1 files changed, 311 insertions, 0 deletions
diff --git a/third_party/nix/src/libutil/serialise.cc b/third_party/nix/src/libutil/serialise.cc
new file mode 100644
index 000000000000..288255089bb6
--- /dev/null
+++ b/third_party/nix/src/libutil/serialise.cc
@@ -0,0 +1,311 @@
+#include "libutil/serialise.hh"
+
+#include <boost/coroutine2/coroutine.hpp>
+#include <cerrno>
+#include <cstring>
+#include <memory>
+#include <utility>
+
+#include <glog/logging.h>
+
+#include "libutil/util.hh"
+
+namespace nix {
+
+void BufferedSink::operator()(const unsigned char* data, size_t len) {
+  if (!buffer) {
+    buffer = decltype(buffer)(new unsigned char[bufSize]);
+  }
+
+  while (len != 0u) {
+    /* Optimisation: bypass the buffer if the data exceeds the
+       buffer size. */
+    if (bufPos + len >= bufSize) {
+      flush();
+      write(data, len);
+      break;
+    }
+    /* Otherwise, copy the bytes to the buffer.  Flush the buffer
+       when it's full. */
+    size_t n = bufPos + len > bufSize ? bufSize - bufPos : len;
+    memcpy(buffer.get() + bufPos, data, n);
+    data += n;
+    bufPos += n;
+    len -= n;
+    if (bufPos == bufSize) {
+      flush();
+    }
+  }
+}
+
+void BufferedSink::flush() {
+  if (bufPos == 0) {
+    return;
+  }
+  size_t n = bufPos;
+  bufPos = 0;  // don't trigger the assert() in ~BufferedSink()
+  write(buffer.get(), n);
+}
+
+FdSink::~FdSink() {
+  try {
+    flush();
+  } catch (...) {
+    ignoreException();
+  }
+}
+
+size_t threshold = 256 * 1024 * 1024;
+
+static void warnLargeDump() {
+  LOG(WARNING)
+      << "dumping very large path (> 256 MiB); this may run out of memory";
+}
+
+void FdSink::write(const unsigned char* data, size_t len) {
+  written += len;
+  static bool warned = false;
+  if (warn && !warned) {
+    if (written > threshold) {
+      warnLargeDump();
+      warned = true;
+    }
+  }
+  try {
+    writeFull(fd, data, len);
+  } catch (SysError& e) {
+    _good = false;
+    throw;
+  }
+}
+
+bool FdSink::good() { return _good; }
+
+void Source::operator()(unsigned char* data, size_t len) {
+  while (len != 0u) {
+    size_t n = read(data, len);
+    data += n;
+    len -= n;
+  }
+}
+
+std::string Source::drain() {
+  std::string s;
+  std::vector<unsigned char> buf(8192);
+  while (true) {
+    size_t n;
+    try {
+      n = read(buf.data(), buf.size());
+      s.append(reinterpret_cast<char*>(buf.data()), n);
+    } catch (EndOfFile&) {
+      break;
+    }
+  }
+  return s;
+}
+
+size_t BufferedSource::read(unsigned char* data, size_t len) {
+  if (!buffer) {
+    buffer = decltype(buffer)(new unsigned char[bufSize]);
+  }
+
+  if (bufPosIn == 0u) {
+    bufPosIn = readUnbuffered(buffer.get(), bufSize);
+  }
+
+  /* Copy out the data in the buffer. */
+  size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len;
+  memcpy(data, buffer.get() + bufPosOut, n);
+  bufPosOut += n;
+  if (bufPosIn == bufPosOut) {
+    bufPosIn = bufPosOut = 0;
+  }
+  return n;
+}
+
+bool BufferedSource::hasData() { return bufPosOut < bufPosIn; }
+
+size_t FdSource::readUnbuffered(unsigned char* data, size_t len) {
+  ssize_t n;
+  do {
+    checkInterrupt();
+    n = ::read(fd, reinterpret_cast<char*>(data), len);
+  } while (n == -1 && errno == EINTR);
+  if (n == -1) {
+    _good = false;
+    throw SysError("reading from file");
+  }
+  if (n == 0) {
+    _good = false;
+    throw EndOfFile("unexpected end-of-file");
+  }
+  read += n;
+  return n;
+}
+
+bool FdSource::good() { return _good; }
+
+size_t StringSource::read(unsigned char* data, size_t len) {
+  if (pos == s.size()) {
+    throw EndOfFile("end of string reached");
+  }
+  size_t n = s.copy(reinterpret_cast<char*>(data), len, pos);
+  pos += n;
+  return n;
+}
+
+#if BOOST_VERSION >= 106300 && BOOST_VERSION < 106600
+#error Coroutines are broken in this version of Boost!
+#endif
+
+std::unique_ptr<Source> sinkToSource(const std::function<void(Sink&)>& fun,
+                                     const std::function<void()>& eof) {
+  struct SinkToSource : Source {
+    using coro_t = boost::coroutines2::coroutine<std::string>;
+
+    std::function<void(Sink&)> fun;
+    std::function<void()> eof;
+    std::optional<coro_t::pull_type> coro;
+    bool started = false;
+
+    SinkToSource(std::function<void(Sink&)> fun, std::function<void()> eof)
+        : fun(std::move(fun)), eof(std::move(eof)) {}
+
+    std::string cur;
+    size_t pos = 0;
+
+    size_t read(unsigned char* data, size_t len) override {
+      if (!coro) {
+        coro = coro_t::pull_type([&](coro_t::push_type& yield) {
+          LambdaSink sink([&](const unsigned char* data, size_t len) {
+            if (len != 0u) {
+              yield(std::string(reinterpret_cast<const char*>(data), len));
+            }
+          });
+          fun(sink);
+        });
+      }
+
+      if (!*coro) {
+        eof();
+        abort();
+      }
+
+      if (pos == cur.size()) {
+        if (!cur.empty()) {
+          (*coro)();
+        }
+        cur = coro->get();
+        pos = 0;
+      }
+
+      auto n = std::min(cur.size() - pos, len);
+      memcpy(data, reinterpret_cast<unsigned char*>(cur.data()) + pos, n);
+      pos += n;
+
+      return n;
+    }
+  };
+
+  return std::make_unique<SinkToSource>(fun, eof);
+}
+
+void writePadding(size_t len, Sink& sink) {
+  if ((len % 8) != 0u) {
+    unsigned char zero[8];
+    memset(zero, 0, sizeof(zero));
+    sink(zero, 8 - (len % 8));
+  }
+}
+
+void writeString(const unsigned char* buf, size_t len, Sink& sink) {
+  sink << len;
+  sink(buf, len);
+  writePadding(len, sink);
+}
+
+Sink& operator<<(Sink& sink, const std::string& s) {
+  writeString(reinterpret_cast<const unsigned char*>(s.data()), s.size(), sink);
+  return sink;
+}
+
+template <class T>
+void writeStrings(const T& ss, Sink& sink) {
+  sink << ss.size();
+  for (auto& i : ss) {
+    sink << i;
+  }
+}
+
+Sink& operator<<(Sink& sink, const Strings& s) {
+  writeStrings(s, sink);
+  return sink;
+}
+
+Sink& operator<<(Sink& sink, const StringSet& s) {
+  writeStrings(s, sink);
+  return sink;
+}
+
+void readPadding(size_t len, Source& source) {
+  if ((len % 8) != 0u) {
+    unsigned char zero[8];
+    size_t n = 8 - (len % 8);
+    source(zero, n);
+    for (unsigned int i = 0; i < n; i++) {
+      if (zero[i] != 0u) {
+        throw SerialisationError("non-zero padding");
+      }
+    }
+  }
+}
+
+size_t readString(unsigned char* buf, size_t max, Source& source) {
+  auto len = readNum<size_t>(source);
+  if (len > max) {
+    throw SerialisationError("string is too long");
+  }
+  source(buf, len);
+  readPadding(len, source);
+  return len;
+}
+
+std::string readString(Source& source, size_t max) {
+  auto len = readNum<size_t>(source);
+  if (len > max) {
+    throw SerialisationError("string is too long");
+  }
+  std::string res(len, 0);
+  source(reinterpret_cast<unsigned char*>(res.data()), len);
+  readPadding(len, source);
+  return res;
+}
+
+Source& operator>>(Source& in, std::string& s) {
+  s = readString(in);
+  return in;
+}
+
+template <class T>
+T readStrings(Source& source) {
+  auto count = readNum<size_t>(source);
+  T ss;
+  while (count--) {
+    ss.insert(ss.end(), readString(source));
+  }
+  return ss;
+}
+
+template Paths readStrings(Source& source);
+template PathSet readStrings(Source& source);
+
+void StringSink::operator()(const unsigned char* data, size_t len) {
+  static bool warned = false;
+  if (!warned && s->size() > threshold) {
+    warnLargeDump();
+    warned = true;
+  }
+  s->append(reinterpret_cast<const char*>(data), len);
+}
+
+}  // namespace nix