1 files changed, 152 insertions, 0 deletions
diff --git a/utils/process/systembuf.cpp b/utils/process/systembuf.cpp
new file mode 100644
index 000000000000..661b336221ac
--- /dev/null
+++ b/utils/process/systembuf.cpp
@@ -0,0 +1,152 @@
+// 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;
+}