Add disk extraction tools

1 files changed, 104 insertions, 0 deletions

diff --git a/extractArchive.py b/extractArchive.py
new file mode 100755
index 0000000..2e66879
--- /dev/null
+++ b/extractArchive.py
@@ -0,0 +1,104 @@
+#!/usr/bin/env python3
+
+"""
+Extract linearized (see linearizeDisk.py) EUMEL archive disk.
+"""
+
+import struct, sys, io, logging
+import codecs
+from eumel import Dataspace
+
+def take (it, n):
+    for i in range (n):
+        yield next (it)
+
+def parseEntry (blocks):
+    while True:
+        header = next (blocks)
+        unknown1, unknown2, length, unknown3 = struct.unpack ('<HHHH', header[:8])
+        logging.debug ('Got dataspace with {} blocks'.format (length))
+        yield b''.join (take (blocks, length))
+
+def readBlocks (fd):
+    while True:
+        buf = fd.read (512)
+        if not buf:
+            break
+        yield buf
+
+class FileHeaderDataspace (Dataspace):
+    TYPE = 0
+
+    def __init__ (self, fd):
+        Dataspace.__init__ (self, fd)
+        self.name = self.parseText ()
+        self.mtime = self.parseText ()
+        self.seek (0x40)
+        self.parseHeap ()
+
+if __name__ == '__main__':
+    import argparse, sys, codecs, os
+    from datetime import datetime
+    from io import BytesIO
+    from eumel import pagesize
+    
+    parser = argparse.ArgumentParser(description='Extract EUMEL disk archive.')
+    parser.add_argument ('-f', '--force', help='Overwrite existing files', action='store_true')
+    parser.add_argument ('-o', '--output', help='Output directory, defaults to archive name')
+    parser.add_argument ('-v', '--verbose', help='Enable debugging messages', action='store_true')
+    parser.add_argument ('file', help='Input file')
+    args = parser.parse_args ()
+
+    if args.verbose:
+        logging.basicConfig (level=logging.DEBUG)
+    else:
+        logging.basicConfig (level=logging.INFO)
+
+    with open (args.file, 'rb') as infd:
+        entries = parseEntry (readBlocks (infd))
+
+        # first entry is always disk info
+        diskinfo = FileHeaderDataspace (BytesIO (next (entries)))
+        if not args.output:
+            args.output = codecs.decode (diskinfo.name, 'eumel', 'replace')
+            logging.debug ('Using disk name {} as output directory'.format (args.output))
+
+        # create output dir
+        try:
+            os.makedirs (args.output)
+        except FileExistsError:
+            pass
+
+        while True:
+            # file header dataspace
+            fileheader = FileHeaderDataspace (BytesIO (next (entries)))
+            filename = codecs.decode (fileheader.name, 'eumel', 'replace').replace ('/', '-')
+            if len (filename) == 0:
+                logging.debug ('Filename was empty, i.e. last item in archive. I’m done')
+                break
+            try:
+                mtime = datetime.strptime (codecs.decode (fileheader.mtime, 'eumel', 'replace'), '%d.%m.%y')
+            except ValueError as e:
+                logging.warning ('Cannot parse date of file {}, {}'.format (filename, e))
+                mtime = datetime.now ()
+            logging.debug ('Got file {}, last modified {}'.format (filename, mtime))
+
+            # actual file contents
+            e = next (entries)
+
+            # quirks: if the first page starts with a magic sequence, skip it.
+            # Not sure what it is used for.
+            if e.startswith (2*b'\x30\x00\x00\x00'):
+                logging.debug ('skipping quirks')
+                e = e[pagesize:]
+
+            outfile = os.path.join (args.output, filename)
+            if os.path.exists (outfile) and not args.force:
+                logging.info ('File {} exists, skipping'.format (outfile))
+                continue
+            logging.info ('Extracting {} bytes to file {}'.format (len (e), outfile))
+            with open (outfile, 'wb') as outfd:
+                outfd.write (e)
+            stamp = mtime.timestamp ()
+            os.utime (outfile, (stamp, stamp))
+