Organize content addressing, use SourceAccessor with Store::addToStore

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>

src/libutil/file-content-address.cc

@@ -0,0 +1,49 @@
+#include "file-content-address.hh"
+#include "archive.hh"
+
+namespace nix {
+
+void dumpPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    Sink & sink,
+    FileIngestionMethod method,
+    PathFilter & filter)
+{
+    switch (method) {
+    case FileIngestionMethod::Flat:
+        accessor.readFile(path, sink);
+        break;
+    case FileIngestionMethod::Recursive:
+        accessor.dumpPath(path, sink, filter);
+        break;
+    }
+}
+
+
+void restorePath(
+    const Path & path,
+    Source & source,
+    FileIngestionMethod method)
+{
+    switch (method) {
+    case FileIngestionMethod::Flat:
+        writeFile(path, source);
+        break;
+    case FileIngestionMethod::Recursive:
+        restorePath(path, source);
+        break;
+    }
+}
+
+
+HashResult hashPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    FileIngestionMethod method, HashAlgorithm ht,
+    PathFilter & filter)
+{
+    HashSink sink { ht };
+    dumpPath(accessor, path, sink, method, filter);
+    return sink.finish();
+}
+
+}

src/libutil/file-content-address.hh

@@ -0,0 +1,56 @@
+#pragma once
+///@file
+
+#include "source-accessor.hh"
+#include "fs-sink.hh"
+#include "util.hh"
+
+namespace nix {
+
+/**
+ * An enumeration of the main ways we can serialize file system
+ * objects.
+ */
+enum struct FileIngestionMethod : uint8_t {
+    /**
+     * Flat-file hashing. Directly ingest the contents of a single file
+     */
+    Flat = 0,
+    /**
+     * Recursive (or NAR) hashing. Serializes the file-system object in
+     * Nix Archive format and ingest that.
+     */
+    Recursive = 1,
+};
+
+/**
+ * Dump a serialization of the given file system object.
+ */
+void dumpPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    Sink & sink,
+    FileIngestionMethod method,
+    PathFilter & filter = defaultPathFilter);
+
+/**
+ * Restore a serialization of the given file system object.
+ *
+ * @TODO use an arbitrary `ParseSink`.
+ */
+void restorePath(
+    const Path & path,
+    Source & source,
+    FileIngestionMethod method);
+
+/**
+ * Compute the hash of the given file system object according to the
+ * given method.
+ *
+ * The hash is defined as (essentially) hashString(ht, dumpPath(path)).
+ */
+HashResult hashPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    FileIngestionMethod method, HashAlgorithm ht,
+    PathFilter & filter = defaultPathFilter);
+
+}

src/libutil/hash.cc

@@ -367,15 +367,6 @@ HashResult HashSink::currentHash()
 }
 
 
-HashResult hashPath(
-        HashAlgorithm ha, const Path & path, PathFilter & filter)
-{
-    HashSink sink(ha);
-    dumpPath(path, sink, filter);
-    return sink.finish();
-}
-
-
 Hash compressHash(const Hash & hash, unsigned int newSize)
 {
     Hash h(hash.algo);

src/libutil/hash.hh

@@ -168,14 +168,11 @@ Hash hashString(HashAlgorithm ha, std::string_view s);
 Hash hashFile(HashAlgorithm ha, const Path & path);
 
 /**
- * Compute the hash of the given path, serializing as a Nix Archive and
- * then hashing that.
+ * The final hash and the number of bytes digested.
  *
- * The hash is defined as (essentially) hashString(ht, dumpPath(path)).
+ * @todo Convert to proper struct
  */
 typedef std::pair<Hash, uint64_t> HashResult;
-HashResult hashPath(HashAlgorithm ha, const Path & path,
-                    PathFilter & filter = defaultPathFilter);
 
 /**
  * Compress a hash to the specified number of bytes by cyclically