Initial remote commit

misc_tools/check_translation.py

@@ -0,0 +1,80 @@
+CHUNK    = 128*512
+LV_START = 5120000*512
+BSIZE    = 4096
+
+# What if block 5251104 is an ABSOLUTE block number on md0
+# (not relative to LV start)?
+# Then: md0_byte = 5251104 * 4096 = 21,508,521,984
+# And we DON'T add LV_START
+
+abs_byte = 5251104 * BSIZE
+print(f'Block 5251104 as absolute md0 byte: {abs_byte}')
+print(f'md0 sector: {abs_byte//512}')
+
+# Read it directly from md0 (no translation)
+with open('/dev/md0','rb') as f:
+    f.seek(abs_byte)
+    data = f.read(BSIZE)
+
+import struct
+nonzero = sum(1 for b in data if b != 0)
+print(f'Nonzero bytes: {nonzero}/4096')
+print(f'First 32: {data[:32].hex()}')
+
+# Try as directory
+off = 0
+entries = []
+while off < BSIZE-8:
+    ino     = struct.unpack_from('<I', data, off)[0]
+    rec_len = struct.unpack_from('<H', data, off+4)[0]
+    name_len= data[off+6]
+    ftype   = data[off+7]
+    if rec_len < 8: break
+    if ino > 0 and name_len > 0:
+        name = data[off+8:off+8+name_len].decode('utf-8',errors='replace')
+        tname = {1:'file',2:'dir',7:'link'}.get(ftype,'?')
+        entries.append((ino,name,ftype))
+    off += rec_len
+
+if entries:
+    print('Directory entries:')
+    for ino,name,ftype in entries:
+        tname = {1:'file',2:'dir',7:'link'}.get(ftype,'?')
+        print(f'  {tname} inode={ino} {name!r}')
+else:
+    print('No valid directory entries')
+
+# Also try: what if the block number is relative to LV start
+# but WITHOUT the 4/5 chunk translation?
+# i.e. just: md0_byte = LV_START + block * BSIZE
+direct_byte = LV_START + 5251104 * BSIZE
+print()
+print(f'Block 5251104 relative to LV, no translation: {direct_byte}')
+with open('/dev/md0','rb') as f:
+    f.seek(direct_byte)
+    data2 = f.read(BSIZE)
+nonzero2 = sum(1 for b in data2 if b != 0)
+print(f'Nonzero bytes: {nonzero2}/4096')
+print(f'First 32: {data2[:32].hex()}')
+
+off = 0
+entries2 = []
+while off < BSIZE-8:
+    ino     = struct.unpack_from('<I', data2, off)[0]
+    rec_len = struct.unpack_from('<H', data2, off+4)[0]
+    name_len= data2[off+6]
+    ftype   = data2[off+7]
+    if rec_len < 8: break
+    if ino > 0 and name_len > 0:
+        name = data2[off+8:off+8+name_len].decode('utf-8',errors='replace')
+        tname = {1:'file',2:'dir',7:'link'}.get(ftype,'?')
+        entries2.append((ino,name,ftype))
+    off += rec_len
+
+if entries2:
+    print('Directory entries (no translation):')
+    for ino,name,ftype in entries2:
+        tname = {1:'file',2:'dir',7:'link'}.get(ftype,'?')
+        print(f'  {tname} inode={ino} {name!r}')
+else:
+    print('No valid directory entries')