micropython/tests/basics/struct1.py
Damien George 79d5acbd01 py/modstruct: Check and prevent buffer-read overflow in struct unpacking
Prior to this patch, the size of the buffer given to unpack/unpack_from was
checked for being too small by using the count of the arguments, not their
actual size.  For example, a format spec of '4I' would only check that
there was 4 bytes available, not 16; and 'I' would check for 1 byte, not 4.

This bug is fixed in this patch by calculating the total size of the format
spec at the start of the unpacking function.  This function anyway needs to
calculate the number of items at the start, so calculating the total size
can be done at the same time.
2017-09-01 10:53:29 +10:00

93 lines
2.1 KiB
Python

try:
import ustruct as struct
except:
try:
import struct
except ImportError:
print("SKIP")
raise SystemExit
print(struct.calcsize("<bI"))
print(struct.unpack("<bI", b"\x80\0\0\x01\0"))
print(struct.calcsize(">bI"))
print(struct.unpack(">bI", b"\x80\0\0\x01\0"))
# 32-bit little-endian specific
#print(struct.unpack("bI", b"\x80\xaa\x55\xaa\0\0\x01\0"))
print(struct.pack("<l", 1))
print(struct.pack(">l", 1))
print(struct.pack("<i", 1))
print(struct.pack(">i", 1))
print(struct.pack("<h", 1))
print(struct.pack(">h", 1))
print(struct.pack("<b", 1))
print(struct.pack(">b", 1))
print(struct.pack("<bI", -128, 256))
print(struct.pack(">bI", -128, 256))
print(struct.calcsize("100sI"))
print(struct.calcsize("97sI"))
print(struct.unpack("<6sH", b"foo\0\0\0\x12\x34"))
print(struct.pack("<6sH", b"foo", 10000))
s = struct.pack("BHBI", 10, 100, 200, 300)
v = struct.unpack("BHBI", s)
print(v == (10, 100, 200, 300))
# network byte order
print(struct.pack('!i', 123))
# check that we get an error if the buffer is too small
try:
struct.unpack('I', b'\x00\x00\x00')
except:
print('struct.error')
# first arg must be a string
try:
struct.pack(1, 2)
except TypeError:
print('TypeError')
# make sure that unknown types are detected
try:
struct.pack("z", 1)
except:
print("Unknown type")
# Initially repitition counters were supported only for strings,
# but later were implemented for all.
print(struct.unpack("<3B2h", b"foo\x12\x34\xff\xff"))
print(struct.pack("<3B", 1, 2, 3))
# pack_into
buf = bytearray(b'>>>123<<<')
struct.pack_into('<bbb', buf, 3, 0x41, 0x42, 0x43)
print(buf)
struct.pack_into('<bbb', buf, -6, 0x44, 0x45, 0x46)
print(buf)
try:
struct.pack_into('<bbb', buf, 7, 0x41, 0x42, 0x43)
except:
print('struct.error')
try:
struct.pack_into('<bbb', buf, -10, 0x41, 0x42, 0x43)
except:
print('struct.error')
# unpack_from
buf = b'0123456789'
print(struct.unpack_from('<b', buf, 4))
print(struct.unpack_from('<b', buf, -4))
try:
print(struct.unpack_from('<b', buf, 10))
except:
print('struct.error')
try:
print(struct.unpack_from('<b', buf, -11))
except:
print('struct.error')