mirror of
https://github.com/NixOS/nix
synced 2025-07-06 09:11:47 +02:00
96eeb6f4ff
This is good practice to avoid pessimisations. Left comments for the reasoning why ctors should be noexcept. There are some tricky cases where we intentionally want throwing move ctors/assignments. But those cases should really be reviewed, since some of those can be replaced with more idiomatic copy/move-and-swap.
151 lines
2.8 KiB
C++
151 lines
2.8 KiB
C++
#include "file-system.hh"
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#include "signals.hh"
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#include "finally.hh"
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#include "serialise.hh"
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#include "util.hh"
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#include <fcntl.h>
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#include <unistd.h>
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#ifdef _WIN32
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# include <winnt.h>
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# include <fileapi.h>
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# include "windows-error.hh"
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#endif
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namespace nix {
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void writeLine(Descriptor fd, std::string s)
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{
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s += '\n';
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writeFull(fd, s);
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}
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std::string drainFD(Descriptor fd, bool block, const size_t reserveSize)
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{
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// the parser needs two extra bytes to append terminating characters, other users will
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// not care very much about the extra memory.
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StringSink sink(reserveSize + 2);
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#ifdef _WIN32
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// non-blocking is not supported this way on Windows
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assert(block);
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drainFD(fd, sink);
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#else
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drainFD(fd, sink, block);
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#endif
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return std::move(sink.s);
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}
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//////////////////////////////////////////////////////////////////////
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AutoCloseFD::AutoCloseFD() : fd{INVALID_DESCRIPTOR} {}
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AutoCloseFD::AutoCloseFD(Descriptor fd) : fd{fd} {}
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// NOTE: This can be noexcept since we are just copying a value and resetting
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// the file descriptor in the rhs.
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AutoCloseFD::AutoCloseFD(AutoCloseFD && that) noexcept : fd{that.fd}
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{
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that.fd = INVALID_DESCRIPTOR;
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}
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AutoCloseFD & AutoCloseFD::operator =(AutoCloseFD && that)
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{
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close();
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fd = that.fd;
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that.fd = INVALID_DESCRIPTOR;
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return *this;
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}
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AutoCloseFD::~AutoCloseFD()
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{
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try {
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close();
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} catch (...) {
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ignoreExceptionInDestructor();
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}
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}
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Descriptor AutoCloseFD::get() const
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{
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return fd;
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}
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void AutoCloseFD::close()
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{
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if (fd != INVALID_DESCRIPTOR) {
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if(
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#ifdef _WIN32
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::CloseHandle(fd)
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#else
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::close(fd)
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#endif
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== -1)
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/* This should never happen. */
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throw NativeSysError("closing file descriptor %1%", fd);
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fd = INVALID_DESCRIPTOR;
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}
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}
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void AutoCloseFD::fsync() const
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{
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if (fd != INVALID_DESCRIPTOR) {
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int result;
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result =
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#ifdef _WIN32
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::FlushFileBuffers(fd)
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#elif __APPLE__
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::fcntl(fd, F_FULLFSYNC)
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#else
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::fsync(fd)
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#endif
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;
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if (result == -1)
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throw NativeSysError("fsync file descriptor %1%", fd);
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}
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}
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void AutoCloseFD::startFsync() const
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{
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#if __linux__
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if (fd != -1) {
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/* Ignore failure, since fsync must be run later anyway. This is just a performance optimization. */
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::sync_file_range(fd, 0, 0, SYNC_FILE_RANGE_WRITE);
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}
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#endif
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}
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AutoCloseFD::operator bool() const
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{
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return fd != INVALID_DESCRIPTOR;
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}
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Descriptor AutoCloseFD::release()
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{
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Descriptor oldFD = fd;
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fd = INVALID_DESCRIPTOR;
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return oldFD;
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}
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//////////////////////////////////////////////////////////////////////
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void Pipe::close()
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{
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readSide.close();
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writeSide.close();
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}
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}
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