nix-super/src/libutil/fs-sink.hh
2024-02-27 06:39:30 +01:00

106 lines
2.5 KiB
C++

#pragma once
///@file
#include "types.hh"
#include "serialise.hh"
#include "source-accessor.hh"
#include "file-system.hh"
namespace nix {
/**
* Actions on an open regular file in the process of creating it.
*
* See `FileSystemObjectSink::createRegularFile`.
*/
struct CreateRegularFileSink : Sink
{
virtual void isExecutable() = 0;
/**
* An optimization. By default, do nothing.
*/
virtual void preallocateContents(uint64_t size) { };
};
struct FileSystemObjectSink
{
virtual ~FileSystemObjectSink() = default;
virtual void createDirectory(const Path & path) = 0;
/**
* This function in general is no re-entrant. Only one file can be
* written at a time.
*/
virtual void createRegularFile(
const Path & path,
std::function<void(CreateRegularFileSink &)>) = 0;
virtual void createSymlink(const Path & path, const std::string & target) = 0;
};
/**
* Recursively copy file system objects from the source into the sink.
*/
void copyRecursive(
SourceAccessor & accessor, const CanonPath & sourcePath,
FileSystemObjectSink & sink, const Path & destPath);
/**
* Ignore everything and do nothing
*/
struct NullFileSystemObjectSink : FileSystemObjectSink
{
void createDirectory(const Path & path) override { }
void createSymlink(const Path & path, const std::string & target) override { }
void createRegularFile(
const Path & path,
std::function<void(CreateRegularFileSink &)>) override;
};
/**
* Write files at the given path
*/
struct RestoreSink : FileSystemObjectSink
{
Path dstPath;
void createDirectory(const Path & path) override;
void createRegularFile(
const Path & path,
std::function<void(CreateRegularFileSink &)>) override;
void createSymlink(const Path & path, const std::string & target) override;
};
/**
* Restore a single file at the top level, passing along
* `receiveContents` to the underlying `Sink`. For anything but a single
* file, set `regular = true` so the caller can fail accordingly.
*/
struct RegularFileSink : FileSystemObjectSink
{
bool regular = true;
Sink & sink;
RegularFileSink(Sink & sink) : sink(sink) { }
void createDirectory(const Path & path) override
{
regular = false;
}
void createSymlink(const Path & path, const std::string & target) override
{
regular = false;
}
void createRegularFile(
const Path & path,
std::function<void(CreateRegularFileSink &)>) override;
};
}