179         StringDecoder sd = deref(decoder);
 180         String csn = (charsetName == null) ? "ISO-8859-1" : charsetName;
 181         if ((sd == null) || !(csn.equals(sd.requestedCharsetName())
 182                               || csn.equals(sd.charsetName()))) {
 183             sd = null;
 184             try {
 185                 Charset cs = lookupCharset(csn);
 186                 if (cs != null)
 187                     sd = new StringDecoder(cs, csn);
 188             } catch (IllegalCharsetNameException x) {}
 189             if (sd == null)
 190                 throw new UnsupportedEncodingException(csn);
 191             set(decoder, sd);
 192         }
 193         return sd.decode(ba, off, len);
 194     }
 195 
 196     static char[] decode(Charset cs, byte[] ba, int off, int len) {
 197         // (1)We never cache the "external" cs, the only benefit of creating
 198         // an additional StringDe/Encoder object to wrap it is to share the
 199         // de/encode() method. These SD/E objects are short-lifed, the young-gen
 200         // gc should be able to take care of them well. But the best approash
 201         // is still not to generate them if not really necessary.
 202         // (2)The defensive copy of the input byte/char[] has a big performance
 203         // impact, as well as the outgoing result byte/char[]. Need to do the
 204         // optimization check of (sm==null && classLoader0==null) for both.
 205         // (3)getClass().getClassLoader0() is expensive
 206         // (4)There might be a timing gap in isTrusted setting. getClassLoader0()
 207         // is only chcked (and then isTrusted gets set) when (SM==null). It is
 208         // possible that the SM==null for now but then SM is NOT null later
 209         // when safeTrim() is invoked...the "safe" way to do is to redundant
 210         // check (... && (isTrusted || SM == null || getClassLoader0())) in trim
 211         // but it then can be argued that the SM is null when the opertaion
 212         // is started...
 213         CharsetDecoder cd = cs.newDecoder();
 214         int en = scale(len, cd.maxCharsPerByte());
 215         char[] ca = new char[en];
 216         if (len == 0)
 217             return ca;
 218         boolean isTrusted = false;
 219         if (System.getSecurityManager() != null) {
 220             if (!(isTrusted = (cs.getClass().getClassLoader0() == null))) {
 221                 ba =  Arrays.copyOfRange(ba, off, off + len);
 222                 off = 0;
 223             }
 224         }
 225         cd.onMalformedInput(CodingErrorAction.REPLACE)
 226           .onUnmappableCharacter(CodingErrorAction.REPLACE)
 227           .reset();
 228         if (cd instanceof ArrayDecoder) {
 229             int clen = ((ArrayDecoder)cd).decode(ba, off, len, ca);
 230             return safeTrim(ca, clen, cs, isTrusted);
 231         } else {

 179         StringDecoder sd = deref(decoder);
 180         String csn = (charsetName == null) ? "ISO-8859-1" : charsetName;
 181         if ((sd == null) || !(csn.equals(sd.requestedCharsetName())
 182                               || csn.equals(sd.charsetName()))) {
 183             sd = null;
 184             try {
 185                 Charset cs = lookupCharset(csn);
 186                 if (cs != null)
 187                     sd = new StringDecoder(cs, csn);
 188             } catch (IllegalCharsetNameException x) {}
 189             if (sd == null)
 190                 throw new UnsupportedEncodingException(csn);
 191             set(decoder, sd);
 192         }
 193         return sd.decode(ba, off, len);
 194     }
 195 
 196     static char[] decode(Charset cs, byte[] ba, int off, int len) {
 197         // (1)We never cache the "external" cs, the only benefit of creating
 198         // an additional StringDe/Encoder object to wrap it is to share the
 199         // de/encode() method. These SD/E objects are short-lived, the young-gen
 200         // gc should be able to take care of them well. But the best approach
 201         // is still not to generate them if not really necessary.
 202         // (2)The defensive copy of the input byte/char[] has a big performance
 203         // impact, as well as the outgoing result byte/char[]. Need to do the
 204         // optimization check of (sm==null && classLoader0==null) for both.
 205         // (3)getClass().getClassLoader0() is expensive
 206         // (4)There might be a timing gap in isTrusted setting. getClassLoader0()
 207         // is only checked (and then isTrusted gets set) when (SM==null). It is
 208         // possible that the SM==null for now but then SM is NOT null later
 209         // when safeTrim() is invoked...the "safe" way to do is to redundant
 210         // check (... && (isTrusted || SM == null || getClassLoader0())) in trim
 211         // but it then can be argued that the SM is null when the operation
 212         // is started...
 213         CharsetDecoder cd = cs.newDecoder();
 214         int en = scale(len, cd.maxCharsPerByte());
 215         char[] ca = new char[en];
 216         if (len == 0)
 217             return ca;
 218         boolean isTrusted = false;
 219         if (System.getSecurityManager() != null) {
 220             if (!(isTrusted = (cs.getClass().getClassLoader0() == null))) {
 221                 ba =  Arrays.copyOfRange(ba, off, off + len);
 222                 off = 0;
 223             }
 224         }
 225         cd.onMalformedInput(CodingErrorAction.REPLACE)
 226           .onUnmappableCharacter(CodingErrorAction.REPLACE)
 227           .reset();
 228         if (cd instanceof ArrayDecoder) {
 229             int clen = ((ArrayDecoder)cd).decode(ba, off, len, ca);
 230             return safeTrim(ca, clen, cs, isTrusted);
 231         } else {