6365bbfa81
More invariants are enforced in the type, and less state needs to be stored in the main sink itself. The method here is roughly that known as "session types". Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
105 lines
2.4 KiB
C++
105 lines
2.4 KiB
C++
#pragma once
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///@file
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#include "types.hh"
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#include "serialise.hh"
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#include "source-accessor.hh"
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#include "file-system.hh"
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namespace nix {
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/**
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* Actions on an open regular file in the process of creating it.
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*
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* See `FileSystemObjectSink::createRegularFile`.
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*/
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struct CreateRegularFileSink : Sink
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{
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virtual void isExecutable() = 0;
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/**
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* An optimization. By default, do nothing.
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*/
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virtual void preallocateContents(uint64_t size) { };
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};
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struct FileSystemObjectSink
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{
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virtual void createDirectory(const Path & path) = 0;
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/**
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* This function in general is no re-entrant. Only one file can be
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* written at a time.
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*/
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virtual void createRegularFile(
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const Path & path,
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std::function<void(CreateRegularFileSink &)>) = 0;
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virtual void createSymlink(const Path & path, const std::string & target) = 0;
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};
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/**
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* Recursively copy file system objects from the source into the sink.
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*/
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void copyRecursive(
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SourceAccessor & accessor, const CanonPath & sourcePath,
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FileSystemObjectSink & sink, const Path & destPath);
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/**
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* Ignore everything and do nothing
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*/
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struct NullFileSystemObjectSink : FileSystemObjectSink
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{
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void createDirectory(const Path & path) override { }
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void createSymlink(const Path & path, const std::string & target) override { }
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void createRegularFile(
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const Path & path,
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std::function<void(CreateRegularFileSink &)>) override;
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};
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/**
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* Write files at the given path
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*/
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struct RestoreSink : FileSystemObjectSink
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{
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Path dstPath;
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void createDirectory(const Path & path) override;
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void createRegularFile(
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const Path & path,
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std::function<void(CreateRegularFileSink &)>) override;
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void createSymlink(const Path & path, const std::string & target) override;
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};
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/**
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* Restore a single file at the top level, passing along
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* `receiveContents` to the underlying `Sink`. For anything but a single
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* file, set `regular = true` so the caller can fail accordingly.
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*/
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struct RegularFileSink : FileSystemObjectSink
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{
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bool regular = true;
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Sink & sink;
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RegularFileSink(Sink & sink) : sink(sink) { }
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void createDirectory(const Path & path) override
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{
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regular = false;
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}
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void createSymlink(const Path & path, const std::string & target) override
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{
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regular = false;
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}
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void createRegularFile(
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const Path & path,
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std::function<void(CreateRegularFileSink &)>) override;
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};
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}
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