diff options
Diffstat (limited to 'tools/binman/cbfs_util.py')
| -rw-r--r-- | tools/binman/cbfs_util.py | 68 |
1 files changed, 65 insertions, 3 deletions
diff --git a/tools/binman/cbfs_util.py b/tools/binman/cbfs_util.py index 197cff89509..ec4a2e5a8c6 100644 --- a/tools/binman/cbfs_util.py +++ b/tools/binman/cbfs_util.py @@ -11,7 +11,8 @@ The format is somewhat defined by documentation in the coreboot tree although it is necessary to rely on the C structures and source code (mostly cbfstool) to fully understand it. -Currently supported: raw and stage types with compression +Currently supported: raw and stage types with compression, padding empty areas + with empty files """ from __future__ import print_function @@ -102,6 +103,7 @@ ARCH_NAMES = { TYPE_CBFSHEADER = 0x02 # Master header, HEADER_FORMAT TYPE_STAGE = 0x10 # Stage, holding an executable, see STAGE_FORMAT TYPE_RAW = 0x50 # Raw file, possibly compressed +TYPE_EMPTY = 0xffffffff # Empty data # Compression types COMPRESS_NONE, COMPRESS_LZMA, COMPRESS_LZ4 = range(3) @@ -152,6 +154,19 @@ def align_int(val, align): """ return int((val + align - 1) / align) * align +def align_int_down(val, align): + """Align a value down to the given alignment + + Args: + val: Integer value to align + align: Integer alignment value (e.g. 4 to align to 4-byte boundary) + + Returns: + integer value aligned to the required boundary, rounding down if + necessary + """ + return int(val / align) * align + def _pack_string(instr): """Pack a string to the required aligned size by adding padding @@ -184,6 +199,9 @@ class CbfsFile(object): entry: Entry address in memory if known, else None. This is where execution starts after the file is loaded base_address: Base address to use for 'stage' files + erase_byte: Erase byte to use for padding between the file header and + contents (used for empty files) + size: Size of the file in bytes (used for empty files) """ def __init__(self, name, ftype, data, compress=COMPRESS_NONE): self.name = name @@ -196,6 +214,8 @@ class CbfsFile(object): self.entry = None self.base_address = None self.data_len = 0 + self.erase_byte = None + self.size = None def decompress(self): """Handle decompressing data if necessary""" @@ -242,6 +262,24 @@ class CbfsFile(object): """ return CbfsFile(name, TYPE_RAW, data, compress) + @classmethod + def empty(cls, space_to_use, erase_byte): + """Create a new empty file of a given size + + Args: + space_to_use:: Size of available space, which must be at least as + large as the alignment size for this CBFS + erase_byte: Byte to use for contents of file (repeated through the + whole file) + + Returns: + CbfsFile object containing the file information + """ + cfile = CbfsFile('', TYPE_EMPTY, b'') + cfile.size = space_to_use - FILE_HEADER_LEN - FILENAME_ALIGN + cfile.erase_byte = erase_byte + return cfile + def get_data(self): """Obtain the contents of the file, in CBFS format @@ -270,6 +308,8 @@ class CbfsFile(object): attr = struct.pack(ATTR_COMPRESSION_FORMAT, FILE_ATTR_TAG_COMPRESSION, ATTR_COMPRESSION_LEN, self.compress, len(orig_data)) + elif self.ftype == TYPE_EMPTY: + data = tools.GetBytes(self.erase_byte, self.size) else: raise ValueError('Unknown type %#x when writing\n' % self.ftype) if attr: @@ -357,6 +397,24 @@ class CbfsWriter(object): (offset, fd.tell())) fd.write(tools.GetBytes(self._erase_byte, offset - fd.tell())) + def _pad_to(self, fd, offset): + """Write out pad bytes and/or an empty file until a given offset + + Args: + fd: File objext to write to + offset: Offset to write to + """ + self._align_to(fd, self._align) + upto = fd.tell() + if upto > offset: + raise ValueError('No space for data before pad offset %#x (current offset %#x)' % + (offset, upto)) + todo = align_int_down(offset - upto, self._align) + if todo: + cbf = CbfsFile.empty(todo, self._erase_byte) + fd.write(cbf.get_data()) + self._skip_to(fd, offset) + def _align_to(self, fd, align): """Write out pad bytes until a given alignment is reached @@ -416,7 +474,7 @@ class CbfsWriter(object): raise ValueError('No space for header at offset %#x (current offset %#x)' % (self._header_offset, fd.tell())) if not add_fileheader: - self._skip_to(fd, self._header_offset) + self._pad_to(fd, self._header_offset) hdr = struct.pack(HEADER_FORMAT, HEADER_MAGIC, HEADER_VERSION2, self._size, self._bootblock_size, self._align, self._contents_offset, self._arch, 0xffffffff) @@ -455,7 +513,7 @@ class CbfsWriter(object): self._write_header(fd, add_fileheader=self._add_fileheader) # Pad to the end and write a pointer to the CBFS master header - self._skip_to(fd, self._base_address or self._size - 4) + self._pad_to(fd, self._base_address or self._size - 4) rel_offset = self._header_offset - self._size fd.write(struct.pack('<I', rel_offset & 0xffffffff)) @@ -596,6 +654,10 @@ class CbfsReader(object): cfile.decompress() if DEBUG: print('data', data) + elif ftype == TYPE_EMPTY: + # Just read the data and discard it, since it is only padding + fd.read(size) + cfile = CbfsFile('', TYPE_EMPTY, b'') else: raise ValueError('Unknown type %#x when reading\n' % ftype) if cfile: |