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-rw-r--r--utils/process/systembuf.cpp152
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diff --git a/utils/process/systembuf.cpp b/utils/process/systembuf.cpp
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+// Copyright 2010 The Kyua Authors.
+// 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/noncopyable.hpp"
+#include "utils/sanity.hpp"
+
+using utils::process::systembuf;
+
+
+/// Private implementation fields for systembuf.
+struct systembuf::impl : utils::noncopyable {
+ /// 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;
+}