3 files changed, 25 insertions, 3 deletions
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 128e287f3..5780c93a6 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -77,7 +77,6 @@ struct BufferedSource : Source
 
     size_t read(unsigned char * data, size_t len) override;
 
-
     bool hasData();
 
 protected:
diff --git a/src/libutil/tarfile.cc b/src/libutil/tarfile.cc
index ae6d512bd..f7d3ad417 100644
--- a/src/libutil/tarfile.cc
+++ b/src/libutil/tarfile.cc
@@ -1,4 +1,5 @@
 #include "rust-ffi.hh"
+#include "compression.hh"
 
 extern "C" {
     rust::CBox2<rust::Result<std::tuple<>>> unpack_tarfile(rust::Source source, rust::StringSlice dest_dir);
@@ -6,9 +7,28 @@ extern "C" {
 
 namespace nix {
 
-void unpackTarfile(Source & source, Path destDir)
+void unpackTarfile(Source & source, const Path & destDir)
 {
     unpack_tarfile(source, destDir).use()->unwrap();
 }
 
+void unpackTarfile(const Path & tarFile, const Path & destDir,
+    std::optional<std::string> baseName)
+{
+    if (!baseName) baseName = baseNameOf(tarFile);
+
+    auto source = sinkToSource([&](Sink & sink) {
+        // FIXME: look at first few bytes to determine compression type.
+        auto decompressor =
+            // FIXME: add .gz support
+            hasSuffix(*baseName, ".bz2") ? makeDecompressionSink("bzip2", sink) :
+            hasSuffix(*baseName, ".xz") ? makeDecompressionSink("xz", sink) :
+            makeDecompressionSink("none", sink);
+        readFile(tarFile, *decompressor);
+        decompressor->finish();
+    });
+
+    unpackTarfile(*source, destDir);
+}
+
 }
diff --git a/src/libutil/tarfile.hh b/src/libutil/tarfile.hh
index c3e95fb0c..ce0911e2a 100644
--- a/src/libutil/tarfile.hh
+++ b/src/libutil/tarfile.hh
@@ -2,6 +2,9 @@
 
 namespace nix {
 
-void unpackTarfile(Source & source, Path destDir);
+void unpackTarfile(Source & source, const Path & destDir);
+
+void unpackTarfile(const Path & tarFile, const Path & destDir,
+    std::optional<std::string> baseName = {});
 
 }