#!/usr/bin/env python import os import sys import subprocess import struct import optparse import binascii from io import BytesIO class GitWrapper: @classmethod def command(cls, txt): cmd = "git " + txt pr = subprocess.Popen( cmd , shell = True, stdout = subprocess.PIPE, stderr = subprocess.PIPE ) (out, error) = pr.communicate() if len(error): raise Exception(cmd +" failed with [" + error.strip() + "]") return out class AppDescriptor(object): """ UAVCAN firmware image descriptor format: uint64_t signature (bytes [7:0] set to 'APDesc00' by linker script) uint64_t image_crc (set to 0 by linker script) uint32_t image_size (set to 0 by linker script) uint32_t vcs_commit (set in source or by this tool) uint8_t version_major (set in source) uint8_t version_minor (set in source) uint8_t reserved[6] (set to 0xFF by linker script) """ LENGTH = 8 + 8 + 4 + 4 + 1 + 1 + 6 SIGNATURE = b"APDesc00" RESERVED = b"\xFF" * 6 def __init__(self, bytes=None): self.signature = AppDescriptor.SIGNATURE self.image_crc = 0 self.image_size = 0 self.vcs_commit = 0 self.version_major = 0 self.version_minor = 0 self.reserved = AppDescriptor.RESERVED if bytes: try: self.unpack(bytes) except Exception: raise ValueError("Invalid AppDescriptor: {0}".format( binascii.b2a_hex(bytes))) def pack(self): return struct.pack("<8sQLLBB6s", self.signature, self.image_crc, self.image_size, self.vcs_commit, self.version_major, self.version_minor, self.reserved) def unpack(self, bytes): (self.signature, self.image_crc, self.image_size, self.vcs_commit, self.version_major, self.version_minor, self.reserved) = \ struct.unpack("<8sQLLBB6s", bytes) if not self.empty and not self.valid: raise ValueError() @property def empty(self): return (self.signature == AppDescriptor.SIGNATURE and self.image_crc == 0 and self.image_size == 0 and self.reserved == AppDescriptor.RESERVED) @property def valid(self): return (self.signature == AppDescriptor.SIGNATURE and self.image_crc != 0 and self.image_size > 0 and self.reserved == AppDescriptor.RESERVED) class FirmwareImage(object): def __init__(self, path_or_file, mode="r"): if getattr(path_or_file, "read", None): self._file = path_or_file self._do_close = False self._padding = 0 else: if "b" not in mode: self._file = open(path_or_file, mode + "b") else: self._file = open(path_or_file, mode) self._do_close = True self._padding = 4 if "r" in mode: self._contents = BytesIO(self._file.read()) else: self._contents = BytesIO() self._do_write = False self._length = None self._descriptor_offset = None self._descriptor_bytes = None self._descriptor = None def __enter__(self): return self def __getattr__(self, attr): if attr == "write": self._do_write = True return getattr(self._contents, attr) def __iter__(self): return iter(self._contents) def __exit__(self, *args): if self._do_write: if getattr(self._file, "seek", None): self._file.seek(0) self._file.write(self._contents.getvalue()) if self._padding: self._file.write(b'\xff' * self._padding) if self._do_close: self._file.close() def _write_descriptor_raw(self): # Seek to the appropriate location, write the serialized # descriptor, and seek back. prev_offset = self._contents.tell() self._contents.seek(self._descriptor_offset) self._contents.write(self._descriptor.pack()) self._contents.seek(prev_offset) def write_descriptor(self): # Set the descriptor's length and CRC to the values required for # CRC computation self.app_descriptor.image_size = self.length self.app_descriptor.image_crc = 0 self._write_descriptor_raw() # Update the descriptor's CRC based on the computed value and write # it out again self.app_descriptor.image_crc = self.crc self._write_descriptor_raw() @property def crc(self): MASK = 0xFFFFFFFFFFFFFFFF POLY = 0x42F0E1EBA9EA3693 # Calculate the image CRC with the image_crc field in the app # descriptor zeroed out. crc_offset = self.app_descriptor_offset + len(AppDescriptor.SIGNATURE) content = bytearray(self._contents.getvalue()) content[crc_offset:crc_offset + 8] = bytearray.fromhex("00" * 8) if self._padding: content += bytearray.fromhex("ff" * self._padding) val = MASK for byte in content: val ^= (byte << 56) & MASK for bit in range(8): if val & (1 << 63): val = ((val << 1) & MASK) ^ POLY else: val <<= 1 return (val & MASK) ^ MASK @property def padding(self): return self._padding @property def length(self): if not self._length: # Find the length of the file by seeking to the end and getting # the offset prev_offset = self._contents.tell() self._contents.seek(0, os.SEEK_END) self._length = self._contents.tell() if self._padding: fill = self._length % self._padding if fill: self._length += fill self._padding = fill self._contents.seek(prev_offset) return self._length @property def app_descriptor_offset(self): if not self._descriptor_offset: # Save the current position prev_offset = self._contents.tell() # Check each byte in the file to see if a valid descriptor starts # at that location. Slow, but not slow enough to matter. offset = 0 while offset < self.length - AppDescriptor.LENGTH: self._contents.seek(offset) try: # If this throws an exception, there isn't a valid # descriptor at this offset AppDescriptor(self._contents.read(AppDescriptor.LENGTH)) except Exception: offset += 1 else: self._descriptor_offset = offset break # Go back to the previous position self._contents.seek(prev_offset) if not self._descriptor_offset: raise Exception('AppDescriptor not found') return self._descriptor_offset @property def app_descriptor(self): if not self._descriptor: # Save the current position prev_offset = self._contents.tell() # Jump to the descriptor adn parse it self._contents.seek(self.app_descriptor_offset) self._descriptor_bytes = self._contents.read(AppDescriptor.LENGTH) self._descriptor = AppDescriptor(self._descriptor_bytes) # Go back to the previous offset self._contents.seek(prev_offset) return self._descriptor @app_descriptor.setter def app_descriptor(self, value): self._descriptor = value if __name__ == "__main__": parser = optparse.OptionParser(usage="usage: %prog [options] [IN OUT]") parser.add_option("--vcs-commit", dest="vcs_commit", default=None, help="set the descriptor's VCS commit value to COMMIT", metavar="COMMIT") parser.add_option("-g", "--use-git-hash", dest="use_git_hash", action="store_true", help="set the descriptor's VCS commit value to the current git hash", metavar="GIT") parser.add_option("--bootloader-size", dest="bootloader_size", default=0, help="don't write the first SIZE bytes of the image", metavar="SIZE") parser.add_option("--bootloader-image", dest="bootloader_image", default=0, help="prepend a bootloader image to the output file", metavar="IMAGE") parser.add_option("-v", "--verbose", dest="verbose", action="store_true", help="show additional firmware information on stdout") options, args = parser.parse_args() if len(args) not in (0, 2): parser.error("specify both IN or OUT for file operation, or " + "neither for stdin/stdout operation") if options.vcs_commit and options.use_git_hash: parser.error("options --vcs-commit and --use-git-commit are mutually exclusive") if options.use_git_hash: try: options.vcs_commit = int(GitWrapper.command("rev-list HEAD --max-count=1 --abbrev=8 --abbrev-commit"),16) except Exception as e: print("Git Command failed "+ str(e) +"- Exiting!") quit() if args: in_file = args[0] out_file = args[1] else: in_file = sys.stdin out_file = sys.stdout bootloader_image = b"" if options.bootloader_image: with open(options.bootloader_image, "rb") as bootloader: bootloader_image = bootloader.read() bootloader_size = int(options.bootloader_size) with FirmwareImage(in_file, "rb") as in_image: with FirmwareImage(out_file, "wb") as out_image: image = in_image.read() out_image.write(bootloader_image) out_image.write(image[bootloader_size:]) if options.vcs_commit: out_image.app_descriptor.vcs_commit = options.vcs_commit out_image.write_descriptor() if options.verbose: sys.stderr.write( """ Application descriptor located at offset 0x{0.app_descriptor_offset:08X} """.format(in_image, in_image.app_descriptor, out_image.app_descriptor, bootloader_size, len(bootloader_image))) if bootloader_size: sys.stderr.write( """Ignored the first {3:d} bytes of the input image. Prepended {4:d} bytes of bootloader image to the output image. """.format(in_image, in_image.app_descriptor, out_image.app_descriptor, bootloader_size, len(bootloader_image))) sys.stderr.write( """READ VALUES ------------------------------------------------------------------------------ Field Type Value signature uint64 {1.signature!r} image_crc uint64 0x{1.image_crc:016X} image_size uint32 0x{1.image_size:X} ({1.image_size:d} B) vcs_commit uint32 {1.vcs_commit:08X} version_major uint8 {1.version_major:d} version_minor uint8 {1.version_minor:d} reserved uint8[6] {1.reserved!r} WRITTEN VALUES ------------------------------------------------------------------------------ Field Type Value signature uint64 {2.signature!r} image_crc uint64 0x{2.image_crc:016X} image_size uint32 0x{2.image_size:X} ({2.image_size:d} B) vcs_commit uint32 {2.vcs_commit:08X} version_major uint8 {2.version_major:d} version_minor uint8 {2.version_minor:d} reserved uint8[6] {2.reserved!r} """.format(in_image, in_image.app_descriptor, out_image.app_descriptor, bootloader_size, len(bootloader_image))) if out_image.padding: sys.stderr.write( """ padding added {} """.format(out_image.padding))