dlopen-notes: add mode to generate rpm Provides/Requires

This can be used to insert the appropriate deps into the spec file:
$ ./dlopen-notes.py .../libsystemd-shared-256.so --rpm-requires zstd,qrencode --rpm-recommends tpm
Requires: libqrencode.so.4()(64bit)
Requires: libzstd.so.1()(64bit)
Recommends: libtss2-esys.so.0()(64bit)
Recommends: libtss2-rc.so.0()(64bit)
Recommends: libtss2-mu.so.0()(64bit)

Most likely, it needs to be used manually. Rpm doesn't really have a
notion of dynamically generated deps at the package level :(

(There is the fileattr mechanism,
https://rpm-software-management.github.io/rpm/manual/dependency_generators.html,
but that is per-file. It has the shortcoming that it assumes that the
generated deps depend only on the file itself, and not the subpackage that the
file lands in, and there is no notion of package configuration. We _could_ use
that, but it seems a poor fit.

Also, before rpm 4.20, fileattr generators could not be provided by the
package being built, they needed to be installed in the filesystem. I don't
think we're at the point where it makes sense to make this "global".

4.15 added %generate_buildrequires. Obviously that only works for
BuildRequires. Also, the mechanism with generating src.rpms in a loop is
rather convoluted and heavyweight.)

I'll open an RFE in rpm. For now, the generator can be used manually in
systemd. That is still nicer than the previous method of looking at the
sources.

Author: keszybz

dlopen-notes.py

@@ -131,6 +131,18 @@ def filter_features(features, filter):
         sys.exit('Some features not found:', ', '.join(missing))
     return ans
 
+@listify
+def generate_rpm(elffiles, stanza, filter):
+    # Produces output like:
+    # Requires: libqrencode.so.4()(64bit)
+    # Requires: libzstd.so.1()(64bit)
+    for elffile in elffiles:
+        suffix = '()(64bit)' if elffile.elffile.elfclass == 64 else ''
+        for note in elffile.notes():
+            if note['feature'] in filter or not filter:
+                soname = next(iter(note['soname']))  # we take the first — most recommended — soname
+                yield f"{stanza}: {soname}{suffix}"
+
 def make_parser():
     p = argparse.ArgumentParser(
         description=__doc__,
@@ -157,6 +169,24 @@ def make_parser():
         metavar='FEATURE1,FEATURE2',
         help='Describe features, can be specified multiple times',
     )
+    p.add_argument(
+        '--rpm-requires',
+        nargs='?',
+        const=[],
+        type=lambda s: s.split(','),
+        action='extend',
+        metavar='FEATURE1,FEATURE2',
+        help='Generate rpm Requires for listed features',
+    )
+    p.add_argument(
+        '--rpm-recommends',
+        nargs='?',
+        const=[],
+        type=lambda s: s.split(','),
+        action='extend',
+        metavar='FEATURE1,FEATURE2',
+        help='Generate rpm Recommends for listed features',
+    )
     p.add_argument(
         'filenames',
         nargs='+',
@@ -173,7 +203,11 @@ def make_parser():
 def parse_args():
     args = make_parser().parse_args()
 
-    if not args.raw and args.features is None and not args.sonames:
+    if (not args.raw
+        and not args.sonames
+        and args.features is None
+        and args.rpm_requires is None
+        and args.rpm_recommends is None):
         # Make --raw the default if no action is specified.
         args.raw = True
 
@@ -196,6 +230,14 @@ def parse_args():
                               indent=2,
                               default=lambda prio: prio.name))
 
+    if args.rpm_requires is not None:
+        lines = generate_rpm(elffiles, 'Requires', args.rpm_requires)
+        print('\n'.join(lines))
+
+    if args.rpm_recommends is not None:
+        lines = generate_rpm(elffiles, 'Recommends', args.rpm_recommends)
+        print('\n'.join(lines))
+
     if args.sonames:
         sonames = group_by_soname(elffiles)
         for soname in sorted(sonames.keys()):

test/test.py

@@ -1,8 +1,8 @@
 # SPDX-License-Identifier: CC0-1.0
 
-from _notes import ELFFileReader, group_by_soname
+from _notes import ELFFileReader, group_by_soname, generate_rpm
 
-def test_notes():
+def test_sonames():
     expected = {
         'libfido2.so.1': 'required',
         'liblz4.so.1': 'recommended',
@@ -11,5 +11,25 @@ def test_notes():
         'libtss2-esys.so.0': 'recommended',
         'libtss2-mu.so.0': 'recommended',
     }
-    notes = [ELFFileReader('notes')]
-    assert group_by_soname(notes) == expected
+    notes = ELFFileReader('notes')
+    assert group_by_soname([notes]) == expected
+
+def test_requires():
+    notes = ELFFileReader('notes')
+
+    expected = {
+        32: [
+            'Suggests: libpcre2-8.so.0',
+            'Suggests: libtss2-mu.so.0',
+            'Suggests: libtss2-esys.so.0',
+        ],
+        64: [
+            'Suggests: libpcre2-8.so.0()(64bit)',
+            'Suggests: libtss2-mu.so.0()(64bit)',
+            'Suggests: libtss2-esys.so.0()(64bit)',
+        ],
+    }
+
+    lines = generate_rpm([notes], 'Suggests', ('pcre2', 'tpm'))
+    expect = expected[notes.elffile.elfclass]
+    assert lines == expect