1 files changed, 93 insertions, 0 deletions
diff --git a/third_party/nix/src/libutil/xml-writer.cc b/third_party/nix/src/libutil/xml-writer.cc
new file mode 100644
index 000000000000..d34e9a2f0d59
--- /dev/null
+++ b/third_party/nix/src/libutil/xml-writer.cc
@@ -0,0 +1,93 @@
+#include "xml-writer.hh"
+
+#include <cassert>
+
+namespace nix {
+
+XMLWriter::XMLWriter(bool indent, std::ostream& output)
+    : output(output), indent(indent) {
+  output << "<?xml version='1.0' encoding='utf-8'?>" << std::endl;
+  closed = false;
+}
+
+XMLWriter::~XMLWriter() { close(); }
+
+void XMLWriter::close() {
+  if (closed) {
+    return;
+  }
+  while (!pendingElems.empty()) {
+    closeElement();
+  }
+  closed = true;
+}
+
+void XMLWriter::indent_(size_t depth) {
+  if (!indent) {
+    return;
+  }
+  output << std::string(depth * 2, ' ');
+}
+
+void XMLWriter::openElement(const std::string& name, const XMLAttrs& attrs) {
+  assert(!closed);
+  indent_(pendingElems.size());
+  output << "<" << name;
+  writeAttrs(attrs);
+  output << ">";
+  if (indent) {
+    output << std::endl;
+  }
+  pendingElems.push_back(name);
+}
+
+void XMLWriter::closeElement() {
+  assert(!pendingElems.empty());
+  indent_(pendingElems.size() - 1);
+  output << "</" << pendingElems.back() << ">";
+  if (indent) {
+    output << std::endl;
+  }
+  pendingElems.pop_back();
+  if (pendingElems.empty()) {
+    closed = true;
+  }
+}
+
+void XMLWriter::writeEmptyElement(const std::string& name,
+                                  const XMLAttrs& attrs) {
+  assert(!closed);
+  indent_(pendingElems.size());
+  output << "<" << name;
+  writeAttrs(attrs);
+  output << " />";
+  if (indent) {
+    output << std::endl;
+  }
+}
+
+void XMLWriter::writeAttrs(const XMLAttrs& attrs) {
+  for (auto& i : attrs) {
+    output << " " << i.first << "=\"";
+    for (char c : i.second) {
+      if (c == '"') {
+        output << "&quot;";
+      } else if (c == '<') {
+        output << "&lt;";
+      } else if (c == '>') {
+        output << "&gt;";
+      } else if (c == '&') {
+        output << "&amp;";
+        /* Escape newlines to prevent attribute normalisation (see
+           XML spec, section 3.3.3. */
+      } else if (c == '\n') {
+        output << "&#xA;";
+      } else {
+        output << c;
+      }
+    }
+    output << "\"";
+  }
+}
+
+}  // namespace nix