Initial remote commit

misc_tools/read_root.py

@@ -0,0 +1,95 @@
+import struct
+
+CHUNK    = 128*512
+LV_START = 5120000*512
+BSIZE    = 4096
+IPG      = 8192
+INODE_SZ = 256
+
+def phys_from_virt(virt):
+    grp      = virt//(5*CHUNK)
+    in_group = virt%(5*CHUNK)
+    chunk_idx= in_group//CHUNK
+    intra    = in_group%CHUNK
+    if chunk_idx == 4: return None
+    return LV_START + grp*4*CHUNK + chunk_idx*CHUNK + intra
+
+def read_phys(phys, length):
+    with open('/dev/sda','rb') as f:
+        f.seek(phys)
+        return f.read(length)
+
+def read_virt(virt, length):
+    phys = phys_from_virt(virt)
+    if phys is None: return b'\x00'*length
+    return read_phys(phys, length)
+
+def read_inode(inode_num):
+    group    = (inode_num-1)//IPG
+    idx      = (inode_num-1)%IPG
+    it_block = 1070 + group*512
+    virt     = it_block*BSIZE + idx*INODE_SZ
+    phys     = phys_from_virt(virt)
+    if phys is None: return None
+    return read_phys(phys, INODE_SZ)
+
+def get_extents(inode_data):
+    blocks = []
+    if struct.unpack_from('<H', inode_data, 40)[0] != 0xf30a:
+        return blocks
+    entries = struct.unpack_from('<H', inode_data, 42)[0]
+    depth   = struct.unpack_from('<H', inode_data, 46)[0]
+    if depth == 0:
+        for i in range(min(entries,4)):
+            off = 52+i*12
+            ee_len = struct.unpack_from('<H', inode_data, off+4)[0]
+            ee_hi  = struct.unpack_from('<H', inode_data, off+6)[0]
+            ee_lo  = struct.unpack_from('<I', inode_data, off+8)[0]
+            start  = (ee_hi<<32)|ee_lo
+            for b in range(min(ee_len,8)):
+                blocks.append(start+b)
+    return blocks
+
+def list_dir(inode_num):
+    data = read_inode(inode_num)
+    if not data: return []
+    entries = []
+    for blk in get_extents(data):
+        blk_data = read_virt(blk*BSIZE, BSIZE)
+        off = 0
+        while off < BSIZE-8:
+            ino     = struct.unpack_from('<I', blk_data, off)[0]
+            rec_len = struct.unpack_from('<H', blk_data, off+4)[0]
+            name_len= blk_data[off+6]
+            ftype   = blk_data[off+7]
+            if rec_len < 8: break
+            if ino > 0 and name_len > 0:
+                name = blk_data[off+8:off+8+name_len].decode('utf-8',errors='replace')
+                entries.append((ino, name, ftype))
+            off += rec_len
+    return entries
+
+# List root directory
+print('Root directory (inode 2):')
+for ino, name, ftype in list_dir(2):
+    tname = {1:'file',2:'dir',7:'link'}.get(ftype,'?')
+    print(f'  {tname:4s} {name:20s} inode={ino}')
+
+# Find var
+print()
+for ino, name, ftype in list_dir(2):
+    if name == 'var':
+        print(f'Found /var at inode {ino}')
+        print('Contents of /var:')
+        for i2, n2, f2 in list_dir(ino):
+            tname = {1:'file',2:'dir',7:'link'}.get(f2,'?')
+            print(f'  {tname:4s} {n2:20s} inode={i2}')
+        
+        # Find var/lib
+        for i2, n2, f2 in list_dir(ino):
+            if n2 == 'lib':
+                print(f'\nFound /var/lib at inode {i2}')
+                print('Contents of /var/lib:')
+                for i3, n3, f3 in list_dir(i2):
+                    tname = {1:'file',2:'dir',7:'link'}.get(f3,'?')
+                    print(f'  {tname:4s} {n3:20s} inode={i3}')