Fix master node error

ubireader/ubifs/__init__.py

@@ -25,6 +25,8 @@
 
 if TYPE_CHECKING:
     from ubireader.ubi_io import ubi_file as UbiFile, leb_virtual_file as LebVirtualFile
+from typing import Optional
+from zlib import crc32
 
 class ubifs():
     """UBIFS object
@@ -65,24 +67,50 @@ def __init__(self, ubifs_file: UbiFile | LebVirtualFile, master_key: bytes | Non
 
         self._mst_nodes: list[nodes.mst_node | None] = [None, None]
         for i in range(0, 2):
+            s_mst_offset = self.leb_size * (UBIFS_MST_LNUM + i)
+            mst_offset = s_mst_offset
+            mst_nodes = []
             try:
-                mst_offset = self.leb_size * (UBIFS_MST_LNUM + i) 
-                self.file.seek(mst_offset)
-                mst_chdr = nodes.common_hdr(self.file.read(UBIFS_COMMON_HDR_SZ))
-                log(self , '%s file addr: %s' % (mst_chdr, self.file.last_read_addr()))
-                verbose_display(mst_chdr)
+                while mst_offset < self.leb_size + s_mst_offset:
+                    self.file.seek(mst_offset)
+                    mst_chdr = nodes.common_hdr(self.file.read(UBIFS_COMMON_HDR_SZ))
+                    log(self , '%s file addr: %s' % (mst_chdr, self.file.last_read_addr()))
+                    verbose_display(mst_chdr)
+                    # crc
+                    cpos = self.file.tell()
+                    self.file.seek(mst_offset + 8)
+                    crcdata = self.file.read(mst_chdr.len-8)
+                    self.file.seek(cpos)
+                    crc = (~crc32(crcdata) & 0xFFFFFFFF)
+
+                    if crc != mst_chdr.crc:
+                        log(self, 'Master node CRC check failed: expected 0x%x got 0x%x' % (crc, mst_chdr.crc))
+                        mst_offset += mst_chdr.len
+                        continue
 
-                if mst_chdr.node_type == UBIFS_MST_NODE:
                     self.file.seek(mst_offset + UBIFS_COMMON_HDR_SZ)
-                    buf = self.file.read(UBIFS_MST_NODE_SZ)
-                    self._mst_nodes[i] = nodes.mst_node(buf, self.file.last_read_addr())
-                    log(self , '%s%s file addr: %s' % (self._mst_nodes[i], i, self.file.last_read_addr()))
-                    verbose_display(self._mst_nodes[i])
-                else:
-                    raise Exception('Wrong node type.')
+                    if mst_chdr.node_type == UBIFS_MST_NODE:
+                        buf = self.file.read(UBIFS_MST_NODE_SZ)
+                        mst_node = nodes.mst_node(buf, self.file.last_read_addr())
+                        mst_nodes.append(mst_node)
+                        log(self , '%s%s file addr: %s' % (mst_node, i, self.file.last_read_addr()))
+                        verbose_display(mst_node)
+                    elif mst_chdr.node_type == UBIFS_PAD_NODE:
+                        buf = self.file.read(UBIFS_PAD_NODE_SZ)
+                        padnode = nodes.pad_node(buf, self.file.last_read_addr())
+                        mst_offset += padnode.pad_len
+                        log(self , '%s%s file addr: %s' % (padnode, i, self.file.last_read_addr()))
+                        verbose_display(padnode)
+                    else:
+                        raise Exception('Wrong node type.')
+                    mst_offset += mst_chdr.len
             except Exception as e:
                 error(self, 'Warn', 'Master block %s error: %s' % (i, e))
 
+            # Get the valid master node with the highest sequence number.
+            if len(mst_nodes):
+                self._mst_nodes[i] = max(mst_nodes, key=lambda x: x.cmt_no)
+
         if self._mst_nodes[0] is None and self._mst_nodes[1] is None:
             error(self, 'Fatal', 'No valid Master Node found.')
 

ubireader/ubifs/display.py

@@ -99,6 +99,14 @@ def mst_node(node: nodes.mst_node, tab: str = '') -> str:
             buf += '%s%s: %r\n' % (tab, key, value)
     return buf
 
+def pad_node(node, tab=''):
+    buf = '%s%s\n' % (tab, node)
+    buf += '%sFile offset: %s\n' % (tab, node.file_offset)
+    buf += '%s---------------------\n' % (tab)
+    tab += '\t'
+    for key, value in node:
+        buf += '%s%s: %r\n' % (tab, key, value)
+    return buf
 
 def dent_node(node: nodes.dent_node, tab: str = '') -> str:
     buf = '%s%s\n' % (tab, node)

ubireader/ubifs/nodes.py

@@ -445,3 +445,31 @@ def __iter__(self) -> Iterator[tuple[str, Any]]:
 
     def display(self, tab: str = '') -> str:
         return display.mst_node(self, tab)
+
+class pad_node(object):
+    """Get pad node at given LEB number + offset.
+
+    Arguments:
+    Bin:buf     -- Raw data to extract header information from.
+    Int:offset  -- Offset in LEB of data node.
+
+    See ubifs/defines.py for object attributes.
+    """
+    def __init__(self, buf, file_offset=-1):
+        self.file_offset = file_offset
+        fields = dict(list(zip(UBIFS_PAD_NODE_FIELDS, struct.unpack(UBIFS_PAD_NODE_FORMAT, buf))))
+        for key in fields:
+            setattr(self, key, fields[key])
+
+        setattr(self, 'errors', [])
+
+    def __repr__(self):
+        return 'UBIFS Pad Node'
+
+    def __iter__(self):
+        for key in dir(self):
+            if not key.startswith('_'):
+                yield key, getattr(self, key)
+
+    def display(self, tab=''):
+        return display.pad_node(self, tab)

ubireader/ubifs/output.py

@@ -174,7 +174,11 @@ def _set_file_perms(path, inode):
     verbose_log(_set_file_perms, 'perms:%s, owner: %s.%s, path: %s' % (inode['ino'].mode, inode['ino'].uid, inode['ino'].gid, path))
 
 def _set_file_timestamps(path, inode):
-    os.utime(path, (inode['ino'].atime_sec, inode['ino'].mtime_sec), follow_symlinks = False)
+    times = (inode['ino'].atime_sec, inode['ino'].mtime_sec)
+    if os.utime in os.supports_follow_symlinks:
+        os.utime(path, times, follow_symlinks=False)
+    else:
+        os.utime(path, times)
     verbose_log(_set_file_timestamps, 'timestamps: access: %s, modify: %s, path: %s' % (inode['ino'].atime_sec, inode['ino'].mtime_sec, path))
 
 def _write_reg_file(path, data):