Add 'third_party/nix/' from commit 'be66c7a6b24e3c3c6157fd37b86c7203d14acf10' r/724

git-subtree-dir: third_party/nix
git-subtree-mainline: cf8cd640c1adf74a3706efbcb0ea4625da106fb2
git-subtree-split: be66c7a6b24e3c3c6157fd37b86c7203d14acf10

1 files changed, 542 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..f057fdb2c041
--- /dev/null
+++ b/third_party/nix/src/libutil/util.hh
@@ -0,0 +1,542 @@
+#pragma once
+
+#include "types.hh"
+#include "logging.hh"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <signal.h>
+
+#include <functional>
+#include <limits>
+#include <cstdio>
+#include <map>
+#include <sstream>
+#include <optional>
+#include <future>
+
+#ifndef HAVE_STRUCT_DIRENT_D_TYPE
+#define DT_UNKNOWN 0
+#define DT_REG 1
+#define DT_LNK 2
+#define DT_DIR 3
+#endif
+
+namespace nix {
+
+struct Sink;
+struct Source;
+
+
+/* The system for which Nix is compiled. */
+extern const std::string nativeSystem;
+
+
+/* Return an environment variable. */
+string getEnv(const string & key, const string & def = "");
+
+/* 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(const Path & path);
+
+/* Return the base name of the given canonical path, i.e., everything
+   following the final `/'. */
+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
+{
+    string name;
+    ino_t ino;
+    unsigned char type; // one of DT_*
+    DirEntry(const string & name, ino_t ino, unsigned char type)
+        : name(name), ino(ino), type(type) { }
+};
+
+typedef vector<DirEntry> DirEntries;
+
+DirEntries readDirectory(const Path & path);
+
+unsigned char getFileType(const Path & path);
+
+/* Read the contents of a file into a string. */
+string readFile(int fd);
+string readFile(const Path & path, bool drain = false);
+void readFile(const Path & path, Sink & sink);
+
+/* Write a string to a file. */
+void writeFile(const Path & path, const string & s, mode_t mode = 0666);
+
+void writeFile(const Path & path, Source & source, mode_t mode = 0666);
+
+/* Read a line from a file descriptor. */
+string readLine(int fd);
+
+/* Write a line to a file descriptor. */
+void writeLine(int fd, 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 string & s, bool allowInterrupts = true);
+
+MakeError(EndOfFile, Error)
+
+
+/* Read a file descriptor until EOF occurs. */
+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();
+    AutoDelete(const Path & p, bool recursive = true);
+    ~AutoDelete();
+    void cancel();
+    void reset(const Path & p, bool recursive = true);
+    operator Path() const { return path; }
+};
+
+
+class AutoCloseFD
+{
+    int fd;
+    void close();
+public:
+    AutoCloseFD();
+    AutoCloseFD(int fd);
+    AutoCloseFD(const AutoCloseFD & fd) = delete;
+    AutoCloseFD(AutoCloseFD&& fd);
+    ~AutoCloseFD();
+    AutoCloseFD& operator =(const AutoCloseFD & fd) = delete;
+    AutoCloseFD& operator =(AutoCloseFD&& fd);
+    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);
+    }
+};
+
+typedef std::unique_ptr<DIR, DIRDeleter> AutoCloseDir;
+
+
+class Pid
+{
+    pid_t pid = -1;
+    bool separatePG = false;
+    int killSignal = SIGKILL;
+public:
+    Pid();
+    Pid(pid_t pid);
+    ~Pid();
+    void operator =(pid_t pid);
+    operator pid_t();
+    int kill();
+    int wait();
+
+    void setSeparatePG(bool separatePG);
+    void setKillSignal(int signal);
+    pid_t release();
+};
+
+
+/* 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
+{
+    string errorPrefix = "error: ";
+    bool dieWithParent = true;
+    bool runExitHandlers = false;
+    bool allowVfork = true;
+};
+
+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). */
+string runProgram(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>
+    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 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)
+
+
+/* String tokenizer. */
+template<class C> C tokenizeString(const string & s, const string & separators = " \t\n\r");
+
+
+/* Concatenate the given strings with a separator between the
+   elements. */
+string concatStringsSep(const string & sep, const Strings & ss);
+string concatStringsSep(const string & sep, const StringSet & ss);
+
+
+/* Remove trailing whitespace from a string. */
+string chomp(const string & s);
+
+
+/* Remove whitespace from the start and end of a string. */
+string trim(const string & s, const string & whitespace = " \n\r\t");
+
+
+/* Replace all occurrences of a string inside another string. */
+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. */
+string statusToString(int status);
+
+bool statusOk(int status);
+
+
+/* Parse a string into an integer. */
+template<class N> bool string2Int(const string & s, N & n)
+{
+    if (string(s, 0, 1) == "-" && !std::numeric_limits<N>::is_signed)
+        return false;
+    std::istringstream str(s);
+    str >> n;
+    return str && str.get() == EOF;
+}
+
+/* Parse a string into a float. */
+template<class N> bool string2Float(const string & s, N & n)
+{
+    std::istringstream str(s);
+    str >> n;
+    return str && str.get() == EOF;
+}
+
+
+/* Return true iff `s' starts with `prefix'. */
+bool hasPrefix(const string & s, const string & prefix);
+
+
+/* Return true iff `s' ends in `suffix'. */
+bool hasSuffix(const string & s, const string & suffix);
+
+
+/* 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());
+
+
+/* Base64 encoding/decoding. */
+string base64Encode(const string & s);
+string base64Decode(const string & s);
+
+
+/* Get a value for the specified key from an associate container, or a
+   default value if the key doesn't exist. */
+template <class T>
+string get(const T & map, const string & key, const 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:
+
+    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();
+    }
+
+    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());
+    }
+};
+
+
+/* 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(
+    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;
+    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. */
+typedef std::function<bool(const Path & path)> PathFilter;
+
+extern PathFilter defaultPathFilter;
+
+
+}