libutil: add makeDecompressionSource

Change-Id: Iac7f24d79e24417436b9b5cbefd6af051aeea0a6

2 files changed, 17 insertions, 5 deletions

diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index e78d76500..d93a1b1d6 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -192,11 +192,9 @@ struct BrotliDecompressionSource : Source
 
 std::string decompress(const std::string & method, std::string_view in)
 {
-    StringSink ssink;
-    auto sink = makeDecompressionSink(method, ssink);
-    (*sink)(in);
-    sink->finish();
-    return std::move(ssink.s);
+    StringSource src{in};
+    auto filter = makeDecompressionSource(method, src);
+    return filter->drain();
 }
 
 std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink)
@@ -224,6 +222,19 @@ std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Si
         });
 }
 
+std::unique_ptr<Source> makeDecompressionSource(const std::string & method, Source & inner)
+{
+    if (method == "none" || method == "") {
+        return std::make_unique<LambdaSource>([&](char * data, size_t len) {
+            return inner.read(data, len);
+        });
+    } else if (method == "br") {
+        return std::make_unique<BrotliDecompressionSource>(inner);
+    } else {
+        return std::make_unique<ArchiveDecompressionSource>(inner);
+    }
+}
+
 struct BrotliCompressionSink : ChunkedCompressionSink
 {
     Sink & nextSink;
diff --git a/src/libutil/compression.hh b/src/libutil/compression.hh
index 4e53a7b3c..8affdddd6 100644
--- a/src/libutil/compression.hh
+++ b/src/libutil/compression.hh
@@ -19,6 +19,7 @@ struct CompressionSink : BufferedSink, FinishSink
 std::string decompress(const std::string & method, std::string_view in);
 
 std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink);
+std::unique_ptr<Source> makeDecompressionSource(const std::string & method, Source & inner);
 
 std::string compress(const std::string & method, std::string_view in, const bool parallel = false, int level = -1);