShortMethodV(env, clazz, mid, args);
        break;
    case 'I':
        result.i = (*env)->CallStaticIntMethodV(env, clazz, mid, args);
        break;
    case 'J':
        result.j = (*env)->CallStaticLongMethodV(env, clazz, mid, args);
        break;
    case 'F':
        result.f = (*env)->CallStaticFloatMethodV(env, clazz, mid, args);
        break;
    case 'D':
        result.d = (*env)->CallStaticDoubleMethodV(env, clazz, mid, args);
        break;
    default:
        (*env)->FatalError(env, "JNU_CallStaticMethodByName: illegal signature");
    }
    va_end(args);

 done1:
    (*env)->DeleteLocalRef(env, clazz);
 done2:
    if (hasException) {
        *hasException = (*env)->ExceptionCheck(env);
    }
    return result;
}

JNIEXPORT jvalue JNICALL
JNU_CallMethodByName(JNIEnv *env,
                     jboolean *hasException,
                     jobject obj,
                     const char *name,
                     const char *signature,
                     ...)
{
    jvalue result;
    va_list args;

    va_start(args, signature);
    result = JNU_CallMethodByNameV(env, hasException, obj, name, signature,
                                   args);
    va_end(args);

    return result;
}


JNIEXPORT jvalue JNICALL
JNU_CallMethodByNameV(JNIEnv *env,
                      jboolean *hasException,
                      jobject obj,
                      const char *name,
                      const char *signature,
                      va_list args)
{
    jclass clazz;
    jmethodID mid;
    jvalue result;
    const char *p = signature;

    /* find out the return type */
    while (*p && *p != ')')
        p++;
    p++;

    result.i = 0;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        goto done2;

    clazz = (*env)->GetObjectClass(env, obj);
    mid = (*env)->GetMethodID(env, clazz, name, signature);
    if (mid == 0)
        goto done1;

    switch (*p) {
    case 'V':
        (*env)->CallVoidMethodV(env, obj, mid, args);
        break;
    case '[':
    case 'L':
        result.l = (*env)->CallObjectMethodV(env, obj, mid, args);
        break;
    case 'Z':
        result.z = (*env)->CallBooleanMethodV(env, obj, mid, args);
        break;
    case 'B':
        result.b = (*env)->CallByteMethodV(env, obj, mid, args);
        break;
    case 'C':
        result.c = (*env)->CallCharMethodV(env, obj, mid, args);
        break;
    case 'S':
        result.s = (*env)->CallShortMethodV(env, obj, mid, args);
        break;
    case 'I':
        result.i = (*env)->CallIntMethodV(env, obj, mid, args);
        break;
    case 'J':
        result.j = (*env)->CallLongMethodV(env, obj, mid, args);
        break;
    case 'F':
        result.f = (*env)->CallFloatMethodV(env, obj, mid, args);
        break;
    case 'D':
        result.d = (*env)->CallDoubleMethodV(env, obj, mid, args);
        break;
    default:
        (*env)->FatalError(env, "JNU_CallMethodByNameV: illegal signature");
    }
 done1:
    (*env)->DeleteLocalRef(env, clazz);
 done2:
    if (hasException) {
        *hasException = (*env)->ExceptionCheck(env);
    }
    return result;
}

JNIEXPORT jobject JNICALL
JNU_NewObjectByName(JNIEnv *env, const char *class_name,
                    const char *constructor_sig, ...)
{
    jobject obj = NULL;

    jclass cls = 0;
    jmethodID cls_initMID;
    va_list args;

    if ((*env)->EnsureLocalCapacity(env, 2) < 0)
        goto done;

    cls = (*env)->FindClass(env, class_name);
    if (cls == 0) {
        goto done;
    }
    cls_initMID  = (*env)->GetMethodID(env, cls,
                                       "<init>", constructor_sig);
    if (cls_initMID == NULL) {
        goto done;
    }
    va_start(args, constructor_sig);
    obj = (*env)->NewObjectV(env, cls, cls_initMID, args);
    va_end(args);

 done:
    (*env)->DeleteLocalRef(env, cls);
    return obj;
}

/* Optimized for charset ISO_8559_1 */
static jstring
newSizedString8859_1(JNIEnv *env, const char *str, const int len)
{
    jchar buf[512] = {0};
    jchar *str1;
    jstring result;
    int i;

    if ((*env)->EnsureLocalCapacity(env, 1) < 0)
        return NULL;

    if (len > 512) {
        str1 = (jchar *)malloc(len * sizeof(jchar));
        if (str1 == 0) {
            JNU_ThrowOutOfMemoryError(env, 0);
            return 0;
        }
    } else
        str1 = buf;

    for (i=0;i<len;i++)
        str1[i] = (unsigned char)str[i];

    result = (*env)->NewString(env, str1, len);
    if (str1 != buf)
        free(str1);
    return result;
}

static jstring
newString8859_1(JNIEnv *env, const char *str)
{
    int len = (int)strlen(str);
    return newSizedString8859_1(env, str, len);
}

static const char*
getString8859_1Chars(JNIEnv *env, jstring jstr, jboolean strict)
{
    int i;
    char *result;
    jint len = (*env)->GetStringLength(env, jstr);
    const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
    if (str == 0) {
        return 0;
    }

    result = MALLOC_MIN4(len);
    if (result == 0) {
        (*env)->ReleaseStringCritical(env, jstr, str);
        JNU_ThrowOutOfMemoryError(env, 0);
        return 0;
    }

    for (i=0; i<len; i++) {
        jchar unicode = str[i];
        if (strict && unicode == 0) {
            (*env)->ReleaseStringCritical(env, jstr, str);
            free(result);
            JNU_ThrowIllegalArgumentException(env, "NUL character not allowed in platform string");
            return 0;
        }

        if (unicode <= 0x00ff)
            result[i] = (char)unicode;
        else
            result[i] = '?';
    }

    result[len] = 0;
    (*env)->ReleaseStringCritical(env, jstr, str);
    return result;
}


/* Optimized for charset ISO646-US (us-ascii) */
static jstring
newString646_US(JNIEnv *env, const char *str)
{
    int len = (int)strlen(str);
    jchar buf[512] = {0};
    jchar *str1;
    jstring result;
    int i;

    if ((*env)->EnsureLocalCapacity(env, 1) < 0)
        return NULL;

    if (len > 512) {
        str1 = (jchar *)malloc(len * sizeof(jchar));
        if (str1 == 0) {
            JNU_ThrowOutOfMemoryError(env, 0);
            return 0;
        }
    } else
        str1 = buf;

    for (i=0; i<len; i++) {
        unsigned char c = (unsigned char)str[i];
        if (c <= 0x7f)
            str1[i] = c;
        else
            str1[i] = '?';
    }

    result = (*env)->NewString(env, str1, len);
    if (str1 != buf)
        free(str1);
    return result;
}

static const char*
getString646_USChars(JNIEnv *env, jstring jstr, jboolean strict)
{
    int i;
    char *result;
    jint len = (*env)->GetStringLength(env, jstr);
    const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
    if (str == 0) {
        return 0;
    }

    result = MALLOC_MIN4(len);
    if (result == 0) {
        (*env)->ReleaseStringCritical(env, jstr, str);
        JNU_ThrowOutOfMemoryError(env, 0);
        return 0;
    }

    for (i=0; i<len; i++) {
        jchar unicode = str[i];
        if (strict && unicode == 0) {
            (*env)->ReleaseStringCritical(env, jstr, str);
            free(result);
            JNU_ThrowIllegalArgumentException(env, "NUL character not allowed in platform string");
            return 0;
        }
        if (unicode <= 0x007f )
            result[i] = (char)unicode;
        else
            result[i] = '?';
    }

    result[len] = 0;
    (*env)->ReleaseStringCritical(env, jstr, str);
    return result;
}

/* enumeration of c1 row from Cp1252 */
static int cp1252c1chars[32] = {
    0x20AC,0xFFFD,0x201A,0x0192,0x201E,0x2026,0x2020,0x2021,
    0x02C6,0x2030,0x0160,0x2039,0x0152,0xFFFD,0x017D,0xFFFD,
    0xFFFD,0x2018,0x2019,0x201C,0x201D,0x2022,0x2013,0x2014,
    0x02Dc,0x2122,0x0161,0x203A,0x0153,0xFFFD,0x017E,0x0178
};

/* Optimized for charset Cp1252 */
static jstring
newStringCp1252(JNIEnv *env, const char *str)
{
    int len = (int) strlen(str);
    jchar buf[512] = {0};
    jchar *str1;
    jstring result;
    int i;

    if ((*env)->EnsureLocalCapacity(env, 1) < 0)
        return NULL;

    if (len > 512) {
        str1 = (jchar *)malloc(len * sizeof(jchar));
        if (str1 == 0) {
            JNU_ThrowOutOfMemoryError(env, 0);
            return 0;
        }
    } else
        str1 = buf;

    for (i=0; i<len; i++) {
        unsigned char c = (unsigned char)str[i];
        if ((c >= 0x80) && (c <= 0x9f))
            str1[i] = cp1252c1chars[c-128];
        else
            str1[i] = c;
    }

    result = (*env)->NewString(env, str1, len);
    if (str1 != buf)
        free(str1);
    return result;
}

static const char*
getStringCp1252Chars(JNIEnv *env, jstring jstr, jboolean strict)
{
    int i;
    char *result;
    jint len = (*env)->GetStringLength(env, jstr);
    const jchar *str = (*env)->GetStringCritical(env, jstr, 0);
    if (str == 0) {
        return 0;
    }

    result = MALLOC_MIN4(len);
    if (result == 0) {
        (*env)->ReleaseStringCritical(env, jstr, str);
        JNU_ThrowOutOfMemoryError(env, 0);
        return 0;
    }

    for (i=0; i<len; i++) {
        jchar c = str[i];
        if (strict && c == 0) {
            (*env)->ReleaseStringCritical(env, jstr, str);
            free(result);
            JNU_ThrowIllegalArgumentException(env,
                   "NUL character not allowed in platform string");
            return 0;
        }
        if (c < 256) {
            if ((c >= 0x80) && (c <= 0x9f)) {
                result[i] = '?';
            } else {
                result[i] = (char)c;
            }
        } else switch(c) {
            case 0x20AC: result[i] = (char)0x80; break;
            case 0x201A: result[i] = (char)0x82; break;
            case 0x0192: result[i] = (char)0x83; break;
            case 0x201E: result[i] = (char)0x84; break;
            case 0x2026: result[i] = (char)0x85; break;
            case 0x2020: result[i] = (char)0x86; break;
            case 0x2021: result[i] = (char)0x87; break;
            case 0x02C6: result[i] = (char)0x88; break;
            case 0x2030: result[i] = (char)0x89; break;
            case 0x0160: result[i] = (char)0x8A; break;
            case 0x2039: result[i] = (char)0x8B; break;
            case 0x0152: result[i] = (char)0x8C; break;
            case 0x017D: result[i] = (char)0x8E; break;
            case 0x2018: result[i] = (char)0x91; break;
            case 0x2019: result[i] = (char)0x92; break;
            case 0x201C: result[i] = (char)0x93; break;
            case 0x201D: result[i] = (char)0x94; break;
            case 0x2022: result[i] = (char)0x95; break;
            case 0x2013: result[i] = (char)0x96; break;
            case 0x2014: result[i] = (char)0x97; break;
            case 0x02DC: result[i] = (char)0x98; break;
            case 0x2122: result[i] = (char)0x99; break;
            case 0x0161: result[i] = (char)0x9A; break;
            case 0x203A: result[i] = (char)0x9B; break;
            case 0x0153: result[i] = (char)0x9C; break;
            case 0x017E: result[i] = (char)0x9E; break;
            case 0x0178: result[i] = (char)0x9F; break;
            default:     result[i] = '?';  break;
        }
    }

    result[len] = 0;
    (*env)->ReleaseStringCritical(env, jstr, str);
    return result;
}

static int fastEncoding = NO_ENCODING_YET;
static jobject jnuCharset = NULL;

/* Cached method IDs */
static jmethodID String_init_ID;        /* String(byte[], Charset) */
static jmethodID String_getBytes_ID;    /* String.getBytes(Charset) */

/* Cached field IDs */
static jfieldID String_coder_ID;        /* String.coder */
static jfieldID String_value_ID;        /* String.value */

/* Create a new string by converting str to a heap-allocated byte array and
 * calling the appropriate String constructor.
 */
static jstring
newSizedStringJava(JNIEnv *env, const char *str, const int len)
{
    jstring result = NULL;
    jbyteArray bytes = 0;

    if ((*env)->EnsureLocalCapacity(env, 2) < 0)
        return NULL;

    bytes = (*env)->NewByteArray(env, len);
    if (bytes != NULL) {
        jclass strClazz = JNU_ClassString(env);
        CHECK_NULL_RETURN(strClazz, 0);
        (*env)->SetByteArrayRegion(env, bytes, 0, len, (jbyte *)str);
        result = (*env)->NewObject(env, strClazz,
                                   String_init_ID, bytes, jnuCharset);
        (*env)->DeleteLocalRef(env, bytes);
        return result;
    }
    return NULL;
}

static jstring
newStringJava(JNIEnv *env, const char *str)
{
    int len = (int)strlen(str);
    return newSizedStringJava(env, str, len);
}

/* Optimized for charset UTF-8 */
static jstring
newStringUTF8(JNIEnv *env, const char *str)
{
    int len;
    const unsigned char *p;
    unsigned char asciiCheck;
    for (asciiCheck = 0, p = (const unsigned char*)str; *p != '\0'; p++) {
        asciiCheck |= *p;
    }
    len = (int)((const char*)p - str);

    if (asciiCheck < 0x80) {
        // ascii fast-path
        return newSizedString8859_1(env, str, len);
    }

    return newSizedStringJava(env, str, len);
}

/* Initialize the fast encoding from the encoding name.
 * Export InitializeEncoding so that the VM can initialize it if required.
 */
JNIEXPORT void
InitializeEncoding(JNIEnv *env, const char *encname)
{
    jclass strClazz = NULL;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        return;

    strClazz = JNU_ClassString(env);
    CHECK_NULL(strClazz);

    if (encname) {
        /*
         * On Solaris with nl_langinfo() called in GetJavaProperties():
         *
         *   locale undefined -> NULL -> hardcoded default
         *   "C" locale       -> "" -> hardcoded default     (on 2.6)
         *   "C" locale       -> "ISO646-US"                 (on Sol 7/8)
         *   "en_US" locale -> "ISO8859-1"
         *   "en_GB" locale -> "ISO8859-1"                   (on Sol 7/8)
         *   "en_UK" locale -> "ISO8859-1"                   (on 2.6)
         */
        const char *charsetname = NULL;
        if ((strcmp(encname, "8859_1") == 0) ||
            (strcmp(encname, "ISO8859-1") == 0) ||
            (strcmp(encname, "ISO8859_1") == 0) ||
            (strcmp(encname, "ISO-8859-1") == 0)) {
            fastEncoding = FAST_8859_1;
        } else if (strcmp(encname, "UTF-8") == 0) {
            charsetname = encname;
            fastEncoding = FAST_UTF_8;
        } else if (strcmp(encname, "ISO646-US") == 0) {
            fastEncoding = FAST_646_US;
        } else if (strcmp(encname, "Cp1252") == 0 ||
            /* This is a temporary fix until we move */
            /* to wide character versions of all Windows */
            /* calls. */
            strcmp(encname, "utf-16le") == 0) {
            fastEncoding = FAST_CP1252;
        } else {
            charsetname = encname;
            fastEncoding = NO_FAST_ENCODING;
        }
        while (charsetname != NULL) {
            jstring enc = (*env)->NewStringUTF(env, charsetname);
            if (enc == NULL) {
                fastEncoding = NO_ENCODING_YET;
                return;
            }
            jboolean exc;
            jvalue charset = JNU_CallStaticMethodByName(
                    env, &exc,
                    "java/nio/charset/Charset",
                    "forName",
                    "(Ljava/lang/String;)Ljava/nio/charset/Charset;",
                    enc);
            if (exc) {
                (*env)->ExceptionClear(env);
            }
            (*env)->DeleteLocalRef(env, enc);

            if (!exc && charset.l != NULL) {
                jnuCharset = (*env)->NewGlobalRef(env, charset.l);
                (*env)->DeleteLocalRef(env, charset.l);
                break; // success, continue below
            } else if (strcmp(charsetname, "UTF-8") != 0) { // fall back
                charsetname = "UTF-8";
                fastEncoding = FAST_UTF_8;
            } else { // give up
                fastEncoding = NO_ENCODING_YET;
                return;
            }
        }
    } else {
        JNU_ThrowInternalError(env, "platform encoding undefined");
        return;
    }

    /* Initialize method-id cache */
    String_getBytes_ID = (*env)->GetMethodID(env, strClazz,
                                             "getBytes", "(Ljava/nio/charset/Charset;)[B");
    CHECK_NULL(String_getBytes_ID);
    String_init_ID = (*env)->GetMethodID(env, strClazz,
                                         "<init>", "([BLjava/nio/charset/Charset;)V");
    CHECK_NULL(String_init_ID);
    String_coder_ID = (*env)->GetFieldID(env, strClazz, "coder", "B");
    CHECK_NULL(String_coder_ID);
    String_value_ID = (*env)->GetFieldID(env, strClazz, "value", "[B");
    CHECK_NULL(String_value_ID);
}

JNIEXPORT jstring JNICALL
JNU_NewStringPlatform(JNIEnv *env, const char *str)
{
    if (fastEncoding == FAST_UTF_8)
        return newStringUTF8(env, str);
    if (fastEncoding == FAST_8859_1)
        return newString8859_1(env, str);
    if (fastEncoding == FAST_646_US)
        return newString646_US(env, str);
    if (fastEncoding == FAST_CP1252)
        return newStringCp1252(env, str);
    if (fastEncoding == NO_ENCODING_YET) {
        JNU_ThrowInternalError(env, "platform encoding not initialized");
        return NULL;
    }
    return newStringJava(env, str);
}

static const char *
getStringPlatformChars0(JNIEnv *env, jstring jstr, jboolean *isCopy, jboolean);

JNIEXPORT const char *
GetStringPlatformChars(JNIEnv *env, jstring jstr, jboolean *isCopy)
{
    return getStringPlatformChars0(env, jstr, isCopy, JNI_FALSE);
}

JNIEXPORT const char *
GetStringPlatformCharsStrict(JNIEnv *env, jstring jstr, jboolean *isCopy)
{
    return getStringPlatformChars0(env, jstr, isCopy, JNI_TRUE);
}

static const char* getStringBytes(JNIEnv *env, jstring jstr, jboolean strict) {
    char *result = NULL;
    jbyteArray hab = 0;

    if ((*env)->EnsureLocalCapacity(env, 2) < 0)
        return 0;

    hab = (*env)->CallObjectMethod(env, jstr, String_getBytes_ID, jnuCharset);
    if (hab != 0) {
        if (!(*env)->ExceptionCheck(env)) {
            jint len = (*env)->GetArrayLength(env, hab);
            result = MALLOC_MIN4(len);
            if (result == 0) {
                JNU_ThrowOutOfMemoryError(env, 0);
                (*env)->DeleteLocalRef(env, hab);
                return 0;
            }
            (*env)->GetByteArrayRegion(env, hab, 0, len, (jbyte *)result);
            result[len] = 0; /* NULL-terminate */
            if (strict) {
                for (int i=0; i<len; i++) {
                    if (result[i] == 0) {
                        JNU_ThrowIllegalArgumentException(env,
                            "NUL character not allowed in platform string");
                        free(result);
                        result = 0;
                        break;
                    }
                }
            }
        }
        (*env)->DeleteLocalRef(env, hab);
    }
    return result;
}

static const char*
getStringUTF8(JNIEnv *env, jstring jstr, jboolean strict)
{
    int i;
    char *result;
    jbyteArray value;
    jint len;
    jbyte *str;
    jint rlen;
    int ri;
    jbyte coder = (*env)->GetByteField(env, jstr, String_coder_ID);
    if (coder != java_lang_String_LATIN1) {
        return getStringBytes(env, jstr, strict);
    }
    if ((*env)->EnsureLocalCapacity(env, 2) < 0) {
        return NULL;
    }
    value = (*env)->GetObjectField(env, jstr, String_value_ID);
    if (value == NULL)
        return NULL;
    len = (*env)->GetArrayLength(env, value);
    str = (*env)->GetPrimitiveArrayCritical(env, value, NULL);
    if (str == NULL) {
        return NULL;
    }

    rlen = len;
    // we need two bytes for each latin-1 char above 127 (negative jbytes)
    for (i = 0; i < len; i++) {
        if (strict && str[i] == 0) {
            (*env)->ReleasePrimitiveArrayCritical(env, value, str, JNI_ABORT);
            JNU_ThrowIllegalArgumentException(env, "NUL character not allowed in platform string");
            return NULL;
        }
        if (str[i] < 0) {
            rlen++;
        }
    }

    result = MALLOC_MIN4(rlen);
    if (result == NULL) {
        (*env)->ReleasePrimitiveArrayCritical(env, value, str, JNI_ABORT);
        JNU_ThrowOutOfMemoryError(env, "requested array size exceeds VM limit");
        return NULL;
    }

    for (ri = 0, i = 0; i < len; i++) {
        jbyte c = str[i];
        if (c < 0) {
            result[ri++] = (char)(0xc0 | ((c & 0xff) >> 6));
            result[ri++] = (char)(0x80 | (c & 0x3f));
        } else {
            result[ri++] = c;
        }
    }
    (*env)->ReleasePrimitiveArrayCritical(env, value, str, JNI_ABORT);
    result[rlen] = '\0';
    return result;
}

JNIEXPORT const char * JNICALL
JNU_GetStringPlatformChars(JNIEnv *env, jstring jstr, jboolean *isCopy)
{
    return getStringPlatformChars0(env, jstr, isCopy, JNI_FALSE);
}

JNIEXPORT const char * JNICALL
JNU_GetStringPlatformCharsStrict(JNIEnv *env, jstring jstr, jboolean *isCopy)
{
    return getStringPlatformChars0(env, jstr, isCopy, JNI_TRUE);
}

static const char *
getStringPlatformChars0(JNIEnv *env, jstring jstr, jboolean *isCopy, jboolean strict)
{

    if (isCopy)
        *isCopy = JNI_TRUE;

    if (fastEncoding == FAST_UTF_8)
        return getStringUTF8(env, jstr, strict);
    if (fastEncoding == FAST_8859_1)
        return getString8859_1Chars(env, jstr, strict);
    if (fastEncoding == FAST_646_US)
        return getString646_USChars(env, jstr, strict);
    if (fastEncoding == FAST_CP1252)
        return getStringCp1252Chars(env, jstr, strict);
    if (fastEncoding == NO_ENCODING_YET) {
        JNU_ThrowInternalError(env, "platform encoding not initialized");
        return 0;
    } else
        return getStringBytes(env, jstr, strict);
}

JNIEXPORT void JNICALL
JNU_ReleaseStringPlatformChars(JNIEnv *env, jstring jstr, const char *str)
{
    free((void *)str);
}

JNIEXPORT jclass JNICALL
JNU_ClassString(JNIEnv *env)
{
    static jclass cls = 0;
    if (cls == 0) {
        jclass c;
        if ((*env)->EnsureLocalCapacity(env, 1) < 0)
            return 0;
        c = (*env)->FindClass(env, "java/lang/String");
        CHECK_NULL_RETURN(c, NULL);
        cls = (*env)->NewGlobalRef(env, c);
        (*env)->DeleteLocalRef(env, c);
    }
    return cls;
}

JNIEXPORT jint JNICALL
JNU_CopyObjectArray(JNIEnv *env, jobjectArray dst, jobjectArray src,
                         jint count)
{
    int i;
    if ((*env)->EnsureLocalCapacity(env, 1) < 0)
        return -1;
    for (i=0; i<count; i++) {
        jstring p = (*env)->GetObjectArrayElement(env, src, i);
        (*env)->SetObjectArrayElement(env, dst, i, p);
        (*env)->DeleteLocalRef(env, p);
    }
    return 0;
}

JNIEXPORT void * JNICALL
JNU_GetEnv(JavaVM *vm, jint version)
{
    void *env;
    (*vm)->GetEnv(vm, &env, version);
    return env;
}

JNIEXPORT jint JNICALL
JNU_IsInstanceOfByName(JNIEnv *env, jobject object, const char* classname)
{
    jclass cls;
    if ((*env)->EnsureLocalCapacity(env, 1) < 0)
        return JNI_ERR;
    cls = (*env)->FindClass(env, classname);
    if (cls != NULL) {
        jint result = (*env)->IsInstanceOf(env, object, cls);
        (*env)->DeleteLocalRef(env, cls);
        return result;
    }
    return JNI_ERR;
}

/************************************************************************
 * Debugging utilities
 */

JNIEXPORT jstring JNICALL
JNU_ToString(JNIEnv *env, jobject object)
{
    if (object == NULL) {
        return (*env)->NewStringUTF(env, "NULL");
    } else {
        return (jstring)JNU_CallMethodByName(env,
                                             NULL,
                                             object,
                                             "toString",
                                             "()Ljava/lang/String;").l;
    }
}

JNIEXPORT jvalue JNICALL
JNU_GetFieldByName(JNIEnv *env,
                   jboolean *hasException,
                   jobject obj,
                   const char *name,
                   const char *signature)
{
    jclass cls;
    jfieldID fid;
    jvalue result;

    result.i = 0;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        goto done2;

    cls = (*env)->GetObjectClass(env, obj);
    fid = (*env)->GetFieldID(env, cls, name, signature);
    if (fid == 0)
        goto done1;

    switch (*signature) {
    case '[':
    case 'L':
        result.l = (*env)->GetObjectField(env, obj, fid);
        break;
    case 'Z':
        result.z = (*env)->GetBooleanField(env, obj, fid);
        break;
    case 'B':
        result.b = (*env)->GetByteField(env, obj, fid);
        break;
    case 'C':
        result.c = (*env)->GetCharField(env, obj, fid);
        break;
    case 'S':
        result.s = (*env)->GetShortField(env, obj, fid);
        break;
    case 'I':
        result.i = (*env)->GetIntField(env, obj, fid);
        break;
    case 'J':
        result.j = (*env)->GetLongField(env, obj, fid);
        break;
    case 'F':
        result.f = (*env)->GetFloatField(env, obj, fid);
        break;
    case 'D':
        result.d = (*env)->GetDoubleField(env, obj, fid);
        break;

    default:
        (*env)->FatalError(env, "JNU_GetFieldByName: illegal signature");
    }

 done1:
    (*env)->DeleteLocalRef(env, cls);
 done2:
    if (hasException) {
        *hasException = (*env)->ExceptionCheck(env);
    }
    return result;
}

JNIEXPORT void JNICALL
JNU_SetFieldByName(JNIEnv *env,
                   jboolean *hasException,
                   jobject obj,
                   const char *name,
                   const char *signature,
                   ...)
{
    jclass cls;
    jfieldID fid;
    va_list args;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        goto done2;

    cls = (*env)->GetObjectClass(env, obj);
    fid = (*env)->GetFieldID(env, cls, name, signature);
    if (fid == 0)
        goto done1;

    va_start(args, signature);
    switch (*signature) {
    case '[':
    case 'L':
        (*env)->SetObjectField(env, obj, fid, va_arg(args, jobject));
        break;
    case 'Z':
        (*env)->SetBooleanField(env, obj, fid, (jboolean)va_arg(args, int));
        break;
    case 'B':
        (*env)->SetByteField(env, obj, fid, (jbyte)va_arg(args, int));
        break;
    case 'C':
        (*env)->SetCharField(env, obj, fid, (jchar)va_arg(args, int));
        break;
    case 'S':
        (*env)->SetShortField(env, obj, fid, (jshort)va_arg(args, int));
        break;
    case 'I':
        (*env)->SetIntField(env, obj, fid, va_arg(args, jint));
        break;
    case 'J':
        (*env)->SetLongField(env, obj, fid, va_arg(args, jlong));
        break;
    case 'F':
        (*env)->SetFloatField(env, obj, fid, (jfloat)va_arg(args, jdouble));
        break;
    case 'D':
        (*env)->SetDoubleField(env, obj, fid, va_arg(args, jdouble));
        break;

    default:
        (*env)->FatalError(env, "JNU_SetFieldByName: illegal signature");
    }
    va_end(args);

 done1:
    (*env)->DeleteLocalRef(env, cls);
 done2:
    if (hasException) {
        *hasException = (*env)->ExceptionCheck(env);
    }
}

JNIEXPORT jvalue JNICALL
JNU_GetStaticFieldByName(JNIEnv *env,
                         jboolean *hasException,
                         const char *classname,
                         const char *name,
                         const char *signature)
{
    jclass cls;
    jfieldID fid;
    jvalue result;

    result.i = 0;

    if ((*env)->EnsureLocalCapacity(env, 3) < 0)
        goto done2;

    cls = (*env)->FindClass(env, classname);
    if (cls == 0)
        goto done2;

    fid = (*env)->GetStaticFieldID(env, cls, name, signature);
    if (fid == 0)
        goto done1;

    switch (*signature) {
    case '[':
    case 'L':
        result.l = (*env)->GetStaticObjectField(env, cls, fid);
        break;
    case 'Z':
        result.z = (*env)->GetStaticBooleanField(env, cls, fid);
        break;
    case 'B':
        result.b = (*env)->GetStaticByteField(env, cls, fid);
        break;
    case 'C':
        result.c = (*env)->GetStaticCharField(env, cls, fid);
        break;
    case 'S':
        result.s = (*env)->GetStaticShortField(env, cls, fid);
        break;
    case 'I':
        result.i = (*env)->GetStaticIntField(env, cls, fid);
        break;
    case 'J':
        result.j = (*env)->GetStaticLongField(env, cls, fid);
        break;
    case 'F':
        result.f = (*env)->GetStaticFloatField(env, cls, fid);
        break;
    case 'D':
        result.d = (*env)->GetStaticDoubleField(env, cls, fid);
        break;

    default:
        (*env)->FatalError(env, "JNU_GetStaticFieldByName: illegal signature");
    }

 done1:
    (*env)->DeleteLocalRef(env, cls);
 done2:
    if (hasException) {
        *hasException = (*env)->ExceptionCheck(env);
    }
    return result;
}