def NextFwFileSection(sections, ssize, sof, polarity):
EFI_COMMON_SECTION_HEADER_size = struct.calcsize(EFI_COMMON_SECTION_HEADER)
res = None
curr_offset = sof
ssize = min(ssize, len(sections))
while curr_offset + EFI_COMMON_SECTION_HEADER_size < ssize:
Size, Type = struct.unpack(
EFI_COMMON_SECTION_HEADER,
sections[curr_offset:curr_offset + EFI_COMMON_SECTION_HEADER_size])
Size = get_3b_size(Size)
Header_Size = EFI_COMMON_SECTION_HEADER_size
if Size == 0xFFFFFF and (curr_offset + EFI_COMMON_SECTION_HEADER_size +
struct.calcsize("I")) < ssize:
Size = struct.unpack(
"I", sections[curr_offset +
EFI_COMMON_SECTION_HEADER_size:curr_offset +
EFI_COMMON_SECTION_HEADER_size +
struct.calcsize("I")])[0]
Header_Size = EFI_COMMON_SECTION_HEADER_size + struct.calcsize("I")
if Type in SECTION_NAMES.keys():
sec_name = SECTION_NAMES[Type]
else:
sec_name = "S_UNKNOWN_{:02X}".format(Type)
if (Size == 0xffffff and Type == 0xff) or (Size == 0):
curr_offset = align(curr_offset + 4, 4)
continue
sec_body = sections[curr_offset:curr_offset + Size]
res = EFI_SECTION(curr_offset, sec_name, Type, sec_body, Header_Size,
align(Size, 4))
break
return res
def NextFwFile(FvImage, FvLength, fof, polarity):
file_header_size = struct.calcsize(EFI_FFS_FILE_HEADER)
fof = align(fof, 8)
cur_offset = fof
res = None
update_or_deleted = False
while cur_offset + file_header_size < min(FvLength, len(FvImage)):
fsize = 0
#if (fof + file_header_size) <= min(FvLength, len(FvImage)):
#Check for a blank header
if polarity:
blank = b"\xff" * file_header_size
else:
blank = b"\x00" * file_header_size
if (blank == FvImage[cur_offset:cur_offset + file_header_size]):
#next_offset = fof + 8
cur_offset += 8
continue
Name0, IntegrityCheck, Type, Attributes, Size, State = struct.unpack(
EFI_FFS_FILE_HEADER,
FvImage[cur_offset:cur_offset + file_header_size])
#Get File Header Size
if Attributes & FFS_ATTRIB_LARGE_FILE:
header_size = struct.calcsize(EFI_FFS_FILE_HEADER2)
else:
header_size = struct.calcsize(EFI_FFS_FILE_HEADER)
#Get File size
if Attributes & FFS_ATTRIB_LARGE_FILE and len(
FvImage) > fof + struct.calcsize(EFI_FFS_FILE_HEADER2):
fsize = struct.unpack(
"Q", FvImage[fof + file_header_size:fof + file_header_size +
struct.calcsize("Q")])[0]
fsize &= 0xFFFFFFFF
if fsize == 0 or fsize > FvLength - cur_offset:
fsize = get_3b_size(Size)
#Validate fsize is a legal value
if fsize == 0 or fsize > FvLength - cur_offset:
logger().log(
"Unable to get correct file size for NextFwFile corrupt header information"
)
break
#Get next_offset
update_or_deleted = (bit_set(State, EFI_FILE_MARKED_FOR_UPDATE,
polarity)) or (bit_set(
State, EFI_FILE_DELETED, polarity))
if not ((bit_set(State, EFI_FILE_DATA_VALID, polarity))
or update_or_deleted):
#else:
cur_offset = align(cur_offset + 1, 8)
continue
Name = UUID(bytes_le=Name0)
#TODO need to fix up checksum?
fheader = struct.pack(EFI_FFS_FILE_HEADER, Name0, 0, Type, Attributes,
Size, 0)
hsum = FvChecksum8(fheader)
if (Attributes & FFS_ATTRIB_CHECKSUM):
fsum = FvChecksum8(FvImage[cur_offset +
file_header_size:cur_offset + fsize])
else:
fsum = FFS_FIXED_CHECKSUM
CalcSum = (hsum | (fsum << 8))
res = EFI_FILE(cur_offset, Name, Type, Attributes, State,
IntegrityCheck, fsize,
FvImage[cur_offset:cur_offset + fsize], header_size,
update_or_deleted, CalcSum)
break
return res