2 files changed, 29 insertions, 6 deletions
diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index beede13211fa..e8a820d30429 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -15,7 +15,7 @@ struct LzmaStream
     lzma_stream & operator()() { return strm; }
 };
 
-std::string compressXZ(const std::string & in)
+static ref<std::string> compressXZ(const std::string & in)
 {
     LzmaStream strm;
 
@@ -28,7 +28,7 @@ std::string compressXZ(const std::string & in)
 
     lzma_action action = LZMA_RUN;
     uint8_t outbuf[BUFSIZ];
-    string res;
+    ref<std::string> res = make_ref<std::string>();
     strm().next_in = (uint8_t *) in.c_str();
     strm().avail_in = in.size();
     strm().next_out = outbuf;
@@ -43,7 +43,7 @@ std::string compressXZ(const std::string & in)
         lzma_ret ret = lzma_code(&strm(), action);
 
         if (strm().avail_out == 0 || ret == LZMA_STREAM_END) {
-            res.append((char *) outbuf, sizeof(outbuf) - strm().avail_out);
+            res->append((char *) outbuf, sizeof(outbuf) - strm().avail_out);
             strm().next_out = outbuf;
             strm().avail_out = sizeof(outbuf);
         }
@@ -56,7 +56,7 @@ std::string compressXZ(const std::string & in)
     }
 }
 
-ref<std::string> decompressXZ(const std::string & in)
+static ref<std::string> decompressXZ(const std::string & in)
 {
     LzmaStream strm;
 
@@ -95,4 +95,24 @@ ref<std::string> decompressXZ(const std::string & in)
     }
 }
 
+ref<std::string> compress(const std::string & method, ref<std::string> in)
+{
+    if (method == "none")
+        return in;
+    else if (method == "xz")
+        return compressXZ(*in);
+    else
+        throw UnknownCompressionMethod(format("unknown compression method ‘%s’") % method);
+}
+
+ref<std::string> decompress(const std::string & method, ref<std::string> in)
+{
+    if (method == "none")
+        return in;
+    else if (method == "xz")
+        return decompressXZ(*in);
+    else
+        throw UnknownCompressionMethod(format("unknown compression method ‘%s’") % method);
+}
+
 }
diff --git a/src/libutil/compression.hh b/src/libutil/compression.hh
index 79a796db7756..33c465df8455 100644
--- a/src/libutil/compression.hh
+++ b/src/libutil/compression.hh
@@ -1,13 +1,16 @@
 #pragma once
 
 #include "ref.hh"
+#include "types.hh"
 
 #include <string>
 
 namespace nix {
 
-std::string compressXZ(const std::string & in);
+ref<std::string> compress(const std::string & method, ref<std::string> in);
 
-ref<std::string> decompressXZ(const std::string & in);
+ref<std::string> decompress(const std::string & method, ref<std::string> in);
+
+MakeError(UnknownCompressionMethod, Error);
 
 }