PR#965: check rpm headers support directly

Merges #965
https://pagure.io/koji/pull-request/965

Fixes: #931
https://pagure.io/koji/issue/931
Koji hub will not render weak dependencies on an EL7.5 host, even though host rpm can read them

koji/__init__.py

@@ -111,13 +111,17 @@ RPM_FILEDIGESTALGO_IDS = {
     11:   'SHA224'
     }
 
-# rpm 4.12 introduces optional deps
-try:
-    RPM_SUPPORTS_OPTIONAL_DEPS = int(rpm.__version_info__[0]) > 4 or \
-                                 (int(rpm.__version_info__[0]) == 4 and int(rpm.__version_info__[1]) >= 12)
-except AttributeError:
-    # older versions don't even have __version_info__
-    RPM_SUPPORTS_OPTIONAL_DEPS = False
+# rpm 4.12 introduces optional deps, but they can also be backported in some
+# rpm installations. So, we need to check their real support, not only rpm
+# version.
+SUPPORTED_OPT_DEP_HDRS = {}
+for h in (
+        'SUGGESTNAME', 'SUGGESTVERSION', 'SUGGESTFLAGS',
+        'ENHANCENAME', 'ENHANCEVERSION', 'ENHANCEFLAGS',
+        'SUPPLEMENTNAME', 'SUPPLEMENTVERSION', 'SUPPLEMENTFLAGS',
+        'RECOMMENDNAME', 'RECOMMENDVERSION', 'RECOMMENDFLAGS'):
+    SUPPORTED_OPT_DEP_HDRS[h] = hasattr(rpm, 'RPMTAG_%s' % h)
+
 
 class Enum(dict):
     """A simple class to track our enumerated constants
@@ -893,12 +897,8 @@ def get_rpm_header(f, ts=None):
 def get_header_field(hdr, name, src_arch=False):
     """Extract named field from an rpm header"""
     name = name.upper()
-    opt_dep_hdrs = (
-            'SUGGESTNAME', 'SUGGESTVERSION', 'SUGGESTFLAGS',
-            'ENHANCENAME', 'ENHANCEVERSION', 'ENHANCEFLAGS',
-            'SUPPLEMENTNAME', 'SUPPLEMENTVERSION', 'SUPPLEMENTFLAGS',
-            'RECOMMENDNAME', 'RECOMMENDVERSION', 'RECOMMENDFLAGS')
-    if not RPM_SUPPORTS_OPTIONAL_DEPS and name in opt_dep_hdrs:
+    # if field is not supported by host's rpm (>4.12), return empty list
+    if not SUPPORTED_OPT_DEP_HDRS.get(name, True):
         return []
 
     if (src_arch and name == "ARCH"

tests/test_hub/test_getRPMDeps.py

@@ -19,7 +19,7 @@ class TestGetRPMDeps(unittest.TestCase):
         getRPMDeps = kojihub.RootExports().getRPMDeps
         res = getRPMDeps('')
         # limit test for rpm < 4.12
-        if koji.RPM_SUPPORTS_OPTIONAL_DEPS:
+        if any(koji.SUPPORTED_OPT_DEP_HDRS.values()):
             self.assertEqual(len(res), 22)
             types = set([x['type'] for x in res])
             self.assertEqual(set([koji.DEP_REQUIRE,

tests/test_lib/test_parsers.py

@@ -200,7 +200,7 @@ class HeaderTestCase(unittest.TestCase):
 
     @mock.patch('rpm.RPMTAG_NOSOURCE', new=None)
     @mock.patch('rpm.RPMTAG_NOPATCH', new=None)
-    @mock.patch('koji.RPM_SUPPORTS_OPTIONAL_DEPS', new=False)
+    @mock.patch('koji.SUPPORTED_OPT_DEP_HDRS', new={'SUGGESTNAME': False})
     def test_get_header_field_workarounds(self):
         srpm0 = os.path.join(self.rpmdir, 'test-src-1-1.fc24.src.rpm')
         srpm1 = os.path.join(self.rpmdir, 'test-nosrc-1-1.fc24.nosrc.rpm')