Add script to unpack tar archives into fake filesystems

siloam72761 · Oct 30, 2017 · 46983d5 · 46983d5
1 parent 8ada948
commit 46983d5
Showing 1 changed file with 66 additions and 0 deletions.
diff --git a/tools/fakefsify.py b/tools/fakefsify.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+import sys
+from pathlib import Path
+import struct
+import urllib
+import tarfile
+import dbm
+
+def extract_archive(archive, db):
+    for member in archive.getmembers():
+        path = data/(member.name)
+        major = member.devmajor
+        minor = member.devminor
+        rdev = ((minor & 0xfff00) << 12) | (major << 8) | (minor & 0xff) # copied from fs/dev.h
+        mode = member.mode
+        if member.isfile():
+            mode |= 0o100000	
+        elif member.isdir():
+            mode |= 0o040000	
+        elif member.issym():
+            mode |= 0o120000
+        elif member.ischr():
+            mode |= 0o020000
+        elif member.isblk():
+            mode |= 0o060000
+        elif member.isfifo():
+            mode |= 0o010000
+        else:
+            raise ValueError('unrecognized tar entry type')
+
+        metadata = struct.pack(
+            '=iiii',
+            mode,
+            member.uid,
+            member.gid,
+            rdev,
+        )
+        db[b'meta:' + bytes(path)] = metadata
+
+        if member.isdir():
+            path.mkdir(parents=True, exist_ok=True)
+        elif member.issym():
+            path.symlink_to(member.linkname)
+        elif member.isfile():
+            archive.extract(member, data)
+        else:
+            path.touch()
+
+_, archive_path, fs = sys.argv
+
+fs = Path(fs)
+fs.mkdir(parents=True, exist_ok=True)
+data = fs/'data'
+data.mkdir()
+db = dbm.ndbm.open(str(fs/'meta'), 'c')
+
+try:
+    archive = open(archive_path, 'rb')
+except FileNotFoundError:
+    archive = urllib.request.urlopen(archive_path)
+
+with archive:
+    archive = tarfile.open(fileobj=archive)
+    with archive:
+        with db:
+            extract_archive(archive, db)