glusterfs/ghetto-purge.py: handle symlinks

I had some issues with symlinks and finally decided to handle them
instead of skipping. Now I am sure that we can just remove them w-
ithout worrying that os.remove() will remove the link target. Also,
we don't need to try to get the xattrs because symlinks don't have
them, and we don't need to remove the .glusterfs hard link because
there isn't one.

Author: alanorth

glusterfs/ghetto-purge.py

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-only
 #
-# ghetto-purge.py v0.0.2
+# ghetto-purge.py v0.0.3
 #
 # Read files and directories from an input file, one per line, and attempt to
 # remove them from the GlusterFS brick along with their .glusterfs links. This
@@ -32,18 +32,12 @@ def main():
         # Note that we have to remove \n from the line
         path_to_analyze = f"{brick_path}/{line.strip()}"
 
-        # To be safe I check if this is a symlink first, because we only
-        # want to process entries named in our input file and not follow them
-        # all over the file system. I am not sure how to deal with these yet...
-        # pathlib's exists() will follow symlinks and return False if they are
-        # broken, for example (note that pathlib's is_dir() is different than
-        # os.is_dir(), and the latter has follow_symlinks(false)).
-        if Path(f"{path_to_analyze}").is_symlink():
-            print(f"Skipping symlink: {path_to_analyze}")
-
-            continue
-
-        if Path(f"{path_to_analyze}").exists():
+        # Pathlib's Path.exists() will return false if the path is a broken
+        # symlink so we need to check for the symlink case here as well.
+        if (
+            Path(f"{path_to_analyze}").exists()
+            or Path(f"{path_to_analyze}").is_symlink()
+        ):
             if Path(f"{path_to_analyze}").is_dir():
                 if args.debug:
                     print(f"Descend into: {path_to_analyze}")
@@ -122,8 +116,22 @@ def process_file(brick_path, path):
     if args.debug:
         print(f"Processing file: {path}")
 
-    # Get a string representation of the xattr from hex bytes
-    file_gfid = os.getxattr(path, "trusted.gfid").hex()
+    # Try to get a string representation of the xattr from hex bytes. We need
+    # to try/except because os.getxattr() returns FileNotFoundError when the
+    # file is a broken symlink, and OSError when the link goes somewhere that
+    # does not have GlusterFS metadata. This happens in the case of eg Python
+    # virtual environments in user's home directories and it is not a problem
+    # to remove it and return without trying to remove a .glusterfs hard link.
+    try:
+        file_gfid = os.getxattr(path, "trusted.gfid").hex()
+    except (FileNotFoundError, OSError):
+        if not args.dry_run:
+            os.remove(path)
+
+        print(f'{"(DRY RUN) " if args.dry_run else ""}Removed symlink: {path}')
+
+        return
+
     file_glusterfs_path = dot_glusterfs_path(brick_path, file_gfid)
 
     if Path(path).exists():