From 31478c810a79403fbb670ef7c4ef1d0d48271c80 Mon Sep 17 00:00:00 2001
From: eldritch horrors <pennae@lix.systems>
Date: Sat, 11 May 2024 00:45:39 +0200
Subject: [PATCH] libutil: remove makeDecompressionSink

the sole remaining user of this function can use makeDecompressionSource
instead, while making the sinkToSource in the caller unnecessary as well

Change-Id: I4258227b5dbbb735a75b477d8a57007bfca305e9
---
 src/libstore/builtins/fetchurl.cc | 22 +++++++++-------------
 src/libutil/compression.cc        | 25 -------------------------
 src/libutil/compression.hh        |  1 -
 3 files changed, 9 insertions(+), 39 deletions(-)

diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index 37d640fe4..3a4cdd6e7 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -32,23 +32,19 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
 
     auto fetch = [&](const std::string & url) {
 
-        auto source = sinkToSource([&](Sink & sink) {
+        /* No need to do TLS verification, because we check the hash of
+           the result anyway. */
+        FileTransferRequest request(url);
+        request.verifyTLS = false;
 
-            /* No need to do TLS verification, because we check the hash of
-               the result anyway. */
-            FileTransferRequest request(url);
-            request.verifyTLS = false;
-
-            auto decompressor = makeDecompressionSink(
-                unpack && mainUrl.ends_with(".xz") ? "xz" : "none", sink);
-            fileTransfer->download(std::move(request))->drainInto(*decompressor);
-            decompressor->finish();
-        });
+        auto raw = fileTransfer->download(std::move(request));
+        auto decompressor = makeDecompressionSource(
+            unpack && mainUrl.ends_with(".xz") ? "xz" : "none", *raw);
 
         if (unpack)
-            restorePath(storePath, *source);
+            restorePath(storePath, *decompressor);
         else
-            writeFile(storePath, *source);
+            writeFile(storePath, *decompressor);
 
         auto executable = drv.env.find("executable");
         if (executable != drv.env.end() && executable->second == "1") {
diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index a66069e52..773617031 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -198,31 +198,6 @@ std::string decompress(const std::string & method, std::string_view in)
     return filter->drain();
 }
 
-std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink)
-{
-    if (method == "none" || method == "")
-        return std::make_unique<NoneSink>(nextSink);
-    else if (method == "br")
-        return sourceToSink([&](Source & source) {
-            BrotliDecompressionSource wrapped{source};
-            wrapped.drainInto(nextSink);
-            // special handling because sourceToSink is screwy: try
-            // to read the source one final time and fail when that
-            // succeeds (to reject trailing garbage in input data).
-            try {
-                char buf;
-                source(&buf, 1);
-                throw Error("garbage at end of brotli stream detected");
-            } catch (EndOfFile &) {
-            }
-        });
-    else
-        return sourceToSink([&](Source & source) {
-            auto decompressionSource = std::make_unique<ArchiveDecompressionSource>(source);
-            decompressionSource->drainInto(nextSink);
-        });
-}
-
 std::unique_ptr<Source> makeDecompressionSource(const std::string & method, Source & inner)
 {
     if (method == "none" || method == "") {
diff --git a/src/libutil/compression.hh b/src/libutil/compression.hh
index 8affdddd6..9b22a0282 100644
--- a/src/libutil/compression.hh
+++ b/src/libutil/compression.hh
@@ -18,7 +18,6 @@ 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);