1 files changed, 476 insertions, 0 deletions
diff --git a/third_party/nix/src/libutil/util.hh b/third_party/nix/src/libutil/util.hh
new file mode 100644
index 000000000000..b3349c4f39c4
--- /dev/null
+++ b/third_party/nix/src/libutil/util.hh
@@ -0,0 +1,476 @@
+#pragma once
+
+#include <cstdio>
+#include <functional>
+#include <future>
+#include <limits>
+#include <map>
+#include <optional>
+#include <sstream>
+
+#include <absl/strings/string_view.h>
+#include <dirent.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "libutil/types.hh"
+
+namespace nix {
+
+struct Sink;
+struct Source;
+
+/* The system for which Nix is compiled. */
+extern const std::string nativeSystem;
+
+/* Return an environment variable. */
+std::optional<std::string> getEnv(const std::string& key);
+
+/* Get the entire environment. */
+std::map<std::string, std::string> getEnv();
+
+/* Clear the environment. */
+void clearEnv();
+
+/* Return an absolutized path, resolving paths relative to the
+   specified directory, or the current directory otherwise.  The path
+   is also canonicalised. */
+Path absPath(Path path, Path dir = "");
+
+/* Canonicalise a path by removing all `.' or `..' components and
+   double or trailing slashes.  Optionally resolves all symlink
+   components such that each component of the resulting path is *not*
+   a symbolic link. */
+Path canonPath(const Path& path, bool resolveSymlinks = false);
+
+/* Return the directory part of the given canonical path, i.e.,
+   everything before the final `/'.  If the path is the root or an
+   immediate child thereof (e.g., `/foo'), this means an empty string
+   is returned. */
+Path dirOf(absl::string_view path);
+
+/* Return the base name of the given canonical path, i.e., everything
+   following the final `/'. */
+std::string baseNameOf(const Path& path);
+
+/* Check whether 'path' is a descendant of 'dir'. */
+bool isInDir(const Path& path, const Path& dir);
+
+/* Check whether 'path' is equal to 'dir' or a descendant of 'dir'. */
+bool isDirOrInDir(const Path& path, const Path& dir);
+
+/* Get status of `path'. */
+struct stat lstat(const Path& path);
+
+/* Return true iff the given path exists. */
+bool pathExists(const Path& path);
+
+/* Read the contents (target) of a symbolic link.  The result is not
+   in any way canonicalised. */
+Path readLink(const Path& path);
+
+bool isLink(const Path& path);
+
+/* Read the contents of a directory.  The entries `.' and `..' are
+   removed. */
+struct DirEntry {
+  std::string name;
+  ino_t ino;
+  unsigned char type;  // one of DT_*
+  DirEntry(const std::string& name, ino_t ino, unsigned char type)
+      : name(name), ino(ino), type(type) {}
+};
+
+typedef std::vector<DirEntry> DirEntries;
+
+DirEntries readDirectory(const Path& path);
+
+unsigned char getFileType(const Path& path);
+
+/* Read the contents of a file into a string. */
+std::string readFile(int fd);
+std::string readFile(absl::string_view path, bool drain = false);
+void readFile(absl::string_view path, Sink& sink);
+
+/* Write a string to a file. */
+void writeFile(const Path& path, const std::string& s, mode_t mode = 0666);
+
+void writeFile(const Path& path, Source& source, mode_t mode = 0666);
+
+/* Read a line from a file descriptor. */
+std::string readLine(int fd);
+
+/* Write a line to a file descriptor. */
+void writeLine(int fd, std::string s);
+
+/* Delete a path; i.e., in the case of a directory, it is deleted
+   recursively. It's not an error if the path does not exist. The
+   second variant returns the number of bytes and blocks freed. */
+void deletePath(const Path& path);
+
+void deletePath(const Path& path, unsigned long long& bytesFreed);
+
+/* Create a temporary directory. */
+Path createTempDir(const Path& tmpRoot = "", const Path& prefix = "nix",
+                   bool includePid = true, bool useGlobalCounter = true,
+                   mode_t mode = 0755);
+
+std::string getUserName();
+
+/* Return $HOME or the user's home directory from /etc/passwd. */
+Path getHome();
+
+/* Return $XDG_CACHE_HOME or $HOME/.cache. */
+Path getCacheDir();
+
+/* Return $XDG_CONFIG_HOME or $HOME/.config. */
+Path getConfigDir();
+
+/* Return the directories to search for user configuration files */
+std::vector<Path> getConfigDirs();
+
+/* Return $XDG_DATA_HOME or $HOME/.local/share. */
+Path getDataDir();
+
+/* Create a directory and all its parents, if necessary.  Returns the
+   list of created directories, in order of creation. */
+Paths createDirs(const Path& path);
+
+/* Create a symlink. */
+void createSymlink(const Path& target, const Path& link);
+
+/* Atomically create or replace a symlink. */
+void replaceSymlink(const Path& target, const Path& link);
+
+/* Wrappers arount read()/write() that read/write exactly the
+   requested number of bytes. */
+void readFull(int fd, unsigned char* buf, size_t count);
+void writeFull(int fd, const unsigned char* buf, size_t count,
+               bool allowInterrupts = true);
+void writeFull(int fd, const std::string& s, bool allowInterrupts = true);
+
+MakeError(EndOfFile, Error);
+
+/* Read a file descriptor until EOF occurs. */
+std::string drainFD(int fd, bool block = true);
+
+void drainFD(int fd, Sink& sink, bool block = true);
+
+/* Automatic cleanup of resources. */
+
+class AutoDelete {
+  Path path;
+  bool del;
+  bool recursive;
+
+ public:
+  AutoDelete();
+  explicit AutoDelete(Path p, bool recursive = true);
+  ~AutoDelete();
+  void cancel();
+  void reset(const Path& p, bool recursive = true);
+  explicit operator Path() const { return path; }
+};
+
+class AutoCloseFD {
+  int fd;
+  void close();
+
+ public:
+  AutoCloseFD();
+  explicit AutoCloseFD(int fd);
+  AutoCloseFD(const AutoCloseFD& fd) = delete;
+  AutoCloseFD(AutoCloseFD&& that);
+  ~AutoCloseFD();
+  AutoCloseFD& operator=(const AutoCloseFD& fd) = delete;
+  AutoCloseFD& operator=(AutoCloseFD&& that);
+  int get() const;
+  explicit operator bool() const;
+  int release();
+};
+
+class Pipe {
+ public:
+  AutoCloseFD readSide, writeSide;
+  void create();
+};
+
+struct DIRDeleter {
+  void operator()(DIR* dir) const { closedir(dir); }
+};
+
+using AutoCloseDir = std::unique_ptr<DIR, DIRDeleter>;
+
+class Pid {
+  pid_t pid = -1;
+  bool separatePG = false;
+  int killSignal = SIGKILL;
+
+ public:
+  Pid();
+  explicit Pid(pid_t pid);
+  ~Pid();
+  void operator=(pid_t pid);
+  explicit operator pid_t();
+  int kill();
+  int wait();
+
+  void setSeparatePG(bool separatePG);
+  void setKillSignal(int signal);
+  pid_t release();
+
+  friend bool operator==(const Pid& lhs, const Pid& rhs) {
+    return lhs.pid == rhs.pid;
+  }
+
+  friend bool operator!=(const Pid& lhs, const Pid& rhs) {
+    return !(lhs == rhs);
+  }
+};
+
+/* Kill all processes running under the specified uid by sending them
+   a SIGKILL. */
+void killUser(uid_t uid);
+
+/* Fork a process that runs the given function, and return the child
+   pid to the caller. */
+struct ProcessOptions {
+  std::string errorPrefix = "error: ";
+  bool dieWithParent = true;
+  bool runExitHandlers = false;
+};
+
+pid_t startProcess(std::function<void()> fun,
+                   const ProcessOptions& options = ProcessOptions());
+
+/* Run a program and return its stdout in a string (i.e., like the
+   shell backtick operator). */
+std::string runProgram(const Path& program, bool searchPath = false,
+                       const Strings& args = Strings(),
+                       const std::optional<std::string>& input = {});
+
+struct RunOptions {
+  std::optional<uid_t> uid;
+  std::optional<uid_t> gid;
+  std::optional<Path> chdir;
+  std::optional<std::map<std::string, std::string>> environment;
+  Path program;
+  bool searchPath = true;
+  Strings args;
+  std::optional<std::string> input;
+  Source* standardIn = nullptr;
+  Sink* standardOut = nullptr;
+  bool mergeStderrToStdout = false;
+  bool _killStderr = false;
+
+  RunOptions(const Path& program, const Strings& args)
+      : program(program), args(args){};
+
+  RunOptions& killStderr(bool v) {
+    _killStderr = true;
+    return *this;
+  }
+};
+
+std::pair<int, std::string> runProgram(const RunOptions& options);
+
+void runProgram2(const RunOptions& options);
+
+class ExecError : public Error {
+ public:
+  int status;
+
+  template <typename... Args>
+  explicit ExecError(int status, Args... args)
+      : Error(args...), status(status) {}
+};
+
+/* Convert a list of strings to a null-terminated vector of char
+   *'s. The result must not be accessed beyond the lifetime of the
+   list of strings. */
+std::vector<char*> stringsToCharPtrs(const Strings& ss);
+
+/* Close all file descriptors except those listed in the given set.
+   Good practice in child processes. */
+void closeMostFDs(const std::set<int>& exceptions);
+
+/* Set the close-on-exec flag for the given file descriptor. */
+void closeOnExec(int fd);
+
+/* User interruption. */
+
+extern bool _isInterrupted;
+
+extern thread_local std::function<bool()> interruptCheck;
+
+void setInterruptThrown();
+
+void _interrupted();
+
+void inline checkInterrupt() {
+  if (_isInterrupted || (interruptCheck && interruptCheck())) {
+    _interrupted();
+  }
+}
+
+MakeError(Interrupted, BaseError);
+
+MakeError(FormatError, Error);
+
+/* Concatenate the given strings with a separator between the
+   elements. */
+std::string concatStringsSep(const std::string& sep, const Strings& ss);
+std::string concatStringsSep(const std::string& sep, const StringSet& ss);
+
+/* Replace all occurrences of a string inside another string. */
+std::string replaceStrings(const std::string& s, const std::string& from,
+                           const std::string& to);
+
+/* Convert the exit status of a child as returned by wait() into an
+   error string. */
+std::string statusToString(int status);
+
+bool statusOk(int status);
+
+/* Parse a string into a float. */
+template <class N>
+bool string2Float(const std::string& s, N& n) {
+  std::istringstream str(s);
+  str >> n;
+  return str && str.get() == EOF;
+}
+
+/* Convert a string to lower case. */
+std::string toLower(const std::string& s);
+
+/* Escape a string as a shell word. */
+std::string shellEscape(const std::string& s);
+
+/* Exception handling in destructors: print an error message, then
+   ignore the exception. */
+void ignoreException();
+
+/* Some ANSI escape sequences. */
+#define ANSI_NORMAL "\e[0m"
+#define ANSI_BOLD "\e[1m"
+#define ANSI_FAINT "\e[2m"
+#define ANSI_RED "\e[31;1m"
+#define ANSI_GREEN "\e[32;1m"
+#define ANSI_BLUE "\e[34;1m"
+
+/* Truncate a string to 'width' printable characters. If 'filterAll'
+   is true, all ANSI escape sequences are filtered out. Otherwise,
+   some escape sequences (such as colour setting) are copied but not
+   included in the character count. Also, tabs are expanded to
+   spaces. */
+std::string filterANSIEscapes(
+    const std::string& s, bool filterAll = false,
+    unsigned int width = std::numeric_limits<unsigned int>::max());
+
+/* Get a value for the specified key from an associate container, or a
+   default value if the key doesn't exist. */
+template <class T>
+std::string get(const T& map, const std::string& key,
+                const std::string& def = "") {
+  auto i = map.find(key);
+  return i == map.end() ? def : i->second;
+}
+
+/* A callback is a wrapper around a lambda that accepts a valid of
+   type T or an exception. (We abuse std::future<T> to pass the value or
+   exception.) */
+template <typename T>
+class Callback {
+  std::function<void(std::future<T>)> fun;
+  std::atomic_flag done = ATOMIC_FLAG_INIT;
+
+ public:
+  explicit Callback(std::function<void(std::future<T>)> fun) : fun(fun) {}
+
+  Callback(Callback&& callback) : fun(std::move(callback.fun)) {
+    auto prev = callback.done.test_and_set();
+    if (prev) {
+      done.test_and_set();
+    }
+  }
+
+// The unused-variable assert is disabled in this block because the
+// `prev` variables are only used in debug mode (in the asserts).
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+
+  void operator()(T&& t) noexcept {
+    auto prev = done.test_and_set();
+    assert(!prev);
+    std::promise<T> promise;
+    promise.set_value(std::move(t));
+    fun(promise.get_future());
+  }
+
+  void rethrow(
+      const std::exception_ptr& exc = std::current_exception()) noexcept {
+    auto prev = done.test_and_set();
+    assert(!prev);
+    std::promise<T> promise;
+    promise.set_exception(exc);
+    fun(promise.get_future());
+  }
+
+#pragma clang diagnostic pop
+};
+
+/* Start a thread that handles various signals. Also block those signals
+   on the current thread (and thus any threads created by it). */
+void startSignalHandlerThread();
+
+/* Restore default signal handling. */
+void restoreSignals();
+
+struct InterruptCallback {
+  virtual ~InterruptCallback(){};
+};
+
+/* Register a function that gets called on SIGINT (in a non-signal
+   context). */
+std::unique_ptr<InterruptCallback> createInterruptCallback(
+    const std::function<void()>& callback);
+
+void triggerInterrupt();
+
+/* A RAII class that causes the current thread to receive SIGUSR1 when
+   the signal handler thread receives SIGINT. That is, this allows
+   SIGINT to be multiplexed to multiple threads. */
+struct ReceiveInterrupts {
+  pthread_t target;
+  std::unique_ptr<InterruptCallback> callback;
+
+  ReceiveInterrupts()
+      : target(pthread_self()), callback(createInterruptCallback([&]() {
+          pthread_kill(target, SIGUSR1);
+        })) {}
+};
+
+/* A RAII helper that increments a counter on construction and
+   decrements it on destruction. */
+template <typename T>
+struct MaintainCount {
+  T& counter;
+  long delta;
+  explicit MaintainCount(T& counter, long delta = 1)
+      : counter(counter), delta(delta) {
+    counter += delta;
+  }
+  ~MaintainCount() { counter -= delta; }
+};
+
+/* Return the number of rows and columns of the terminal. */
+std::pair<unsigned short, unsigned short> getWindowSize();
+
+/* Used in various places. */
+using PathFilter = std::function<bool(const Path&)>;
+
+extern PathFilter defaultPathFilter;
+
+}  // namespace nix