buildcache: do one less tar file extraction

The buildcache is now extracted in a temporary folder within the current store,
moved to its final place and relocated. 

"spack clean -s" has been extended to also clean the temporary extraction directory.

Add hardlinks with absolute paths for libraries in the corge, garply and quux packages
to detect incorrect handling of hardlinks in tests.

2 files changed, 25 insertions, 35 deletions

diff --git a/lib/spack/spack/binary_distribution.py b/lib/spack/spack/binary_distribution.py
index c976dc80fb..165ba219b3 100644
--- a/lib/spack/spack/binary_distribution.py
+++ b/lib/spack/spack/binary_distribution.py
@@ -4,11 +4,9 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import codecs
-import glob
 import hashlib
 import json
 import os
-import re
 import shutil
 import sys
 import tarfile
@@ -1428,42 +1426,30 @@ def extract_tarball(spec, filename, allow_root=False, unsigned=False,
     buildinfo = spec_dict.get('buildinfo', {})
     old_relative_prefix = buildinfo.get('relative_prefix', new_relative_prefix)
     rel = buildinfo.get('relative_rpaths')
-    # if the original relative prefix and new relative prefix differ the
-    # directory layout has changed and the  buildcache cannot be installed
-    # if it was created with relative rpaths
     info = 'old relative prefix %s\nnew relative prefix %s\nrelative rpaths %s'
     tty.debug(info %
               (old_relative_prefix, new_relative_prefix, rel))
-#    if (old_relative_prefix != new_relative_prefix and (rel)):
-#        shutil.rmtree(tmpdir)
-#        msg = "Package tarball was created from an install "
-#        msg += "prefix with a different directory layout. "
-#        msg += "It cannot be relocated because it "
-#        msg += "uses relative rpaths."
-#        raise NewLayoutException(msg)
-
-    # extract the tarball in a temp directory
-    with closing(tarfile.open(tarfile_path, 'r')) as tar:
-        tar.extractall(path=tmpdir)
-    # get the parent directory of the file .spack/binary_distribution
-    # this should the directory unpacked from the tarball whose
-    # name is unknown because the prefix naming is unknown
-    bindist_file = glob.glob('%s/*/.spack/binary_distribution' % tmpdir)[0]
-    workdir = re.sub('/.spack/binary_distribution$', '', bindist_file)
-    tty.debug('workdir %s' % workdir)
-    # install_tree copies hardlinks
-    # create a temporary tarfile from prefix and exract it to workdir
-    # tarfile preserves hardlinks
-    temp_tarfile_name = tarball_name(spec, '.tar')
-    temp_tarfile_path = os.path.join(tmpdir, temp_tarfile_name)
-    with closing(tarfile.open(temp_tarfile_path, 'w')) as tar:
-        tar.add(name='%s' % workdir,
-                arcname='.')
-    with closing(tarfile.open(temp_tarfile_path, 'r')) as tar:
-        tar.extractall(spec.prefix)
-    os.remove(temp_tarfile_path)
 
-    # cleanup
+    # Extract the tarball into the store root, presumably on the same filesystem.
+    # The directory created is the base directory name of the old prefix.
+    # Moving the old prefix name to the new prefix location should preserve
+    # hard links and symbolic links.
+    extract_tmp = os.path.join(spack.store.layout.root, '.tmp')
+    mkdirp(extract_tmp)
+    extracted_dir = os.path.join(extract_tmp,
+                                 old_relative_prefix.split(os.path.sep)[-1])
+
+    with closing(tarfile.open(tarfile_path, 'r')) as tar:
+        try:
+            tar.extractall(path=extract_tmp)
+        except Exception as e:
+            shutil.rmtree(extracted_dir)
+            raise e
+    try:
+        shutil.move(extracted_dir, spec.prefix)
+    except Exception as e:
+        shutil.rmtree(extracted_dir)
+        raise e
     os.remove(tarfile_path)
     os.remove(specfile_path)
 
diff --git a/lib/spack/spack/cmd/clean.py b/lib/spack/spack/cmd/clean.py
index c4012f5032..de4abd2fc2 100644
--- a/lib/spack/spack/cmd/clean.py
+++ b/lib/spack/spack/cmd/clean.py
@@ -76,7 +76,11 @@ def clean(parser, args):
     if args.stage:
         tty.msg('Removing all temporary build stages')
         spack.stage.purge()
-
+        # Temp directory where buildcaches are extracted
+        extract_tmp = os.path.join(spack.store.layout.root, '.tmp')
+        if os.path.exists(extract_tmp):
+            tty.debug('Removing {0}'.format(extract_tmp))
+            shutil.rmtree(extract_tmp)
     if args.downloads:
         tty.msg('Removing cached downloads')
         spack.caches.fetch_cache.destroy()