This makes setup.py work well with Darwin + Homebrew

libarchive/library.py

@@ -1,12 +1,43 @@
 import logging
 import os
+import platform
+import json
+import subprocess
+
+def _check_homebrew():
+    if platform.system() == 'Darwin':
+        try:
+            # From homebrew on libarchive:
+            # This formula is keg-only, which means it was not symlinked
+            # into /usr/local.
+            #
+            # macOS already provides this software and installing
+            # another version in parallel can cause all kinds of
+            # trouble.
+            #
+            # so... let's see if we can't find it ourselves and set the
+            # envvar
+            # /Usr/local/opt/libarchive/lib/
+            libarchive_info = json.loads(
+                    subprocess.check_output(['brew', 'info', '--json=v1',
+                        'libarchive']))
+            libarchive_version = libarchive_info[0]['installed'][0]['version']
+            # set the direct dylib envvar
+            libarchive_path = os.path.join(subprocess.check_output([ 'brew',
+                '--cellar', 'libarchive'])[:-1], libarchive_version, 'lib',
+                'libarchive.dylib')
+            return libarchive_path
+        except Exception as e:
+            return ''
+    else:
+        return ''
 
 import ctypes
 import ctypes.util
 
 _logger = logging.getLogger(__name__)
 
-_FILEPATH = os.environ.get('LA_LIBRARY_FILEPATH', '')
+_FILEPATH = os.environ.get('LA_LIBRARY_FILEPATH', _check_homebrew())
 if _FILEPATH == '':
     _FILEPATH = ctypes.util.find_library('libarchive')
     if _FILEPATH is None:

setup.py

@@ -1,7 +1,6 @@
 import setuptools
 import setuptools.command.install
 import os.path
-
 def _pre_install():
     print("Verifying that the library is accessible.")