Use BSD tar's libarchive LZMA support if available

Avoid using an unnecessary `xz` dependency when it's not needed.

1 files changed, 13 insertions, 9 deletions

diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 4f2f1b6b0..057768246 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -222,7 +222,7 @@ end
 
 class AbstractFileDownloadStrategy < AbstractDownloadStrategy
   def stage
-    case cached_location.compression_type
+    case type = cached_location.compression_type
     when :zip
       with_system_path { quiet_safe_system "unzip", "-qq", cached_location }
       chdir
@@ -230,19 +230,23 @@ class AbstractFileDownloadStrategy < AbstractDownloadStrategy
       with_system_path { buffered_write("gunzip") }
     when :bzip2_only
       with_system_path { buffered_write("bunzip2") }
-    when :gzip, :bzip2, :compress, :tar
+    when :gzip, :bzip2, :xz, :compress, :tar
       tar_flags = "x"
-      # Older versions of tar require an explicit format flag
-      if cached_location.compression_type == :gzip
+      if type == :gzip
         tar_flags << "z"
-      elsif cached_location.compression_type == :bzip2
+      elsif type == :bzip2
         tar_flags << "j"
+      elsif type == :xz
+        tar_flags << "J"
       end
       tar_flags << "f"
-      with_system_path { safe_system "tar", tar_flags, cached_location }
-      chdir
-    when :xz
-      with_system_path { pipe_to_tar(xzpath) }
+      with_system_path do
+        if type == :xz && DependencyCollector.tar_needs_xz_dependency?
+          pipe_to_tar(xzpath)
+        else
+          safe_system "tar", tar_flags, cached_location
+        end
+      end
       chdir
     when :lzip
       with_system_path { pipe_to_tar(lzippath) }