Factor out StoreDirConfig

More progress on #5729.

src/libstore/store-dir-config.hh

@@ -0,0 +1,126 @@
+#pragma once
+
+#include "path.hh"
+#include "hash.hh"
+#include "content-address.hh"
+#include "globals.hh"
+#include "config.hh"
+
+#include <map>
+#include <string>
+#include <variant>
+
+
+namespace nix {
+
+MakeError(BadStorePath, Error);
+
+struct StoreDirConfig : public Config
+{
+    using Config::Config;
+
+    StoreDirConfig() = delete;
+
+    virtual ~StoreDirConfig() = default;
+
+    const PathSetting storeDir_{this, settings.nixStore,
+        "store",
+        R"(
+          Logical location of the Nix store, usually
+          `/nix/store`. Note that you can only copy store paths
+          between stores if they have the same `store` setting.
+        )"};
+    const Path storeDir = storeDir_;
+
+    // pure methods
+
+    StorePath parseStorePath(std::string_view path) const;
+
+    std::optional<StorePath> maybeParseStorePath(std::string_view path) const;
+
+    std::string printStorePath(const StorePath & path) const;
+
+    /**
+     * Deprecated
+     *
+     * \todo remove
+     */
+    StorePathSet parseStorePathSet(const PathSet & paths) const;
+
+    PathSet printStorePathSet(const StorePathSet & path) const;
+
+    /**
+     * Display a set of paths in human-readable form (i.e., between quotes
+     * and separated by commas).
+     */
+    std::string showPaths(const StorePathSet & paths);
+
+    /**
+     * @return true if ‘path’ is in the Nix store (but not the Nix
+     * store itself).
+     */
+    bool isInStore(PathView path) const;
+
+    /**
+     * @return true if ‘path’ is a store path, i.e. a direct child of the
+     * Nix store.
+     */
+    bool isStorePath(std::string_view path) const;
+
+    /**
+     * Split a path like /nix/store/<hash>-<name>/<bla> into
+     * /nix/store/<hash>-<name> and /<bla>.
+     */
+    std::pair<StorePath, Path> toStorePath(PathView path) const;
+
+    /**
+     * Constructs a unique store path name.
+     */
+    StorePath makeStorePath(std::string_view type,
+        std::string_view hash, std::string_view name) const;
+    StorePath makeStorePath(std::string_view type,
+        const Hash & hash, std::string_view name) const;
+
+    StorePath makeOutputPath(std::string_view id,
+        const Hash & hash, std::string_view name) const;
+
+    StorePath makeFixedOutputPath(std::string_view name, const FixedOutputInfo & info) const;
+
+    StorePath makeTextPath(std::string_view name, const TextInfo & info) const;
+
+    StorePath makeFixedOutputPathFromCA(std::string_view name, const ContentAddressWithReferences & ca) const;
+
+    /**
+     * Read-only variant of addToStoreFromDump(). It returns the store
+     * path to which a NAR or flat file would be written.
+     */
+    std::pair<StorePath, Hash> computeStorePathFromDump(
+        Source & dump,
+        std::string_view name,
+        FileIngestionMethod method = FileIngestionMethod::Recursive,
+        HashType hashAlgo = htSHA256,
+        const StorePathSet & references = {}) const;
+
+    /**
+     * Preparatory part of addTextToStore().
+     *
+     * !!! Computation of the path should take the references given to
+     * addTextToStore() into account, otherwise we have a (relatively
+     * minor) security hole: a caller can register a source file with
+     * bogus references.  If there are too many references, the path may
+     * not be garbage collected when it has to be (not really a problem,
+     * the caller could create a root anyway), or it may be garbage
+     * collected when it shouldn't be (more serious).
+     *
+     * Hashing the references would solve this (bogus references would
+     * simply yield a different store path, so other users wouldn't be
+     * affected), but it has some backwards compatibility issues (the
+     * hashing scheme changes), so I'm not doing that for now.
+     */
+    StorePath computeStorePathForText(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references) const;
+};
+
+}