From 73f3179954ef8db5c8774c79272dd1215fe6f5c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Fri, 5 Jul 2024 17:26:58 +0200
Subject: [PATCH 1/2] src/nix/prefetch: fix prefetch containing current
 directory instead of tarball

When --unpack was used the nix would add the current directory to the
nix store instead of the content of unpacked.
The reason for this is that std::distance already consumes the iterator.
To fix this we re-instantiate the directory iterator in case the
directory only contains a single entry.

(cherry picked from commit 8cea1fbd97903e58b4de780bbf428b981f196e20)
---
 src/nix/prefetch.cc         | 11 ++++++-----
 tests/functional/tarball.sh | 12 ++++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 3ce52acc5..2aa27441a 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -113,14 +113,15 @@ std::tuple<StorePath, Hash> prefetchFile(
             createDirs(unpacked);
             unpackTarfile(tmpFile.string(), unpacked);
 
+            auto entries = std::filesystem::directory_iterator{unpacked};
             /* If the archive unpacks to a single file/directory, then use
                that as the top-level. */
-            auto entries = std::filesystem::directory_iterator{unpacked};
-            auto file_count = std::distance(entries, std::filesystem::directory_iterator{});
-            if (file_count == 1)
-                tmpFile = entries->path();
-            else
+            tmpFile = entries->path();
+            unsigned fileCount = std::distance(entries, std::filesystem::directory_iterator{});
+            if (fileCount != 1) {
+                /* otherwise, use the directory itself */
                 tmpFile = unpacked;
+            }
         }
 
         Activity act(*logger, lvlChatty, actUnknown,
diff --git a/tests/functional/tarball.sh b/tests/functional/tarball.sh
index ce162ddce..28ed62207 100755
--- a/tests/functional/tarball.sh
+++ b/tests/functional/tarball.sh
@@ -54,6 +54,18 @@ test_tarball() {
     # with the content-addressing
     (! nix-instantiate --eval -E "fetchTree { type = \"tarball\"; url = file://$tarball; narHash = \"$hash\"; name = \"foo\"; }")
 
+    store_path=$(nix store prefetch-file --json "file://$tarball" | jq -r .storePath)
+    if ! cmp -s "$store_path" "$tarball"; then
+        echo "prefetched tarball differs from original: $store_path vs $tarball" >&2
+        exit 1
+    fi
+    store_path2=$(nix store prefetch-file --json --unpack "file://$tarball" | jq -r .storePath)
+    diff_output=$(diff -r "$store_path2" "$tarroot")
+    if [ -n "$diff_output" ]; then
+        echo "prefetched tarball differs from original: $store_path2 vs $tarroot" >&2
+        echo "$diff_output"
+        exit 1
+    fi
 }
 
 test_tarball '' cat

From d58592469db6ade17c047e39f2af44e45f3d07de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <Mic92@users.noreply.github.com>
Date: Fri, 5 Jul 2024 19:45:03 +0200
Subject: [PATCH 2/2] Update src/nix/prefetch.cc

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
(cherry picked from commit 05381c0b3093a0b5e091946ce2f6fa9f02b981ec)
---
 src/nix/prefetch.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 2aa27441a..f19a01ca3 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -117,7 +117,7 @@ std::tuple<StorePath, Hash> prefetchFile(
             /* If the archive unpacks to a single file/directory, then use
                that as the top-level. */
             tmpFile = entries->path();
-            unsigned fileCount = std::distance(entries, std::filesystem::directory_iterator{});
+            auto fileCount = std::distance(entries, std::filesystem::directory_iterator{});
             if (fileCount != 1) {
                 /* otherwise, use the directory itself */
                 tmpFile = unpacked;