def _create_header(info, format_, encoding, errors):
"""Return a header block. info is a dictionary with file
information, format must be one of the *_FORMAT constants.
"""
parts = [
tarfile.stn(info.get("name", ""), 100, encoding, errors),
tarfile.itn(info.get("mode", 0), 8, format_),
tarfile.itn(info.get("uid", 0), 8, format_),
tarfile.itn(info.get("gid", 0), 8, format_),
tarfile.itn(info.get("size", 0), 12, format_),
tarfile.itn(info.get("mtime", 0), 12, format_),
b" " * 8, # checksum field
info.get("type", tarfile.REGTYPE),
tarfile.stn(info.get("linkname", ""), 100, encoding, errors),
info.get("magic", tarfile.POSIX_MAGIC),
tarfile.stn(info.get("uname", ""), 32, encoding, errors),
tarfile.stn(info.get("gname", ""), 32, encoding, errors),
tarfile.itn(info.get("devmajor", 0), 8, format_),
tarfile.itn(info.get("devminor", 0), 8, format_),
tarfile.stn(info.get("prefix", ""), 155, encoding, errors)
]
buf = struct.pack("%ds" % tarfile.BLOCKSIZE, b"".join(parts))
chksum = tarfile.calc_chksums(buf[-tarfile.BLOCKSIZE:])[0]
buf = buf[:-364] + bytes("%06o\0" % chksum, "ascii") + buf[-357:]
return buf
def parse_tar_header_simple(header_data):
header = {
'size':
tarfile.nti(header_data[size_offset:size_offset + size_len]),
'chksum':
tarfile.nti(header_data[checksum_offset:checksum_offset +
checksum_len])
}
if header['chksum'] not in tarfile.calc_chksums(header_data):
raise tarfile.InvalidHeaderError("chksum not match")
return header
def main():
parser = argparse.ArgumentParser(description="The MinLin distro build system.")
parser.add_argument("--build-dir", help="The build directory.", required=True)
parser.add_argument("-o", dest="outfile", required=True)
args = parser.parse_args()
root_dir = Path(args.build_dir)
shutil.rmtree(root_dir, ignore_errors=True)
os.makedirs(root_dir, exist_ok=True)
packages = get_packages()
for pkg in packages.values():
pkg.build()
build_package(root_dir, pkg)
tar = tarfile.open(args.outfile, "w")
tar.add(root_dir, "/", recursive=True)
tar.close()
# Add symlinks.
tar_data = bytes()
for src, dst in all_symlinks.items():
src = src.lstrip("/")
dst = dst.lstrip("/")
fmt = f"100s{8+8+8}x12s12s8sc100s8s{32+32+8+8+155+12}x"
magic = b"ustar \x00"
size = b"00000000000\0"
time_modified = b"00000000000\0"
type_ = b"2" # symbolic link
header = struct.pack(fmt, src.encode("ascii"), size, time_modified,
b"", type_, dst.encode("ascii"), magic)
from tarfile import calc_chksums
checksum = bytes("%06o\0" % calc_chksums(header)[0], "ascii")
header = struct.pack(fmt, src.encode("ascii"), size, time_modified,
checksum, type_, dst.encode("ascii"), magic)
tar_data += header
tar_data += open(args.outfile, "rb").read()
open(args.outfile, "wb").write(tar_data)
def parse_tar_header(header_data):
header = dict()
tar_header = struct.unpack(
'=100s8s8s8s12s12s8sc100s6s2s32s32s8s8s155s12x', header_data)
header['name'] = tar_header[0]
header['mode'] = tar_header[1]
header['uid'] = tar_header[2]
header['gid'] = tar_header[3]
header['size'] = tarfile.nti(tar_header[4])
header['mtime'] = tar_header[5]
header['chksum'] = tarfile.nti(tar_header[6])
header['typeflag'] = tar_header[7]
header['linkname'] = tar_header[8]
header['magic'] = tar_header[9]
header['version'] = tar_header[10]
header['uname'] = tar_header[11]
header['gname'] = tar_header[12]
header['devmajor'] = tar_header[13]
header['devminor'] = tar_header[14]
header['prefix'] = tar_header[15]
if header['chksum'] not in tarfile.calc_chksums(header_data):
raise tarfile.InvalidHeaderError("chksum not match")
return header
def write_archivefile(data):
# Intercept writes to the archive file and rewrite any headers matching our criteria
for block_idx in range(
(len(data) + tarfile.BLOCKSIZE - 1) //
tarfile.BLOCKSIZE):
block = data[block_idx *
tarfile.BLOCKSIZE:(block_idx +
1) *
tarfile.BLOCKSIZE]
cur_offset = archive_props["offset"]
archive_props["offset"] += len(block)
if cur_offset != archive_props[
"next_header_offset"]:
continue
try:
tarinfo = out_archive.tarinfo.frombuf(
block, out_archive.encoding,
out_archive.errors)
except tarfile.EOFHeaderError: # type: ignore[attr-defined]
break
block_count = (tarinfo.size + tarfile.BLOCKSIZE
- 1) // tarfile.BLOCKSIZE
archive_props[
"next_header_offset"] = archive_props[
"offset"] + block_count * tarfile.BLOCKSIZE
if tarinfo.devmajor != 0 or tarinfo.devmajor != 0 or tarinfo.type in (
tarfile.CHRTYPE, tarfile.BLKTYPE):
continue
# Erase major/minor fields for non-device files as other tar-archive producing tools do.
if not isinstance(data, bytearray):
data = bytearray(data)
DEVNUMBERS_OFFSET = 329
DEVNUMBERS_LENGTH = 2 * 8
DEVNUMBERS_RANGE = slice(
block_idx * tarfile.BLOCKSIZE +
DEVNUMBERS_OFFSET,
block_idx * tarfile.BLOCKSIZE +
DEVNUMBERS_OFFSET + DEVNUMBERS_LENGTH,
)
CHECKSUM_OFFSET = 148
CHECKSUM_LENGTH = 8
CHECKSUM_RANGE = slice(
block_idx * tarfile.BLOCKSIZE +
CHECKSUM_OFFSET,
block_idx * tarfile.BLOCKSIZE +
CHECKSUM_OFFSET + CHECKSUM_LENGTH,
)
data[
DEVNUMBERS_RANGE] = b"\0" * DEVNUMBERS_LENGTH
# Recompute checksum, but whipe checksum field (with spaces) before doing so
data[CHECKSUM_RANGE] = b" " * CHECKSUM_LENGTH
chksum, *_ = tarfile.calc_chksums( # type: ignore[attr-defined]
data[block_idx *
tarfile.BLOCKSIZE:(block_idx + 1) *
tarfile.BLOCKSIZE])
data[CHECKSUM_RANGE] = b"%06o\0 " % (chksum, )
return original_write(data)
def update_event(self, inp=-1):
self.set_output_val(0, tarfile.calc_chksums(self.input(0)))