mirror of
https://github.com/AsahiLinux/u-boot
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4583c00236
The patman directory has a number of modules which are used by other tools in U-Boot. This makes it hard to package the tools using pypi since the common files must be copied along with the tool that uses them. To address this, move these files into a new u_boot_pylib library. This can be packaged separately and listed as a dependency of each tool. Signed-off-by: Simon Glass <sjg@chromium.org>
866 lines
31 KiB
Python
866 lines
31 KiB
Python
# SPDX-License-Identifier: GPL-2.0+
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# Copyright 2019 Google LLC
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# Written by Simon Glass <sjg@chromium.org>
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"""Support for coreboot's CBFS format
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CBFS supports a header followed by a number of files, generally targeted at SPI
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flash.
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The format is somewhat defined by documentation in the coreboot tree although
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it is necessary to rely on the C structures and source code (mostly cbfstool)
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to fully understand it.
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Currently supported: raw and stage types with compression, padding empty areas
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with empty files, fixed-offset files
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"""
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from collections import OrderedDict
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import io
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import struct
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import sys
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from binman import bintool
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from binman import elf
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from u_boot_pylib import command
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from u_boot_pylib import tools
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# Set to True to enable printing output while working
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DEBUG = False
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# Set to True to enable output from running cbfstool for debugging
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VERBOSE = False
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# The master header, at the start of the CBFS
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HEADER_FORMAT = '>IIIIIIII'
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HEADER_LEN = 0x20
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HEADER_MAGIC = 0x4f524243
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HEADER_VERSION1 = 0x31313131
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HEADER_VERSION2 = 0x31313132
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# The file header, at the start of each file in the CBFS
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FILE_HEADER_FORMAT = b'>8sIIII'
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FILE_HEADER_LEN = 0x18
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FILE_MAGIC = b'LARCHIVE'
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FILENAME_ALIGN = 16 # Filename lengths are aligned to this
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# A stage header containing information about 'stage' files
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# Yes this is correct: this header is in litte-endian format
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STAGE_FORMAT = '<IQQII'
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STAGE_LEN = 0x1c
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# An attribute describring the compression used in a file
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ATTR_COMPRESSION_FORMAT = '>IIII'
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ATTR_COMPRESSION_LEN = 0x10
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# Attribute tags
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# Depending on how the header was initialised, it may be backed with 0x00 or
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# 0xff. Support both.
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FILE_ATTR_TAG_UNUSED = 0
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FILE_ATTR_TAG_UNUSED2 = 0xffffffff
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FILE_ATTR_TAG_COMPRESSION = 0x42435a4c
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FILE_ATTR_TAG_HASH = 0x68736148
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FILE_ATTR_TAG_POSITION = 0x42435350 # PSCB
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FILE_ATTR_TAG_ALIGNMENT = 0x42434c41 # ALCB
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FILE_ATTR_TAG_PADDING = 0x47444150 # PDNG
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# This is 'the size of bootblock reserved in firmware image (cbfs.txt)'
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# Not much more info is available, but we set it to 4, due to this comment in
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# cbfstool.c:
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# This causes 4 bytes to be left out at the end of the image, for two reasons:
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# 1. The cbfs master header pointer resides there
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# 2. Ssme cbfs implementations assume that an image that resides below 4GB has
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# a bootblock and get confused when the end of the image is at 4GB == 0.
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MIN_BOOTBLOCK_SIZE = 4
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# Files start aligned to this boundary in the CBFS
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ENTRY_ALIGN = 0x40
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# CBFSs must declare an architecture since much of the logic is designed with
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# x86 in mind. The effect of setting this value is not well documented, but in
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# general x86 is used and this makes use of a boot block and an image that ends
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# at the end of 32-bit address space.
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ARCHITECTURE_UNKNOWN = 0xffffffff
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ARCHITECTURE_X86 = 0x00000001
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ARCHITECTURE_ARM = 0x00000010
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ARCHITECTURE_AARCH64 = 0x0000aa64
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ARCHITECTURE_MIPS = 0x00000100
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ARCHITECTURE_RISCV = 0xc001d0de
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ARCHITECTURE_PPC64 = 0x407570ff
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ARCH_NAMES = {
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ARCHITECTURE_UNKNOWN : 'unknown',
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ARCHITECTURE_X86 : 'x86',
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ARCHITECTURE_ARM : 'arm',
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ARCHITECTURE_AARCH64 : 'arm64',
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ARCHITECTURE_MIPS : 'mips',
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ARCHITECTURE_RISCV : 'riscv',
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ARCHITECTURE_PPC64 : 'ppc64',
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}
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# File types. Only supported ones are included here
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TYPE_CBFSHEADER = 0x02 # Master header, HEADER_FORMAT
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TYPE_STAGE = 0x10 # Stage, holding an executable, see STAGE_FORMAT
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TYPE_RAW = 0x50 # Raw file, possibly compressed
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TYPE_EMPTY = 0xffffffff # Empty data
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# Compression types
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COMPRESS_NONE, COMPRESS_LZMA, COMPRESS_LZ4 = range(3)
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COMPRESS_NAMES = {
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COMPRESS_NONE : 'none',
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COMPRESS_LZMA : 'lzma',
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COMPRESS_LZ4 : 'lz4',
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}
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def find_arch(find_name):
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"""Look up an architecture name
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Args:
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find_name: Architecture name to find
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Returns:
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ARCHITECTURE_... value or None if not found
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"""
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for arch, name in ARCH_NAMES.items():
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if name == find_name:
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return arch
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return None
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def find_compress(find_name):
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"""Look up a compression algorithm name
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Args:
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find_name: Compression algorithm name to find
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Returns:
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COMPRESS_... value or None if not found
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"""
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for compress, name in COMPRESS_NAMES.items():
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if name == find_name:
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return compress
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return None
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def compress_name(compress):
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"""Look up the name of a compression algorithm
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Args:
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compress: Compression algorithm number to find (COMPRESS_...)
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Returns:
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Compression algorithm name (string)
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Raises:
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KeyError if the algorithm number is invalid
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"""
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return COMPRESS_NAMES[compress]
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def align_int(val, align):
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"""Align a value up to the given alignment
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Args:
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val: Integer value to align
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align: Integer alignment value (e.g. 4 to align to 4-byte boundary)
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Returns:
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integer value aligned to the required boundary, rounding up if necessary
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"""
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return int((val + align - 1) / align) * align
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def align_int_down(val, align):
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"""Align a value down to the given alignment
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Args:
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val: Integer value to align
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align: Integer alignment value (e.g. 4 to align to 4-byte boundary)
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Returns:
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integer value aligned to the required boundary, rounding down if
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necessary
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"""
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return int(val / align) * align
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def _pack_string(instr):
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"""Pack a string to the required aligned size by adding padding
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Args:
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instr: String to process
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Returns:
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String with required padding (at least one 0x00 byte) at the end
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"""
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val = tools.to_bytes(instr)
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pad_len = align_int(len(val) + 1, FILENAME_ALIGN)
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return val + tools.get_bytes(0, pad_len - len(val))
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class CbfsFile(object):
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"""Class to represent a single CBFS file
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This is used to hold the information about a file, including its contents.
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Use the get_data_and_offset() method to obtain the raw output for writing to
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CBFS.
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Properties:
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name: Name of file
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offset: Offset of file data from start of file header
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cbfs_offset: Offset of file data in bytes from start of CBFS, or None to
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place this file anyway
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data: Contents of file, uncompressed
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orig_data: Original data added to the file, possibly compressed
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data_len: Length of (possibly compressed) data in bytes
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ftype: File type (TYPE_...)
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compression: Compression type (COMPRESS_...)
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memlen: Length of data in memory, i.e. the uncompressed length, None if
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no compression algortihm is selected
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load: Load address in memory if known, else None
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entry: Entry address in memory if known, else None. This is where
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execution starts after the file is loaded
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base_address: Base address to use for 'stage' files
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erase_byte: Erase byte to use for padding between the file header and
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contents (used for empty files)
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size: Size of the file in bytes (used for empty files)
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"""
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def __init__(self, name, ftype, data, cbfs_offset, compress=COMPRESS_NONE):
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self.name = name
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self.offset = None
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self.cbfs_offset = cbfs_offset
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self.data = data
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self.orig_data = data
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self.ftype = ftype
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self.compress = compress
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self.memlen = None
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self.load = None
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self.entry = None
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self.base_address = None
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self.data_len = len(data)
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self.erase_byte = None
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self.size = None
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if self.compress == COMPRESS_LZ4:
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self.comp_bintool = bintool.Bintool.create('lz4')
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elif self.compress == COMPRESS_LZMA:
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self.comp_bintool = bintool.Bintool.create('lzma_alone')
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else:
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self.comp_bintool = None
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def decompress(self):
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"""Handle decompressing data if necessary"""
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indata = self.data
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if self.comp_bintool:
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data = self.comp_bintool.decompress(indata)
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else:
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data = indata
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self.memlen = len(data)
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self.data = data
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self.data_len = len(indata)
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@classmethod
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def stage(cls, base_address, name, data, cbfs_offset):
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"""Create a new stage file
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Args:
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base_address: Int base address for memory-mapping of ELF file
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name: String file name to put in CBFS (does not need to correspond
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to the name that the file originally came from)
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data: Contents of file
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cbfs_offset: Offset of file data in bytes from start of CBFS, or
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None to place this file anyway
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Returns:
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CbfsFile object containing the file information
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"""
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cfile = CbfsFile(name, TYPE_STAGE, data, cbfs_offset)
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cfile.base_address = base_address
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return cfile
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@classmethod
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def raw(cls, name, data, cbfs_offset, compress):
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"""Create a new raw file
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Args:
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name: String file name to put in CBFS (does not need to correspond
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to the name that the file originally came from)
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data: Contents of file
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cbfs_offset: Offset of file data in bytes from start of CBFS, or
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None to place this file anyway
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compress: Compression algorithm to use (COMPRESS_...)
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Returns:
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CbfsFile object containing the file information
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"""
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return CbfsFile(name, TYPE_RAW, data, cbfs_offset, compress)
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@classmethod
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def empty(cls, space_to_use, erase_byte):
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"""Create a new empty file of a given size
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Args:
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space_to_use:: Size of available space, which must be at least as
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large as the alignment size for this CBFS
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erase_byte: Byte to use for contents of file (repeated through the
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whole file)
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Returns:
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CbfsFile object containing the file information
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"""
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cfile = CbfsFile('', TYPE_EMPTY, b'', None)
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cfile.size = space_to_use - FILE_HEADER_LEN - FILENAME_ALIGN
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cfile.erase_byte = erase_byte
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return cfile
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def calc_start_offset(self):
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"""Check if this file needs to start at a particular offset in CBFS
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Returns:
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None if the file can be placed anywhere, or
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the largest offset where the file could start (integer)
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"""
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if self.cbfs_offset is None:
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return None
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return self.cbfs_offset - self.get_header_len()
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def get_header_len(self):
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"""Get the length of headers required for a file
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This is the minimum length required before the actual data for this file
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could start. It might start later if there is padding.
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Returns:
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Total length of all non-data fields, in bytes
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"""
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name = _pack_string(self.name)
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hdr_len = len(name) + FILE_HEADER_LEN
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if self.ftype == TYPE_STAGE:
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pass
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elif self.ftype == TYPE_RAW:
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hdr_len += ATTR_COMPRESSION_LEN
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elif self.ftype == TYPE_EMPTY:
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pass
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else:
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raise ValueError('Unknown file type %#x\n' % self.ftype)
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return hdr_len
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def get_data_and_offset(self, offset=None, pad_byte=None):
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"""Obtain the contents of the file, in CBFS format and the offset of
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the data within the file
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Returns:
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tuple:
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bytes representing the contents of this file, packed and aligned
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for directly inserting into the final CBFS output
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offset to the file data from the start of the returned data.
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"""
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name = _pack_string(self.name)
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hdr_len = len(name) + FILE_HEADER_LEN
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attr_pos = 0
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content = b''
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attr = b''
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pad = b''
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data = self.data
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if self.ftype == TYPE_STAGE:
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elf_data = elf.DecodeElf(data, self.base_address)
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content = struct.pack(STAGE_FORMAT, self.compress,
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elf_data.entry, elf_data.load,
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len(elf_data.data), elf_data.memsize)
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data = elf_data.data
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elif self.ftype == TYPE_RAW:
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orig_data = data
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if self.comp_bintool:
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data = self.comp_bintool.compress(orig_data)
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self.memlen = len(orig_data)
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self.data_len = len(data)
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attr = struct.pack(ATTR_COMPRESSION_FORMAT,
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FILE_ATTR_TAG_COMPRESSION, ATTR_COMPRESSION_LEN,
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self.compress, self.memlen)
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elif self.ftype == TYPE_EMPTY:
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data = tools.get_bytes(self.erase_byte, self.size)
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else:
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raise ValueError('Unknown type %#x when writing\n' % self.ftype)
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if attr:
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attr_pos = hdr_len
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hdr_len += len(attr)
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if self.cbfs_offset is not None:
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pad_len = self.cbfs_offset - offset - hdr_len
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if pad_len < 0: # pragma: no cover
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# Test coverage of this is not available since this should never
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# happen. It indicates that get_header_len() provided an
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# incorrect value (too small) so that we decided that we could
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# put this file at the requested place, but in fact a previous
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# file extends far enough into the CBFS that this is not
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# possible.
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raise ValueError("Internal error: CBFS file '%s': Requested offset %#x but current output position is %#x" %
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(self.name, self.cbfs_offset, offset))
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pad = tools.get_bytes(pad_byte, pad_len)
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hdr_len += pad_len
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# This is the offset of the start of the file's data,
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size = len(content) + len(data)
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hdr = struct.pack(FILE_HEADER_FORMAT, FILE_MAGIC, size,
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self.ftype, attr_pos, hdr_len)
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# Do a sanity check of the get_header_len() function, to ensure that it
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# stays in lockstep with this function
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expected_len = self.get_header_len()
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actual_len = len(hdr + name + attr)
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if expected_len != actual_len: # pragma: no cover
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# Test coverage of this is not available since this should never
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# happen. It probably indicates that get_header_len() is broken.
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raise ValueError("Internal error: CBFS file '%s': Expected headers of %#x bytes, got %#d" %
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(self.name, expected_len, actual_len))
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return hdr + name + attr + pad + content + data, hdr_len
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class CbfsWriter(object):
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"""Class to handle writing a Coreboot File System (CBFS)
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Usage is something like:
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cbw = CbfsWriter(size)
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cbw.add_file_raw('u-boot', tools.read_file('u-boot.bin'))
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...
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data, cbfs_offset = cbw.get_data_and_offset()
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Attributes:
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_master_name: Name of the file containing the master header
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_size: Size of the filesystem, in bytes
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_files: Ordered list of files in the CBFS, each a CbfsFile
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_arch: Architecture of the CBFS (ARCHITECTURE_...)
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_bootblock_size: Size of the bootblock, typically at the end of the CBFS
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_erase_byte: Byte to use for empty space in the CBFS
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_align: Alignment to use for files, typically ENTRY_ALIGN
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_base_address: Boot block offset in bytes from the start of CBFS.
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Typically this is located at top of the CBFS. It is 0 when there is
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no boot block
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_header_offset: Offset of master header in bytes from start of CBFS
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_contents_offset: Offset of first file header
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_hdr_at_start: True if the master header is at the start of the CBFS,
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instead of the end as normal for x86
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_add_fileheader: True to add a fileheader around the master header
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"""
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def __init__(self, size, arch=ARCHITECTURE_X86):
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"""Set up a new CBFS
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This sets up all properties to default values. Files can be added using
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add_file_raw(), etc.
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Args:
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size: Size of CBFS in bytes
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arch: Architecture to declare for CBFS
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"""
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self._master_name = 'cbfs master header'
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self._size = size
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self._files = OrderedDict()
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self._arch = arch
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self._bootblock_size = 0
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self._erase_byte = 0xff
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self._align = ENTRY_ALIGN
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self._add_fileheader = False
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if self._arch == ARCHITECTURE_X86:
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# Allow 4 bytes for the header pointer. That holds the
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# twos-compliment negative offset of the master header in bytes
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# measured from one byte past the end of the CBFS
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self._base_address = self._size - max(self._bootblock_size,
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MIN_BOOTBLOCK_SIZE)
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self._header_offset = self._base_address - HEADER_LEN
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self._contents_offset = 0
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self._hdr_at_start = False
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else:
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# For non-x86, different rules apply
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self._base_address = 0
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self._header_offset = align_int(self._base_address +
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self._bootblock_size, 4)
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self._contents_offset = align_int(self._header_offset +
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FILE_HEADER_LEN +
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self._bootblock_size, self._align)
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self._hdr_at_start = True
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def _skip_to(self, fd, offset):
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"""Write out pad bytes until a given offset
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Args:
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fd: File objext to write to
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offset: Offset to write to
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"""
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if fd.tell() > offset:
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raise ValueError('No space for data before offset %#x (current offset %#x)' %
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(offset, fd.tell()))
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fd.write(tools.get_bytes(self._erase_byte, offset - fd.tell()))
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def _pad_to(self, fd, offset):
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"""Write out pad bytes and/or an empty file until a given offset
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Args:
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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_and_offset()[0])
|
|
self._skip_to(fd, offset)
|
|
|
|
def _align_to(self, fd, align):
|
|
"""Write out pad bytes until a given alignment is reached
|
|
|
|
This only aligns if the resulting output would not reach the end of the
|
|
CBFS, since we want to leave the last 4 bytes for the master-header
|
|
pointer.
|
|
|
|
Args:
|
|
fd: File objext to write to
|
|
align: Alignment to require (e.g. 4 means pad to next 4-byte
|
|
boundary)
|
|
"""
|
|
offset = align_int(fd.tell(), align)
|
|
if offset < self._size:
|
|
self._skip_to(fd, offset)
|
|
|
|
def add_file_stage(self, name, data, cbfs_offset=None):
|
|
"""Add a new stage file to the CBFS
|
|
|
|
Args:
|
|
name: String file name to put in CBFS (does not need to correspond
|
|
to the name that the file originally came from)
|
|
data: Contents of file
|
|
cbfs_offset: Offset of this file's data within the CBFS, in bytes,
|
|
or None to place this file anywhere
|
|
|
|
Returns:
|
|
CbfsFile object created
|
|
"""
|
|
cfile = CbfsFile.stage(self._base_address, name, data, cbfs_offset)
|
|
self._files[name] = cfile
|
|
return cfile
|
|
|
|
def add_file_raw(self, name, data, cbfs_offset=None,
|
|
compress=COMPRESS_NONE):
|
|
"""Create a new raw file
|
|
|
|
Args:
|
|
name: String file name to put in CBFS (does not need to correspond
|
|
to the name that the file originally came from)
|
|
data: Contents of file
|
|
cbfs_offset: Offset of this file's data within the CBFS, in bytes,
|
|
or None to place this file anywhere
|
|
compress: Compression algorithm to use (COMPRESS_...)
|
|
|
|
Returns:
|
|
CbfsFile object created
|
|
"""
|
|
cfile = CbfsFile.raw(name, data, cbfs_offset, compress)
|
|
self._files[name] = cfile
|
|
return cfile
|
|
|
|
def _write_header(self, fd, add_fileheader):
|
|
"""Write out the master header to a CBFS
|
|
|
|
Args:
|
|
fd: File object
|
|
add_fileheader: True to place the master header in a file header
|
|
record
|
|
"""
|
|
if fd.tell() > self._header_offset:
|
|
raise ValueError('No space for header at offset %#x (current offset %#x)' %
|
|
(self._header_offset, fd.tell()))
|
|
if not add_fileheader:
|
|
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)
|
|
if add_fileheader:
|
|
name = _pack_string(self._master_name)
|
|
fd.write(struct.pack(FILE_HEADER_FORMAT, FILE_MAGIC, len(hdr),
|
|
TYPE_CBFSHEADER, 0,
|
|
FILE_HEADER_LEN + len(name)))
|
|
fd.write(name)
|
|
self._header_offset = fd.tell()
|
|
fd.write(hdr)
|
|
self._align_to(fd, self._align)
|
|
else:
|
|
fd.write(hdr)
|
|
|
|
def get_data(self):
|
|
"""Obtain the full contents of the CBFS
|
|
|
|
Thhis builds the CBFS with headers and all required files.
|
|
|
|
Returns:
|
|
'bytes' type containing the data
|
|
"""
|
|
fd = io.BytesIO()
|
|
|
|
# THe header can go at the start in some cases
|
|
if self._hdr_at_start:
|
|
self._write_header(fd, add_fileheader=self._add_fileheader)
|
|
self._skip_to(fd, self._contents_offset)
|
|
|
|
# Write out each file
|
|
for cbf in self._files.values():
|
|
# Place the file at its requested place, if any
|
|
offset = cbf.calc_start_offset()
|
|
if offset is not None:
|
|
self._pad_to(fd, align_int_down(offset, self._align))
|
|
pos = fd.tell()
|
|
data, data_offset = cbf.get_data_and_offset(pos, self._erase_byte)
|
|
fd.write(data)
|
|
self._align_to(fd, self._align)
|
|
cbf.calced_cbfs_offset = pos + data_offset
|
|
if not self._hdr_at_start:
|
|
self._write_header(fd, add_fileheader=self._add_fileheader)
|
|
|
|
# Pad to the end and write a pointer to the CBFS master header
|
|
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))
|
|
|
|
return fd.getvalue()
|
|
|
|
|
|
class CbfsReader(object):
|
|
"""Class to handle reading a Coreboot File System (CBFS)
|
|
|
|
Usage is something like:
|
|
cbfs = cbfs_util.CbfsReader(data)
|
|
cfile = cbfs.files['u-boot']
|
|
self.WriteFile('u-boot.bin', cfile.data)
|
|
|
|
Attributes:
|
|
files: Ordered list of CbfsFile objects
|
|
align: Alignment to use for files, typically ENTRT_ALIGN
|
|
stage_base_address: Base address to use when mapping ELF files into the
|
|
CBFS for TYPE_STAGE files. If this is larger than the code address
|
|
of the ELF file, then data at the start of the ELF file will not
|
|
appear in the CBFS. Currently there are no tests for behaviour as
|
|
documentation is sparse
|
|
magic: Integer magic number from master header (HEADER_MAGIC)
|
|
version: Version number of CBFS (HEADER_VERSION2)
|
|
rom_size: Size of CBFS
|
|
boot_block_size: Size of boot block
|
|
cbfs_offset: Offset of the first file in bytes from start of CBFS
|
|
arch: Architecture of CBFS file (ARCHITECTURE_...)
|
|
"""
|
|
def __init__(self, data, read=True):
|
|
self.align = ENTRY_ALIGN
|
|
self.arch = None
|
|
self.boot_block_size = None
|
|
self.cbfs_offset = None
|
|
self.files = OrderedDict()
|
|
self.magic = None
|
|
self.rom_size = None
|
|
self.stage_base_address = 0
|
|
self.version = None
|
|
self.data = data
|
|
if read:
|
|
self.read()
|
|
|
|
def read(self):
|
|
"""Read all the files in the CBFS and add them to self.files"""
|
|
with io.BytesIO(self.data) as fd:
|
|
# First, get the master header
|
|
if not self._find_and_read_header(fd, len(self.data)):
|
|
raise ValueError('Cannot find master header')
|
|
fd.seek(self.cbfs_offset)
|
|
|
|
# Now read in the files one at a time
|
|
while True:
|
|
cfile = self._read_next_file(fd)
|
|
if cfile:
|
|
self.files[cfile.name] = cfile
|
|
elif cfile is False:
|
|
break
|
|
|
|
def _find_and_read_header(self, fd, size):
|
|
"""Find and read the master header in the CBFS
|
|
|
|
This looks at the pointer word at the very end of the CBFS. This is an
|
|
offset to the header relative to the size of the CBFS, which is assumed
|
|
to be known. Note that the offset is in *little endian* format.
|
|
|
|
Args:
|
|
fd: File to read from
|
|
size: Size of file
|
|
|
|
Returns:
|
|
True if header was found, False if not
|
|
"""
|
|
orig_pos = fd.tell()
|
|
fd.seek(size - 4)
|
|
rel_offset, = struct.unpack('<I', fd.read(4))
|
|
pos = (size + rel_offset) & 0xffffffff
|
|
fd.seek(pos)
|
|
found = self._read_header(fd)
|
|
if not found:
|
|
print('Relative offset seems wrong, scanning whole image')
|
|
for pos in range(0, size - HEADER_LEN, 4):
|
|
fd.seek(pos)
|
|
found = self._read_header(fd)
|
|
if found:
|
|
break
|
|
fd.seek(orig_pos)
|
|
return found
|
|
|
|
def _read_next_file(self, fd):
|
|
"""Read the next file from a CBFS
|
|
|
|
Args:
|
|
fd: File to read from
|
|
|
|
Returns:
|
|
CbfsFile object, if found
|
|
None if no object found, but data was parsed (e.g. TYPE_CBFSHEADER)
|
|
False if at end of CBFS and reading should stop
|
|
"""
|
|
file_pos = fd.tell()
|
|
data = fd.read(FILE_HEADER_LEN)
|
|
if len(data) < FILE_HEADER_LEN:
|
|
print('File header at %#x ran out of data' % file_pos)
|
|
return False
|
|
magic, size, ftype, attr, offset = struct.unpack(FILE_HEADER_FORMAT,
|
|
data)
|
|
if magic != FILE_MAGIC:
|
|
return False
|
|
pos = fd.tell()
|
|
name = self._read_string(fd)
|
|
if name is None:
|
|
print('String at %#x ran out of data' % pos)
|
|
return False
|
|
|
|
if DEBUG:
|
|
print('name', name)
|
|
|
|
# If there are attribute headers present, read those
|
|
compress = self._read_attr(fd, file_pos, attr, offset)
|
|
if compress is None:
|
|
return False
|
|
|
|
# Create the correct CbfsFile object depending on the type
|
|
cfile = None
|
|
cbfs_offset = file_pos + offset
|
|
fd.seek(cbfs_offset, io.SEEK_SET)
|
|
if ftype == TYPE_CBFSHEADER:
|
|
self._read_header(fd)
|
|
elif ftype == TYPE_STAGE:
|
|
data = fd.read(STAGE_LEN)
|
|
cfile = CbfsFile.stage(self.stage_base_address, name, b'',
|
|
cbfs_offset)
|
|
(cfile.compress, cfile.entry, cfile.load, cfile.data_len,
|
|
cfile.memlen) = struct.unpack(STAGE_FORMAT, data)
|
|
cfile.data = fd.read(cfile.data_len)
|
|
elif ftype == TYPE_RAW:
|
|
data = fd.read(size)
|
|
cfile = CbfsFile.raw(name, data, cbfs_offset, compress)
|
|
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'', cbfs_offset)
|
|
else:
|
|
raise ValueError('Unknown type %#x when reading\n' % ftype)
|
|
if cfile:
|
|
cfile.offset = offset
|
|
|
|
# Move past the padding to the start of a possible next file. If we are
|
|
# already at an alignment boundary, then there is no padding.
|
|
pad = (self.align - fd.tell() % self.align) % self.align
|
|
fd.seek(pad, io.SEEK_CUR)
|
|
return cfile
|
|
|
|
@classmethod
|
|
def _read_attr(cls, fd, file_pos, attr, offset):
|
|
"""Read attributes from the file
|
|
|
|
CBFS files can have attributes which are things that cannot fit into the
|
|
header. The only attributes currently supported are compression and the
|
|
unused tag.
|
|
|
|
Args:
|
|
fd: File to read from
|
|
file_pos: Position of file in fd
|
|
attr: Offset of attributes, 0 if none
|
|
offset: Offset of file data (used to indicate the end of the
|
|
attributes)
|
|
|
|
Returns:
|
|
Compression to use for the file (COMPRESS_...)
|
|
"""
|
|
compress = COMPRESS_NONE
|
|
if not attr:
|
|
return compress
|
|
attr_size = offset - attr
|
|
fd.seek(file_pos + attr, io.SEEK_SET)
|
|
while attr_size:
|
|
pos = fd.tell()
|
|
hdr = fd.read(8)
|
|
if len(hdr) < 8:
|
|
print('Attribute tag at %x ran out of data' % pos)
|
|
return None
|
|
atag, alen = struct.unpack(">II", hdr)
|
|
data = hdr + fd.read(alen - 8)
|
|
if atag == FILE_ATTR_TAG_COMPRESSION:
|
|
# We don't currently use this information
|
|
atag, alen, compress, _decomp_size = struct.unpack(
|
|
ATTR_COMPRESSION_FORMAT, data)
|
|
elif atag == FILE_ATTR_TAG_UNUSED2:
|
|
break
|
|
else:
|
|
print('Unknown attribute tag %x' % atag)
|
|
attr_size -= len(data)
|
|
return compress
|
|
|
|
def _read_header(self, fd):
|
|
"""Read the master header
|
|
|
|
Reads the header and stores the information obtained into the member
|
|
variables.
|
|
|
|
Args:
|
|
fd: File to read from
|
|
|
|
Returns:
|
|
True if header was read OK, False if it is truncated or has the
|
|
wrong magic or version
|
|
"""
|
|
pos = fd.tell()
|
|
data = fd.read(HEADER_LEN)
|
|
if len(data) < HEADER_LEN:
|
|
print('Header at %x ran out of data' % pos)
|
|
return False
|
|
(self.magic, self.version, self.rom_size, self.boot_block_size,
|
|
self.align, self.cbfs_offset, self.arch, _) = struct.unpack(
|
|
HEADER_FORMAT, data)
|
|
return self.magic == HEADER_MAGIC and (
|
|
self.version == HEADER_VERSION1 or
|
|
self.version == HEADER_VERSION2)
|
|
|
|
@classmethod
|
|
def _read_string(cls, fd):
|
|
"""Read a string from a file
|
|
|
|
This reads a string and aligns the data to the next alignment boundary
|
|
|
|
Args:
|
|
fd: File to read from
|
|
|
|
Returns:
|
|
string read ('str' type) encoded to UTF-8, or None if we ran out of
|
|
data
|
|
"""
|
|
val = b''
|
|
while True:
|
|
data = fd.read(FILENAME_ALIGN)
|
|
if len(data) < FILENAME_ALIGN:
|
|
return None
|
|
pos = data.find(b'\0')
|
|
if pos == -1:
|
|
val += data
|
|
else:
|
|
val += data[:pos]
|
|
break
|
|
return val.decode('utf-8')
|