Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/beetsplug/permissions.py

@@ -0,0 +1,121 @@
+"""Fixes file permissions after the file gets written on import. Put something
+like the following in your config.yaml to configure:
+
+    permissions:
+            file: 644
+            dir: 755
+"""
+import os
+from beets import config, util
+from beets.plugins import BeetsPlugin
+from beets.util import ancestry
+
+
+def convert_perm(perm):
+    """Convert a string to an integer, interpreting the text as octal.
+    Or, if `perm` is an integer, reinterpret it as an octal number that
+    has been "misinterpreted" as decimal.
+    """
+    if isinstance(perm, int):
+        perm = str(perm)
+    return int(perm, 8)
+
+
+def check_permissions(path, permission):
+    """Check whether the file's permissions equal the given vector.
+    Return a boolean.
+    """
+    return oct(os.stat(path).st_mode & 0o777) == oct(permission)
+
+
+def assert_permissions(path, permission, log):
+    """Check whether the file's permissions are as expected, otherwise,
+    log a warning message. Return a boolean indicating the match, like
+    `check_permissions`.
+    """
+    if not check_permissions(util.syspath(path), permission):
+        log.warning(
+            'could not set permissions on {}',
+            util.displayable_path(path),
+        )
+        log.debug(
+            'set permissions to {}, but permissions are now {}',
+            permission,
+            os.stat(util.syspath(path)).st_mode & 0o777,
+        )
+
+
+def dirs_in_library(library, item):
+    """Creates a list of ancestor directories in the beets library path.
+    """
+    return [ancestor
+            for ancestor in ancestry(item)
+            if ancestor.startswith(library)][1:]
+
+
+class Permissions(BeetsPlugin):
+    def __init__(self):
+        super().__init__()
+
+        # Adding defaults.
+        self.config.add({
+            'file': '644',
+            'dir': '755',
+        })
+
+        self.register_listener('item_imported', self.fix)
+        self.register_listener('album_imported', self.fix)
+        self.register_listener('art_set', self.fix_art)
+
+    def fix(self, lib, item=None, album=None):
+        """Fix the permissions for an imported Item or Album.
+        """
+        files = []
+        dirs = set()
+        if item:
+            files.append(item.path)
+            dirs.update(dirs_in_library(lib.directory, item.path))
+        elif album:
+            for album_item in album.items():
+                files.append(album_item.path)
+                dirs.update(dirs_in_library(lib.directory, album_item.path))
+        self.set_permissions(files=files, dirs=dirs)
+
+    def fix_art(self, album):
+        """Fix the permission for Album art file.
+        """
+        if album.artpath:
+            self.set_permissions(files=[album.artpath])
+
+    def set_permissions(self, files=[], dirs=[]):
+        # Get the configured permissions. The user can specify this either a
+        # string (in YAML quotes) or, for convenience, as an integer so the
+        # quotes can be omitted. In the latter case, we need to reinterpret the
+        # integer as octal, not decimal.
+        file_perm = config['permissions']['file'].get()
+        dir_perm = config['permissions']['dir'].get()
+        file_perm = convert_perm(file_perm)
+        dir_perm = convert_perm(dir_perm)
+
+        for path in files:
+            # Changing permissions on the destination file.
+            self._log.debug(
+                'setting file permissions on {}',
+                util.displayable_path(path),
+            )
+            os.chmod(util.syspath(path), file_perm)
+
+            # Checks if the destination path has the permissions configured.
+            assert_permissions(path, file_perm, self._log)
+
+        # Change permissions for the directories.
+        for path in dirs:
+            # Changing permissions on the destination directory.
+            self._log.debug(
+                'setting directory permissions on {}',
+                util.displayable_path(path),
+            )
+            os.chmod(util.syspath(path), dir_perm)
+
+            # Checks if the destination path has the permissions configured.
+            assert_permissions(path, dir_perm, self._log)