binman: Avoid setting sys.path globally

At present we set the Python path at the start of binman so we can read
modules in the 'etype' directory. This is a bit messy since it affects
'import' statements through binman.

Adjust the code to set the path locally, just where it is needed. Move
the 'entry' module in with the other base modules to help with this. It
makes more sense here anyway since it does not implement an entry type.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 222 insertions, 0 deletions

diff --git a/tools/binman/entry.py b/tools/binman/entry.py
new file mode 100644
index 0000000000..5374178542
--- /dev/null
+++ b/tools/binman/entry.py
@@ -0,0 +1,222 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (c) 2016 Google, Inc
+#
+# Base class for all entries
+#
+
+# importlib was introduced in Python 2.7 but there was a report of it not
+# working in 2.7.12, so we work around this:
+# http://lists.denx.de/pipermail/u-boot/2016-October/269729.html
+try:
+    import importlib
+    have_importlib = True
+except:
+    have_importlib = False
+
+import fdt_util
+import os
+import sys
+import tools
+
+modules = {}
+
+our_path = os.path.dirname(os.path.realpath(__file__))
+
+class Entry(object):
+    """An Entry in the section
+
+    An entry corresponds to a single node in the device-tree description
+    of the section. Each entry ends up being a part of the final section.
+    Entries can be placed either right next to each other, or with padding
+    between them. The type of the entry determines the data that is in it.
+
+    This class is not used by itself. All entry objects are subclasses of
+    Entry.
+
+    Attributes:
+        section: The section containing this entry
+        node: The node that created this entry
+        pos: Absolute position of entry within the section, None if not known
+        size: Entry size in bytes, None if not known
+        contents_size: Size of contents in bytes, 0 by default
+        align: Entry start position alignment, or None
+        align_size: Entry size alignment, or None
+        align_end: Entry end position alignment, or None
+        pad_before: Number of pad bytes before the contents, 0 if none
+        pad_after: Number of pad bytes after the contents, 0 if none
+        data: Contents of entry (string of bytes)
+    """
+    def __init__(self, section, etype, node, read_node=True):
+        self.section = section
+        self.etype = etype
+        self._node = node
+        self.pos = None
+        self.size = None
+        self.contents_size = 0
+        self.align = None
+        self.align_size = None
+        self.align_end = None
+        self.pad_before = 0
+        self.pad_after = 0
+        self.pos_unset = False
+        if read_node:
+            self.ReadNode()
+
+    @staticmethod
+    def Create(section, node, etype=None):
+        """Create a new entry for a node.
+
+        Args:
+            section:  Image object containing this node
+            node:   Node object containing information about the entry to create
+            etype:  Entry type to use, or None to work it out (used for tests)
+
+        Returns:
+            A new Entry object of the correct type (a subclass of Entry)
+        """
+        if not etype:
+            etype = fdt_util.GetString(node, 'type', node.name)
+
+        # Convert something like 'u-boot@0' to 'u_boot' since we are only
+        # interested in the type.
+        module_name = etype.replace('-', '_')
+        if '@' in module_name:
+            module_name = module_name.split('@')[0]
+        module = modules.get(module_name)
+
+        # Also allow entry-type modules to be brought in from the etype directory.
+
+        # Import the module if we have not already done so.
+        if not module:
+            old_path = sys.path
+            sys.path.insert(0, os.path.join(our_path, 'etype'))
+            try:
+                if have_importlib:
+                    module = importlib.import_module(module_name)
+                else:
+                    module = __import__(module_name)
+            except ImportError:
+                raise ValueError("Unknown entry type '%s' in node '%s'" %
+                        (etype, node.path))
+            finally:
+                sys.path = old_path
+            modules[module_name] = module
+
+        # Call its constructor to get the object we want.
+        obj = getattr(module, 'Entry_%s' % module_name)
+        return obj(section, etype, node)
+
+    def ReadNode(self):
+        """Read entry information from the node
+
+        This reads all the fields we recognise from the node, ready for use.
+        """
+        self.pos = fdt_util.GetInt(self._node, 'pos')
+        self.size = fdt_util.GetInt(self._node, 'size')
+        self.align = fdt_util.GetInt(self._node, 'align')
+        if tools.NotPowerOfTwo(self.align):
+            raise ValueError("Node '%s': Alignment %s must be a power of two" %
+                             (self._node.path, self.align))
+        self.pad_before = fdt_util.GetInt(self._node, 'pad-before', 0)
+        self.pad_after = fdt_util.GetInt(self._node, 'pad-after', 0)
+        self.align_size = fdt_util.GetInt(self._node, 'align-size')
+        if tools.NotPowerOfTwo(self.align_size):
+            raise ValueError("Node '%s': Alignment size %s must be a power "
+                             "of two" % (self._node.path, self.align_size))
+        self.align_end = fdt_util.GetInt(self._node, 'align-end')
+        self.pos_unset = fdt_util.GetBool(self._node, 'pos-unset')
+
+    def ObtainContents(self):
+        """Figure out the contents of an entry.
+
+        Returns:
+            True if the contents were found, False if another call is needed
+            after the other entries are processed.
+        """
+        # No contents by default: subclasses can implement this
+        return True
+
+    def Pack(self, pos):
+        """Figure out how to pack the entry into the section
+
+        Most of the time the entries are not fully specified. There may be
+        an alignment but no size. In that case we take the size from the
+        contents of the entry.
+
+        If an entry has no hard-coded position, it will be placed at @pos.
+
+        Once this function is complete, both the position and size of the
+        entry will be know.
+
+        Args:
+            Current section position pointer
+
+        Returns:
+            New section position pointer (after this entry)
+        """
+        if self.pos is None:
+            if self.pos_unset:
+                self.Raise('No position set with pos-unset: should another '
+                           'entry provide this correct position?')
+            self.pos = tools.Align(pos, self.align)
+        needed = self.pad_before + self.contents_size + self.pad_after
+        needed = tools.Align(needed, self.align_size)
+        size = self.size
+        if not size:
+            size = needed
+        new_pos = self.pos + size
+        aligned_pos = tools.Align(new_pos, self.align_end)
+        if aligned_pos != new_pos:
+            size = aligned_pos - self.pos
+            new_pos = aligned_pos
+
+        if not self.size:
+            self.size = size
+
+        if self.size < needed:
+            self.Raise("Entry contents size is %#x (%d) but entry size is "
+                       "%#x (%d)" % (needed, needed, self.size, self.size))
+        # Check that the alignment is correct. It could be wrong if the
+        # and pos or size values were provided (i.e. not calculated), but
+        # conflict with the provided alignment values
+        if self.size != tools.Align(self.size, self.align_size):
+            self.Raise("Size %#x (%d) does not match align-size %#x (%d)" %
+                  (self.size, self.size, self.align_size, self.align_size))
+        if self.pos != tools.Align(self.pos, self.align):
+            self.Raise("Position %#x (%d) does not match align %#x (%d)" %
+                  (self.pos, self.pos, self.align, self.align))
+
+        return new_pos
+
+    def Raise(self, msg):
+        """Convenience function to raise an error referencing a node"""
+        raise ValueError("Node '%s': %s" % (self._node.path, msg))
+
+    def GetPath(self):
+        """Get the path of a node
+
+        Returns:
+            Full path of the node for this entry
+        """
+        return self._node.path
+
+    def GetData(self):
+        return self.data
+
+    def GetPositions(self):
+        return {}
+
+    def SetPositionSize(self, pos, size):
+        self.pos = pos
+        self.size = size
+
+    def ProcessContents(self):
+        pass
+
+    def WriteSymbols(self, section):
+        """Write symbol values into binary files for access at run time
+
+        Args:
+          section: Section containing the entry
+        """
+        pass