Issue 19544 and Issue #7457: Restore the read_pkg_file method to distutils.dist.DistributionMetadata accidentally removed in the undo of distutils2.

Lib/distutils/dist.py

@@ -5,6 +5,7 @@ being built/installed/distributed.
 """
 
 import sys, os, re
+from email import message_from_file
 
 try:
     import warnings
@@ -999,25 +1000,80 @@ class DistributionMetadata:
                          "provides", "requires", "obsoletes",
                          )
 
-    def __init__ (self):
-        self.name = None
-        self.version = None
-        self.author = None
-        self.author_email = None
+    def __init__(self, path=None):
+        if path is not None:
+            self.read_pkg_file(open(path))
+        else:
+            self.name = None
+            self.version = None
+            self.author = None
+            self.author_email = None
+            self.maintainer = None
+            self.maintainer_email = None
+            self.url = None
+            self.license = None
+            self.description = None
+            self.long_description = None
+            self.keywords = None
+            self.platforms = None
+            self.classifiers = None
+            self.download_url = None
+            # PEP 314
+            self.provides = None
+            self.requires = None
+            self.obsoletes = None
+
+    def read_pkg_file(self, file):
+        """Reads the metadata values from a file object."""
+        msg = message_from_file(file)
+
+        def _read_field(name):
+            value = msg[name]
+            if value == 'UNKNOWN':
+                return None
+            return value
+
+        def _read_list(name):
+            values = msg.get_all(name, None)
+            if values == []:
+                return None
+            return values
+
+        metadata_version = msg['metadata-version']
+        self.name = _read_field('name')
+        self.version = _read_field('version')
+        self.description = _read_field('summary')
+        # we are filling author only.
+        self.author = _read_field('author')
         self.maintainer = None
+        self.author_email = _read_field('author-email')
         self.maintainer_email = None
-        self.url = None
-        self.license = None
-        self.description = None
-        self.long_description = None
-        self.keywords = None
-        self.platforms = None
-        self.classifiers = None
-        self.download_url = None
-        # PEP 314
-        self.provides = None
-        self.requires = None
-        self.obsoletes = None
+        self.url = _read_field('home-page')
+        self.license = _read_field('license')
+
+        if 'download-url' in msg:
+            self.download_url = _read_field('download-url')
+        else:
+            self.download_url = None
+
+        self.long_description = _read_field('description')
+        self.description = _read_field('summary')
+
+        if 'keywords' in msg:
+            self.keywords = _read_field('keywords').split(',')
+
+        self.platforms = _read_list('platform')
+        self.classifiers = _read_list('classifier')
+
+        # PEP 314 - these fields only exist in 1.1
+        if metadata_version == '1.1':
+            self.requires = _read_list('requires')
+            self.provides = _read_list('provides')
+            self.obsoletes = _read_list('obsoletes')
+        else:
+            self.requires = None
+            self.provides = None
+            self.obsoletes = None
 
     def write_pkg_info(self, base_dir):
         """Write the PKG-INFO file into the release tree.