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// Copyright 2010 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "utils/process/systembuf.hpp"
extern "C" {
#include <unistd.h>
}
#include "utils/auto_array.ipp"
#include "utils/sanity.hpp"
using utils::process::systembuf;
/// Private implementation fields for systembuf.
struct systembuf::impl {
/// File descriptor attached to the systembuf.
int _fd;
/// Size of the _read_buf and _write_buf buffers.
std::size_t _bufsize;
/// In-memory buffer for read operations.
utils::auto_array< char > _read_buf;
/// In-memory buffer for write operations.
utils::auto_array< char > _write_buf;
/// Initializes private implementation data.
///
/// \param fd The file descriptor.
/// \param bufsize The size of the created read and write buffers.
impl(const int fd, const std::size_t bufsize) :
_fd(fd),
_bufsize(bufsize),
_read_buf(new char[bufsize]),
_write_buf(new char[bufsize])
{
}
};
/// Constructs a new systembuf based on an open file descriptor.
///
/// This grabs ownership of the file descriptor.
///
/// \param fd The file descriptor to wrap. Must be open and valid.
/// \param bufsize The size to use for the internal read/write buffers.
systembuf::systembuf(const int fd, std::size_t bufsize) :
_pimpl(new impl(fd, bufsize))
{
setp(_pimpl->_write_buf.get(), _pimpl->_write_buf.get() + _pimpl->_bufsize);
}
/// Destroys a systembuf object.
///
/// \post The file descriptor attached to this systembuf is closed.
systembuf::~systembuf(void)
{
::close(_pimpl->_fd);
}
/// Reads new data when the systembuf read buffer underflows.
///
/// \return The new character to be read, or EOF if no more.
systembuf::int_type
systembuf::underflow(void)
{
PRE(gptr() >= egptr());
bool ok;
ssize_t cnt = ::read(_pimpl->_fd, _pimpl->_read_buf.get(),
_pimpl->_bufsize);
ok = (cnt != -1 && cnt != 0);
if (!ok)
return traits_type::eof();
else {
setg(_pimpl->_read_buf.get(), _pimpl->_read_buf.get(),
_pimpl->_read_buf.get() + cnt);
return traits_type::to_int_type(*gptr());
}
}
/// Writes data to the file descriptor when the write buffer overflows.
///
/// \param c The character that causes the overflow.
///
/// \return EOF if error, some other value for success.
///
/// \throw something TODO(jmmv): According to the documentation, it is OK for
/// this method to throw in case of errors. Revisit this code to see if we
/// can do better.
systembuf::int_type
systembuf::overflow(int c)
{
PRE(pptr() >= epptr());
if (sync() == -1)
return traits_type::eof();
if (!traits_type::eq_int_type(c, traits_type::eof())) {
traits_type::assign(*pptr(), c);
pbump(1);
}
return traits_type::not_eof(c);
}
/// Synchronizes the stream with the file descriptor.
///
/// \return 0 on success, -1 on error.
int
systembuf::sync(void)
{
ssize_t cnt = pptr() - pbase();
bool ok;
ok = ::write(_pimpl->_fd, pbase(), cnt) == cnt;
if (ok)
pbump(-cnt);
return ok ? 0 : -1;
}
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