1 files changed, 306 insertions, 0 deletions
diff --git a/apt-pkg/cachefilter-patterns.cc b/apt-pkg/cachefilter-patterns.cc
new file mode 100644
index 000000000..bf6166ee4
--- /dev/null
+++ b/apt-pkg/cachefilter-patterns.cc
@@ -0,0 +1,306 @@
+/*
+ * cachefilter-patterns.cc - Parser for aptitude-style patterns
+ *
+ * Copyright (c) 2019 Canonical Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <apt-pkg/cachefilter-patterns.h>
+
+namespace APT
+{
+namespace Internal
+{
+
+template <class... Args>
+std::string rstrprintf(Args... args)
+{
+   std::string str;
+   strprintf(str, std::forward<Args>(args)...);
+   return str;
+}
+
+// Parse a complete pattern, make sure it's the entire input
+std::unique_ptr<PatternTreeParser::Node> PatternTreeParser::parseTop()
+{
+   skipSpace();
+   auto node = parse();
+   skipSpace();
+
+   if (node->end != sentence.size())
+   {
+      Node node2;
+
+      node2.start = node->end;
+      node2.end = sentence.size();
+      throw Error{node2, "Expected end of file"};
+   }
+
+   return node;
+}
+
+// Parse any pattern
+std::unique_ptr<PatternTreeParser::Node> PatternTreeParser::parse()
+{
+   std::unique_ptr<Node> node;
+   if ((node = parsePattern()) != nullptr)
+      return node;
+   if ((node = parseQuotedWord()) != nullptr)
+      return node;
+   if ((node = parseWord()) != nullptr)
+      return node;
+
+   Node eNode;
+   eNode.end = eNode.start = state.offset;
+   throw Error{eNode, "Expected pattern, quoted word, or word"};
+}
+
+// Parse a list pattern (or function call pattern)
+std::unique_ptr<PatternTreeParser::Node> PatternTreeParser::parsePattern()
+{
+   static const APT::StringView CHARS("0123456789"
+				      "abcdefghijklmnopqrstuvwxyz"
+				      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+				      "-");
+   if (sentence[state.offset] != '?')
+      return nullptr;
+
+   auto node = std::make_unique<PatternNode>();
+   node->end = node->start = state.offset;
+   state.offset++;
+
+   while (CHARS.find(sentence[state.offset]) != APT::StringView::npos)
+   {
+      ++state.offset;
+   }
+
+   node->term = sentence.substr(node->start, state.offset - node->start);
+
+   node->end = skipSpace();
+   // We don't have any arguments, return node;
+   if (sentence[state.offset] != '(')
+      return node;
+   node->end = ++state.offset;
+   skipSpace();
+
+   node->haveArgumentList = true;
+
+   // Empty argument list, return
+   if (sentence[state.offset] == ')')
+   {
+      node->end = ++state.offset;
+      return node;
+   }
+
+   node->arguments.push_back(parse());
+   skipSpace();
+   while (sentence[state.offset] == ',')
+   {
+      ++state.offset;
+      skipSpace();
+      // This was a trailing comma - allow it and break the loop
+      if (sentence[state.offset] == ')')
+	 break;
+      node->arguments.push_back(parse());
+      skipSpace();
+   }
+
+   node->end = state.offset;
+   if (sentence[state.offset] != ')')
+      throw Error{node->arguments.empty() ? *node : *node->arguments[node->arguments.size() - 1],
+		  rstrprintf("Expected closing parenthesis or comma after last argument, received %c", sentence[state.offset])};
+
+   node->end = ++state.offset;
+   return node;
+}
+
+// Parse a quoted word atom
+std::unique_ptr<PatternTreeParser::Node> PatternTreeParser::parseQuotedWord()
+{
+   if (sentence[state.offset] != '"')
+      return nullptr;
+
+   auto node = std::make_unique<WordNode>();
+   node->start = state.offset;
+
+   // Eat beginning of string
+   state.offset++;
+
+   while (sentence[state.offset] != '"' && sentence[state.offset] != '\0')
+      state.offset++;
+
+   // End of string
+   if (sentence[state.offset] != '"')
+      throw Error{*node, "Could not find end of string"};
+   state.offset++;
+
+   node->end = state.offset;
+   node->word = sentence.substr(node->start + 1, node->end - node->start - 2);
+
+   return node;
+}
+
+// Parse a bare word atom
+std::unique_ptr<PatternTreeParser::Node> PatternTreeParser::parseWord()
+{
+   static const APT::StringView DISALLOWED_START("?~,()\0", 6);
+   static const APT::StringView DISALLOWED(",()\0", 4);
+   if (DISALLOWED_START.find(sentence[state.offset]) != APT::StringView::npos)
+      return nullptr;
+
+   auto node = std::make_unique<WordNode>();
+   node->start = state.offset;
+
+   while (DISALLOWED.find(sentence[state.offset]) == APT::StringView::npos)
+      state.offset++;
+
+   node->end = state.offset;
+   node->word = sentence.substr(node->start, node->end - node->start);
+   return node;
+}
+
+// Rendering of the tree in JSON for debugging
+std::ostream &PatternTreeParser::PatternNode::render(std::ostream &os)
+{
+   os << "{"
+      << "\"term\": \"" << term.to_string() << "\",\n"
+      << "\"arguments\": [\n";
+   for (auto &node : arguments)
+      node->render(os) << "," << std::endl;
+   os << "null]\n";
+   os << "}\n";
+   return os;
+}
+
+std::ostream &PatternTreeParser::WordNode::render(std::ostream &os)
+{
+   os << '"' << word.to_string() << '"';
+   return os;
+}
+
+std::nullptr_t PatternTreeParser::Node::error(std::string message)
+{
+   throw Error{*this, message};
+}
+
+bool PatternTreeParser::PatternNode::matches(APT::StringView name, int min, int max)
+{
+   if (name != term)
+      return false;
+   if (max != 0 && !haveArgumentList)
+      error(rstrprintf("%s expects an argument list", term.to_string().c_str()));
+   if (max == 0 && haveArgumentList)
+      error(rstrprintf("%s does not expect an argument list", term.to_string().c_str()));
+   if (min >= 0 && min == max && (arguments.size() != size_t(min)))
+      error(rstrprintf("%s expects %d arguments, but received %d arguments", term.to_string().c_str(), min, arguments.size()));
+   if (min >= 0 && arguments.size() < size_t(min))
+      error(rstrprintf("%s expects at least %d arguments, but received %d arguments", term.to_string().c_str(), min, arguments.size()));
+   if (max >= 0 && arguments.size() > size_t(max))
+      error(rstrprintf("%s expects at most %d arguments, but received %d arguments", term.to_string().c_str(), max, arguments.size()));
+   return true;
+}
+
+std::unique_ptr<APT::CacheFilter::Matcher> PatternParser::aPattern(std::unique_ptr<PatternTreeParser::Node> &nodeP)
+{
+   assert(nodeP != nullptr);
+   auto node = dynamic_cast<PatternTreeParser::PatternNode *>(nodeP.get());
+   if (node == nullptr)
+      nodeP->error("Expected a pattern");
+
+   if (node->matches("?architecture", 1, 1))
+      return std::make_unique<APT::CacheFilter::PackageArchitectureMatchesSpecification>(aWord(node->arguments[0]));
+   if (node->matches("?automatic", 0, 0))
+      return std::make_unique<Patterns::PackageIsAutomatic>(file);
+   if (node->matches("?broken", 0, 0))
+      return std::make_unique<Patterns::PackageIsBroken>(file);
+   if (node->matches("?config-files", 0, 0))
+      return std::make_unique<Patterns::PackageIsConfigFiles>();
+   if (node->matches("?essential", 0, 0))
+      return std::make_unique<Patterns::PackageIsEssential>();
+   if (node->matches("?exact-name", 1, 1))
+      return std::make_unique<Patterns::PackageHasExactName>(aWord(node->arguments[0]));
+   if (node->matches("?false", 0, 0))
+      return std::make_unique<APT::CacheFilter::FalseMatcher>();
+   if (node->matches("?garbage", 0, 0))
+      return std::make_unique<Patterns::PackageIsGarbage>(file);
+   if (node->matches("?installed", 0, 0))
+      return std::make_unique<Patterns::PackageIsInstalled>(file);
+   if (node->matches("?name", 1, 1))
+      return std::make_unique<APT::CacheFilter::PackageNameMatchesRegEx>(aWord(node->arguments[0]));
+   if (node->matches("?not", 1, 1))
+      return std::make_unique<APT::CacheFilter::NOTMatcher>(aPattern(node->arguments[0]).release());
+   if (node->matches("?obsolete", 0, 0))
+      return std::make_unique<Patterns::PackageIsObsolete>();
+   if (node->matches("?true", 0, 0))
+      return std::make_unique<APT::CacheFilter::TrueMatcher>();
+   if (node->matches("?upgradable", 0, 0))
+      return std::make_unique<Patterns::PackageIsUpgradable>(file);
+   if (node->matches("?virtual", 0, 0))
+      return std::make_unique<Patterns::PackageIsVirtual>();
+   if (node->matches("?x-name-fnmatch", 1, 1))
+      return std::make_unique<APT::CacheFilter::PackageNameMatchesFnmatch>(aWord(node->arguments[0]));
+
+   // Variable argument patterns
+   if (node->matches("?and", 0, -1))
+   {
+      auto pattern = std::make_unique<APT::CacheFilter::ANDMatcher>();
+      for (auto &arg : node->arguments)
+	 pattern->AND(aPattern(arg).release());
+      return pattern;
+   }
+   if (node->matches("?or", 0, -1))
+   {
+      auto pattern = std::make_unique<APT::CacheFilter::ORMatcher>();
+
+      for (auto &arg : node->arguments)
+	 pattern->OR(aPattern(arg).release());
+      return pattern;
+   }
+
+   node->error(rstrprintf("Unrecognized pattern '%s'", node->term.to_string().c_str()));
+
+   return nullptr;
+}
+
+std::string PatternParser::aWord(std::unique_ptr<PatternTreeParser::Node> &nodeP)
+{
+   assert(nodeP != nullptr);
+   auto node = dynamic_cast<PatternTreeParser::WordNode *>(nodeP.get());
+   if (node == nullptr)
+      nodeP->error("Expected a word");
+   return node->word.to_string();
+}
+
+} // namespace Internal
+
+// The bridge into the public world
+std::unique_ptr<APT::CacheFilter::Matcher> APT::CacheFilter::ParsePattern(APT::StringView pattern, pkgCacheFile *file)
+{
+   if (file != nullptr && !file->BuildDepCache())
+      return nullptr;
+
+   try
+   {
+      auto top = APT::Internal::PatternTreeParser(pattern).parseTop();
+      APT::Internal::PatternParser parser{file};
+      return parser.aPattern(top);
+   }
+   catch (APT::Internal::PatternTreeParser::Error &e)
+   {
+      std::stringstream ss;
+      ss << "input:" << e.location.start << "-" << e.location.end << ": error: " << e.message << "\n";
+      ss << pattern.to_string() << "\n";
+      for (size_t i = 0; i < e.location.start; i++)
+	 ss << " ";
+      for (size_t i = e.location.start; i < e.location.end; i++)
+	 ss << "^";
+
+      ss << "\n";
+
+      _error->Error("%s", ss.str().c_str());
+      return nullptr;
+   }
+}
+
+} // namespace APT