1 files changed, 165 insertions, 0 deletions
diff --git a/dlopen-notes.py b/dlopen-notes.py
new file mode 100755
index 0000000..29ea270
--- /dev/null
+++ b/dlopen-notes.py
@@ -0,0 +1,165 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: CC0-1.0
+
+"""\
+Read .note.dlopen notes from ELF files and report the contents
+"""
+
+import argparse
+import enum
+import functools
+import json
+import sys
+from elftools.elf.elffile import ELFFile
+from elftools.elf.sections import NoteSection
+
+try:
+    import rich
+    print_json = rich.print_json
+except ImportError:
+    print_json = print
+
+def listify(f):
+    def wrap(*args, **kwargs):
+        return list(f(*args, **kwargs))
+    return functools.update_wrapper(wrap, f)
+
+@listify
+def read_dlopen_notes(filename):
+    elffile = ELFFile(open(filename, 'rb'))
+
+    for section in elffile.iter_sections():
+        if not isinstance(section, NoteSection) or section.name != '.note.dlopen':
+            continue
+
+        for note in section.iter_notes():
+            if note['n_type'] != 0x407c0c0a or note['n_name'] != 'FDO':
+                continue
+            note_desc = note['n_desc']
+
+            try:
+                # On older Python versions (e.g.: Ubuntu 22.04) we get a string, on
+                # newer versions a bytestring
+                if not isinstance(note_desc, str):
+                    text = note_desc.decode('utf-8').rstrip('\0')
+                else:
+                    text = note_desc.rstrip('\0')
+            except UnicodeDecodeError as e:
+                raise ValueError(f'{filename}: Invalid UTF-8 in .note.dlopen n_desc') from e
+
+            try:
+                j = json.loads(text)
+            except json.JSONDecodeError as e:
+                raise ValueError(f'{filename}: Invalid JSON in .note.dlopen note_desc') from e
+
+            if not isinstance(j, list):
+                print(f'{filename}: ignoring .note.dlopen n_desc with JSON that is not a list',
+                      file=sys.stderr)
+                continue
+
+            yield from j
+
+def dictify(f):
+    def wrap(*args, **kwargs):
+        return dict(f(*args, **kwargs))
+    return functools.update_wrapper(wrap, f)
+
+@dictify
+def group_by_soname(notes):
+    for note in notes:
+        for element in note:
+            priority = element.get('priority', 'recommended')
+            for soname in element['soname']:
+                yield soname, priority
+
+class Priority(enum.Enum):
+    suggested   = 1
+    recommended = 2
+    required    = 3
+
+    def __lt__(self, other):
+        return self.value < other.value
+
+def group_by_feature(filenames, notes):
+    features = {}
+
+    # We expect each note to be in the format:
+    # [
+    #   {
+    #     "feature": "...",
+    #     "description": "...",
+    #     "priority": "required"|"recommended"|"suggested",
+    #     "soname": ["..."],
+    #   }
+    # ]
+    for filename, note_group in zip(filenames, notes):
+        for note in note_group:
+            prio = Priority[note.get('priority', 'recommened')]
+            feature_name = note['feature']
+
+            try:
+                feature = features[feature_name]
+            except KeyError:
+                # Create new
+                feature = features[feature_name] = {
+                    'description': note.get('description', ''),
+                    'sonames': { soname:prio for soname in note['soname'] },
+                }
+            else:
+                # Merge
+                if feature['description'] != note.get('description', ''):
+                    print(f"{filename}: feature {note['feature']!r} found with different description, ignoring",
+                          file=sys.stderr)
+
+                for soname in note['soname']:
+                    highest = max(feature['sonames'].get(soname, Priority.suggested),
+                                  prio)
+                    feature['sonames'][soname] = highest
+
+    return features
+
+def parse_args():
+    p = argparse.ArgumentParser(description=__doc__)
+    p.add_argument('--raw',
+                   action='store_true',
+                   help='show the original JSON extracted from input files')
+    p.add_argument('--sonames',
+                   action='store_true',
+                   help='list all sonames and their priorities, one soname per line')
+    p.add_argument('--features',
+                   nargs='?',
+                   const=[],
+                   type=lambda s: s.split(','),
+                   action='extend',
+                   metavar='FEATURE1,FEATURE2',
+                   help='describe features, can be specified multiple times')
+    p.add_argument('filenames', nargs='+', metavar='filename')
+    return p.parse_args()
+
+if __name__ == '__main__':
+    args = parse_args()
+
+    notes = [read_dlopen_notes(filename) for filename in args.filenames]
+
+    if args.raw:
+        for filename, note in zip(args.filenames, notes):
+            print(f'# {filename}')
+            print_json(json.dumps(note, indent=2))
+
+    if args.features is not None:
+        features = group_by_feature(args.filenames, notes)
+
+        toprint = {name:feature for name,feature in features.items()
+                   if name in args.features or not args.features}
+        if len(toprint) < len(args.features):
+            sys.exit('Some features were not found')
+
+        print('# grouped by feature')
+        print_json(json.dumps(toprint,
+                              indent=2,
+                              default=lambda prio: prio.name))
+
+    if args.sonames:
+        sonames = group_by_soname(notes)
+        for soname in sorted(sonames.keys()):
+            print(f"{soname} {sonames[soname]}")