345 lines
16 KiB
C#
345 lines
16 KiB
C#
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// ==++==
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// ==--==
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namespace System.Text
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{
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using System.Runtime.Serialization;
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using System.Text;
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using System;
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using System.Diagnostics.Contracts;
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// An Encoder is used to encode a sequence of blocks of characters into
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// a sequence of blocks of bytes. Following instantiation of an encoder,
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// sequential blocks of characters are converted into blocks of bytes through
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// calls to the GetBytes method. The encoder maintains state between the
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// conversions, allowing it to correctly encode character sequences that span
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// adjacent blocks.
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//
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// Instances of specific implementations of the Encoder abstract base
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// class are typically obtained through calls to the GetEncoder method
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// of Encoding objects.
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//
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[System.Runtime.InteropServices.ComVisible(true)]
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[Serializable]
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public abstract class Encoder
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{
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internal EncoderFallback m_fallback = null;
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[NonSerialized]
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internal EncoderFallbackBuffer m_fallbackBuffer = null;
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internal void SerializeEncoder(SerializationInfo info)
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{
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info.AddValue("m_fallback", this.m_fallback);
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}
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protected Encoder()
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{
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// We don't call default reset because default reset probably isn't good if we aren't initialized.
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}
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[System.Runtime.InteropServices.ComVisible(false)]
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public EncoderFallback Fallback
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{
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get
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{
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return m_fallback;
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}
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set
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{
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if (value == null)
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throw new ArgumentNullException("value");
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Contract.EndContractBlock();
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// Can't change fallback if buffer is wrong
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if (m_fallbackBuffer != null && m_fallbackBuffer.Remaining > 0)
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throw new ArgumentException(
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Environment.GetResourceString("Argument_FallbackBufferNotEmpty"), "value");
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m_fallback = value;
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m_fallbackBuffer = null;
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}
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}
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// Note: we don't test for threading here because async access to Encoders and Decoders
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// doesn't work anyway.
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[System.Runtime.InteropServices.ComVisible(false)]
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public EncoderFallbackBuffer FallbackBuffer
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{
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get
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{
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if (m_fallbackBuffer == null)
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{
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if (m_fallback != null)
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m_fallbackBuffer = m_fallback.CreateFallbackBuffer();
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else
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m_fallbackBuffer = EncoderFallback.ReplacementFallback.CreateFallbackBuffer();
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}
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return m_fallbackBuffer;
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}
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}
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internal bool InternalHasFallbackBuffer
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{
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get
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{
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return m_fallbackBuffer != null;
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}
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}
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// Reset the Encoder
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//
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// Normally if we call GetBytes() and an error is thrown we don't change the state of the encoder. This
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// would allow the caller to correct the error condition and try again (such as if they need a bigger buffer.)
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//
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// If the caller doesn't want to try again after GetBytes() throws an error, then they need to call Reset().
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//
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// Virtual implimentation has to call GetBytes with flush and a big enough buffer to clear a 0 char string
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// We avoid GetMaxByteCount() because a) we can't call the base encoder and b) it might be really big.
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[System.Runtime.InteropServices.ComVisible(false)]
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public virtual void Reset()
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{
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char[] charTemp = {};
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byte[] byteTemp = new byte[GetByteCount(charTemp, 0, 0, true)];
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GetBytes(charTemp, 0, 0, byteTemp, 0, true);
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if (m_fallbackBuffer != null)
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m_fallbackBuffer.Reset();
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}
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// Returns the number of bytes the next call to GetBytes will
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// produce if presented with the given range of characters and the given
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// value of the flush parameter. The returned value takes into
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// account the state in which the encoder was left following the last call
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// to GetBytes. The state of the encoder is not affected by a call
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// to this method.
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//
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public abstract int GetByteCount(char[] chars, int index, int count, bool flush);
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// We expect this to be the workhorse for NLS encodings
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// unfortunately for existing overrides, it has to call the [] version,
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// which is really slow, so avoid this method if you might be calling external encodings.
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[System.Security.SecurityCritical] // auto-generated
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[CLSCompliant(false)]
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[System.Runtime.InteropServices.ComVisible(false)]
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public virtual unsafe int GetByteCount(char* chars, int count, bool flush)
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{
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// Validate input parameters
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if (chars == null)
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throw new ArgumentNullException("chars",
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Environment.GetResourceString("ArgumentNull_Array"));
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if (count < 0)
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throw new ArgumentOutOfRangeException("count",
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Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
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Contract.EndContractBlock();
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char[] arrChar = new char[count];
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int index;
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for (index = 0; index < count; index++)
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arrChar[index] = chars[index];
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return GetByteCount(arrChar, 0, count, flush);
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}
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// Encodes a range of characters in a character array into a range of bytes
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// in a byte array. The method encodes charCount characters from
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// chars starting at index charIndex, storing the resulting
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// bytes in bytes starting at index byteIndex. The encoding
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// takes into account the state in which the encoder was left following the
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// last call to this method. The flush parameter indicates whether
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// the encoder should flush any shift-states and partial characters at the
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// end of the conversion. To ensure correct termination of a sequence of
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// blocks of encoded bytes, the last call to GetBytes should specify
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// a value of true for the flush parameter.
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//
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// An exception occurs if the byte array is not large enough to hold the
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// complete encoding of the characters. The GetByteCount method can
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// be used to determine the exact number of bytes that will be produced for
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// a given range of characters. Alternatively, the GetMaxByteCount
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// method of the Encoding that produced this encoder can be used to
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// determine the maximum number of bytes that will be produced for a given
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// number of characters, regardless of the actual character values.
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//
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public abstract int GetBytes(char[] chars, int charIndex, int charCount,
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byte[] bytes, int byteIndex, bool flush);
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// We expect this to be the workhorse for NLS Encodings, but for existing
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// ones we need a working (if slow) default implimentation)
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//
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// WARNING WARNING WARNING
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//
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// WARNING: If this breaks it could be a security threat. Obviously we
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// call this internally, so you need to make sure that your pointers, counts
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// and indexes are correct when you call this method.
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//
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// In addition, we have internal code, which will be marked as "safe" calling
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// this code. However this code is dependent upon the implimentation of an
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// external GetBytes() method, which could be overridden by a third party and
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// the results of which cannot be guaranteed. We use that result to copy
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// the byte[] to our byte* output buffer. If the result count was wrong, we
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// could easily overflow our output buffer. Therefore we do an extra test
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// when we copy the buffer so that we don't overflow byteCount either.
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[System.Security.SecurityCritical] // auto-generated
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[CLSCompliant(false)]
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[System.Runtime.InteropServices.ComVisible(false)]
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public virtual unsafe int GetBytes(char* chars, int charCount,
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byte* bytes, int byteCount, bool flush)
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{
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// Validate input parameters
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if (bytes == null || chars == null)
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throw new ArgumentNullException(bytes == null ? "bytes" : "chars",
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Environment.GetResourceString("ArgumentNull_Array"));
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if (charCount < 0 || byteCount < 0)
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throw new ArgumentOutOfRangeException((charCount<0 ? "charCount" : "byteCount"),
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Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
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Contract.EndContractBlock();
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// Get the char array to convert
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char[] arrChar = new char[charCount];
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int index;
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for (index = 0; index < charCount; index++)
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arrChar[index] = chars[index];
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// Get the byte array to fill
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byte[] arrByte = new byte[byteCount];
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// Do the work
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int result = GetBytes(arrChar, 0, charCount, arrByte, 0, flush);
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// The only way this could fail is a bug in GetBytes
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Contract.Assert(result <= byteCount, "Returned more bytes than we have space for");
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// Copy the byte array
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// WARNING: We MUST make sure that we don't copy too many bytes. We can't
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// rely on result because it could be a 3rd party implimentation. We need
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// to make sure we never copy more than byteCount bytes no matter the value
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// of result
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if (result < byteCount)
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byteCount = result;
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// Don't copy too many bytes!
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for (index = 0; index < byteCount; index++)
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bytes[index] = arrByte[index];
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return byteCount;
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}
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// This method is used to avoid running out of output buffer space.
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// It will encode until it runs out of chars, and then it will return
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// true if it the entire input was converted. In either case it
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// will also return the number of converted chars and output bytes used.
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// It will only throw a buffer overflow exception if the entire lenght of bytes[] is
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// too small to store the next byte. (like 0 or maybe 1 or 4 for some encodings)
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// We're done processing this buffer only if completed returns true.
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//
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// Might consider checking Max...Count to avoid the extra counting step.
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//
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// Note that if all of the input chars are not consumed, then we'll do a /2, which means
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// that its likely that we didn't consume as many chars as we could have. For some
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// applications this could be slow. (Like trying to exactly fill an output buffer from a bigger stream)
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[System.Runtime.InteropServices.ComVisible(false)]
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public virtual void Convert(char[] chars, int charIndex, int charCount,
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byte[] bytes, int byteIndex, int byteCount, bool flush,
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out int charsUsed, out int bytesUsed, out bool completed)
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{
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// Validate parameters
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if (chars == null || bytes == null)
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throw new ArgumentNullException((chars == null ? "chars" : "bytes"),
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Environment.GetResourceString("ArgumentNull_Array"));
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if (charIndex < 0 || charCount < 0)
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throw new ArgumentOutOfRangeException((charIndex<0 ? "charIndex" : "charCount"),
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Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
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if (byteIndex < 0 || byteCount < 0)
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throw new ArgumentOutOfRangeException((byteIndex<0 ? "byteIndex" : "byteCount"),
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Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
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if (chars.Length - charIndex < charCount)
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throw new ArgumentOutOfRangeException("chars",
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Environment.GetResourceString("ArgumentOutOfRange_IndexCountBuffer"));
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if (bytes.Length - byteIndex < byteCount)
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throw new ArgumentOutOfRangeException("bytes",
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Environment.GetResourceString("ArgumentOutOfRange_IndexCountBuffer"));
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Contract.EndContractBlock();
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charsUsed = charCount;
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// Its easy to do if it won't overrun our buffer.
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// Note: We don't want to call unsafe version because that might be an untrusted version
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// which could be really unsafe and we don't want to mix it up.
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while (charsUsed > 0)
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{
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if (GetByteCount(chars, charIndex, charsUsed, flush) <= byteCount)
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{
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bytesUsed = GetBytes(chars, charIndex, charsUsed, bytes, byteIndex, flush);
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completed = (charsUsed == charCount &&
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(m_fallbackBuffer == null || m_fallbackBuffer.Remaining == 0));
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return;
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}
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// Try again with 1/2 the count, won't flush then 'cause won't read it all
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flush = false;
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charsUsed /= 2;
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}
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// Oops, we didn't have anything, we'll have to throw an overflow
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throw new ArgumentException(Environment.GetResourceString("Argument_ConversionOverflow"));
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}
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// Same thing, but using pointers
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//
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// Might consider checking Max...Count to avoid the extra counting step.
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//
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// Note that if all of the input chars are not consumed, then we'll do a /2, which means
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// that its likely that we didn't consume as many chars as we could have. For some
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// applications this could be slow. (Like trying to exactly fill an output buffer from a bigger stream)
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[System.Security.SecurityCritical] // auto-generated
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[CLSCompliant(false)]
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[System.Runtime.InteropServices.ComVisible(false)]
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public virtual unsafe void Convert(char* chars, int charCount,
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byte* bytes, int byteCount, bool flush,
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out int charsUsed, out int bytesUsed, out bool completed)
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{
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// Validate input parameters
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if (bytes == null || chars == null)
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throw new ArgumentNullException(bytes == null ? "bytes" : "chars",
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Environment.GetResourceString("ArgumentNull_Array"));
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if (charCount < 0 || byteCount < 0)
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throw new ArgumentOutOfRangeException((charCount<0 ? "charCount" : "byteCount"),
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Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
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Contract.EndContractBlock();
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// Get ready to do it
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charsUsed = charCount;
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// Its easy to do if it won't overrun our buffer.
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while (charsUsed > 0)
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{
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if (GetByteCount(chars, charsUsed, flush) <= byteCount)
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{
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bytesUsed = GetBytes(chars, charsUsed, bytes, byteCount, flush);
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completed = (charsUsed == charCount &&
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(m_fallbackBuffer == null || m_fallbackBuffer.Remaining == 0));
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return;
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}
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// Try again with 1/2 the count, won't flush then 'cause won't read it all
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flush = false;
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charsUsed /= 2;
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}
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// Oops, we didn't have anything, we'll have to throw an overflow
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throw new ArgumentException(Environment.GetResourceString("Argument_ConversionOverflow"));
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}
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}
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}
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