lix-releng-staging/src/libutil/util.hh

434 lines
11 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

#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>
#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 {
/* Return an environment variable. */
string getEnv(const string & key, const string & def = "");
/* Get the entire environment. */
std::map<std::string, std::string> getEnv();
/* 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 a given path is a descendant of the given
directory. */
bool isInDir(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);
/* Write a string to a file. */
void writeFile(const Path & path, const string & s);
/* 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);
/* Return the path to $XDG_CACHE_HOME/.cache. */
Path getCacheDir();
/* 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);
/* Automatic cleanup of resources. */
template <class T>
struct AutoDeleteArray
{
T * p;
AutoDeleteArray(T * p) : p(p) { }
~AutoDeleteArray()
{
delete [] p;
}
};
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();
};
class AutoCloseDir
{
DIR * dir;
public:
AutoCloseDir();
AutoCloseDir(DIR * dir);
~AutoCloseDir();
void operator =(DIR * dir);
operator DIR *();
void close();
};
class Pid
{
pid_t pid;
bool separatePG;
int killSignal;
public:
Pid();
Pid(pid_t pid);
~Pid();
void operator =(pid_t pid);
operator pid_t();
void kill(bool quiet = false);
int wait(bool block);
void setSeparatePG(bool separatePG);
void setKillSignal(int signal);
};
/* 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;
bool dieWithParent;
bool runExitHandlers;
bool allowVfork;
ProcessOptions() : errorPrefix("error: "), dieWithParent(true), runExitHandlers(false), 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 string & input = "");
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 stdin, stdout, stderr, and 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);
/* Restore default handling of SIGPIPE, otherwise some programs will
randomly say "Broken pipe". */
void restoreSIGPIPE();
/* User interruption. */
extern volatile sig_atomic_t _isInterrupted;
extern thread_local bool interruptThrown;
void _interrupted();
void inline checkInterrupt()
{
if (_isInterrupted) _interrupted();
}
MakeError(Interrupted, BaseError)
/* 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 that contains octal-encoded escape codes such as
used in /etc/fstab and /proc/mounts (e.g. "foo\040bar" decodes to
"foo bar"). */
string decodeOctalEscaped(const 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_RED "\e[31;1m"
/* Filter out ANSI escape codes from the given string. If nixOnly is
set, only filter escape codes generated by Nixpkgs' stdenv (used to
denote nesting etc.). */
string filterANSIEscapes(const string & s, bool nixOnly = false);
/* 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;
}
/* Call failure with the current exception as argument. If failure
throws an exception, abort the program. */
void callFailure(const std::function<void(std::exception_ptr exc)> & failure,
std::exception_ptr exc = std::current_exception());
/* Evaluate the function f. If it returns a value, call success
with that value as its argument. If it or success throws an
exception, call failure. If failure throws an exception, abort
the program. */
template<class T>
void sync2async(
const std::function<void(T)> & success,
const std::function<void(std::exception_ptr exc)> & failure,
const std::function<T()> & f)
{
try {
success(f());
} catch (...) {
callFailure(failure);
}
}
/* Call the function success. If it throws an exception, call
failure. If that throws an exception, abort the program. */
template<class T>
void callSuccess(
const std::function<void(T)> & success,
const std::function<void(std::exception_ptr exc)> & failure,
T && arg)
{
try {
success(arg);
} catch (...) {
callFailure(failure);
}
}
}