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diff --git a/utils/units.cpp b/utils/units.cpp
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+// Copyright 2012 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/units.hpp"
+
+extern "C" {
+#include <stdint.h>
+}
+
+#include <stdexcept>
+
+#include "utils/format/macros.hpp"
+#include "utils/text/exceptions.hpp"
+#include "utils/text/operations.ipp"
+
+namespace units = utils::units;
+
+
+/// Constructs a zero bytes quantity.
+units::bytes::bytes(void) :
+    _count(0)
+{
+}
+
+
+/// Constructs an arbitrary bytes quantity.
+///
+/// \param count_ The amount of bytes in the quantity.
+units::bytes::bytes(const uint64_t count_) :
+    _count(count_)
+{
+}
+
+
+/// Parses a string into a bytes quantity.
+///
+/// \param in_str The user-provided string to be converted.
+///
+/// \return The converted bytes quantity.
+///
+/// \throw std::runtime_error If the input string is empty or invalid.
+units::bytes
+units::bytes::parse(const std::string& in_str)
+{
+    if (in_str.empty())
+        throw std::runtime_error("Bytes quantity cannot be empty");
+
+    uint64_t multiplier;
+    std::string str = in_str;
+    {
+        const char unit = str[str.length() - 1];
+        switch (unit) {
+        case 'T': case 't': multiplier = TB; break;
+        case 'G': case 'g': multiplier = GB; break;
+        case 'M': case 'm': multiplier = MB; break;
+        case 'K': case 'k': multiplier = KB; break;
+        default: multiplier = 1;
+        }
+        if (multiplier != 1)
+            str.erase(str.length() - 1);
+    }
+
+    if (str.empty())
+        throw std::runtime_error("Bytes quantity cannot be empty");
+    if (str[0] == '.' || str[str.length() - 1] == '.') {
+        // The standard parser for float values accepts things like ".3" and
+        // "3.", which means that we would interpret ".3K" and "3.K" as valid
+        // quantities.  I think this is ugly and should not be allowed, so
+        // special-case this condition and just error out.
+        throw std::runtime_error(F("Invalid bytes quantity '%s'") % in_str);
+    }
+
+    double count;
+    try {
+        count = text::to_type< double >(str);
+    } catch (const text::value_error& e) {
+        throw std::runtime_error(F("Invalid bytes quantity '%s'") % in_str);
+    }
+
+    return bytes(uint64_t(count * multiplier));
+}
+
+
+/// Formats a bytes quantity for user consumption.
+///
+/// \return A textual representation of the bytes quantiy.
+std::string
+units::bytes::format(void) const
+{
+    if (_count >= TB) {
+        return F("%.2sT") % (static_cast< float >(_count) / TB);
+    } else if (_count >= GB) {
+        return F("%.2sG") % (static_cast< float >(_count) / GB);
+    } else if (_count >= MB) {
+        return F("%.2sM") % (static_cast< float >(_count) / MB);
+    } else if (_count >= KB) {
+        return F("%.2sK") % (static_cast< float >(_count) / KB);
+    } else {
+        return F("%s") % _count;
+    }
+}
+
+
+/// Implicit conversion to an integral representation.
+units::bytes::operator uint64_t(void) const
+{
+    return _count;
+}
+
+
+/// Extracts a bytes quantity from a stream.
+///
+/// \param input The stream from which to read a single word representing the
+///     bytes quantity.
+/// \param rhs The variable into which to store the parsed value.
+///
+/// \return The input stream.
+///
+/// \post The bad bit of input is set to 1 if the parsing failed.
+std::istream&
+units::operator>>(std::istream& input, bytes& rhs)
+{
+    std::string word;
+    input >> word;
+    if (input.good() || input.eof()) {
+        try {
+            rhs = bytes::parse(word);
+        } catch (const std::runtime_error& e) {
+            input.setstate(std::ios::badbit);
+        }
+    }
+    return input;
+}
+
+
+/// Injects a bytes quantity into a stream.
+///
+/// \param output The stream into which to inject the bytes quantity as a
+///     user-readable string.
+/// \param rhs The bytes quantity to format.
+///
+/// \return The output stream.
+std::ostream&
+units::operator<<(std::ostream& output, const bytes& rhs)
+{
+    return (output << rhs.format());
+}