dlopen-notes: make output stable regardless of order of inputs

When multiple files are passed to dlopen-notes --sonames the output
depends on the order of inputs in case the same soname is used
with different priorities across different binaries:

$ ./dlopen-notes.py --sonames systemd-sbsign systemd-repart
libblkid.so.1 required
libcrypto.so.3 recommended
libcryptsetup.so.12 recommended
libfdisk.so.1 required
libmount.so.1 required

$ ./dlopen-notes.py --sonames systemd-repart systemd-sbsign
libblkid.so.1 required
libcrypto.so.3 required
libcryptsetup.so.12 recommended
libfdisk.so.1 required
libmount.so.1 required

sbsign requires libcrypto, and repart recommends it, so the output
changes between required and recommended depending on which is passed last.

Fix it so that the highest priority for any given soname is always
returned, regardless of the number of input binaries.

Author: bluca

dlopen-notes.py

@@ -69,13 +69,15 @@ def notes(self):
 
                 yield from j
 
-@dictify
 def group_by_soname(elffiles):
+    sonames = {}
     for elffile in elffiles:
         for element in elffile.notes():
-            priority = element.get('priority', 'recommended')
+            priority = Priority[element.get('priority', 'recommended')]
             for soname in element['soname']:
-                yield soname, priority
+                sonames[soname] = max(sonames.get(soname, priority), priority)
+
+    return sonames
 
 class Priority(enum.Enum):
     suggested   = 1
@@ -85,6 +87,9 @@ class Priority(enum.Enum):
     def __lt__(self, other):
         return self.value < other.value
 
+    def __str__(self):
+        return self.name
+
     def rpm_name(self):
         if self == self.__class__.suggested:
             return 'Suggests'

test/test.py

@@ -1,15 +1,15 @@
 # SPDX-License-Identifier: CC0-1.0
 
-from _notes import ELFFileReader, group_by_soname, generate_rpm
+from _notes import ELFFileReader, group_by_soname, generate_rpm, Priority
 
 def test_sonames():
     expected = {
-        'libfido2.so.1': 'required',
-        'liblz4.so.1': 'recommended',
-        'libpcre2-8.so.0': 'suggested',
-        'libpcre2-8.so.1': 'suggested',
-        'libtss2-esys.so.0': 'recommended',
-        'libtss2-mu.so.0': 'recommended',
+        'libfido2.so.1': Priority.required,
+        'liblz4.so.1': Priority.recommended,
+        'libpcre2-8.so.0': Priority.suggested,
+        'libpcre2-8.so.1': Priority.suggested,
+        'libtss2-esys.so.0': Priority.recommended,
+        'libtss2-mu.so.0': Priority.recommended,
     }
     notes = ELFFileReader('notes')
     assert group_by_soname([notes]) == expected
@@ -33,3 +33,20 @@ def test_requires():
     lines = generate_rpm([notes], 'Suggests', ('pcre2', 'tpm'))
     expect = expected[notes.elffile.elfclass]
     assert sorted(lines) == sorted(expect)
+
+class FakeReader:
+    def __init__(self, notes):
+        self._notes = notes
+
+    def notes(self):
+        return self._notes
+
+def test_sonames_highest_priority_stable():
+    a = FakeReader([{'soname': ['libcrypto.so.3'], 'priority': 'required'}])
+    b = FakeReader([{'soname': ['libcrypto.so.3'], 'priority': 'recommended'}])
+    c = FakeReader([{'soname': ['libcrypto.so.3'], 'priority': 'suggested'}])
+
+    expected = {'libcrypto.so.3': Priority.required}
+    assert group_by_soname([a, b, c]) == expected
+    assert group_by_soname([c, b, a]) == expected
+    assert group_by_soname([b, a, c]) == expected