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package com.sun.mail.util;
import java.io.*;
import java.nio.charset.
StandardCharsets;
/**
* This class is to support reading CRLF terminated lines that
* contain only US-ASCII characters from an input stream. Provides
* functionality that is similar to the deprecated
* <code>DataInputStream.readLine()</code>. Expected use is to read
* lines as String objects from a RFC822 stream.
*
* It is implemented as a FilterInputStream, so one can just wrap
* this class around any input stream and read bytes from this filter.
*
* @author John Mani
* @author Bill Shannon
*/
public class
LineInputStream extends
FilterInputStream {
private boolean
allowutf8;
private byte[]
lineBuffer = null; // reusable byte buffer
private static int
MAX_INCR = 1024*1024; // 1MB
public
LineInputStream(
InputStream in) {
this(
in, false);
}
/**
* @param in the InputStream
* @param allowutf8 allow UTF-8 characters?
* @since JavaMail 1.6
*/
public
LineInputStream(
InputStream in, boolean
allowutf8) {
super(
in);
this.
allowutf8 =
allowutf8;
}
/**
* Read a line containing only ASCII characters from the input
* stream. A line is terminated by a CR or NL or CR-NL sequence.
* A common error is a CR-CR-NL sequence, which will also terminate
* a line.
* The line terminator is not returned as part of the returned
* String. Returns null if no data is available. <p>
*
* This class is similar to the deprecated
* <code>DataInputStream.readLine()</code>
*
* @return the line
* @exception IOException for I/O errors
*/
@
SuppressWarnings("deprecation") // for old String constructor
public
String readLine() throws
IOException {
//InputStream in = this.in;
byte[]
buf =
lineBuffer;
if (
buf == null)
buf =
lineBuffer = new byte[128];
int
c1;
int
room =
buf.length;
int
offset = 0;
while ((
c1 =
in.
read()) != -1) {
if (
c1 == '\n') // Got NL, outa here.
break;
else if (
c1 == '\r') {
// Got CR, is the next char NL ?
boolean
twoCRs = false;
if (
in.
markSupported())
in.
mark(2);
int
c2 =
in.
read();
if (
c2 == '\r') { // discard extraneous CR
twoCRs = true;
c2 =
in.
read();
}
if (
c2 != '\n') {
/*
* If the stream supports it (which we hope will always
* be the case), reset to after the first CR. Otherwise,
* we wrap a PushbackInputStream around the stream so we
* can unread the characters we don't need. The only
* problem with that is that the caller might stop
* reading from this LineInputStream, throw it away,
* and then start reading from the underlying stream.
* If that happens, the pushed back characters will be
* lost forever.
*/
if (
in.
markSupported())
in.
reset();
else {
if (!(
in instanceof
PushbackInputStream))
in /*= this.in*/ = new
PushbackInputStream(
in, 2);
if (
c2 != -1)
((
PushbackInputStream)
in).
unread(
c2);
if (
twoCRs)
((
PushbackInputStream)
in).
unread('\r');
}
}
break; // outa here.
}
// Not CR, NL or CR-NL ...
// .. Insert the byte into our byte buffer
if (--
room < 0) { // No room, need to grow.
if (
buf.length <
MAX_INCR)
buf = new byte[
buf.length * 2];
else
buf = new byte[
buf.length +
MAX_INCR];
room =
buf.length -
offset - 1;
System.
arraycopy(
lineBuffer, 0,
buf, 0,
offset);
lineBuffer =
buf;
}
buf[
offset++] = (byte)
c1;
}
if ((
c1 == -1) && (
offset == 0))
return null;
if (
allowutf8)
return new
String(
buf, 0,
offset,
StandardCharsets.
UTF_8);
else
return new
String(
buf, 0, 0,
offset);
}
}