//===- CheckerRegistry.cpp - Maintains all available checkers -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/LLVM.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/AnalyzerOptions.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/DynamicLibrary.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>

using namespace clang;
using namespace ento;
using llvm::sys::DynamicLibrary;

using RegisterCheckersFn = void (*)(CheckerRegistry &);

static bool isCompatibleAPIVersion(const char *VersionString) {
  // If the version string is null, its not an analyzer plugin.
  if (!VersionString)
    return false;

  // For now, none of the static analyzer API is considered stable.
  // Versions must match exactly.
  return strcmp(VersionString, CLANG_ANALYZER_API_VERSION_STRING) == 0;
}

namespace {
template <class T> struct FullNameLT {
  bool operator()(const T &Lhs, const T &Rhs) {
    return Lhs.FullName < Rhs.FullName;
  }
};

using CheckerNameLT = FullNameLT<CheckerRegistry::CheckerInfo>;
} // end of anonymous namespace

static constexpr char PackageSeparator = '.';

static bool isInPackage(const CheckerRegistry::CheckerInfo &Checker,
                        StringRef PackageName) {
  // Does the checker's full name have the package as a prefix?
  if (!Checker.FullName.startswith(PackageName))
    return false;

  // Is the package actually just the name of a specific checker?
  if (Checker.FullName.size() == PackageName.size())
    return true;

  // Is the checker in the package (or a subpackage)?
  if (Checker.FullName[PackageName.size()] == PackageSeparator)
    return true;

  return false;
}

CheckerRegistry::CheckerInfoListRange
CheckerRegistry::getMutableCheckersForCmdLineArg(StringRef CmdLineArg) {

  assert(std::is_sorted(Checkers.begin(), Checkers.end(), CheckerNameLT{}) &&
         "In order to efficiently gather checkers, this function expects them "
         "to be already sorted!");

  // Use a binary search to find the possible start of the package.
  CheckerRegistry::CheckerInfo PackageInfo(nullptr, nullptr, CmdLineArg, "",
                                           "");
  auto It = std::lower_bound(Checkers.begin(), Checkers.end(), PackageInfo,
                             CheckerNameLT{});

  if (!isInPackage(*It, CmdLineArg))
    return {Checkers.end(), Checkers.end()};

  // See how large the package is.
  // If the package doesn't exist, assume the option refers to a single
  // checker.
  size_t Size = 1;
  llvm::StringMap<size_t>::const_iterator PackageSize =
      PackageSizes.find(CmdLineArg);

  if (PackageSize != PackageSizes.end())
    Size = PackageSize->getValue();

  return {It, It + Size};
}

CheckerRegistry::CheckerRegistry(
    ArrayRef<std::string> Plugins, DiagnosticsEngine &Diags,
    AnalyzerOptions &AnOpts, const LangOptions &LangOpts,
    ArrayRef<std::function<void(CheckerRegistry &)>> CheckerRegistrationFns)
    : Diags(Diags), AnOpts(AnOpts), LangOpts(LangOpts) {

  // Register builtin checkers.
#define GET_CHECKERS
#define CHECKER(FULLNAME, CLASS, HELPTEXT, DOC_URI)                            \
  addChecker(register##CLASS, shouldRegister##CLASS, FULLNAME, HELPTEXT,       \
             DOC_URI);

#include "clang/StaticAnalyzer/Checkers/Checkers.inc"
#undef CHECKER
#undef GET_CHECKERS
#undef PACKAGE
#undef GET_PACKAGES

  // Register checkers from plugins.
  for (const std::string &Plugin : Plugins) {
    // Get access to the plugin.
    std::string ErrorMsg;
    DynamicLibrary Lib =
        DynamicLibrary::getPermanentLibrary(Plugin.c_str(), &ErrorMsg);
    if (!Lib.isValid()) {
      Diags.Report(diag::err_fe_unable_to_load_plugin) << Plugin << ErrorMsg;
      continue;
    }

    // See if its compatible with this build of clang.
    const char *PluginAPIVersion = static_cast<const char *>(
        Lib.getAddressOfSymbol("clang_analyzerAPIVersionString"));

    if (!isCompatibleAPIVersion(PluginAPIVersion)) {
      Diags.Report(diag::warn_incompatible_analyzer_plugin_api)
          << llvm::sys::path::filename(Plugin);
      Diags.Report(diag::note_incompatible_analyzer_plugin_api)
          << CLANG_ANALYZER_API_VERSION_STRING << PluginAPIVersion;
      continue;
    }

    // Register its checkers.
    RegisterCheckersFn RegisterPluginCheckers =
        reinterpret_cast<RegisterCheckersFn>(
            Lib.getAddressOfSymbol("clang_registerCheckers"));
    if (RegisterPluginCheckers)
      RegisterPluginCheckers(*this);
  }

  // Register statically linked checkers, that aren't generated from the tblgen
  // file, but rather passed their registry function as a parameter in
  // checkerRegistrationFns.

  for (const auto &Fn : CheckerRegistrationFns)
    Fn(*this);

  // Sort checkers for efficient collection.
  // FIXME: Alphabetical sort puts 'experimental' in the middle.
  // Would it be better to name it '~experimental' or something else
  // that's ASCIIbetically last?
  llvm::sort(Checkers, CheckerNameLT{});

#define GET_CHECKER_DEPENDENCIES

#define CHECKER_DEPENDENCY(FULLNAME, DEPENDENCY)                               \
  addDependency(FULLNAME, DEPENDENCY);

#include "clang/StaticAnalyzer/Checkers/Checkers.inc"
#undef CHECKER_DEPENDENCY
#undef GET_CHECKER_DEPENDENCIES

  // Parse '-analyzer-checker' and '-analyzer-disable-checker' options from the
  // command line.
  for (const std::pair<std::string, bool> &Opt : AnOpts.CheckersControlList) {
    CheckerInfoListRange CheckerForCmdLineArg =
        getMutableCheckersForCmdLineArg(Opt.first);

    if (CheckerForCmdLineArg.begin() == CheckerForCmdLineArg.end()) {
      Diags.Report(diag::err_unknown_analyzer_checker) << Opt.first;
      Diags.Report(diag::note_suggest_disabling_all_checkers);
    }

    for (CheckerInfo &checker : CheckerForCmdLineArg) {
      checker.State = Opt.second ? StateFromCmdLine::State_Enabled
                                 : StateFromCmdLine::State_Disabled;
    }
  }
}

/// Collects dependencies in \p ret, returns false on failure.
static bool
collectDependenciesImpl(const CheckerRegistry::ConstCheckerInfoList &Deps,
                        const LangOptions &LO,
                        CheckerRegistry::CheckerInfoSet &Ret);

/// Collects dependenies in \p enabledCheckers. Return None on failure.
LLVM_NODISCARD
static llvm::Optional<CheckerRegistry::CheckerInfoSet>
collectDependencies(const CheckerRegistry::CheckerInfo &checker,
                    const LangOptions &LO) {

  CheckerRegistry::CheckerInfoSet Ret;
  // Add dependencies to the enabled checkers only if all of them can be
  // enabled.
  if (!collectDependenciesImpl(checker.Dependencies, LO, Ret))
    return None;

  return Ret;
}

static bool
collectDependenciesImpl(const CheckerRegistry::ConstCheckerInfoList &Deps,
                        const LangOptions &LO,
                        CheckerRegistry::CheckerInfoSet &Ret) {

  for (const CheckerRegistry::CheckerInfo *Dependency : Deps) {

    if (Dependency->isDisabled(LO))
      return false;

    // Collect dependencies recursively.
    if (!collectDependenciesImpl(Dependency->Dependencies, LO, Ret))
      return false;

    Ret.insert(Dependency);
  }

  return true;
}

CheckerRegistry::CheckerInfoSet CheckerRegistry::getEnabledCheckers() const {

  CheckerInfoSet EnabledCheckers;

  for (const CheckerInfo &Checker : Checkers) {
    if (!Checker.isEnabled(LangOpts))
      continue;

    // Recursively enable its dependencies.
    llvm::Optional<CheckerInfoSet> Deps =
        collectDependencies(Checker, LangOpts);

    if (!Deps) {
      // If we failed to enable any of the dependencies, don't enable this
      // checker.
      continue;
    }

    // Note that set_union also preserves the order of insertion.
    EnabledCheckers.set_union(*Deps);

    // Enable the checker.
    EnabledCheckers.insert(&Checker);
  }

  return EnabledCheckers;
}

void CheckerRegistry::addChecker(InitializationFunction Rfn,
                                 ShouldRegisterFunction Sfn, StringRef Name,
                                 StringRef Desc, StringRef DocsUri) {
  Checkers.emplace_back(Rfn, Sfn, Name, Desc, DocsUri);

  // Record the presence of the checker in its packages.
  StringRef PackageName, LeafName;
  std::tie(PackageName, LeafName) = Name.rsplit(PackageSeparator);
  while (!LeafName.empty()) {
    PackageSizes[PackageName] += 1;
    std::tie(PackageName, LeafName) = PackageName.rsplit(PackageSeparator);
  }
}

void CheckerRegistry::addDependency(StringRef FullName, StringRef dependency) {
  auto CheckerThatNeedsDeps = [&FullName](const CheckerInfo &Chk) {
    return Chk.FullName == FullName;
  };
  auto Dependency = [&dependency](const CheckerInfo &Chk) {
    return Chk.FullName == dependency;
  };

  auto CheckerIt = llvm::find_if(Checkers, CheckerThatNeedsDeps);
  assert(CheckerIt != Checkers.end() &&
         "Failed to find the checker while attempting to set up its "
         "dependencies!");

  auto DependencyIt = llvm::find_if(Checkers, Dependency);
  assert(DependencyIt != Checkers.end() &&
         "Failed to find the dependency of a checker!");

  CheckerIt->Dependencies.push_back(&*DependencyIt);
}

void CheckerRegistry::initializeManager(CheckerManager &CheckerMgr) const {
  // Collect checkers enabled by the options.
  CheckerInfoSet enabledCheckers = getEnabledCheckers();

  // Initialize the CheckerManager with all enabled checkers.
  for (const auto *Checker : enabledCheckers) {
    CheckerMgr.setCurrentCheckName(CheckName(Checker->FullName));
    Checker->Initialize(CheckerMgr);
  }
}

void CheckerRegistry::validateCheckerOptions() const {
  for (const auto &Config : AnOpts.Config) {
    size_t Pos = Config.getKey().find(':');
    if (Pos == StringRef::npos)
      continue;

    bool HasChecker = false;
    StringRef CheckerName = Config.getKey().substr(0, Pos);
    for (const auto &Checker : Checkers) {
      if (Checker.FullName.startswith(CheckerName) &&
          (Checker.FullName.size() == Pos || Checker.FullName[Pos] == '.')) {
        HasChecker = true;
        break;
      }
    }
    if (!HasChecker)
      Diags.Report(diag::err_unknown_analyzer_checker) << CheckerName;
  }
}

void CheckerRegistry::printCheckerWithDescList(raw_ostream &Out,
                                               size_t MaxNameChars) const {
  // FIXME: Print available packages.

  Out << "CHECKERS:\n";

  // Find the maximum option length.
  size_t OptionFieldWidth = 0;
  for (const auto &Checker : Checkers) {
    // Limit the amount of padding we are willing to give up for alignment.
    //   Package.Name     Description  [Hidden]
    size_t NameLength = Checker.FullName.size();
    if (NameLength <= MaxNameChars)
      OptionFieldWidth = std::max(OptionFieldWidth, NameLength);
  }

  const size_t InitialPad = 2;
  for (const auto &Checker : Checkers) {
    Out.indent(InitialPad) << Checker.FullName;

    int Pad = OptionFieldWidth - Checker.FullName.size();

    // Break on long option names.
    if (Pad < 0) {
      Out << '\n';
      Pad = OptionFieldWidth + InitialPad;
    }
    Out.indent(Pad + 2) << Checker.Desc;

    Out << '\n';
  }
}

void CheckerRegistry::printEnabledCheckerList(raw_ostream &Out) const {
  // Collect checkers enabled by the options.
  CheckerInfoSet EnabledCheckers = getEnabledCheckers();

  for (const auto *i : EnabledCheckers)
    Out << i->FullName << '\n';
}