/// <include file='doc\OracleLob.uex' path='docs/doc[@for="OracleLob.Read"]/*' />
public override int Read(
byte[] buffer,
int offset,
int count
)
{
AssertObjectNotDisposed();
if (count < 0)
{
throw ADP.MustBePositive("count");
}
if (offset < 0)
{
throw ADP.MustBePositive("offset");
}
if (null == buffer)
{
throw ADP.ArgumentNull("buffer");
}
if ((long)buffer.Length < ((long)offset + (long)count))
{
throw ADP.BufferExceeded();
}
if (IsNull || 0 == count)
{
return(0);
}
AssertConnectionIsOpen();
AssertAmountIsValidOddOK(offset, "offset");
AssertAmountIsValidOddOK(count, "count");
int amount;
uint readPosition = (uint)_currentPosition;
// Bless their hearts: Oracle won't let us use odd addresses to read
// character data, nor will they let us read a single byte from a
// character lob. Instead, we allocate our own buffer and copy the
// value to the caller's buffer.
int oddPosition = 0;
int oddOffset = 0;
int oddCount = 0;
byte[] readBuffer = buffer;
int readOffset = offset;
int readCount = count;
if (IsCharacterLob)
{
oddPosition = (int)(readPosition & 0x1);
oddOffset = offset & 0x1;
oddCount = count & 0x1;
readPosition /= 2;
if (1 == oddOffset || 1 == oddPosition || 1 == oddCount)
{
readOffset = 0;
readCount = count + oddCount + (2 * oddPosition);
readBuffer = new byte[readCount];
}
}
short charsetId = IsCharacterLob ? OCI.OCI_UCS2ID : (short)0;
int rc = 0;
amount = AdjustOffsetToOracle(readCount);
#if EXPOSELOBBUFFERING
EnsureBuffering(_bufferedRequested);
#endif //EXPOSELOBBUFFERING
// We need to pin the buffer and get the address of the offset that
// the user requested; Oracle doesn't allow us to specify an offset
// into the buffer.
GCHandle handle = new GCHandle();
try
{
try
{
handle = GCHandle.Alloc(readBuffer, GCHandleType.Pinned);
IntPtr bufferPtr = new IntPtr((long)handle.AddrOfPinnedObject() + readOffset);
rc = TracedNativeMethods.OCILobRead(
ServiceContextHandle,
ErrorHandle,
Descriptor,
ref amount,
readPosition + 1,
bufferPtr,
readCount,
ADP.NullHandleRef,
ADP.NullHandleRef,
charsetId,
_charsetForm
);
}
finally
{
if (handle.IsAllocated)
{
handle.Free(); // Unpin the buffer
}
}
}
catch // Prevent exception filters from running in our space
{
throw;
}
if ((int)OCI.RETURNCODE.OCI_NEED_DATA == rc)
{
rc = 0;
}
if ((int)OCI.RETURNCODE.OCI_NO_DATA == rc)
{
return(0);
}
if (0 != rc)
{
Connection.CheckError(ErrorHandle, rc);
}
amount = AdjustOracleToOffset(amount);
if (readBuffer as object != buffer as object)
{
if (amount >= count)
{
amount = count;
}
else
{
amount -= oddPosition;
}
Buffer.BlockCopy(readBuffer, oddPosition, buffer, offset, amount);
readBuffer = null;
}
_currentPosition += amount;
return(amount);
}
public override int Read(byte[] buffer, int offset, int count)
{
this.AssertObjectNotDisposed();
if (count < 0)
{
throw System.Data.Common.ADP.MustBePositive("count");
}
if (offset < 0)
{
throw System.Data.Common.ADP.MustBePositive("offset");
}
if (buffer == null)
{
throw System.Data.Common.ADP.ArgumentNull("buffer");
}
if (buffer.Length < (offset + count))
{
throw System.Data.Common.ADP.BufferExceeded("count");
}
if (this.IsNull || (count == 0))
{
return(0);
}
this.AssertConnectionIsOpen();
this.AssertAmountIsValidOddOK((long)offset, "offset");
this.AssertAmountIsValidOddOK((long)count, "count");
uint num5 = (uint)this._currentPosition;
int srcOffset = 0;
int num8 = 0;
int num6 = 0;
byte[] buffer2 = buffer;
int num7 = offset;
int amount = count;
if (this.IsCharacterLob)
{
srcOffset = ((int)num5) & 1;
num8 = offset & 1;
num6 = count & 1;
num5 /= 2;
if (((1 == num8) || (1 == srcOffset)) || (1 == num6))
{
num7 = 0;
amount = (count + num6) + (2 * srcOffset);
buffer2 = new byte[amount];
}
}
ushort csid = this.IsCharacterLob ? ((ushort)0x3e8) : ((ushort)0);
int rc = 0;
int amtp = this.AdjustOffsetToOracle(amount);
GCHandle handle = new GCHandle();
try
{
handle = GCHandle.Alloc(buffer2, GCHandleType.Pinned);
IntPtr bufp = new IntPtr(((long)handle.AddrOfPinnedObject()) + num7);
rc = TracedNativeMethods.OCILobRead(this.ServiceContextHandle, this.ErrorHandle, this.Descriptor, ref amtp, num5 + 1, bufp, (uint)amount, csid, this._charsetForm);
}
finally
{
if (handle.IsAllocated)
{
handle.Free();
}
}
if (0x63 == rc)
{
rc = 0;
}
if (100 == rc)
{
return(0);
}
if (rc != 0)
{
this.Connection.CheckError(this.ErrorHandle, rc);
}
amtp = this.AdjustOracleToOffset(amtp);
if (buffer2 != buffer)
{
if (amtp >= count)
{
amtp = count;
}
else
{
amtp -= srcOffset;
}
Buffer.BlockCopy(buffer2, srcOffset, buffer, offset, amtp);
buffer2 = null;
}
this._currentPosition += amtp;
return(amtp);
}
