eldritch horrors
e01ae1f453
previously we used this only for SSH, but other uses may appear soon. Change-Id: Ibe9666d63aaea07525ebad57decda88b11964cc0
129 lines
2.9 KiB
C++
129 lines
2.9 KiB
C++
#pragma once
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///@file
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#include "lix/libutil/error.hh"
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#include "lix/libutil/generator.hh"
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namespace nix {
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struct Sink;
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struct Source;
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/**
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* Read a line from a file descriptor.
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*/
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std::string readLine(int fd);
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/**
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* Write a line to a file descriptor.
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*/
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void writeLine(int fd, std::string s);
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/**
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* Read the contents of a file into a string.
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*/
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std::string readFile(int fd);
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/**
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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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*/
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void readFull(int fd, char * buf, size_t count);
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void writeFull(int fd, std::string_view s, bool allowInterrupts = true);
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/**
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* Read a file descriptor until EOF occurs.
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*/
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std::string drainFD(int fd, bool block = true, const size_t reserveSize=0);
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/*
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* Will attempt to guess *A* path associated that might lead to the same file as used by this
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* file descriptor.
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*
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* The returned string should NEVER be used as a valid path.
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*/
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std::string guessOrInventPathFromFD(int fd);
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Generator<Bytes> drainFDSource(int fd, bool block = true);
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class AutoCloseFD
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{
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int fd;
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public:
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AutoCloseFD();
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explicit 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) noexcept(false);
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int get() const;
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/*
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* Will attempt to guess *A* path associated that might lead to the same file as used by this
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* file descriptor.
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*
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* The returned string should NEVER be used as a valid path.
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*/
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std::string guessOrInventPath() const { return guessOrInventPathFromFD(fd); }
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explicit operator bool() const;
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int release();
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void close();
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void fsync();
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void reset() { *this = {}; }
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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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void close();
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};
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struct SocketPair
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{
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/** The two sides of the socket pair. */
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AutoCloseFD a, b;
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/** Create a unix stream socket pair with the `O_CLOEXEC` set on both ends. */
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static SocketPair stream();
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private:
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SocketPair(AutoCloseFD a, AutoCloseFD b) : a(std::move(a)), b(std::move(b)) {}
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};
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/**
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* Close all file descriptors except stdio fds (ie 0, 1, 2).
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* Good practice in child processes.
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*/
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void closeExtraFDs();
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/**
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* Set the close-on-exec flag for the given file descriptor.
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*/
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void closeOnExec(int fd);
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enum class FdBlockingState : int {};
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/**
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* Make the given file descriptor non-blocking. Returns the old flag set; this
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* can be passed to resetBlockingState to return the fd to its original state.
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*/
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FdBlockingState makeNonBlocking(int fd);
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/**
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* Make the given file descriptor blocking. Returns the old flag set; it can
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* be passed to `resetBlockingState` to return the fd to its original state.
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*/
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FdBlockingState makeBlocking(int fd);
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/**
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* Undo a `makeNonBlocking` or `makeBlocking` call.
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*/
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void resetBlockingState(int fd, FdBlockingState prevState);
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MakeError(EndOfFile, Error);
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}
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