[Support] Add path::user_config_directory for $XDG_CONFIG_HOME etc

llvm/include/llvm/Support/Path.h

 void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result);
 
 /// Get the user's home directory.
 ///
 /// @param result Holds the resulting path name.
 /// @result True if a home directory is set, false otherwise.
 bool home_directory(SmallVectorImpl<char> &result);
 
+/// Get the directory where packages should read user-specific configurations.
+/// e.g. $XDG_CONFIG_HOME.
+///
+/// @param result Holds the resulting path name.
+/// @result True if the appropriate path was determined, it need not exist.
+bool user_config_directory(SmallVectorImpl<char> &result);
+
 /// Get the directory where installed packages should put their
 /// machine-local cache, e.g. $XDG_CACHE_HOME.
 ///
 /// @param result Holds the resulting path name.
 /// @result True if the appropriate path was determined, it need not exist.
 bool cache_directory(SmallVectorImpl<char> &result);
 
 /// Has root name?

llvm/lib/Support/Unix/Path.inc

 #endif
 
 using namespace llvm;
 
 namespace llvm {
 namespace sys  {
 namespace fs {
 
 const file_t kInvalidFile = -1;
 
 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) ||     \
     defined(__minix) || defined(__FreeBSD_kernel__) || defined(__linux__) ||   \
     defined(__CYGWIN__) || defined(__DragonFly__) || defined(_AIX) || defined(__GNU__)
 static int
 test_dir(char ret[PATH_MAX], const char *dir, const char *bin)
 {
   struct stat sb;
if (sys::fs::exists(curproc)) {
     }
   }
   // If we don't have procfs mounted, fall back to argv[0]
   if (getprogpath(exe_path, argv0) != NULL)
     return exe_path;
 #elif defined(__linux__) || defined(__CYGWIN__) || defined(__gnu_hurd__)
   char exe_path[PATH_MAX];
   const char *aPath = "/proc/self/exe";
   if (sys::fs::exists(aPath)) {
     // /proc is not always mounted under Linux (chroot for example).
     ssize_t len = readlink(aPath, exe_path, sizeof(exe_path));
     if (len < 0)
       return "";
 
     // Null terminate the string for realpath. readlink never null
     // terminates its output.
     len = std::min(len, ssize_t(sizeof(exe_path) - 1));
#elif defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)
   if (realpath(DLInfo.dli_fname, link_path))
     return link_path;
 #else
 #error GetMainExecutable is not implemented on this host yet.
 #endif
   return "";
 }
 
 TimePoint<> basic_file_status::getLastAccessedTime() const {
   return toTimePoint(fs_st_atime, fs_st_atime_nsec);
 }
 
 TimePoint<> basic_file_status::getLastModificationTime() const {
   return toTimePoint(fs_st_mtime, fs_st_mtime_nsec);
 }
 
 UniqueID file_status::getUniqueID() const {
   return UniqueID(fs_st_dev, fs_st_ino);
 }
 
 uint32_t file_status::getLinkCount() const {
   return fs_st_nlinks;
 }
 
 ErrorOr<space_info> disk_space(const Twine &Path) {
   struct STATVFS Vfs;
   if (::STATVFS(const_cast<char *>(Path.str().c_str()), &Vfs))
     return std::error_code(errno, std::generic_category());
   auto FrSize = STATVFS_F_FRSIZE(Vfs);
   space_info SpaceInfo;
   SpaceInfo.capacity = static_cast<uint64_t>(Vfs.f_blocks) * FrSize;
   SpaceInfo.free = static_cast<uint64_t>(Vfs.f_bfree) * FrSize;
   SpaceInfo.available = static_cast<uint64_t>(Vfs.f_bavail) * FrSize;
   return SpaceInfo;
 }
 
 std::error_code current_path(SmallVectorImpl<char> &result) {
   result.clear();
 
   const char *pwd = ::getenv("PWD");
   llvm::sys::fs::file_status PWDStatus, DotStatus;
   if (pwd && llvm::sys::path::is_absolute(pwd) &&
       !llvm::sys::fs::status(pwd, PWDStatus) &&
       !llvm::sys::fs::status(".", DotStatus) &&
       PWDStatus.getUniqueID() == DotStatus.getUniqueID()) {
     result.append(pwd, pwd + strlen(pwd));
     return std::error_code();
   }
 
   result.reserve(PATH_MAX);
 
   while (true) {
     if (::getcwd(result.data(), result.capacity()) == nullptr) {
       // See if there was a real error.
       if (errno != ENOMEM)
         return std::error_code(errno, std::generic_category());
       // Otherwise there just wasn't enough space.
       result.reserve(result.capacity() * 2);
     } else
       break;
   }
 
   result.set_size(strlen(result.data()));
   return std::error_code();
 }
 
 std::error_code set_current_path(const Twine &path) {
   SmallString<128> path_storage;
   StringRef p = path.toNullTerminatedStringRef(path_storage);
 
   if (::chdir(p.begin()) == -1)
     return std::error_code(errno, std::generic_category());
 
   return std::error_code();
 }
 
 std::error_code create_directory(const Twine &path, bool IgnoreExisting,
                                  perms Perms) {
   SmallString<128> path_storage;
   StringRef p = path.toNullTerminatedStringRef(path_storage);
 
   if (::mkdir(p.begin(), Perms) == -1) {
     if (errno != EEXIST || !IgnoreExisting)
       return std::error_code(errno, std::generic_category());
   }
 
   return std::error_code();
if (ConfLen > 0) {
     }
 
     Result.clear();
   }
   #endif
   return false;
 }
 
+bool user_config_directory(SmallVectorImpl<char> &result) {
+#ifdef __APPLE__
+  // Mac: ~/Library/Preferences/
+  if (home_directory(result)) {
+    append("Library", "Preferences");
+    return true;
+  }
+#else
+  // XDG_CONFIG_HOME as defined in the XDG Base Directory Specification:
+  // http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
+  if (const char *RequestedDir = getenv("XDG_CONFIG_HOME")) {
+    result.clear();
+    result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
+    return true;
+  }
+#endif
+  // Fallback: ~/.config
+  if (!home_directory(result)) {
+    return false;
+  }
+  append(result, ".config");
+  return true;
+}
+
 bool cache_directory(SmallVectorImpl<char> &result) {
 #ifdef __APPLE__
   if (getDarwinConfDir(false/*tempDir*/, result)) {
     return true;
   }
 #else
   // XDG_CACHE_HOME as defined in the XDG Base Directory Specification:
   // http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

llvm/lib/Support/Windows/Path.inc

 //=== WARNING: Implementation here must contain only generic Windows code that
 //===          is guaranteed to work on *all* Windows variants.
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/WindowsError.h"
 #include <fcntl.h>
 #include <io.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
 // These two headers must be included last, and make sure shlobj is required
 // after Windows.h to make sure it picks up our definition of _WIN32_WINNT
 #include "llvm/Support/Windows/WindowsSupport.h"
 #include <shellapi.h>
 #include <shlobj.h>
static bool getKnownFolderPath(KNOWNFOLDERID folderId,
   ::CoTaskMemFree(path);
   return ok;
 }
 
 bool home_directory(SmallVectorImpl<char> &result) {
   return getKnownFolderPath(FOLDERID_Profile, result);
 }
 
+bool user_config_directory(SmallVectorImpl<char> &result) {
+  // Either local or roaming appdata may be suitable in some cases, depending
+  // on the data. Local is more conservative, Roaming may not always be correct.
+  return getKnownFolderPath(FOLDERID_LocalAppData, result);
+}
+
 bool cache_directory(SmallVectorImpl<char> &result) {
   return getKnownFolderPath(FOLDERID_LocalAppData, result);
 }
 
 static bool getTempDirEnvVar(const wchar_t *Var, SmallVectorImpl<char> &Res) {
   SmallVector<wchar_t, 1024> Buf;
   size_t Size = 1024;
   do {

llvm/unittests/Support/Path.cpp

TEST(Support, HomeDirectoryWithNoEnv) {
   if (!pw || !pw->pw_dir) return;
   std::string PwDir = pw->pw_dir;
 
   SmallString<128> HomeDir;
   EXPECT_TRUE(path::home_directory(HomeDir));
   EXPECT_EQ(PwDir, HomeDir);
 }
 
+TEST(Support, ConfigDirectoryWithEnv) {
+  WithEnv Env("XDG_CONFIG_HOME", "/xdg/config");
+
+  SmallString<128> ConfigDir;
+  EXPECT_TRUE(path::user_config_directory(ConfigDir));
+  EXPECT_EQ("/xdg/config", ConfigDir);
+}
+
+TEST(Support, ConfigDirectoryNoEnv) {
+  WithEnv Env("XDG_CONFIG_HOME", nullptr);
+
+  SmallString<128> Fallback;
+  ASSERT_TRUE(path::home_directory(Fallback));
+  path::append(Fallback, ".config");
+
+  SmallString<128> CacheDir;
+  EXPECT_TRUE(path::user_config_directory(CacheDir));
+  EXPECT_EQ(Fallback, CacheDir);
+}
+
 TEST(Support, CacheDirectoryWithEnv) {
   WithEnv Env("XDG_CACHE_HOME", "/xdg/cache");
 
   SmallString<128> CacheDir;
   EXPECT_TRUE(path::cache_directory(CacheDir));
   EXPECT_EQ("/xdg/cache", CacheDir);
 }
 
 TEST(Support, CacheDirectoryNoEnv) {
   WithEnv Env("XDG_CACHE_HOME", nullptr);
 
   SmallString<128> Fallback;
   ASSERT_TRUE(path::home_directory(Fallback));
   path::append(Fallback, ".cache");
 
   SmallString<128> CacheDir;
   EXPECT_TRUE(path::cache_directory(CacheDir));
   EXPECT_EQ(Fallback, CacheDir);
 }
 #endif
 
+#ifdef __APPLE__
+TEST(Support, ConfigDirectory) {
+  SmallString<128> Fallback;
+  ASSERT_TRUE(path::home_directory(Fallback));
+  path::append(Fallback, "Library/Preferences");
+
+  SmallString<128> ConfigDir;
+  EXPECT_TRUE(path::user_config_directory(ConfigDir));
+  EXPECT_EQ(Fallback, ConfigDir);
+}
+#endif
+
 #ifdef _WIN32
+TEST(Support, ConfigDirectory) {
+  std::string Expected = getEnvWin(L"LOCALAPPDATA");
+  // Do not try to test it if we don't know what to expect.
+  if (!Expected.empty()) {
+    SmallString<128> CacheDir;
+    EXPECT_TRUE(path::user_config_directory(CacheDir));
+    EXPECT_EQ(Expected, CacheDir);
+  }
+}
+
 TEST(Support, CacheDirectory) {
   std::string Expected = getEnvWin(L"LOCALAPPDATA");
   // Do not try to test it if we don't know what to expect.
   if (!Expected.empty()) {
     SmallString<128> CacheDir;
     EXPECT_TRUE(path::cache_directory(CacheDir));
     EXPECT_EQ(Expected, CacheDir);
   }