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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.query;
import net.sf.saxon.functions.UnparsedTextFunction;
import net.sf.saxon.resource.ResourceLoader;
import net.sf.saxon.str.UnicodeString;
import net.sf.saxon.trans.Err;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.transpile.CSharpReplaceBody;
import net.sf.saxon.value.Whitespace;
import net.sf.saxon.z.IntPredicateProxy;
import javax.xml.transform.stream.StreamSource;
import java.io.*;
import java.net.URL;
/**
* This class contains static methods used to read a query as a byte stream, infer the encoding if
* necessary, and return the text of the query as a string; also methods to import functions and variables
* from one module into another, and check their consistency.
*/
public class QueryReader {
/**
* The class is never instantiated
*/
private QueryReader() {
}
/**
* Read a query module given a StreamSource
*
* @param ss the supplied StreamSource. This must contain a non-null systemID which defines the base
* URI of the query module, and either an InputStream or a Reader containing the query text. In the
* case of an InputStream the method attempts to infer the encoding; in the case of a Reader, this has
* already been done, and the encoding specified within the query itself is ignored.
* The method reads from the InputStream or Reader contained in the StreamSource up to the end
* of file unless a fatal error occurs. It does not close the InputStream or Reader; this is the caller's
* responsibility.
* @param charChecker this checks XML characters against either the XML 1.0 or XML 1.1 rules
* @return the text of the query
* @throws XPathException if the input cannot be read
*/
public static String readSourceQuery(/*@NotNull*/ StreamSource ss, IntPredicateProxy charChecker) throws XPathException {
CharSequence queryText;
if (ss.getInputStream() != null) {
InputStream is = ss.getInputStream();
is = InputStreamMarker.ensureMarkSupported(is);
String encoding = readEncoding(is);
queryText = readInputStream(is, encoding, charChecker);
} else if (ss.getReader() != null) {
queryText = readQueryFromReader(ss.getReader(), charChecker);
} else if (ss.getSystemId() != null) {
try {
URL url = new URL(ss.getSystemId());
InputStream stream = ResourceLoader.urlStream(url);
stream = InputStreamMarker.ensureMarkSupported(stream);
String encoding = readEncoding(stream);
queryText = readInputStream(stream, encoding, charChecker);
} catch (IOException e) {
throw new XPathException("I/O Error reading input stream from " + ss.getSystemId(), e);
}
} else {
throw new XPathException("Module URI Resolver must supply either an InputStream or a Reader");
}
return queryText.toString();
}
/**
* Read an input stream non-destructively to determine the encoding from the Query Prolog
*
* @param is the input stream: this must satisfy the precondition is.markSupported() = true.
* @return the encoding to be used: defaults to UTF-8 if no encoding was specified explicitly
* in the query prolog
* @throws XPathException if the input stream cannot be read
*/
public static String readEncoding(/*@NotNull*/ InputStream is) throws XPathException {
try {
InputStreamMarker marker = new InputStreamMarker(is);
if (!marker.isMarkSupported()) {
throw new IllegalArgumentException("InputStream must have markSupported() = true");
}
marker.mark(100);
byte[] start = new byte[100];
int read = is.read(start, 0, 100);
if (read == -1) {
throw new XPathException("Query source file is empty");
}
marker.reset();
return inferEncoding(start, read);
} catch (IOException e) {
throw new XPathException("Failed to read query source file", e);
}
}
/**
* Read a query from an InputStream. The method checks that all characters are valid XML
* characters, and also performs normalization of line endings.
*
* @param is the input stream
* @param encoding the encoding, or null if the encoding is unknown
* @param nameChecker the predicate to be used for checking characters
* @return the content of the InputStream as a string
* @throws XPathException if the stream cannot be read, for example if there is a problem with the encoding
*/
public static String readInputStream(InputStream is, String encoding, IntPredicateProxy nameChecker) throws XPathException {
if (encoding == null) {
is = InputStreamMarker.ensureMarkSupported(is);
encoding = readEncoding(is);
}
try {
Reader reader = new BufferedReader(new InputStreamReader(is, encoding));
return readQueryFromReader(reader, nameChecker);
} catch (UnsupportedEncodingException encErr) {
XPathException err = new XPathException("Unknown encoding " + Err.wrap(encoding), encErr);
err.setErrorCode("XQST0087");
throw err;
}
}
/**
* Read a query from a Reader. The method checks that all characters are valid XML
* characters.
*
* @param reader The Reader supplying the input
* @param charChecker used to check characters are valid XML characters
* @return the text of the query module, as a string
* @throws XPathException if the file cannot be read or contains illegal characters
*/
private static String readQueryFromReader(Reader reader, IntPredicateProxy charChecker) throws XPathException {
try {
UnicodeString content = UnparsedTextFunction.readFile(charChecker, reader);
return content.toString();
} catch (XPathException err) {
err.setErrorCode("XPST0003");
err.setIsStaticError(true);
throw err;
} catch (IOException ioErr) {
throw new XPathException("Failed to read supplied query file", ioErr);
}
}
/**
* Attempt to infer the encoding of a file by reading its byte order mark and if necessary
* the encoding declaration in the query prolog
*
* @param start the bytes appearing at the start of the file
* @param read the number of bytes supplied
* @return the inferred encoding
* @throws XPathException if, for example, an explicit encoding is specified but it is unsupported
*/
private static String inferEncoding(byte[] start, int read) throws XPathException {
// Debugging code
// StringBuffer sb = new StringBuffer(read*5);
// for (int i=0; i= 2) {
if (ch(start[0]) == 0xFE && ch(start[1]) == 0xFF) {
return "UTF-16";
} else if (ch(start[0]) == 0xFF && ch(start[1]) == 0xFE) {
return "UTF-16LE";
}
}
if (read >= 3) {
if (ch(start[0]) == 0xEF && ch(start[1]) == 0xBB && ch(start[2]) == 0xBF) {
return "UTF-8";
}
}
// Try to handle a UTF-16 file with no BOM
if (read >= 8 && start[0] == 0 && start[2] == 0 && start[4] == 0 && start[6] == 0) {
return "UTF-16";
}
if (read >= 8 && start[1] == 0 && start[3] == 0 && start[5] == 0 && start[7] == 0) {
return "UTF-16LE";
}
// In all other cases, we assume an encoding that has ISO646 as a subset
// Note, we don't care about syntax errors here: they'll be reported later. We just need to
// establish the encoding.
int i = 0;
String tok = readToken(start, i, read);
if (Whitespace.trim(tok).equals("xquery")) {
i += tok.length();
} else {
return "UTF-8";
}
tok = readToken(start, i, read);
if (Whitespace.trim(tok).equals("encoding")) {
// "version" can be omitted in XQuery 3.0
i += tok.length();
} else {
if (Whitespace.trim(tok).equals("version")) {
i += tok.length();
} else {
return "UTF-8";
}
tok = readToken(start, i, read);
i += tok.length();
tok = readToken(start, i, read);
if (Whitespace.trim(tok).equals("encoding")) {
i += tok.length();
} else {
return "UTF-8";
}
}
tok = Whitespace.trim(readToken(start, i, read));
if (tok.startsWith("\"") && tok.endsWith("\"") && tok.length() > 2) {
return tok.substring(1, tok.length() - 1);
} else if (tok.startsWith("'") && tok.endsWith("'") && tok.length() > 2) {
return tok.substring(1, tok.length() - 1);
} else {
throw new XPathException("Unrecognized encoding " + Err.wrap(tok) + " in query prolog");
}
}
/**
* Simple tokenizer for use when reading the encoding declaration in the query prolog. A token
* is a sequence of characters delimited either by whitespace, or by single or double quotes; the
* quotes if present are returned as part of the token.
*
* @param in the raw content buffer, whose encoding is at this point unknown
* @param i offset where to start reading
* @param len the length of buffer
* @return the next token
*/
private static String readToken(byte[] in, int i, int len) {
int p = i;
while (p < len && " \n\r\t".indexOf(ch(in[p])) >= 0) {
p++;
}
if (ch(in[p]) == '"') {
p++;
while (p < len && ch(in[p]) != '"') {
p++;
}
} else if (ch(in[p]) == '\'') {
p++;
while (p < len && ch(in[p]) != '\'') {
p++;
}
} else {
while (p < len && " \n\r\t".indexOf(ch(in[p])) < 0) {
p++;
}
}
if (p >= len) {
return fromAsciiByteArray(in, i, len - i);
}
StringBuilder sb = new StringBuilder(p - i + 1);
for (int c = i; c <= p; c++) {
sb.append((char) ch(in[c]));
}
return sb.toString();
}
/**
* Form a string from an ascii byte array
* @param bytes the byte array
* @param start offset of the first byte to be included
* @param length the number of bytes to be included
*/
@CSharpReplaceBody(code="return System.Text.Encoding.ASCII.GetString(bytes, start, length);")
private static String fromAsciiByteArray(byte[] bytes, int start, int length) {
return new String(bytes, start, length);
}
/**
* Convert a byte containing an ASCII character to that character
*
* @param b the input byte
* @return the ASCII character
*/
private static char ch(byte b) {
return (char)(b & 0xff);
}
}