diff osx/include/kj/io.h @ 62:0994c39f1e94

Cap'n Proto v0.6 + build for OSX

--- a/osx/include/kj/io.h	Mon Mar 06 13:29:58 2017 +0000
+++ b/osx/include/kj/io.h	Mon May 22 10:01:37 2017 +0100
@@ -1,331 +1,419 @@
-// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
-// Licensed under the MIT License:
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-
-#ifndef KJ_IO_H_
-#define KJ_IO_H_
-
-#if defined(__GNUC__) && !KJ_HEADER_WARNINGS
-#pragma GCC system_header
-#endif
-
-#include <stddef.h>
-#include "common.h"
-#include "array.h"
-#include "exception.h"
-
-namespace kj {
-
-// =======================================================================================
-// Abstract interfaces
-
-class InputStream {
-public:
-  virtual ~InputStream() noexcept(false);
-
-  size_t read(void* buffer, size_t minBytes, size_t maxBytes);
-  // Reads at least minBytes and at most maxBytes, copying them into the given buffer.  Returns
-  // the size read.  Throws an exception on errors.  Implemented in terms of tryRead().
-  //
-  // maxBytes is the number of bytes the caller really wants, but minBytes is the minimum amount
-  // needed by the caller before it can start doing useful processing.  If the stream returns less
-  // than maxBytes, the caller will usually call read() again later to get the rest.  Returning
-  // less than maxBytes is useful when it makes sense for the caller to parallelize processing
-  // with I/O.
-  //
-  // Never blocks if minBytes is zero.  If minBytes is zero and maxBytes is non-zero, this may
-  // attempt a non-blocking read or may just return zero.  To force a read, use a non-zero minBytes.
-  // To detect EOF without throwing an exception, use tryRead().
-  //
-  // If the InputStream can't produce minBytes, it MUST throw an exception, as the caller is not
-  // expected to understand how to deal with partial reads.
-
-  virtual size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) = 0;
-  // Like read(), but may return fewer than minBytes on EOF.
-
-  inline void read(void* buffer, size_t bytes) { read(buffer, bytes, bytes); }
-  // Convenience method for reading an exact number of bytes.
-
-  virtual void skip(size_t bytes);
-  // Skips past the given number of bytes, discarding them.  The default implementation read()s
-  // into a scratch buffer.
-};
-
-class OutputStream {
-public:
-  virtual ~OutputStream() noexcept(false);
-
-  virtual void write(const void* buffer, size_t size) = 0;
-  // Always writes the full size.  Throws exception on error.
-
-  virtual void write(ArrayPtr<const ArrayPtr<const byte>> pieces);
-  // Equivalent to write()ing each byte array in sequence, which is what the default implementation
-  // does.  Override if you can do something better, e.g. use writev() to do the write in a single
-  // syscall.
-};
-
-class BufferedInputStream: public InputStream {
-  // An input stream which buffers some bytes in memory to reduce system call overhead.
-  // - OR -
-  // An input stream that actually reads from some in-memory data structure and wants to give its
-  // caller a direct pointer to that memory to potentially avoid a copy.
-
-public:
-  virtual ~BufferedInputStream() noexcept(false);
-
-  ArrayPtr<const byte> getReadBuffer();
-  // Get a direct pointer into the read buffer, which contains the next bytes in the input.  If the
-  // caller consumes any bytes, it should then call skip() to indicate this.  This always returns a
-  // non-empty buffer or throws an exception.  Implemented in terms of tryGetReadBuffer().
-
-  virtual ArrayPtr<const byte> tryGetReadBuffer() = 0;
-  // Like getReadBuffer() but may return an empty buffer on EOF.
-};
-
-class BufferedOutputStream: public OutputStream {
-  // An output stream which buffers some bytes in memory to reduce system call overhead.
-  // - OR -
-  // An output stream that actually writes into some in-memory data structure and wants to give its
-  // caller a direct pointer to that memory to potentially avoid a copy.
-
-public:
-  virtual ~BufferedOutputStream() noexcept(false);
-
-  virtual ArrayPtr<byte> getWriteBuffer() = 0;
-  // Get a direct pointer into the write buffer.  The caller may choose to fill in some prefix of
-  // this buffer and then pass it to write(), in which case write() may avoid a copy.  It is
-  // incorrect to pass to write any slice of this buffer which is not a prefix.
-};
-
-// =======================================================================================
-// Buffered streams implemented as wrappers around regular streams
-
-class BufferedInputStreamWrapper: public BufferedInputStream {
-  // Implements BufferedInputStream in terms of an InputStream.
-  //
-  // Note that the underlying stream's position is unpredictable once the wrapper is destroyed,
-  // unless the entire stream was consumed.  To read a predictable number of bytes in a buffered
-  // way without going over, you'd need this wrapper to wrap some other wrapper which itself
-  // implements an artificial EOF at the desired point.  Such a stream should be trivial to write
-  // but is not provided by the library at this time.
-
-public:
-  explicit BufferedInputStreamWrapper(InputStream& inner, ArrayPtr<byte> buffer = nullptr);
-  // Creates a buffered stream wrapping the given non-buffered stream.  No guarantee is made about
-  // the position of the inner stream after a buffered wrapper has been created unless the entire
-  // input is read.
-  //
-  // If the second parameter is non-null, the stream uses the given buffer instead of allocating
-  // its own.  This may improve performance if the buffer can be reused.
-
-  KJ_DISALLOW_COPY(BufferedInputStreamWrapper);
-  ~BufferedInputStreamWrapper() noexcept(false);
-
-  // implements BufferedInputStream ----------------------------------
-  ArrayPtr<const byte> tryGetReadBuffer() override;
-  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
-  void skip(size_t bytes) override;
-
-private:
-  InputStream& inner;
-  Array<byte> ownedBuffer;
-  ArrayPtr<byte> buffer;
-  ArrayPtr<byte> bufferAvailable;
-};
-
-class BufferedOutputStreamWrapper: public BufferedOutputStream {
-  // Implements BufferedOutputStream in terms of an OutputStream.  Note that writes to the
-  // underlying stream may be delayed until flush() is called or the wrapper is destroyed.
-
-public:
-  explicit BufferedOutputStreamWrapper(OutputStream& inner, ArrayPtr<byte> buffer = nullptr);
-  // Creates a buffered stream wrapping the given non-buffered stream.
-  //
-  // If the second parameter is non-null, the stream uses the given buffer instead of allocating
-  // its own.  This may improve performance if the buffer can be reused.
-
-  KJ_DISALLOW_COPY(BufferedOutputStreamWrapper);
-  ~BufferedOutputStreamWrapper() noexcept(false);
-
-  void flush();
-  // Force the wrapper to write any remaining bytes in its buffer to the inner stream.  Note that
-  // this only flushes this object's buffer; this object has no idea how to flush any other buffers
-  // that may be present in the underlying stream.
-
-  // implements BufferedOutputStream ---------------------------------
-  ArrayPtr<byte> getWriteBuffer() override;
-  void write(const void* buffer, size_t size) override;
-
-private:
-  OutputStream& inner;
-  Array<byte> ownedBuffer;
-  ArrayPtr<byte> buffer;
-  byte* bufferPos;
-  UnwindDetector unwindDetector;
-};
-
-// =======================================================================================
-// Array I/O
-
-class ArrayInputStream: public BufferedInputStream {
-public:
-  explicit ArrayInputStream(ArrayPtr<const byte> array);
-  KJ_DISALLOW_COPY(ArrayInputStream);
-  ~ArrayInputStream() noexcept(false);
-
-  // implements BufferedInputStream ----------------------------------
-  ArrayPtr<const byte> tryGetReadBuffer() override;
-  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
-  void skip(size_t bytes) override;
-
-private:
-  ArrayPtr<const byte> array;
-};
-
-class ArrayOutputStream: public BufferedOutputStream {
-public:
-  explicit ArrayOutputStream(ArrayPtr<byte> array);
-  KJ_DISALLOW_COPY(ArrayOutputStream);
-  ~ArrayOutputStream() noexcept(false);
-
-  ArrayPtr<byte> getArray() {
-    // Get the portion of the array which has been filled in.
-    return arrayPtr(array.begin(), fillPos);
-  }
-
-  // implements BufferedInputStream ----------------------------------
-  ArrayPtr<byte> getWriteBuffer() override;
-  void write(const void* buffer, size_t size) override;
-
-private:
-  ArrayPtr<byte> array;
-  byte* fillPos;
-};
-
-class VectorOutputStream: public BufferedOutputStream {
-public:
-  explicit VectorOutputStream(size_t initialCapacity = 4096);
-  KJ_DISALLOW_COPY(VectorOutputStream);
-  ~VectorOutputStream() noexcept(false);
-
-  ArrayPtr<byte> getArray() {
-    // Get the portion of the array which has been filled in.
-    return arrayPtr(vector.begin(), fillPos);
-  }
-
-  // implements BufferedInputStream ----------------------------------
-  ArrayPtr<byte> getWriteBuffer() override;
-  void write(const void* buffer, size_t size) override;
-
-private:
-  Array<byte> vector;
-  byte* fillPos;
-
-  void grow(size_t minSize);
-};
-
-// =======================================================================================
-// File descriptor I/O
-
-class AutoCloseFd {
-  // A wrapper around a file descriptor which automatically closes the descriptor when destroyed.
-  // The wrapper supports move construction for transferring ownership of the descriptor.  If
-  // close() returns an error, the destructor throws an exception, UNLESS the destructor is being
-  // called during unwind from another exception, in which case the close error is ignored.
-  //
-  // If your code is not exception-safe, you should not use AutoCloseFd.  In this case you will
-  // have to call close() yourself and handle errors appropriately.
-
-public:
-  inline AutoCloseFd(): fd(-1) {}
-  inline AutoCloseFd(decltype(nullptr)): fd(-1) {}
-  inline explicit AutoCloseFd(int fd): fd(fd) {}
-  inline AutoCloseFd(AutoCloseFd&& other) noexcept: fd(other.fd) { other.fd = -1; }
-  KJ_DISALLOW_COPY(AutoCloseFd);
-  ~AutoCloseFd() noexcept(false);
-
-  inline AutoCloseFd& operator=(AutoCloseFd&& other) {
-    AutoCloseFd old(kj::mv(*this));
-    fd = other.fd;
-    other.fd = -1;
-    return *this;
-  }
-
-  inline AutoCloseFd& operator=(decltype(nullptr)) {
-    AutoCloseFd old(kj::mv(*this));
-    return *this;
-  }
-
-  inline operator int() const { return fd; }
-  inline int get() const { return fd; }
-
-  operator bool() const = delete;
-  // Deleting this operator prevents accidental use in boolean contexts, which
-  // the int conversion operator above would otherwise allow.
-
-  inline bool operator==(decltype(nullptr)) { return fd < 0; }
-  inline bool operator!=(decltype(nullptr)) { return fd >= 0; }
-
-private:
-  int fd;
-  UnwindDetector unwindDetector;
-};
-
-inline auto KJ_STRINGIFY(const AutoCloseFd& fd)
-    -> decltype(kj::toCharSequence(implicitCast<int>(fd))) {
-  return kj::toCharSequence(implicitCast<int>(fd));
-}
-
-class FdInputStream: public InputStream {
-  // An InputStream wrapping a file descriptor.
-
-public:
-  explicit FdInputStream(int fd): fd(fd) {}
-  explicit FdInputStream(AutoCloseFd fd): fd(fd), autoclose(mv(fd)) {}
-  KJ_DISALLOW_COPY(FdInputStream);
-  ~FdInputStream() noexcept(false);
-
-  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
-
-private:
-  int fd;
-  AutoCloseFd autoclose;
-};
-
-class FdOutputStream: public OutputStream {
-  // An OutputStream wrapping a file descriptor.
-
-public:
-  explicit FdOutputStream(int fd): fd(fd) {}
-  explicit FdOutputStream(AutoCloseFd fd): fd(fd), autoclose(mv(fd)) {}
-  KJ_DISALLOW_COPY(FdOutputStream);
-  ~FdOutputStream() noexcept(false);
-
-  void write(const void* buffer, size_t size) override;
-  void write(ArrayPtr<const ArrayPtr<const byte>> pieces) override;
-
-private:
-  int fd;
-  AutoCloseFd autoclose;
-};
-
-}  // namespace kj
-
-#endif  // KJ_IO_H_
+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_IO_H_
+#define KJ_IO_H_
+
+#if defined(__GNUC__) && !KJ_HEADER_WARNINGS
+#pragma GCC system_header
+#endif
+
+#include <stddef.h>
+#include "common.h"
+#include "array.h"
+#include "exception.h"
+
+namespace kj {
+
+// =======================================================================================
+// Abstract interfaces
+
+class InputStream {
+public:
+  virtual ~InputStream() noexcept(false);
+
+  size_t read(void* buffer, size_t minBytes, size_t maxBytes);
+  // Reads at least minBytes and at most maxBytes, copying them into the given buffer.  Returns
+  // the size read.  Throws an exception on errors.  Implemented in terms of tryRead().
+  //
+  // maxBytes is the number of bytes the caller really wants, but minBytes is the minimum amount
+  // needed by the caller before it can start doing useful processing.  If the stream returns less
+  // than maxBytes, the caller will usually call read() again later to get the rest.  Returning
+  // less than maxBytes is useful when it makes sense for the caller to parallelize processing
+  // with I/O.
+  //
+  // Never blocks if minBytes is zero.  If minBytes is zero and maxBytes is non-zero, this may
+  // attempt a non-blocking read or may just return zero.  To force a read, use a non-zero minBytes.
+  // To detect EOF without throwing an exception, use tryRead().
+  //
+  // If the InputStream can't produce minBytes, it MUST throw an exception, as the caller is not
+  // expected to understand how to deal with partial reads.
+
+  virtual size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) = 0;
+  // Like read(), but may return fewer than minBytes on EOF.
+
+  inline void read(void* buffer, size_t bytes) { read(buffer, bytes, bytes); }
+  // Convenience method for reading an exact number of bytes.
+
+  virtual void skip(size_t bytes);
+  // Skips past the given number of bytes, discarding them.  The default implementation read()s
+  // into a scratch buffer.
+};
+
+class OutputStream {
+public:
+  virtual ~OutputStream() noexcept(false);
+
+  virtual void write(const void* buffer, size_t size) = 0;
+  // Always writes the full size.  Throws exception on error.
+
+  virtual void write(ArrayPtr<const ArrayPtr<const byte>> pieces);
+  // Equivalent to write()ing each byte array in sequence, which is what the default implementation
+  // does.  Override if you can do something better, e.g. use writev() to do the write in a single
+  // syscall.
+};
+
+class BufferedInputStream: public InputStream {
+  // An input stream which buffers some bytes in memory to reduce system call overhead.
+  // - OR -
+  // An input stream that actually reads from some in-memory data structure and wants to give its
+  // caller a direct pointer to that memory to potentially avoid a copy.
+
+public:
+  virtual ~BufferedInputStream() noexcept(false);
+
+  ArrayPtr<const byte> getReadBuffer();
+  // Get a direct pointer into the read buffer, which contains the next bytes in the input.  If the
+  // caller consumes any bytes, it should then call skip() to indicate this.  This always returns a
+  // non-empty buffer or throws an exception.  Implemented in terms of tryGetReadBuffer().
+
+  virtual ArrayPtr<const byte> tryGetReadBuffer() = 0;
+  // Like getReadBuffer() but may return an empty buffer on EOF.
+};
+
+class BufferedOutputStream: public OutputStream {
+  // An output stream which buffers some bytes in memory to reduce system call overhead.
+  // - OR -
+  // An output stream that actually writes into some in-memory data structure and wants to give its
+  // caller a direct pointer to that memory to potentially avoid a copy.
+
+public:
+  virtual ~BufferedOutputStream() noexcept(false);
+
+  virtual ArrayPtr<byte> getWriteBuffer() = 0;
+  // Get a direct pointer into the write buffer.  The caller may choose to fill in some prefix of
+  // this buffer and then pass it to write(), in which case write() may avoid a copy.  It is
+  // incorrect to pass to write any slice of this buffer which is not a prefix.
+};
+
+// =======================================================================================
+// Buffered streams implemented as wrappers around regular streams
+
+class BufferedInputStreamWrapper: public BufferedInputStream {
+  // Implements BufferedInputStream in terms of an InputStream.
+  //
+  // Note that the underlying stream's position is unpredictable once the wrapper is destroyed,
+  // unless the entire stream was consumed.  To read a predictable number of bytes in a buffered
+  // way without going over, you'd need this wrapper to wrap some other wrapper which itself
+  // implements an artificial EOF at the desired point.  Such a stream should be trivial to write
+  // but is not provided by the library at this time.
+
+public:
+  explicit BufferedInputStreamWrapper(InputStream& inner, ArrayPtr<byte> buffer = nullptr);
+  // Creates a buffered stream wrapping the given non-buffered stream.  No guarantee is made about
+  // the position of the inner stream after a buffered wrapper has been created unless the entire
+  // input is read.
+  //
+  // If the second parameter is non-null, the stream uses the given buffer instead of allocating
+  // its own.  This may improve performance if the buffer can be reused.
+
+  KJ_DISALLOW_COPY(BufferedInputStreamWrapper);
+  ~BufferedInputStreamWrapper() noexcept(false);
+
+  // implements BufferedInputStream ----------------------------------
+  ArrayPtr<const byte> tryGetReadBuffer() override;
+  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
+  void skip(size_t bytes) override;
+
+private:
+  InputStream& inner;
+  Array<byte> ownedBuffer;
+  ArrayPtr<byte> buffer;
+  ArrayPtr<byte> bufferAvailable;
+};
+
+class BufferedOutputStreamWrapper: public BufferedOutputStream {
+  // Implements BufferedOutputStream in terms of an OutputStream.  Note that writes to the
+  // underlying stream may be delayed until flush() is called or the wrapper is destroyed.
+
+public:
+  explicit BufferedOutputStreamWrapper(OutputStream& inner, ArrayPtr<byte> buffer = nullptr);
+  // Creates a buffered stream wrapping the given non-buffered stream.
+  //
+  // If the second parameter is non-null, the stream uses the given buffer instead of allocating
+  // its own.  This may improve performance if the buffer can be reused.
+
+  KJ_DISALLOW_COPY(BufferedOutputStreamWrapper);
+  ~BufferedOutputStreamWrapper() noexcept(false);
+
+  void flush();
+  // Force the wrapper to write any remaining bytes in its buffer to the inner stream.  Note that
+  // this only flushes this object's buffer; this object has no idea how to flush any other buffers
+  // that may be present in the underlying stream.
+
+  // implements BufferedOutputStream ---------------------------------
+  ArrayPtr<byte> getWriteBuffer() override;
+  void write(const void* buffer, size_t size) override;
+
+private:
+  OutputStream& inner;
+  Array<byte> ownedBuffer;
+  ArrayPtr<byte> buffer;
+  byte* bufferPos;
+  UnwindDetector unwindDetector;
+};
+
+// =======================================================================================
+// Array I/O
+
+class ArrayInputStream: public BufferedInputStream {
+public:
+  explicit ArrayInputStream(ArrayPtr<const byte> array);
+  KJ_DISALLOW_COPY(ArrayInputStream);
+  ~ArrayInputStream() noexcept(false);
+
+  // implements BufferedInputStream ----------------------------------
+  ArrayPtr<const byte> tryGetReadBuffer() override;
+  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
+  void skip(size_t bytes) override;
+
+private:
+  ArrayPtr<const byte> array;
+};
+
+class ArrayOutputStream: public BufferedOutputStream {
+public:
+  explicit ArrayOutputStream(ArrayPtr<byte> array);
+  KJ_DISALLOW_COPY(ArrayOutputStream);
+  ~ArrayOutputStream() noexcept(false);
+
+  ArrayPtr<byte> getArray() {
+    // Get the portion of the array which has been filled in.
+    return arrayPtr(array.begin(), fillPos);
+  }
+
+  // implements BufferedInputStream ----------------------------------
+  ArrayPtr<byte> getWriteBuffer() override;
+  void write(const void* buffer, size_t size) override;
+
+private:
+  ArrayPtr<byte> array;
+  byte* fillPos;
+};
+
+class VectorOutputStream: public BufferedOutputStream {
+public:
+  explicit VectorOutputStream(size_t initialCapacity = 4096);
+  KJ_DISALLOW_COPY(VectorOutputStream);
+  ~VectorOutputStream() noexcept(false);
+
+  ArrayPtr<byte> getArray() {
+    // Get the portion of the array which has been filled in.
+    return arrayPtr(vector.begin(), fillPos);
+  }
+
+  // implements BufferedInputStream ----------------------------------
+  ArrayPtr<byte> getWriteBuffer() override;
+  void write(const void* buffer, size_t size) override;
+
+private:
+  Array<byte> vector;
+  byte* fillPos;
+
+  void grow(size_t minSize);
+};
+
+// =======================================================================================
+// File descriptor I/O
+
+class AutoCloseFd {
+  // A wrapper around a file descriptor which automatically closes the descriptor when destroyed.
+  // The wrapper supports move construction for transferring ownership of the descriptor.  If
+  // close() returns an error, the destructor throws an exception, UNLESS the destructor is being
+  // called during unwind from another exception, in which case the close error is ignored.
+  //
+  // If your code is not exception-safe, you should not use AutoCloseFd.  In this case you will
+  // have to call close() yourself and handle errors appropriately.
+
+public:
+  inline AutoCloseFd(): fd(-1) {}
+  inline AutoCloseFd(decltype(nullptr)): fd(-1) {}
+  inline explicit AutoCloseFd(int fd): fd(fd) {}
+  inline AutoCloseFd(AutoCloseFd&& other) noexcept: fd(other.fd) { other.fd = -1; }
+  KJ_DISALLOW_COPY(AutoCloseFd);
+  ~AutoCloseFd() noexcept(false);
+
+  inline AutoCloseFd& operator=(AutoCloseFd&& other) {
+    AutoCloseFd old(kj::mv(*this));
+    fd = other.fd;
+    other.fd = -1;
+    return *this;
+  }
+
+  inline AutoCloseFd& operator=(decltype(nullptr)) {
+    AutoCloseFd old(kj::mv(*this));
+    return *this;
+  }
+
+  inline operator int() const { return fd; }
+  inline int get() const { return fd; }
+
+  operator bool() const = delete;
+  // Deleting this operator prevents accidental use in boolean contexts, which
+  // the int conversion operator above would otherwise allow.
+
+  inline bool operator==(decltype(nullptr)) { return fd < 0; }
+  inline bool operator!=(decltype(nullptr)) { return fd >= 0; }
+
+private:
+  int fd;
+  UnwindDetector unwindDetector;
+};
+
+inline auto KJ_STRINGIFY(const AutoCloseFd& fd)
+    -> decltype(kj::toCharSequence(implicitCast<int>(fd))) {
+  return kj::toCharSequence(implicitCast<int>(fd));
+}
+
+class FdInputStream: public InputStream {
+  // An InputStream wrapping a file descriptor.
+
+public:
+  explicit FdInputStream(int fd): fd(fd) {}
+  explicit FdInputStream(AutoCloseFd fd): fd(fd), autoclose(mv(fd)) {}
+  KJ_DISALLOW_COPY(FdInputStream);
+  ~FdInputStream() noexcept(false);
+
+  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
+
+  inline int getFd() const { return fd; }
+
+private:
+  int fd;
+  AutoCloseFd autoclose;
+};
+
+class FdOutputStream: public OutputStream {
+  // An OutputStream wrapping a file descriptor.
+
+public:
+  explicit FdOutputStream(int fd): fd(fd) {}
+  explicit FdOutputStream(AutoCloseFd fd): fd(fd), autoclose(mv(fd)) {}
+  KJ_DISALLOW_COPY(FdOutputStream);
+  ~FdOutputStream() noexcept(false);
+
+  void write(const void* buffer, size_t size) override;
+  void write(ArrayPtr<const ArrayPtr<const byte>> pieces) override;
+
+  inline int getFd() const { return fd; }
+
+private:
+  int fd;
+  AutoCloseFd autoclose;
+};
+
+// =======================================================================================
+// Win32 Handle I/O
+
+#ifdef _WIN32
+
+class AutoCloseHandle {
+  // A wrapper around a Win32 HANDLE which automatically closes the handle when destroyed.
+  // The wrapper supports move construction for transferring ownership of the handle.  If
+  // CloseHandle() returns an error, the destructor throws an exception, UNLESS the destructor is
+  // being called during unwind from another exception, in which case the close error is ignored.
+  //
+  // If your code is not exception-safe, you should not use AutoCloseHandle.  In this case you will
+  // have to call close() yourself and handle errors appropriately.
+
+public:
+  inline AutoCloseHandle(): handle((void*)-1) {}
+  inline AutoCloseHandle(decltype(nullptr)): handle((void*)-1) {}
+  inline explicit AutoCloseHandle(void* handle): handle(handle) {}
+  inline AutoCloseHandle(AutoCloseHandle&& other) noexcept: handle(other.handle) {
+    other.handle = (void*)-1;
+  }
+  KJ_DISALLOW_COPY(AutoCloseHandle);
+  ~AutoCloseHandle() noexcept(false);
+
+  inline AutoCloseHandle& operator=(AutoCloseHandle&& other) {
+    AutoCloseHandle old(kj::mv(*this));
+    handle = other.handle;
+    other.handle = (void*)-1;
+    return *this;
+  }
+
+  inline AutoCloseHandle& operator=(decltype(nullptr)) {
+    AutoCloseHandle old(kj::mv(*this));
+    return *this;
+  }
+
+  inline operator void*() const { return handle; }
+  inline void* get() const { return handle; }
+
+  operator bool() const = delete;
+  // Deleting this operator prevents accidental use in boolean contexts, which
+  // the void* conversion operator above would otherwise allow.
+
+  inline bool operator==(decltype(nullptr)) { return handle != (void*)-1; }
+  inline bool operator!=(decltype(nullptr)) { return handle == (void*)-1; }
+
+private:
+  void* handle;  // -1 (aka INVALID_HANDLE_VALUE) if not valid.
+};
+
+class HandleInputStream: public InputStream {
+  // An InputStream wrapping a Win32 HANDLE.
+
+public:
+  explicit HandleInputStream(void* handle): handle(handle) {}
+  explicit HandleInputStream(AutoCloseHandle handle): handle(handle), autoclose(mv(handle)) {}
+  KJ_DISALLOW_COPY(HandleInputStream);
+  ~HandleInputStream() noexcept(false);
+
+  size_t tryRead(void* buffer, size_t minBytes, size_t maxBytes) override;
+
+private:
+  void* handle;
+  AutoCloseHandle autoclose;
+};
+
+class HandleOutputStream: public OutputStream {
+  // An OutputStream wrapping a Win32 HANDLE.
+
+public:
+  explicit HandleOutputStream(void* handle): handle(handle) {}
+  explicit HandleOutputStream(AutoCloseHandle handle): handle(handle), autoclose(mv(handle)) {}
+  KJ_DISALLOW_COPY(HandleOutputStream);
+  ~HandleOutputStream() noexcept(false);
+
+  void write(const void* buffer, size_t size) override;
+
+private:
+  void* handle;
+  AutoCloseHandle autoclose;
+};
+
+#endif  // _WIN32
+
+}  // namespace kj
+
+#endif  // KJ_IO_H_