bugfix: gpg2 is called 'gpg' on macOS

The gpg2 command isn't always around; it's sometimes called gpg.  This is
the case with the brew-installed version, and it's breaking our tests.

- [x] Look for both 'gpg2' and 'gpg' when finding the command
- [x] If we find 'gpg', ensure the version is 2 or higher
- [x] Add tests for version detection.

lib/spack/spack/test/cmd/gpg.py

@@ -7,6 +7,9 @@
 
 import pytest
 
+import llnl.util.filesystem as fs
+
+import spack.util.executable
 import spack.util.gpg
 
 from spack.paths import mock_gpg_data_path, mock_gpg_keys_path
@@ -14,15 +17,45 @@
 from spack.util.executable import ProcessError
 
 
-@pytest.fixture(scope='function')
-def gpg():
-    return SpackCommand('gpg')
+#: spack command used by tests below
+gpg = SpackCommand('gpg')
+
+
+# test gpg command detection
+@pytest.mark.parametrize('cmd_name,version', [
+    ('gpg',  'undetectable'),        # undetectable version
+    ('gpg',  'gpg (GnuPG) 1.3.4'),   # insufficient version
+    ('gpg',  'gpg (GnuPG) 2.2.19'),  # sufficient version
+    ('gpg2', 'gpg (GnuPG) 2.2.19'),  # gpg2 command
+])
+def test_find_gpg(cmd_name, version, tmpdir, mock_gnupghome, monkeypatch):
+    with tmpdir.as_cwd():
+        with open(cmd_name, 'w') as f:
+            f.write("""\
+#!/bin/sh
+echo "{version}"
+""".format(version=version))
+        fs.set_executable(cmd_name)
+
+    monkeypatch.setitem(os.environ, "PATH", str(tmpdir))
+    if version == 'undetectable' or version.endswith('1.3.4'):
+        with pytest.raises(spack.util.gpg.SpackGPGError):
+            exe = spack.util.gpg.Gpg.gpg()
+    else:
+        exe = spack.util.gpg.Gpg.gpg()
+        assert isinstance(exe, spack.util.executable.Executable)
+
+
+def test_no_gpg_in_path(tmpdir, mock_gnupghome, monkeypatch):
+    monkeypatch.setitem(os.environ, "PATH", str(tmpdir))
+    with pytest.raises(spack.util.gpg.SpackGPGError):
+        spack.util.gpg.Gpg.gpg()
 
 
 @pytest.mark.maybeslow
 @pytest.mark.skipif(not spack.util.gpg.Gpg.gpg(),
                     reason='These tests require gnupg2')
-def test_gpg(gpg, tmpdir, mock_gnupghome):
+def test_gpg(tmpdir, mock_gnupghome):
     # Verify a file with an empty keyring.
     with pytest.raises(ProcessError):
         gpg('verify', os.path.join(mock_gpg_data_path, 'content.txt'))

lib/spack/spack/test/conftest.py

@@ -11,6 +11,7 @@
 import os
 import os.path
 import shutil
+import tempfile
 import xml.etree.ElementTree
 
 import ordereddict_backport
@@ -674,9 +675,19 @@ def writer_key_function():
 
 
 @pytest.fixture()
-def mock_gnupghome(tmpdir, monkeypatch):
-    monkeypatch.setattr(spack.util.gpg, 'GNUPGHOME', str(tmpdir.join('gpg')))
+def mock_gnupghome(monkeypatch):
+    # GNU PGP can't handle paths longer than 108 characters (wtf!@#$) so we
+    # have to make our own tmpdir with a shorter name than pytest's.
+    # This comes up because tmp paths on macOS are already long-ish, and
+    # pytest makes them longer.
+    short_name_tmpdir = tempfile.mkdtemp()
+    monkeypatch.setattr(spack.util.gpg, 'GNUPGHOME', short_name_tmpdir)
+    monkeypatch.setattr(spack.util.gpg.Gpg, '_gpg', None)
 
+    yield
+
+    # clean up, since we are doing this manually
+    shutil.rmtree(short_name_tmpdir)
 
 ##########
 # Fake archives and repositories

lib/spack/spack/util/gpg.py

@@ -4,10 +4,14 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import os
+import re
 
+import spack.error
 import spack.paths
-from spack.util.executable import Executable
+import spack.version
+from spack.util.executable import which
 
+_gnupg_version_re = r"^gpg \(GnuPG\) (.*)$"
 
 GNUPGHOME = spack.paths.gpg_path
 
@@ -28,15 +32,39 @@ def parse_keys_output(output):
 
 
 class Gpg(object):
+    _gpg = None
+
     @staticmethod
     def gpg():
         # TODO: Support loading up a GPG environment from a built gpg.
-        gpg = Executable('gpg2')
-        if not os.path.exists(GNUPGHOME):
-            os.makedirs(GNUPGHOME)
-            os.chmod(GNUPGHOME, 0o700)
-        gpg.add_default_env('GNUPGHOME', GNUPGHOME)
-        return gpg
+        if Gpg._gpg is None:
+            gpg = which('gpg2', 'gpg')
+
+            if not gpg:
+                raise SpackGPGError("Spack requires gpg version 2 or higher.")
+
+            # ensure that the version is actually >= 2 if we find 'gpg'
+            if gpg.name == 'gpg':
+                output = gpg('--version', output=str)
+                match = re.search(_gnupg_version_re, output, re.M)
+
+                if not match:
+                    raise SpackGPGError("Couldn't determine version of gpg")
+
+                v = spack.version.Version(match.group(1))
+                if v < spack.version.Version('2'):
+                    raise SpackGPGError("Spack requires GPG version >= 2")
+
+            # make the GNU PG path if we need to
+            # TODO: does this need to be in the spack directory?
+            # we should probably just use GPG's regular conventions
+            if not os.path.exists(GNUPGHOME):
+                os.makedirs(GNUPGHOME)
+                os.chmod(GNUPGHOME, 0o700)
+            gpg.add_default_env('GNUPGHOME', GNUPGHOME)
+
+            Gpg._gpg = gpg
+        return Gpg._gpg
 
     @classmethod
     def create(cls, **kwargs):
@@ -112,3 +140,7 @@ def list(cls, trusted, signing):
             cls.gpg()('--list-public-keys')
         if signing:
             cls.gpg()('--list-secret-keys')
+
+
+class SpackGPGError(spack.error.SpackError):
+    """Class raised when GPG errors are detected."""