tools/versioner/src/versioner.cpp - platform/bionic - Git at Google

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <dirent.h>
 #include <err.h>
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>

 #if defined(__linux__)
 #include <sched.h>
 #endif

 #include <atomic>
 #include <chrono>
 #include <functional>
 #include <iostream>
 #include <map>
 #include <memory>
 #include <set>
 #include <sstream>
 #include <string>
 #include <string_view>
 #include <thread>
 #include <unordered_map>
 #include <vector>

 #include <llvm/ADT/StringRef.h>

 #include <android-base/file.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
 #include <android-base/strings.h>

 #include "Arch.h"
 #include "DeclarationDatabase.h"
 #include "Driver.h"
 #include "Preprocessor.h"
 #include "SymbolDatabase.h"
 #include "Utils.h"
 #include "VFS.h"

 #include "versioner.h"

 using namespace std::chrono_literals;
 using namespace std::string_literals;

 bool strict;
 bool verbose;
 bool add_include;

 static int getCpuCount();
 static int max_thread_count = getCpuCount();

 static int getCpuCount() {
 #if defined(__linux__)
   cpu_set_t cpu_set;
   int rc = sched_getaffinity(getpid(), sizeof(cpu_set), &cpu_set);
   if (rc != 0) {
     err(1, "sched_getaffinity failed");
   }
   return CPU_COUNT(&cpu_set);
 #else
   return 1;
 #endif
 }

 namespace {
 struct HeaderLocationInformation {
   std::string header_path;
   std::string dependency_dir;
   // Absolute paths to ignore all children -- including subdirectories -- of.
   std::unordered_set<std::string> ignored_directories;
 };
 }

 static bool is_dir(const std::string& path) {
   struct stat st;
   return stat(path.c_str(), &st) == 0 && S_ISDIR(st.st_mode);
 }

 static CompilationRequirements collectRequirements(const Arch& arch,
                                                    const HeaderLocationInformation& location) {
   std::vector<std::string> headers =
       collectHeaders(location.header_path, location.ignored_directories);
   std::vector<std::string> dependencies;

   if (is_dir(location.header_path)) {
     dependencies.emplace_back(location.header_path);
   }

   if (!location.dependency_dir.empty()) {
     auto collect_children = [&dependencies](const std::string& dir_path) {
       DIR* dir = opendir(dir_path.c_str());
       if (!dir) {
         err(1, "failed to open dependency directory '%s'", dir_path.c_str());
       }

       struct dirent* dent;
       while ((dent = readdir(dir))) {
         if (dent->d_name[0] == '.') {
           continue;
         }

         // TODO: Resolve symlinks.
         std::string dependency = dir_path + "/" + dent->d_name;

         struct stat st;
         if (stat(dependency.c_str(), &st) != 0) {
           err(1, "failed to stat dependency '%s'", dependency.c_str());
         }

         if (!S_ISDIR(st.st_mode)) {
           errx(1, "'%s' is not a directory", dependency.c_str());
         }

         dependencies.push_back(dependency);
       }

       closedir(dir);
     };

     collect_children(location.dependency_dir + "/common");
     collect_children(location.dependency_dir + "/" + to_string(arch));
   }

   auto new_end = std::remove_if(headers.begin(), headers.end(), [&arch](llvm::StringRef header) {
     for (const auto& it : ignored_headers) {
       if (it.second.find(arch) == it.second.end()) {
         continue;
       }

       if (header.endswith("/" + it.first)) {
         return true;
       }
     }
     return false;
   });

   headers.erase(new_end, headers.end());

   CompilationRequirements result = { .headers = headers, .dependencies = dependencies };
   return result;
 }

 static std::set<CompilationType> generateCompilationTypes(const std::set<Arch> selected_architectures,
                                                           const std::set<int>& selected_levels) {
   std::set<CompilationType> result;
   for (const auto& arch : selected_architectures) {
     int min_api = arch_min_api[arch];
     for (int api_level : selected_levels) {
       if (api_level < min_api) {
         continue;
       }

       for (int file_offset_bits : { 32, 64 }) {
         for (bool cpp : { true, false }) {
           CompilationType type = {
             .arch = arch, .cpp = cpp, .api_level = api_level, .file_offset_bits = file_offset_bits
           };
           result.insert(type);
         }
       }
     }
   }
   return result;
 }

 static std::unique_ptr<HeaderDatabase> compileHeaders(const std::set<CompilationType>& types,
                                                       const HeaderLocationInformation& location) {
   if (types.empty()) {
     errx(1, "compileHeaders received no CompilationTypes");
   }

   auto vfs = createCommonVFS(location.header_path, location.dependency_dir, add_include);

   size_t thread_count = max_thread_count;
   std::vector<std::thread> threads;

   std::map<CompilationType, HeaderDatabase> header_databases;
   std::unordered_map<Arch, CompilationRequirements> requirements;

   auto result = std::make_unique<HeaderDatabase>();
   for (const auto& type : types) {
     if (requirements.count(type.arch) == 0) {
       requirements[type.arch] = collectRequirements(type.arch, location);
     }
   }

   initializeTargetCC1FlagCache(vfs, types, requirements);

   std::vector<std::pair<CompilationType, const std::string&>> jobs;
   std::atomic<size_t> job_index(0);
   for (CompilationType type : types) {
     CompilationRequirements& req = requirements[type.arch];
     for (const std::string& header : req.headers) {
       jobs.emplace_back(type, header);
     }
   }

   // Dup an empty file to stdin, so that we can use `clang -include a.h -` instead of `clang a.h`,
   // since some warnings don't get generated in files that are compiled directly.
   FILE* empty_file = tmpfile();
   if (!empty_file) {
     err(1, "failed to create temporary file");
   }

   int empty_file_fd = fileno(empty_file);
   if (empty_file_fd == -1) {
     errx(1, "fileno failed on tmpfile");
   }

   dup2(empty_file_fd, STDIN_FILENO);
   fclose(empty_file);

   thread_count = std::min(thread_count, jobs.size());

   if (thread_count == 1) {
     for (const auto& job : jobs) {
       compileHeader(vfs, result.get(), job.first, job.second);
     }
   } else {
     // Spawn threads.
     for (size_t i = 0; i < thread_count; ++i) {
       threads.emplace_back([&jobs, &job_index, &result, vfs]() {
         while (true) {
           size_t idx = job_index++;
           if (idx >= jobs.size()) {
             return;
           }

           const auto& job = jobs[idx];
           compileHeader(vfs, result.get(), job.first, job.second);
         }
       });
     }

     // Reap them.
     for (auto& thread : threads) {
       thread.join();
     }
     threads.clear();
   }

   return result;
 }

 static std::set<CompilationType> getCompilationTypes(const Declaration* decl) {
   std::set<CompilationType> result;
   for (const auto& it : decl->availability) {
     result.insert(it.first);
   }
   return result;
 }

 template<typename T>
 static std::vector<T> Intersection(const std::set<T>& a, const std::set<T>& b) {
   std::vector<T> intersection;
   std::set_intersection(a.begin(), a.end(), b.begin(), b.end(), std::back_inserter(intersection));
   return intersection;
 }

 // Perform a validity check on a symbol's declarations, enforcing the following invariants:
 //   1. At most one inline definition of the function exists (overloaded inline functions for
 //      _FORTIFY_SOURCE do not count because they are usually introduced to intercept the original
 //      functions or usually have enable_if attributes).
 //   2. All of the availability declarations for a symbol are compatible.
 //      If a function is declared as an inline before a certain version, the inline definition
 //      should have no version tag.
 //   3. Each availability type must only be present globally or on a per-arch basis.
 //      (e.g. __INTRODUCED_IN_32(21) __INTRODUCED_IN_64(22) __DEPRECATED_IN(23) is fine,
 //      but not __INTRODUCED_IN(9) __INTRODUCED_IN_32(10))
 static bool checkSymbol(const Symbol& symbol) {
   std::string cwd = getWorkingDir() + "/";

   std::unordered_map<const Declaration*, std::set<CompilationType>> inline_definitions;
   for (const auto& decl_it : symbol.declarations) {
     const Declaration* decl = &decl_it.second;
     if (decl->is_definition && !decl->fortify_inline) {
       std::set<CompilationType> compilation_types = getCompilationTypes(decl);
       for (const auto& inline_def_it : inline_definitions) {
         auto intersection = Intersection(compilation_types, inline_def_it.second);
         if (!intersection.empty()) {
           fprintf(stderr, "versioner: conflicting inline definitions for symbol %s:\n",
                   symbol.name.c_str());
           fprintf(stderr, "  declarations visible in: %s\n", Join(intersection, ", ").c_str());
           decl->dump(cwd, stderr, 4);
           inline_def_it.first->dump(cwd, stderr, 4);
           return false;
         }
       }

       inline_definitions[decl] = std::move(compilation_types);
     }

     DeclarationAvailability availability;
     if (!decl->calculateAvailability(&availability)) {
       fprintf(stderr, "versioner: failed to calculate availability for declaration:\n");
       decl->dump(cwd, stderr, 2);
       return false;
     }

     if (decl->is_definition && !availability.empty()) {
       fprintf(stderr, "versioner: inline definition has non-empty versioning information:\n");
       decl->dump(cwd, stderr, 2);
       return false;
     }
   }

   DeclarationAvailability availability;
   if (!symbol.calculateAvailability(&availability)) {
     fprintf(stderr, "versioner: inconsistent availability for symbol '%s'\n", symbol.name.c_str());
     symbol.dump(cwd);
     return false;
   }

   // TODO: Check invariant #3.
   return true;
 }

 static bool validityCheck(const HeaderDatabase* database) {
   bool error = false;
   std::string cwd = getWorkingDir() + "/";

   for (const auto& symbol_it : database->symbols) {
     if (!checkSymbol(symbol_it.second)) {
       error = true;
     }
   }
   return !error;
 }

 // Check that our symbol availability declarations match the actual NDK
 // platform symbol availability.
 static bool checkVersions(const std::set<CompilationType>& types,
                           const HeaderDatabase* header_database,
                           const NdkSymbolDatabase& symbol_database) {
   std::string cwd = getWorkingDir() + "/";
   bool failed = false;

   std::map<Arch, std::set<CompilationType>> arch_types;
   for (const CompilationType& type : types) {
     arch_types[type.arch].insert(type);
   }

   std::set<std::string> completely_unavailable;
   std::map<std::string, std::set<CompilationType>> missing_availability;
   std::map<std::string, std::set<CompilationType>> extra_availability;

   for (const auto& symbol_it : header_database->symbols) {
     const auto& symbol_name = symbol_it.first;
     DeclarationAvailability symbol_availability;

     if (!symbol_it.second.calculateAvailability(&symbol_availability)) {
       errx(1, "failed to calculate symbol availability");
     }

     const auto platform_availability_it = symbol_database.find(symbol_name);
     if (platform_availability_it == symbol_database.end()) {
       completely_unavailable.insert(symbol_name);
       continue;
     }

     const auto& platform_availability = platform_availability_it->second;

     for (const CompilationType& type : types) {
       bool should_be_available = true;
       const auto& global_availability = symbol_availability.global_availability;
       const auto& arch_availability = symbol_availability.arch_availability[type.arch];
       if (global_availability.introduced != 0 && global_availability.introduced > type.api_level) {
         should_be_available = false;
       }

       if (arch_availability.introduced != 0 && arch_availability.introduced > type.api_level) {
         should_be_available = false;
       }

       if (global_availability.obsoleted != 0 && global_availability.obsoleted <= type.api_level) {
         should_be_available = false;
       }

       if (arch_availability.obsoleted != 0 && arch_availability.obsoleted <= type.api_level) {
         should_be_available = false;
       }

       // The function declaration might be (validly) missing for the given CompilationType.
       if (!symbol_it.second.hasDeclaration(type)) {
         should_be_available = false;
       }

       bool is_available = platform_availability.count(type);

       if (should_be_available != is_available) {
         if (is_available) {
           extra_availability[symbol_name].insert(type);
         } else {
           missing_availability[symbol_name].insert(type);
         }
       }
     }
   }

   for (const auto& it : symbol_database) {
     const std::string& symbol_name = it.first;

     bool symbol_error = false;
     if (auto missing_it = missing_availability.find(symbol_name);
         missing_it != missing_availability.end()) {
       printf("%s: declaration marked available but symbol missing in [%s]\n", symbol_name.c_str(),
              Join(missing_it->second, ", ").c_str());
       symbol_error = true;
       failed = true;
     }

     if (strict) {
       if (auto extra_it = extra_availability.find(symbol_name);
           extra_it != extra_availability.end()) {
         printf("%s: declaration marked unavailable but symbol available in [%s]\n",
                symbol_name.c_str(), Join(extra_it->second, ", ").c_str());
         symbol_error = true;
         failed = true;
       }
     }

     if (symbol_error) {
       if (auto symbol_it = header_database->symbols.find(symbol_name);
           symbol_it != header_database->symbols.end()) {
         symbol_it->second.dump(cwd);
       } else {
         errx(1, "failed to find symbol in header database");
       }
     }
   }

   // TODO: Verify that function/variable declarations are actually function/variable symbols.
   return !failed;
 }

 static void usage(bool help = false) {
   fprintf(stderr, "Usage: versioner [OPTION]... [HEADER_PATH] [DEPS_PATH]\n");
   if (!help) {
     printf("Try 'versioner -h' for more information.\n");
     exit(1);
   } else {
     fprintf(stderr, "Version headers at HEADER_PATH, with DEPS_PATH/ARCH/* on the include path\n");
     fprintf(stderr, "Autodetects paths if HEADER_PATH and DEPS_PATH are not specified\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "Target specification (defaults to all):\n");
     fprintf(stderr, "  -a API_LEVEL\tbuild with specified API level (can be repeated)\n");
     fprintf(stderr, "    \t\tdefaults to %s\n", Join(default_levels).c_str());
     fprintf(stderr, "  -r ARCH\tbuild with specified architecture (can be repeated)\n");
     fprintf(stderr, "    \t\tvalid architectures are %s\n", Join(supported_archs).c_str());
     fprintf(stderr, "\n");
     fprintf(stderr, "Validation:\n");
     fprintf(stderr, "  -p PATH\tcompare against NDK platform at PATH\n");
     fprintf(stderr, "  -s\t\tenable strict warnings\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "Preprocessing:\n");
     fprintf(stderr, "  -o PATH\tpreprocess header files and emit them at PATH\n");
     fprintf(stderr, "  -f\t\tpreprocess header files even if validation fails\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "Miscellaneous:\n");
     fprintf(stderr, "  -F\t\tdo not ignore FORTIFY headers by default\n");
     fprintf(stderr, "  -d\t\tdump function availability\n");
     fprintf(stderr, "  -j THREADS\tmaximum number of threads to use\n");
     fprintf(stderr, "  -v\t\tenable verbose logging\n");
     fprintf(stderr, "  -h\t\tdisplay this message\n");
     exit(0);
   }
 }

 // versioner uses a prebuilt version of clang, which is not up-to-date wrt/
 // container annotations. So disable container overflow checking. b/37775238
 extern "C" const char* __asan_default_options() {
   return "detect_container_overflow=0";
 }

 int main(int argc, char** argv) {
   std::string cwd = getWorkingDir() + "/";
   std::string platform_dir;
   std::set<Arch> selected_architectures;
   std::set<int> selected_levels;
   std::string preprocessor_output_path;
   bool force = false;
   bool dump = false;
   bool ignore_fortify_headers = true;

   int c;
   while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhFi")) != -1) {
     switch (c) {
       case 'a': {
         char* end;
         int api_level = strtol(optarg, &end, 10);
         if (end == optarg || strlen(end) > 0) {
           usage();
         }

         selected_levels.insert(api_level);
         break;
       }

       case 'r': {
         std::optional<Arch> arch = arch_from_string(optarg);
         if (!arch) {
           errx(1, "unknown architecture '%s'", optarg);
         }
         selected_architectures.insert(*arch);
         break;
       }

       case 'p': {
         if (!platform_dir.empty()) {
           usage();
         }

         platform_dir = optarg;

         if (platform_dir.empty()) {
           usage();
         }

         struct stat st;
         if (stat(platform_dir.c_str(), &st) != 0) {
           err(1, "failed to stat platform directory '%s'", platform_dir.c_str());
         }
         if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode)) {
           errx(1, "'%s' is not a file or directory", optarg);
         }
         break;
       }

       case 's':
         strict = true;
         break;

       case 'o':
         if (!preprocessor_output_path.empty()) {
           usage();
         }
         preprocessor_output_path = optarg;
         if (preprocessor_output_path.empty()) {
           usage();
         }
         break;

       case 'f':
         force = true;
         break;

       case 'd':
         dump = true;
         break;

       case 'j':
         if (!android::base::ParseInt<int>(optarg, &max_thread_count, 1)) {
           usage();
         }
         break;

       case 'v':
         verbose = true;
         break;

       case 'h':
         usage(true);
         break;

       case 'i':
         // Secret option for tests to -include <android/versioning.h>.
         add_include = true;
         break;

       case 'F':
         ignore_fortify_headers = false;
         break;

       default:
         usage();
         break;
     }
   }

   if (argc - optind > 2 || optind > argc) {
     usage();
   }

   HeaderLocationInformation location;

   const char* top = getenv("ANDROID_BUILD_TOP");
   if (!top && (optind == argc || add_include)) {
     fprintf(stderr, "versioner: failed to autodetect bionic paths. Is ANDROID_BUILD_TOP set?\n");
     usage();
   }

   if (optind == argc) {
     // Neither HEADER_PATH nor DEPS_PATH were specified, so try to figure them out.
     std::string versioner_dir = to_string(top) + "/bionic/tools/versioner";
     location.header_path = versioner_dir + "/current";
     location.dependency_dir = versioner_dir + "/dependencies";
     if (platform_dir.empty()) {
       platform_dir = versioner_dir + "/platforms";
     }
   } else {
     if (!android::base::Realpath(argv[optind], &location.header_path)) {
       err(1, "failed to get realpath for path '%s'", argv[optind]);
     }

     if (argc - optind == 2) {
       location.dependency_dir = argv[optind + 1];
     }
   }

   // Every file that lives in bits/fortify is logically a part of a header outside of bits/fortify.
   // This makes the files there impossible to build on their own.
   if (ignore_fortify_headers) {
     std::string fortify_path = location.header_path;
     if (!android::base::EndsWith(location.header_path, "/")) {
       fortify_path += '/';
     }
     fortify_path += "bits/fortify";
     location.ignored_directories.insert(std::move(fortify_path));
   }

   if (selected_levels.empty()) {
     selected_levels = default_levels;
   }

   if (selected_architectures.empty()) {
     selected_architectures = supported_archs;
   }


   struct stat st;
   if (const char *path = location.header_path.c_str(); stat(path, &st) != 0) {
     err(1, "failed to stat '%s'", path);
   }

   std::set<CompilationType> compilation_types;
   std::optional<NdkSymbolDatabase> symbol_database;

   compilation_types = generateCompilationTypes(selected_architectures, selected_levels);

   // Do this before compiling so that we can early exit if the platforms don't match what we
   // expect.
   if (!platform_dir.empty()) {
     symbol_database = parsePlatforms(compilation_types, platform_dir);
   }

   auto start = std::chrono::high_resolution_clock::now();
   std::unique_ptr<HeaderDatabase> declaration_database =
       compileHeaders(compilation_types, location);
   auto end = std::chrono::high_resolution_clock::now();

   if (verbose) {
     auto diff = (end - start) / 1.0ms;
     printf("Compiled headers for %zu targets in %0.2LFms\n", compilation_types.size(), diff);
   }

   bool failed = false;
   if (dump) {
     declaration_database->dump(location.header_path + "/");
   } else {
     if (!validityCheck(declaration_database.get())) {
       printf("versioner: validity check failed\n");
       failed = true;
     }

     if (symbol_database) {
       if (!checkVersions(compilation_types, declaration_database.get(), *symbol_database)) {
         printf("versioner: version check failed\n");
         failed = true;
       }
     }
   }

   if (!preprocessor_output_path.empty() && (force || !failed)) {
     failed = !preprocessHeaders(preprocessor_output_path, location.header_path,
                                 declaration_database.get());
   }
   return failed;
 }
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <dirent.h>
	#include <err.h>
	#include <limits.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <unistd.h>

	#if defined(__linux__)
	#include <sched.h>
	#endif

	#include <atomic>
	#include <chrono>
	#include <functional>
	#include <iostream>
	#include <map>
	#include <memory>
	#include <set>
	#include <sstream>
	#include <string>
	#include <string_view>
	#include <thread>
	#include <unordered_map>
	#include <vector>

	#include <llvm/ADT/StringRef.h>

	#include <android-base/file.h>
	#include <android-base/macros.h>
	#include <android-base/parseint.h>
	#include <android-base/strings.h>

	#include "Arch.h"
	#include "DeclarationDatabase.h"
	#include "Driver.h"
	#include "Preprocessor.h"
	#include "SymbolDatabase.h"
	#include "Utils.h"
	#include "VFS.h"

	#include "versioner.h"

	using namespace std::chrono_literals;
	using namespace std::string_literals;

	bool strict;
	bool verbose;
	bool add_include;

	static int getCpuCount();
	static int max_thread_count = getCpuCount();

	static int getCpuCount() {
	#if defined(__linux__)
	cpu_set_t cpu_set;
	int rc = sched_getaffinity(getpid(), sizeof(cpu_set), &cpu_set);
	if (rc != 0) {
	err(1, "sched_getaffinity failed");
	}
	return CPU_COUNT(&cpu_set);
	#else
	return 1;
	#endif
	}

	namespace {
	struct HeaderLocationInformation {
	std::string header_path;
	std::string dependency_dir;
	// Absolute paths to ignore all children -- including subdirectories -- of.
	std::unordered_set<std::string> ignored_directories;
	};
	}

	static bool is_dir(const std::string& path) {
	struct stat st;
	return stat(path.c_str(), &st) == 0 && S_ISDIR(st.st_mode);
	}

	static CompilationRequirements collectRequirements(const Arch& arch,
	const HeaderLocationInformation& location) {
	std::vector<std::string> headers =
	collectHeaders(location.header_path, location.ignored_directories);
	std::vector<std::string> dependencies;

	if (is_dir(location.header_path)) {
	dependencies.emplace_back(location.header_path);
	}

	if (!location.dependency_dir.empty()) {
	auto collect_children = [&dependencies](const std::string& dir_path) {
	DIR* dir = opendir(dir_path.c_str());
	if (!dir) {
	err(1, "failed to open dependency directory '%s'", dir_path.c_str());
	}

	struct dirent* dent;
	while ((dent = readdir(dir))) {
	if (dent->d_name[0] == '.') {
	continue;
	}

	// TODO: Resolve symlinks.
	std::string dependency = dir_path + "/" + dent->d_name;

	struct stat st;
	if (stat(dependency.c_str(), &st) != 0) {
	err(1, "failed to stat dependency '%s'", dependency.c_str());
	}

	if (!S_ISDIR(st.st_mode)) {
	errx(1, "'%s' is not a directory", dependency.c_str());
	}

	dependencies.push_back(dependency);
	}

	closedir(dir);
	};

	collect_children(location.dependency_dir + "/common");
	collect_children(location.dependency_dir + "/" + to_string(arch));
	}

	auto new_end = std::remove_if(headers.begin(), headers.end(), [&arch](llvm::StringRef header) {
	for (const auto& it : ignored_headers) {
	if (it.second.find(arch) == it.second.end()) {
	continue;
	}

	if (header.endswith("/" + it.first)) {
	return true;
	}
	}
	return false;
	});

	headers.erase(new_end, headers.end());

	CompilationRequirements result = { .headers = headers, .dependencies = dependencies };
	return result;
	}

	static std::set<CompilationType> generateCompilationTypes(const std::set<Arch> selected_architectures,
	const std::set<int>& selected_levels) {
	std::set<CompilationType> result;
	for (const auto& arch : selected_architectures) {
	int min_api = arch_min_api[arch];
	for (int api_level : selected_levels) {
	if (api_level < min_api) {
	continue;
	}

	for (int file_offset_bits : { 32, 64 }) {
	for (bool cpp : { true, false }) {
	CompilationType type = {
	.arch = arch, .cpp = cpp, .api_level = api_level, .file_offset_bits = file_offset_bits
	};
	result.insert(type);
	}
	}
	}
	}
	return result;
	}

	static std::unique_ptr<HeaderDatabase> compileHeaders(const std::set<CompilationType>& types,
	const HeaderLocationInformation& location) {
	if (types.empty()) {
	errx(1, "compileHeaders received no CompilationTypes");
	}

	auto vfs = createCommonVFS(location.header_path, location.dependency_dir, add_include);

	size_t thread_count = max_thread_count;
	std::vector<std::thread> threads;

	std::map<CompilationType, HeaderDatabase> header_databases;
	std::unordered_map<Arch, CompilationRequirements> requirements;

	auto result = std::make_unique<HeaderDatabase>();
	for (const auto& type : types) {
	if (requirements.count(type.arch) == 0) {
	requirements[type.arch] = collectRequirements(type.arch, location);
	}
	}

	initializeTargetCC1FlagCache(vfs, types, requirements);

	std::vector<std::pair<CompilationType, const std::string&>> jobs;
	std::atomic<size_t> job_index(0);
	for (CompilationType type : types) {
	CompilationRequirements& req = requirements[type.arch];
	for (const std::string& header : req.headers) {
	jobs.emplace_back(type, header);
	}
	}

	// Dup an empty file to stdin, so that we can use `clang -include a.h -` instead of `clang a.h`,
	// since some warnings don't get generated in files that are compiled directly.
	FILE* empty_file = tmpfile();
	if (!empty_file) {
	err(1, "failed to create temporary file");
	}

	int empty_file_fd = fileno(empty_file);
	if (empty_file_fd == -1) {
	errx(1, "fileno failed on tmpfile");
	}

	dup2(empty_file_fd, STDIN_FILENO);
	fclose(empty_file);

	thread_count = std::min(thread_count, jobs.size());

	if (thread_count == 1) {
	for (const auto& job : jobs) {
	compileHeader(vfs, result.get(), job.first, job.second);
	}
	} else {
	// Spawn threads.
	for (size_t i = 0; i < thread_count; ++i) {
	threads.emplace_back([&jobs, &job_index, &result, vfs]() {
	while (true) {
	size_t idx = job_index++;
	if (idx >= jobs.size()) {
	return;
	}

	const auto& job = jobs[idx];
	compileHeader(vfs, result.get(), job.first, job.second);
	}
	});
	}

	// Reap them.
	for (auto& thread : threads) {
	thread.join();
	}
	threads.clear();
	}

	return result;
	}

	static std::set<CompilationType> getCompilationTypes(const Declaration* decl) {
	std::set<CompilationType> result;
	for (const auto& it : decl->availability) {
	result.insert(it.first);
	}
	return result;
	}

	template<typename T>
	static std::vector<T> Intersection(const std::set<T>& a, const std::set<T>& b) {
	std::vector<T> intersection;
	std::set_intersection(a.begin(), a.end(), b.begin(), b.end(), std::back_inserter(intersection));
	return intersection;
	}

	// Perform a validity check on a symbol's declarations, enforcing the following invariants:
	// 1. At most one inline definition of the function exists (overloaded inline functions for
	// _FORTIFY_SOURCE do not count because they are usually introduced to intercept the original
	// functions or usually have enable_if attributes).
	// 2. All of the availability declarations for a symbol are compatible.
	// If a function is declared as an inline before a certain version, the inline definition
	// should have no version tag.
	// 3. Each availability type must only be present globally or on a per-arch basis.
	// (e.g. __INTRODUCED_IN_32(21) __INTRODUCED_IN_64(22) __DEPRECATED_IN(23) is fine,
	// but not __INTRODUCED_IN(9) __INTRODUCED_IN_32(10))
	static bool checkSymbol(const Symbol& symbol) {
	std::string cwd = getWorkingDir() + "/";

	std::unordered_map<const Declaration*, std::set<CompilationType>> inline_definitions;
	for (const auto& decl_it : symbol.declarations) {
	const Declaration* decl = &decl_it.second;
	if (decl->is_definition && !decl->fortify_inline) {
	std::set<CompilationType> compilation_types = getCompilationTypes(decl);
	for (const auto& inline_def_it : inline_definitions) {
	auto intersection = Intersection(compilation_types, inline_def_it.second);
	if (!intersection.empty()) {
	fprintf(stderr, "versioner: conflicting inline definitions for symbol %s:\n",
	symbol.name.c_str());
	fprintf(stderr, " declarations visible in: %s\n", Join(intersection, ", ").c_str());
	decl->dump(cwd, stderr, 4);
	inline_def_it.first->dump(cwd, stderr, 4);
	return false;
	}
	}

	inline_definitions[decl] = std::move(compilation_types);
	}

	DeclarationAvailability availability;
	if (!decl->calculateAvailability(&availability)) {
	fprintf(stderr, "versioner: failed to calculate availability for declaration:\n");
	decl->dump(cwd, stderr, 2);
	return false;
	}

	if (decl->is_definition && !availability.empty()) {
	fprintf(stderr, "versioner: inline definition has non-empty versioning information:\n");
	decl->dump(cwd, stderr, 2);
	return false;
	}
	}

	DeclarationAvailability availability;
	if (!symbol.calculateAvailability(&availability)) {
	fprintf(stderr, "versioner: inconsistent availability for symbol '%s'\n", symbol.name.c_str());
	symbol.dump(cwd);
	return false;
	}

	// TODO: Check invariant #3.
	return true;
	}

	static bool validityCheck(const HeaderDatabase* database) {
	bool error = false;
	std::string cwd = getWorkingDir() + "/";

	for (const auto& symbol_it : database->symbols) {
	if (!checkSymbol(symbol_it.second)) {
	error = true;
	}
	}
	return !error;
	}

	// Check that our symbol availability declarations match the actual NDK
	// platform symbol availability.
	static bool checkVersions(const std::set<CompilationType>& types,
	const HeaderDatabase* header_database,
	const NdkSymbolDatabase& symbol_database) {
	std::string cwd = getWorkingDir() + "/";
	bool failed = false;

	std::map<Arch, std::set<CompilationType>> arch_types;
	for (const CompilationType& type : types) {
	arch_types[type.arch].insert(type);
	}

	std::set<std::string> completely_unavailable;
	std::map<std::string, std::set<CompilationType>> missing_availability;
	std::map<std::string, std::set<CompilationType>> extra_availability;

	for (const auto& symbol_it : header_database->symbols) {
	const auto& symbol_name = symbol_it.first;
	DeclarationAvailability symbol_availability;

	if (!symbol_it.second.calculateAvailability(&symbol_availability)) {
	errx(1, "failed to calculate symbol availability");
	}

	const auto platform_availability_it = symbol_database.find(symbol_name);
	if (platform_availability_it == symbol_database.end()) {
	completely_unavailable.insert(symbol_name);
	continue;
	}

	const auto& platform_availability = platform_availability_it->second;

	for (const CompilationType& type : types) {
	bool should_be_available = true;
	const auto& global_availability = symbol_availability.global_availability;
	const auto& arch_availability = symbol_availability.arch_availability[type.arch];
	if (global_availability.introduced != 0 && global_availability.introduced > type.api_level) {
	should_be_available = false;
	}

	if (arch_availability.introduced != 0 && arch_availability.introduced > type.api_level) {
	should_be_available = false;
	}

	if (global_availability.obsoleted != 0 && global_availability.obsoleted <= type.api_level) {
	should_be_available = false;
	}

	if (arch_availability.obsoleted != 0 && arch_availability.obsoleted <= type.api_level) {
	should_be_available = false;
	}

	// The function declaration might be (validly) missing for the given CompilationType.
	if (!symbol_it.second.hasDeclaration(type)) {
	should_be_available = false;
	}

	bool is_available = platform_availability.count(type);

	if (should_be_available != is_available) {
	if (is_available) {
	extra_availability[symbol_name].insert(type);
	} else {
	missing_availability[symbol_name].insert(type);
	}
	}
	}
	}

	for (const auto& it : symbol_database) {
	const std::string& symbol_name = it.first;

	bool symbol_error = false;
	if (auto missing_it = missing_availability.find(symbol_name);
	missing_it != missing_availability.end()) {
	printf("%s: declaration marked available but symbol missing in [%s]\n", symbol_name.c_str(),
	Join(missing_it->second, ", ").c_str());
	symbol_error = true;
	failed = true;
	}

	if (strict) {
	if (auto extra_it = extra_availability.find(symbol_name);
	extra_it != extra_availability.end()) {
	printf("%s: declaration marked unavailable but symbol available in [%s]\n",
	symbol_name.c_str(), Join(extra_it->second, ", ").c_str());
	symbol_error = true;
	failed = true;
	}
	}

	if (symbol_error) {
	if (auto symbol_it = header_database->symbols.find(symbol_name);
	symbol_it != header_database->symbols.end()) {
	symbol_it->second.dump(cwd);
	} else {
	errx(1, "failed to find symbol in header database");
	}
	}
	}

	// TODO: Verify that function/variable declarations are actually function/variable symbols.
	return !failed;
	}

	static void usage(bool help = false) {
	fprintf(stderr, "Usage: versioner [OPTION]... [HEADER_PATH] [DEPS_PATH]\n");
	if (!help) {
	printf("Try 'versioner -h' for more information.\n");
	exit(1);
	} else {
	fprintf(stderr, "Version headers at HEADER_PATH, with DEPS_PATH/ARCH/* on the include path\n");
	fprintf(stderr, "Autodetects paths if HEADER_PATH and DEPS_PATH are not specified\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "Target specification (defaults to all):\n");
	fprintf(stderr, " -a API_LEVEL\tbuild with specified API level (can be repeated)\n");
	fprintf(stderr, " \t\tdefaults to %s\n", Join(default_levels).c_str());
	fprintf(stderr, " -r ARCH\tbuild with specified architecture (can be repeated)\n");
	fprintf(stderr, " \t\tvalid architectures are %s\n", Join(supported_archs).c_str());
	fprintf(stderr, "\n");
	fprintf(stderr, "Validation:\n");
	fprintf(stderr, " -p PATH\tcompare against NDK platform at PATH\n");
	fprintf(stderr, " -s\t\tenable strict warnings\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "Preprocessing:\n");
	fprintf(stderr, " -o PATH\tpreprocess header files and emit them at PATH\n");
	fprintf(stderr, " -f\t\tpreprocess header files even if validation fails\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "Miscellaneous:\n");
	fprintf(stderr, " -F\t\tdo not ignore FORTIFY headers by default\n");
	fprintf(stderr, " -d\t\tdump function availability\n");
	fprintf(stderr, " -j THREADS\tmaximum number of threads to use\n");
	fprintf(stderr, " -v\t\tenable verbose logging\n");
	fprintf(stderr, " -h\t\tdisplay this message\n");
	exit(0);
	}
	}

	// versioner uses a prebuilt version of clang, which is not up-to-date wrt/
	// container annotations. So disable container overflow checking. b/37775238
	extern "C" const char* __asan_default_options() {
	return "detect_container_overflow=0";
	}

	int main(int argc, char** argv) {
	std::string cwd = getWorkingDir() + "/";
	std::string platform_dir;
	std::set<Arch> selected_architectures;
	std::set<int> selected_levels;
	std::string preprocessor_output_path;
	bool force = false;
	bool dump = false;
	bool ignore_fortify_headers = true;

	int c;
	while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhFi")) != -1) {
	switch (c) {
	case 'a': {
	char* end;
	int api_level = strtol(optarg, &end, 10);
	if (end == optarg \|\| strlen(end) > 0) {
	usage();
	}

	selected_levels.insert(api_level);
	break;
	}

	case 'r': {
	std::optional<Arch> arch = arch_from_string(optarg);
	if (!arch) {
	errx(1, "unknown architecture '%s'", optarg);
	}
	selected_architectures.insert(*arch);
	break;
	}

	case 'p': {
	if (!platform_dir.empty()) {
	usage();
	}

	platform_dir = optarg;

	if (platform_dir.empty()) {
	usage();
	}

	struct stat st;
	if (stat(platform_dir.c_str(), &st) != 0) {
	err(1, "failed to stat platform directory '%s'", platform_dir.c_str());
	}
	if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode)) {
	errx(1, "'%s' is not a file or directory", optarg);
	}
	break;
	}

	case 's':
	strict = true;
	break;

	case 'o':
	if (!preprocessor_output_path.empty()) {
	usage();
	}
	preprocessor_output_path = optarg;
	if (preprocessor_output_path.empty()) {
	usage();
	}
	break;

	case 'f':
	force = true;
	break;

	case 'd':
	dump = true;
	break;

	case 'j':
	if (!android::base::ParseInt<int>(optarg, &max_thread_count, 1)) {
	usage();
	}
	break;

	case 'v':
	verbose = true;
	break;

	case 'h':
	usage(true);
	break;

	case 'i':
	// Secret option for tests to -include <android/versioning.h>.
	add_include = true;
	break;

	case 'F':
	ignore_fortify_headers = false;
	break;

	default:
	usage();
	break;
	}
	}

	if (argc - optind > 2 \|\| optind > argc) {
	usage();
	}

	HeaderLocationInformation location;

	const char* top = getenv("ANDROID_BUILD_TOP");
	if (!top && (optind == argc \|\| add_include)) {
	fprintf(stderr, "versioner: failed to autodetect bionic paths. Is ANDROID_BUILD_TOP set?\n");
	usage();
	}

	if (optind == argc) {
	// Neither HEADER_PATH nor DEPS_PATH were specified, so try to figure them out.
	std::string versioner_dir = to_string(top) + "/bionic/tools/versioner";
	location.header_path = versioner_dir + "/current";
	location.dependency_dir = versioner_dir + "/dependencies";
	if (platform_dir.empty()) {
	platform_dir = versioner_dir + "/platforms";
	}
	} else {
	if (!android::base::Realpath(argv[optind], &location.header_path)) {
	err(1, "failed to get realpath for path '%s'", argv[optind]);
	}

	if (argc - optind == 2) {
	location.dependency_dir = argv[optind + 1];
	}
	}

	// Every file that lives in bits/fortify is logically a part of a header outside of bits/fortify.
	// This makes the files there impossible to build on their own.
	if (ignore_fortify_headers) {
	std::string fortify_path = location.header_path;
	if (!android::base::EndsWith(location.header_path, "/")) {
	fortify_path += '/';
	}
	fortify_path += "bits/fortify";
	location.ignored_directories.insert(std::move(fortify_path));
	}

	if (selected_levels.empty()) {
	selected_levels = default_levels;
	}

	if (selected_architectures.empty()) {
	selected_architectures = supported_archs;
	}


	struct stat st;
	if (const char *path = location.header_path.c_str(); stat(path, &st) != 0) {
	err(1, "failed to stat '%s'", path);
	}

	std::set<CompilationType> compilation_types;
	std::optional<NdkSymbolDatabase> symbol_database;

	compilation_types = generateCompilationTypes(selected_architectures, selected_levels);

	// Do this before compiling so that we can early exit if the platforms don't match what we
	// expect.
	if (!platform_dir.empty()) {
	symbol_database = parsePlatforms(compilation_types, platform_dir);
	}

	auto start = std::chrono::high_resolution_clock::now();
	std::unique_ptr<HeaderDatabase> declaration_database =
	compileHeaders(compilation_types, location);
	auto end = std::chrono::high_resolution_clock::now();

	if (verbose) {
	auto diff = (end - start) / 1.0ms;
	printf("Compiled headers for %zu targets in %0.2LFms\n", compilation_types.size(), diff);
	}

	bool failed = false;
	if (dump) {
	declaration_database->dump(location.header_path + "/");
	} else {
	if (!validityCheck(declaration_database.get())) {
	printf("versioner: validity check failed\n");
	failed = true;
	}

	if (symbol_database) {
	if (!checkVersions(compilation_types, declaration_database.get(), *symbol_database)) {
	printf("versioner: version check failed\n");
	failed = true;
	}
	}
	}

	if (!preprocessor_output_path.empty() && (force \|\| !failed)) {
	failed = !preprocessHeaders(preprocessor_output_path, location.header_path,
	declaration_database.get());
	}
	return failed;
	}