Platform tests and bug fixes.

In adding tests for the new platform code I found a bug in the old code:
if a valid version is passed for version and it is greater than the
version found for an so *and* there is no glibc version, then the
version from the argument was returned.  The code changes here fix
that, as well as fixing my own broken additions.

Author: bitdancer

Lib/platform.py

@@ -190,26 +190,27 @@ def libc_ver(executable=None, lib='', version='', chunksize=16384):
             return lib, version
 
     libc_search = re.compile(
-        b'(__libc_init)'
-        b'|'
-        b'(GLIBC_([0-9.]+))'
-        b'|'
+        br'(__libc_init)'
+        br'|'
+        br'(GLIBC_([0-9.]+))'
+        br'|'
         br'(libc(_\w+)?\.so(?:\.(\d[0-9.]*))?)'
-        b'|'
-        b'(musl-([0-9.]+))'
-        b'',
+        br'|'
+        br'(musl-([0-9.]+))'
+        br'',
         re.ASCII)
 
     V = _comparable_version
     # We use os.path.realpath()
     # here to work around problems with Cygwin not being
     # able to open symlinks for reading
     executable = os.path.realpath(executable)
+    ver = None
     with open(executable, 'rb') as f:
         binary = f.read(chunksize)
         pos = 0
         while pos < len(binary):
-            if b'libc' in binary or b'GLIBC' in binary:
+            if b'libc' in binary or b'GLIBC' or 'musl' in binary:
                 m = libc_search.search(binary, pos)
             else:
                 m = None
@@ -229,21 +230,22 @@ def libc_ver(executable=None, lib='', version='', chunksize=16384):
             elif glibc:
                 if lib != 'glibc':
                     lib = 'glibc'
-                    version = glibcversion
-                elif V(glibcversion) > V(version):
-                    version = glibcversion
+                    ver = glibcversion
+                elif V(glibcversion) > V(ver):
+                    ver = glibcversion
             elif so:
                 if lib != 'glibc':
                     lib = 'libc'
-                    if soversion and (not version or V(soversion) > V(version)):
-                        version = soversion
-                    if threads and version[-len(threads):] != threads:
-                        version = version + threads
+                    if soversion and (not ver or V(soversion) > V(ver)):
+                        ver = soversion
+                    if threads and ver[-len(threads):] != threads:
+                        ver = ver + threads
             elif musl:
                 lib = 'musl'
-                version = muslversion
+                if not ver or V(muslversion) > V(ver):
+                    ver = muslversion
             pos = m.end()
-    return lib, version
+    return lib, version if ver is None else ver
 
 def _norm_version(version, build=''):
 

Lib/test/test_platform.py

@@ -552,6 +552,7 @@ def test_libc_ver(self):
                 (b'GLIBC_2.9', ('glibc', '2.9')),
                 (b'libc.so.1.2.5', ('libc', '1.2.5')),
                 (b'libc_pthread.so.1.2.5', ('libc', '1.2.5_pthread')),
+                (b'/aports/main/musl/src/musl-1.2.5', ('musl', '1.2.5')),
                 (b'', ('', '')),
             ):
                 with open(filename, 'wb') as fp:
@@ -563,14 +564,29 @@ def test_libc_ver(self):
                                  expected)
 
         # binary containing multiple versions: get the most recent,
-        # make sure that 1.9 is seen as older than 1.23.4
-        chunksize = 16384
-        with open(filename, 'wb') as f:
-            # test match at chunk boundary
-            f.write(b'x'*(chunksize - 10))
-            f.write(b'GLIBC_1.23.4\0GLIBC_1.9\0GLIBC_1.21\0')
-        self.assertEqual(platform.libc_ver(filename, chunksize=chunksize),
-                         ('glibc', '1.23.4'))
+        # make sure that eg 1.9 is seen as older than 1.23.4, and that
+        # the arguments don't count even if they are set.
+        chunksize = 200
+        for data, expected in (
+                (b'GLIBC_1.23.4\0GLIBC_1.9\0GLIBC_1.21\0', ('glibc', '1.23.4')),
+                (b'libc.so.2.4\0libc.so.9\0libc.so.23.1\0', ('libc', '23.1')),
+                (b'musl-1.4.1\0musl-2.1.1\0musl-2.0.1\0', ('musl', '2.1.1')),
+                (b'no match here, so defaults are used', ('test', '100.1.0')),
+            ):
+            with open(filename, 'wb') as f:
+                # test match at chunk boundary
+                f.write(b'x'*(chunksize - 10))
+                f.write(data)
+            self.assertEqual(
+                expected,
+                platform.libc_ver(
+                    filename,
+                    lib='test',
+                    version='100.1.0',
+                    chunksize=chunksize,
+                    ),
+                )
+
 
     def test_android_ver(self):
         res = platform.android_ver()