561 lines
14 KiB
C++
561 lines
14 KiB
C++
#pragma once
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#include "types.hh"
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#include "logging.hh"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <dirent.h>
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#include <unistd.h>
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#include <signal.h>
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#include <functional>
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#include <limits>
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#include <cstdio>
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#include <map>
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#include <sstream>
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#include <optional>
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#include <future>
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#ifndef HAVE_STRUCT_DIRENT_D_TYPE
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#define DT_UNKNOWN 0
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#define DT_REG 1
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#define DT_LNK 2
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#define DT_DIR 3
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#endif
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namespace nix {
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struct Sink;
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struct Source;
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/* The system for which Nix is compiled. */
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extern const std::string nativeSystem;
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/* Return an environment variable. */
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std::optional<std::string> getEnv(const std::string & key);
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/* Get the entire environment. */
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std::map<std::string, std::string> getEnv();
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/* Clear the environment. */
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void clearEnv();
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/* Return an absolutized path, resolving paths relative to the
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specified directory, or the current directory otherwise. The path
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is also canonicalised. */
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Path absPath(Path path, Path dir = "");
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/* Canonicalise a path by removing all `.' or `..' components and
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double or trailing slashes. Optionally resolves all symlink
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components such that each component of the resulting path is *not*
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a symbolic link. */
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Path canonPath(const Path & path, bool resolveSymlinks = false);
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/* Return the directory part of the given canonical path, i.e.,
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everything before the final `/'. If the path is the root or an
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immediate child thereof (e.g., `/foo'), this means an empty string
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is returned. */
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Path dirOf(const Path & path);
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/* Return the base name of the given canonical path, i.e., everything
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following the final `/'. */
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std::string_view baseNameOf(std::string_view path);
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/* Check whether 'path' is a descendant of 'dir'. */
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bool isInDir(const Path & path, const Path & dir);
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/* Check whether 'path' is equal to 'dir' or a descendant of 'dir'. */
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bool isDirOrInDir(const Path & path, const Path & dir);
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/* Get status of `path'. */
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struct stat lstat(const Path & path);
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/* Return true iff the given path exists. */
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bool pathExists(const Path & path);
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/* Read the contents (target) of a symbolic link. The result is not
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in any way canonicalised. */
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Path readLink(const Path & path);
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bool isLink(const Path & path);
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/* Read the contents of a directory. The entries `.' and `..' are
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removed. */
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struct DirEntry
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{
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string name;
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ino_t ino;
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unsigned char type; // one of DT_*
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DirEntry(const string & name, ino_t ino, unsigned char type)
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: name(name), ino(ino), type(type) { }
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};
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typedef vector<DirEntry> DirEntries;
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DirEntries readDirectory(const Path & path);
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unsigned char getFileType(const Path & path);
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/* Read the contents of a file into a string. */
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string readFile(int fd);
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string readFile(const Path & path, bool drain = false);
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void readFile(const Path & path, Sink & sink);
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/* Write a string to a file. */
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void writeFile(const Path & path, const string & s, mode_t mode = 0666);
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void writeFile(const Path & path, Source & source, mode_t mode = 0666);
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/* Read a line from a file descriptor. */
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string readLine(int fd);
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/* Write a line to a file descriptor. */
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void writeLine(int fd, string s);
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/* Delete a path; i.e., in the case of a directory, it is deleted
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recursively. It's not an error if the path does not exist. The
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second variant returns the number of bytes and blocks freed. */
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void deletePath(const Path & path);
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void deletePath(const Path & path, unsigned long long & bytesFreed);
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/* Create a temporary directory. */
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Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix",
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bool includePid = true, bool useGlobalCounter = true, mode_t mode = 0755);
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std::string getUserName();
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/* Return $HOME or the user's home directory from /etc/passwd. */
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Path getHome();
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/* Return $XDG_CACHE_HOME or $HOME/.cache. */
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Path getCacheDir();
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/* Return $XDG_CONFIG_HOME or $HOME/.config. */
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Path getConfigDir();
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/* Return the directories to search for user configuration files */
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std::vector<Path> getConfigDirs();
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/* Return $XDG_DATA_HOME or $HOME/.local/share. */
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Path getDataDir();
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/* Create a directory and all its parents, if necessary. Returns the
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list of created directories, in order of creation. */
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Paths createDirs(const Path & path);
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/* Create a symlink. */
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void createSymlink(const Path & target, const Path & link);
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/* Atomically create or replace a symlink. */
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void replaceSymlink(const Path & target, const Path & link);
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/* Wrappers arount read()/write() that read/write exactly the
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requested number of bytes. */
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void readFull(int fd, unsigned char * buf, size_t count);
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void writeFull(int fd, const unsigned char * buf, size_t count, bool allowInterrupts = true);
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void writeFull(int fd, const string & s, bool allowInterrupts = true);
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MakeError(EndOfFile, Error);
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/* Read a file descriptor until EOF occurs. */
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string drainFD(int fd, bool block = true);
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void drainFD(int fd, Sink & sink, bool block = true);
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/* Automatic cleanup of resources. */
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class AutoDelete
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{
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Path path;
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bool del;
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bool recursive;
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public:
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AutoDelete();
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AutoDelete(const Path & p, bool recursive = true);
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~AutoDelete();
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void cancel();
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void reset(const Path & p, bool recursive = true);
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operator Path() const { return path; }
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};
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class AutoCloseFD
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{
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int fd;
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void close();
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public:
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AutoCloseFD();
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AutoCloseFD(int fd);
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AutoCloseFD(const AutoCloseFD & fd) = delete;
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AutoCloseFD(AutoCloseFD&& fd);
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~AutoCloseFD();
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AutoCloseFD& operator =(const AutoCloseFD & fd) = delete;
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AutoCloseFD& operator =(AutoCloseFD&& fd);
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int get() const;
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explicit operator bool() const;
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int release();
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};
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class Pipe
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{
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public:
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AutoCloseFD readSide, writeSide;
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void create();
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};
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struct DIRDeleter
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{
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void operator()(DIR * dir) const {
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closedir(dir);
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}
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};
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typedef std::unique_ptr<DIR, DIRDeleter> AutoCloseDir;
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class Pid
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{
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pid_t pid = -1;
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bool separatePG = false;
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int killSignal = SIGKILL;
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public:
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Pid();
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Pid(pid_t pid);
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~Pid();
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void operator =(pid_t pid);
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operator pid_t();
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int kill();
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int wait();
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void setSeparatePG(bool separatePG);
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void setKillSignal(int signal);
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pid_t release();
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};
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/* Kill all processes running under the specified uid by sending them
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a SIGKILL. */
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void killUser(uid_t uid);
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/* Fork a process that runs the given function, and return the child
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pid to the caller. */
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struct ProcessOptions
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{
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string errorPrefix = "error: ";
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bool dieWithParent = true;
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bool runExitHandlers = false;
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bool allowVfork = true;
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};
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pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = ProcessOptions());
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/* Run a program and return its stdout in a string (i.e., like the
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shell backtick operator). */
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string runProgram(Path program, bool searchPath = false,
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const Strings & args = Strings(),
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const std::optional<std::string> & input = {});
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struct RunOptions
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{
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std::optional<uid_t> uid;
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std::optional<uid_t> gid;
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std::optional<Path> chdir;
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std::optional<std::map<std::string, std::string>> environment;
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Path program;
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bool searchPath = true;
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Strings args;
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std::optional<std::string> input;
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Source * standardIn = nullptr;
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Sink * standardOut = nullptr;
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bool mergeStderrToStdout = false;
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bool _killStderr = false;
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RunOptions(const Path & program, const Strings & args)
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: program(program), args(args) { };
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RunOptions & killStderr(bool v) { _killStderr = true; return *this; }
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};
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std::pair<int, std::string> runProgram(const RunOptions & options);
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void runProgram2(const RunOptions & options);
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class ExecError : public Error
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{
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public:
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int status;
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template<typename... Args>
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ExecError(int status, const Args & ... args)
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: Error(args...), status(status)
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{ }
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};
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/* Convert a list of strings to a null-terminated vector of char
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*'s. The result must not be accessed beyond the lifetime of the
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list of strings. */
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std::vector<char *> stringsToCharPtrs(const Strings & ss);
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/* Close all file descriptors except those listed in the given set.
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Good practice in child processes. */
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void closeMostFDs(const set<int> & exceptions);
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/* Set the close-on-exec flag for the given file descriptor. */
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void closeOnExec(int fd);
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/* User interruption. */
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extern bool _isInterrupted;
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extern thread_local std::function<bool()> interruptCheck;
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void setInterruptThrown();
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void _interrupted();
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void inline checkInterrupt()
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{
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if (_isInterrupted || (interruptCheck && interruptCheck()))
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_interrupted();
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}
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MakeError(Interrupted, BaseError);
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MakeError(FormatError, Error);
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/* String tokenizer. */
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template<class C> C tokenizeString(const string & s, const string & separators = " \t\n\r");
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/* Concatenate the given strings with a separator between the
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elements. */
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string concatStringsSep(const string & sep, const Strings & ss);
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string concatStringsSep(const string & sep, const StringSet & ss);
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/* Remove trailing whitespace from a string. */
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string chomp(const string & s);
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/* Remove whitespace from the start and end of a string. */
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string trim(const string & s, const string & whitespace = " \n\r\t");
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/* Replace all occurrences of a string inside another string. */
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string replaceStrings(const std::string & s,
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const std::string & from, const std::string & to);
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std::string rewriteStrings(const std::string & s, const StringMap & rewrites);
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/* If a set contains 'from', remove it and insert 'to'. */
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template<typename T>
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void replaceInSet(std::set<T> & set, const T & from, const T & to)
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{
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auto i = set.find(from);
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if (i == set.end()) return;
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set.erase(i);
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set.insert(to);
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}
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/* Convert the exit status of a child as returned by wait() into an
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error string. */
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string statusToString(int status);
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bool statusOk(int status);
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/* Parse a string into an integer. */
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template<class N> bool string2Int(const string & s, N & n)
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{
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if (string(s, 0, 1) == "-" && !std::numeric_limits<N>::is_signed)
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return false;
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std::istringstream str(s);
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str >> n;
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return str && str.get() == EOF;
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}
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/* Parse a string into a float. */
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template<class N> bool string2Float(const string & s, N & n)
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{
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std::istringstream str(s);
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str >> n;
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return str && str.get() == EOF;
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}
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/* Return true iff `s' starts with `prefix'. */
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bool hasPrefix(const string & s, const string & prefix);
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/* Return true iff `s' ends in `suffix'. */
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bool hasSuffix(std::string_view s, std::string_view suffix);
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/* Convert a string to lower case. */
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std::string toLower(const std::string & s);
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/* Escape a string as a shell word. */
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std::string shellEscape(const std::string & s);
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/* Exception handling in destructors: print an error message, then
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ignore the exception. */
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void ignoreException();
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/* Some ANSI escape sequences. */
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#define ANSI_NORMAL "\e[0m"
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#define ANSI_BOLD "\e[1m"
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#define ANSI_FAINT "\e[2m"
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#define ANSI_RED "\e[31;1m"
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#define ANSI_GREEN "\e[32;1m"
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#define ANSI_BLUE "\e[34;1m"
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/* Truncate a string to 'width' printable characters. If 'filterAll'
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is true, all ANSI escape sequences are filtered out. Otherwise,
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some escape sequences (such as colour setting) are copied but not
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included in the character count. Also, tabs are expanded to
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spaces. */
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std::string filterANSIEscapes(const std::string & s,
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bool filterAll = false,
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unsigned int width = std::numeric_limits<unsigned int>::max());
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/* Base64 encoding/decoding. */
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string base64Encode(const string & s);
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string base64Decode(const string & s);
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/* Get a value for the specified key from an associate container, or a
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default value if the key doesn't exist. */
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template <class T>
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std::optional<std::string> get(const T & map, const std::string & key)
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{
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auto i = map.find(key);
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return i == map.end() ? std::optional<std::string>() : i->second;
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}
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/* A callback is a wrapper around a lambda that accepts a valid of
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type T or an exception. (We abuse std::future<T> to pass the value or
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exception.) */
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template<typename T>
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class Callback
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{
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std::function<void(std::future<T>)> fun;
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std::atomic_flag done = ATOMIC_FLAG_INIT;
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public:
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Callback(std::function<void(std::future<T>)> fun) : fun(fun) { }
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Callback(Callback && callback) : fun(std::move(callback.fun))
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{
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auto prev = callback.done.test_and_set();
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if (prev) done.test_and_set();
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}
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void operator()(T && t) noexcept
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{
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auto prev = done.test_and_set();
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assert(!prev);
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std::promise<T> promise;
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promise.set_value(std::move(t));
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fun(promise.get_future());
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}
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void rethrow(const std::exception_ptr & exc = std::current_exception()) noexcept
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{
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auto prev = done.test_and_set();
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assert(!prev);
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std::promise<T> promise;
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promise.set_exception(exc);
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fun(promise.get_future());
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}
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};
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/* Start a thread that handles various signals. Also block those signals
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on the current thread (and thus any threads created by it). */
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void startSignalHandlerThread();
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/* Restore default signal handling. */
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void restoreSignals();
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struct InterruptCallback
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{
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virtual ~InterruptCallback() { };
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};
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/* Register a function that gets called on SIGINT (in a non-signal
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context). */
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std::unique_ptr<InterruptCallback> createInterruptCallback(
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std::function<void()> callback);
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void triggerInterrupt();
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/* A RAII class that causes the current thread to receive SIGUSR1 when
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the signal handler thread receives SIGINT. That is, this allows
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SIGINT to be multiplexed to multiple threads. */
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struct ReceiveInterrupts
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{
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pthread_t target;
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std::unique_ptr<InterruptCallback> callback;
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ReceiveInterrupts()
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: target(pthread_self())
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, callback(createInterruptCallback([&]() { pthread_kill(target, SIGUSR1); }))
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{ }
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};
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/* A RAII helper that increments a counter on construction and
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decrements it on destruction. */
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template<typename T>
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struct MaintainCount
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{
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T & counter;
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long delta;
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MaintainCount(T & counter, long delta = 1) : counter(counter), delta(delta) { counter += delta; }
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~MaintainCount() { counter -= delta; }
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};
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/* Return the number of rows and columns of the terminal. */
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std::pair<unsigned short, unsigned short> getWindowSize();
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/* Used in various places. */
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typedef std::function<bool(const Path & path)> PathFilter;
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extern PathFilter defaultPathFilter;
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/* Create a Unix domain socket in listen mode. */
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AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode);
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}
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