binman: Allow external binaries to be missing

Sometimes it is useful to build an image even though external binaries are
not present. This allows the build system to continue to function without
these files, albeit not producing valid images.

U-Boot does with with ATF (ARM Trusted Firmware) today.

Add a new flag to binman to request this behaviour.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

tools/binman/README.entries

@@ -48,6 +48,9 @@ Entry: blob-ext: Entry containing an externally built binary blob
 Note: This should not be used by itself. It is normally used as a parent
 class by other entry types.
 
+If the file providing this blob is missing, binman can optionally ignore it
+and produce a broken image with a warning.
+
 See 'blob' for Properties / Entry arguments.
 
 

tools/binman/cmdline.py

@@ -53,6 +53,8 @@ controlled by a description in the board device tree.'''
             help='Add a path to the list of directories to use for input files')
     build_parser.add_argument('-m', '--map', action='store_true',
         default=False, help='Output a map file for each image')
+    build_parser.add_argument('-M', '--allow-missing', action='store_true',
+        default=False, help='Allow external blobs to be missing')
     build_parser.add_argument('-O', '--outdir', type=str,
         action='store', help='Path to directory to use for intermediate and '
         'output files')

tools/binman/control.py

@@ -387,7 +387,7 @@ def PrepareImagesAndDtbs(dtb_fname, select_images, update_fdt):
 
 
 def ProcessImage(image, update_fdt, write_map, get_contents=True,
-                 allow_resize=True):
+                 allow_resize=True, allow_missing=False):
     """Perform all steps for this image, including checking and # writing it.
 
     This means that errors found with a later image will be reported after
@@ -402,8 +402,10 @@ def ProcessImage(image, update_fdt, write_map, get_contents=True,
             the contents is already present
         allow_resize: True to allow entries to change size (this does a re-pack
             of the entries), False to raise an exception
+        allow_missing: Allow blob_ext objects to be missing
     """
     if get_contents:
+        image.SetAllowMissing(allow_missing)
         image.GetEntryContents()
     image.GetEntryOffsets()
 
@@ -523,7 +525,8 @@ def Binman(args):
             images = PrepareImagesAndDtbs(dtb_fname, args.image,
                                           args.update_fdt)
             for image in images.values():
-                ProcessImage(image, args.update_fdt, args.map)
+                ProcessImage(image, args.update_fdt, args.map,
+                             allow_missing=args.allow_missing)
 
             # Write the updated FDTs to our output files
             for dtb_item in state.GetAllFdts():

tools/binman/entry.py

@@ -794,3 +794,12 @@ features to produce new behaviours.
             elif self == entries[-1]:
                 return 'end'
         return 'middle'
+
+    def SetAllowMissing(self, allow_missing):
+        """Set whether a section allows missing external blobs
+
+        Args:
+            allow_missing: True if allowed, False if not allowed
+        """
+        # This is meaningless for anything other than sections
+        pass

tools/binman/etype/blob_ext.py

@@ -18,6 +18,9 @@ class Entry_blob_ext(Entry_blob):
     Note: This should not be used by itself. It is normally used as a parent
     class by other entry types.
 
+    If the file providing this blob is missing, binman can optionally ignore it
+    and produce a broken image with a warning.
+
     See 'blob' for Properties / Entry arguments.
     """
     def __init__(self, section, etype, node):
@@ -26,6 +29,10 @@ class Entry_blob_ext(Entry_blob):
 
     def ObtainContents(self):
         self._filename = self.GetDefaultFilename()
-        self._pathname = tools.GetInputFilename(self._filename)
-        self.ReadBlobContents()
-        return True
+        self._pathname = tools.GetInputFilename(self._filename,
+                                                self.section.GetAllowMissing())
+        # Allow the file to be missing
+        if not self._pathname:
+            self.SetContents(b'')
+            return True
+        return super().ObtainContents()

tools/binman/etype/section.py

@@ -34,6 +34,11 @@ class Entry_section(Entry):
         name-prefix: Adds a prefix to the name of every entry in the section
             when writing out the map
 
+    Properties:
+        _allow_missing: True if this section permits external blobs to be
+            missing their contents. The second will produce an image but of
+            course it will not work.
+
     Since a section is also an entry, it inherits all the properies of entries
     too.
 
@@ -49,6 +54,7 @@ class Entry_section(Entry):
         self._sort = False
         self._skip_at_start = None
         self._end_4gb = False
+        self._allow_missing = False
 
     def ReadNode(self):
         """Read properties from the image node"""
@@ -535,3 +541,21 @@ class Entry_section(Entry):
 
     def WriteChildData(self, child):
         return True
+
+    def SetAllowMissing(self, allow_missing):
+        """Set whether a section allows missing external blobs
+
+        Args:
+            allow_missing: True if allowed, False if not allowed
+        """
+        self._allow_missing = allow_missing
+        for entry in self._entries.values():
+            entry.SetAllowMissing(allow_missing)
+
+    def GetAllowMissing(self):
+        """Get whether a section allows missing external blobs
+
+        Returns:
+            True if allowed, False if not allowed
+        """
+        return self._allow_missing

tools/binman/ftest.py

@@ -285,7 +285,7 @@ class TestFunctional(unittest.TestCase):
 
     def _DoTestFile(self, fname, debug=False, map=False, update_dtb=False,
                     entry_args=None, images=None, use_real_dtb=False,
-                    verbosity=None):
+                    verbosity=None, allow_missing=False):
         """Run binman with a given test file
 
         Args:
@@ -319,6 +319,8 @@ class TestFunctional(unittest.TestCase):
         if entry_args:
             for arg, value in entry_args.items():
                 args.append('-a%s=%s' % (arg, value))
+        if allow_missing:
+            args.append('-M')
         if images:
             for image in images:
                 args += ['-i', image]
@@ -3376,6 +3378,10 @@ class TestFunctional(unittest.TestCase):
         self.assertIn("Filename 'missing-file' not found in input path",
                       str(e.exception))
 
+    def testExtblobMissingOk(self):
+        """Test an image with an missing external blob that is allowed"""
+        self._DoTestFile('158_blob_ext_missing.dts', allow_missing=True)
+
 
 if __name__ == "__main__":
     unittest.main()

tools/patman/tools.py

@@ -114,14 +114,16 @@ def SetInputDirs(dirname):
     indir = dirname
     tout.Debug("Using input directories %s" % indir)
 
-def GetInputFilename(fname):
+def GetInputFilename(fname, allow_missing=False):
     """Return a filename for use as input.
 
     Args:
         fname: Filename to use for new file
+        allow_missing: True if the filename can be missing
 
     Returns:
-        The full path of the filename, within the input directory
+        The full path of the filename, within the input directory, or
+        None on error
     """
     if not indir or fname[:1] == '/':
         return fname
@@ -130,6 +132,8 @@ def GetInputFilename(fname):
         if os.path.exists(pathname):
             return pathname
 
+    if allow_missing:
+        return None
     raise ValueError("Filename '%s' not found in input path (%s) (cwd='%s')" %
                      (fname, ','.join(indir), os.getcwd()))