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9  * by Oracle in the LICENSE file that accompanied this code.
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11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
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24  */
25 
26 package com.sun.xml.internal.messaging.saaj.util;
27 
28 import java.io.*;
29 
30 import javax.xml.transform.TransformerException;
31 
32 /*
33  * Class that parses the very first construct in the document i.e.
34  *  <?xml ... ?>
35  *
36  * @author Panos Kougiouris (panos@acm.org)
37  * @version
38  */
39 
40 public class XMLDeclarationParser {
41     private String m_encoding;
42     private PushbackReader m_pushbackReader;
43     private boolean m_hasHeader; // preserve the case where no XML Header exists
44     private String xmlDecl = null;
45     static String gt16 = null;
46     static String utf16Decl = null;
47     static {
48          try {
49              gt16 = new String(">".getBytes("utf-16"));
50              utf16Decl = new String("<?xml".getBytes("utf-16"));
51          } catch (Exception e) {}
52     }
53 
54     //---------------------------------------------------------------------
55 
XMLDeclarationParser(PushbackReader pr)56     public XMLDeclarationParser(PushbackReader pr)
57     {
58         m_pushbackReader = pr;
59         m_encoding = "utf-8";
60         m_hasHeader = false;
61     }
62 
63     //---------------------------------------------------------------------
getEncoding()64     public String getEncoding()
65     {
66         return m_encoding;
67     }
68 
getXmlDeclaration()69     public String getXmlDeclaration() {
70         return xmlDecl;
71     }
72 
73     //---------------------------------------------------------------------
74 
parse()75      public void parse()  throws TransformerException, IOException
76      {
77         int c = 0;
78         int index = 0;
79         char[] aChar = new char[65535];
80         StringBuffer xmlDeclStr = new StringBuffer();
81         while ((c = m_pushbackReader.read()) != -1) {
82             aChar[index] = (char)c;
83             xmlDeclStr.append((char)c);
84             index++;
85             if (c == '>') {
86                 break;
87             }
88         }
89         int len = index;
90 
91         String decl = xmlDeclStr.toString();
92         boolean utf16 = false;
93         boolean utf8 = false;
94 
95         int xmlIndex = decl.indexOf(utf16Decl);
96         if (xmlIndex > -1) {
97             utf16 = true;
98         } else {
99             xmlIndex = decl.indexOf("<?xml");
100             if (xmlIndex > -1) {
101                 utf8 = true;
102             }
103         }
104 
105         // no XML decl
106         if (!utf16 && !utf8) {
107             m_pushbackReader.unread(aChar, 0, len);
108             return;
109         }
110         m_hasHeader = true;
111 
112         if (utf16) {
113             xmlDecl = new String(decl.getBytes(), "utf-16");
114             xmlDecl = xmlDecl.substring(xmlDecl.indexOf("<"));
115         } else {
116             xmlDecl = decl;
117         }
118         // do we want to check that there are no other characters preceeding <?xml
119         if (xmlIndex != 0) {
120             throw new IOException("Unexpected characters before XML declaration");
121         }
122 
123         int versionIndex =  xmlDecl.indexOf("version");
124         if (versionIndex == -1) {
125             throw new IOException("Mandatory 'version' attribute Missing in XML declaration");
126         }
127 
128         // now set
129         int encodingIndex = xmlDecl.indexOf("encoding");
130         if (encodingIndex == -1) {
131             return;
132         }
133 
134         if (versionIndex > encodingIndex) {
135             throw new IOException("The 'version' attribute should preceed the 'encoding' attribute in an XML Declaration");
136         }
137 
138         int stdAloneIndex = xmlDecl.indexOf("standalone");
139         if ((stdAloneIndex > -1) && ((stdAloneIndex < versionIndex) || (stdAloneIndex < encodingIndex))) {
140             throw new IOException("The 'standalone' attribute should be the last attribute in an XML Declaration");
141         }
142 
143         int eqIndex = xmlDecl.indexOf("=", encodingIndex);
144         if (eqIndex == -1) {
145             throw new IOException("Missing '=' character after 'encoding' in XML declaration");
146         }
147 
148         m_encoding = parseEncoding(xmlDecl, eqIndex);
149         if(m_encoding.startsWith("\"")){
150             m_encoding = m_encoding.substring(m_encoding.indexOf("\"")+1, m_encoding.lastIndexOf("\""));
151         } else if(m_encoding.startsWith("\'")){
152             m_encoding = m_encoding.substring(m_encoding.indexOf("\'")+1, m_encoding.lastIndexOf("\'"));
153         }
154      }
155 
156      //--------------------------------------------------------------------
157 
writeTo(Writer wr)158     public void writeTo(Writer wr) throws IOException {
159         if (!m_hasHeader) return;
160         wr.write(xmlDecl.toString());
161     }
162 
parseEncoding(String xmlDeclFinal, int eqIndex)163     private String parseEncoding(String xmlDeclFinal, int eqIndex) throws IOException {
164         java.util.StringTokenizer strTok = new java.util.StringTokenizer(
165             xmlDeclFinal.substring(eqIndex + 1));
166         if (strTok.hasMoreTokens()) {
167             String encodingTok = strTok.nextToken();
168             int indexofQ = encodingTok.indexOf("?");
169             if (indexofQ > -1) {
170                 return encodingTok.substring(0,indexofQ);
171             } else {
172                 return encodingTok;
173             }
174         } else {
175             throw new IOException("Error parsing 'encoding' attribute in XML declaration");
176         }
177     }
178 
179 }
180