eldritch horrors
2112a39d2e
this will let us turn copyNAR into a generator as well, which in turn is necessary to turn the users of copyNAR into generators without resorting to sinkToSource coroutines. currently this uses the SerializingTransform in all cases, even for copyNAR where it is not necessary. should this be a performance problem we can easily swap out the transform for one which does not produce any bytes of its own, but that should not be necessary. Change-Id: I7e685879318fcbb78d8b88abfddd7752360eb0ce
136 lines
3.2 KiB
C++
136 lines
3.2 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 "file-system.hh"
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namespace nix {
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/**
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* dumpPath creates a Nix archive of the specified path.
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*
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* @param path the file system data to dump. Dumping is recursive so if
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* this is a directory we dump it and all its children.
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*
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* @param [out] sink The serialised archive is fed into this sink.
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*
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* @param filter Can be used to skip certain files.
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*
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* The format is as follows:
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*
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* ```
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* IF path points to a REGULAR FILE:
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* dump(path) = attrs(
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* [ ("type", "regular")
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* , ("contents", contents(path))
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* ])
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*
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* IF path points to a DIRECTORY:
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* dump(path) = attrs(
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* [ ("type", "directory")
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* , ("entries", concat(map(f, sort(entries(path)))))
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* ])
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* where f(fn) = attrs(
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* [ ("name", fn)
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* , ("file", dump(path + "/" + fn))
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* ])
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*
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* where:
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*
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* attrs(as) = concat(map(attr, as)) + encN(0)
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* attrs((a, b)) = encS(a) + encS(b)
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*
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* encS(s) = encN(len(s)) + s + (padding until next 64-bit boundary)
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*
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* encN(n) = 64-bit little-endian encoding of n.
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*
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* contents(path) = the contents of a regular file.
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*
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* sort(strings) = lexicographic sort by 8-bit value (strcmp).
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*
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* entries(path) = the entries of a directory, without `.` and
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* `..`.
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*
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* `+` denotes string concatenation.
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* ```
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*/
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WireFormatGenerator dumpPath(Path path,
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PathFilter & filter = defaultPathFilter);
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/**
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* Same as dumpPath(), but returns the last modified date of the path.
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*/
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WireFormatGenerator dumpPathAndGetMtime(Path path, time_t & mtime,
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PathFilter & filter = defaultPathFilter);
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/**
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* Dump an archive with a single file with these contents.
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*
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* @param s Contents of the file.
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*/
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WireFormatGenerator dumpString(std::string_view s);
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/**
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* \todo Fix this API, it sucks.
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*/
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struct ParseSink
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{
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virtual void createDirectory(const Path & path) { };
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virtual void createRegularFile(const Path & path) { };
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virtual void closeRegularFile() { };
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virtual void isExecutable() { };
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virtual void preallocateContents(uint64_t size) { };
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virtual void receiveContents(std::string_view data) { };
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virtual void createSymlink(const Path & path, const std::string & target) { };
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};
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/**
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* If the NAR archive contains a single file at top-level, then save
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* the contents of the file to `s`. Otherwise barf.
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*/
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struct RetrieveRegularNARSink : ParseSink
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{
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bool regular = true;
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Sink & sink;
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RetrieveRegularNARSink(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 receiveContents(std::string_view data) override
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{
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sink(data);
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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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};
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WireFormatGenerator parseAndCopyDump(ParseSink & sink, Source & source);
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void parseDump(ParseSink & sink, Source & source);
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void restorePath(const Path & path, Source & source);
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/**
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* Read a NAR from 'source' and write it to 'sink'.
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*/
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void copyNAR(Source & source, Sink & sink);
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inline constexpr std::string_view narVersionMagic1 = "nix-archive-1";
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inline constexpr std::string_view caseHackSuffix = "~nix~case~hack~";
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}
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