Initial checkin. Partially abstract base class for a DataStream object
that simulates a contiguous stream out of one or more not-necessarily- contiguous extents in another stream. Fully implemented, completely untested. git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5697 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Tyler Dauwalder
parent
36f786dc8f
commit
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288
src/apps/bin/makeudfimage/SimulatedStream.cpp
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288
src/apps/bin/makeudfimage/SimulatedStream.cpp
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//----------------------------------------------------------------------
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// This software is part of the OpenBeOS distribution and is covered
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// by the OpenBeOS license.
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//
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// Copyright (c) 2003 Tyler Dauwalder, tyler@dauwalder.net
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//----------------------------------------------------------------------
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/*! \file SimulatedStream.cpp
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*/
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#include "SimulatedStream.h"
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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SimulatedStream::SimulatedStream(DataStream &stream)
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: fPosition(0)
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, fStream(stream)
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{
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}
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ssize_t
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SimulatedStream::Read(void *_buffer, size_t size)
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{
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uint8 *buffer = reinterpret_cast<uint8*>(_buffer);
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status_t error = buffer ? B_OK : B_BAD_VALUE;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(fPosition, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.ReadAt(extent.offset, buffer, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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fPosition += bytes;
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buffer += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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ssize_t
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SimulatedStream::ReadAt(off_t pos, void *_buffer, size_t size)
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{
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uint8 *buffer = reinterpret_cast<uint8*>(_buffer);
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status_t error = buffer ? B_OK : B_BAD_VALUE;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(pos, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.ReadAt(extent.offset, buffer, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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pos += bytes;
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buffer += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of data from \a buffer at the current
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position in the stream, incrementing the stream's position marker as it goes.
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*/
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ssize_t
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SimulatedStream::Write(const void *_buffer, size_t size)
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{
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const uint8 *buffer = reinterpret_cast<const uint8*>(_buffer);
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status_t error = buffer ? B_OK : B_BAD_VALUE;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(fPosition, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.WriteAt(extent.offset, buffer, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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fPosition += bytes;
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buffer += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of data from \a buffer at position
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\a pos in the stream without incrementing the stream's position marker.
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*/
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ssize_t
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SimulatedStream::WriteAt(off_t pos, const void *_buffer, size_t size)
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{
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const uint8 *buffer = reinterpret_cast<const uint8*>(_buffer);
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status_t error = buffer ? B_OK : B_BAD_VALUE;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(pos, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.WriteAt(extent.offset, buffer, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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pos += bytes;
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buffer += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of data from \a data at the current
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position in the stream, incrementing the stream's position marker as it goes.
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*/
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ssize_t
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SimulatedStream::Write(BDataIO &data, size_t size)
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{
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status_t error = B_OK;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(fPosition, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.WriteAt(extent.offset, data, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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fPosition += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of data from \a data at position
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\a pos in the stream without incrementing the stream's position marker.
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*/
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ssize_t
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SimulatedStream::WriteAt(off_t pos, BDataIO &data, size_t size)
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{
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status_t error = B_OK;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(pos, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.WriteAt(extent.offset, data, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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pos += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of zeros at the current position
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in the stream, incrementing the stream's position marker as it goes.
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*/
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ssize_t
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SimulatedStream::Zero(size_t size)
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{
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status_t error = B_OK;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(fPosition, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.ZeroAt(extent.offset, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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fPosition += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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/*! \brief Writes \a size bytes worth of zeros at position \a pos
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in the stream without incrementing the stream's position marker.
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*/
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ssize_t
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SimulatedStream::ZeroAt(off_t pos, size_t size)
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{
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status_t error = B_OK;
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ssize_t bytesTotal = 0;
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while (error == B_OK && size > 0) {
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data_extent extent;
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error = _GetExtent(pos, size, extent);
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if (!error) {
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if (extent.size > 0) {
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ssize_t bytes = fStream.ZeroAt(extent.offset, extent.size);
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if (bytes >= 0) {
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size -= bytes;
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pos += bytes;
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bytesTotal += bytes;
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} else {
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error = status_t(bytes);
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}
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} else {
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// end of simulated stream
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break;
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}
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}
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}
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return !error ? bytesTotal : ssize_t(error);
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}
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off_t
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SimulatedStream::Seek(off_t pos, uint32 seek_mode)
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{
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off_t size = _Size();
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switch (seek_mode) {
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case SEEK_SET:
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fPosition = pos;
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break;
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case SEEK_CUR:
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fPosition += pos;
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break;
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case SEEK_END:
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fPosition = size + pos;
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break;
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default:
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break;
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}
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// Range check
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if (fPosition < 0)
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fPosition = 0;
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else if (fPosition > size && SetSize(fPosition) != B_OK)
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fPosition = size;
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return fPosition;
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}
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76
src/apps/bin/makeudfimage/SimulatedStream.h
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76
src/apps/bin/makeudfimage/SimulatedStream.h
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@ -0,0 +1,76 @@
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//----------------------------------------------------------------------
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// This software is part of the OpenBeOS distribution and is covered
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// by the OpenBeOS license.
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//
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// Copyright (c) 2003 Tyler Dauwalder, tyler@dauwalder.net
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//----------------------------------------------------------------------
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/*! \file SimulatedStream.h
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*/
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#ifndef _SIMULATED_STREAM_H
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#define _SIMULATED_STREAM_H
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#include "DataStream.h"
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/*! \brief Abstract DataStream wrapper around another DataStream and a sequence of
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extents in said stream that allows for easy write access to said sequence
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of extents as though they were a continuous chunk of data.
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NOTE: The SimulatedStream object never modifies the data stream position
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of the underlying data stream; all read/write/zero calls use the underlying
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stream's ReadAt()/WriteAt()/ZeroAt() functions.
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*/
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class SimulatedStream : public DataStream {
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public:
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SimulatedStream(DataStream &stream);
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virtual ssize_t Read(void *buffer, size_t size);
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virtual ssize_t ReadAt(off_t pos, void *buffer, size_t size);
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virtual ssize_t Write(const void *buffer, size_t size);
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virtual ssize_t WriteAt(off_t pos, const void *buffer, size_t size);
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virtual ssize_t Write(BDataIO &data, size_t size);
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virtual ssize_t WriteAt(off_t pos, BDataIO &data, size_t size);
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virtual ssize_t Zero(size_t size);
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virtual ssize_t ZeroAt(off_t pos, size_t size);
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virtual off_t Seek(off_t pos, uint32 seek_mode);
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virtual off_t Position() const { return fPosition; }
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virtual status_t SetSize(off_t size) { return B_ERROR; }
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protected:
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struct data_extent {
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data_extent(off_t offset = 0, size_t size = 0)
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: offset(offset)
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, size(size)
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{
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}
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off_t offset;
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size_t size;
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};
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/*! \brief Should be implemented to return (via the output parameter
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\a extent) the largest extent in the underlying data stream corresponding
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to the extent in the simulated data stream starting at byte position
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\a pos of byte length \a size.
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NOTE: If the position is at or beyond the end of the simulated stream, the
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function should return B_OK, and the value of extent.size should be 0.
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*/
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virtual status_t _GetExtent(off_t pos, size_t size, data_extent &extent) = 0;
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/*! \brief Should be implemented to return the current size of the stream.
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*/
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virtual off_t _Size() = 0;
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private:
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off_t fPosition;
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DataStream &fStream;
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};
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#endif // _SIMULATED_STREAM_H
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