FA-78916 / Image orientation metadata / Open access

IFD offset byte order is inverted · case 01

Every file fails to parse, or the parser reads IFD0 from a wild offset.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The 32-bit reader reverses bytes for big-endian data instead of little-endian data.

THE FAILURE

The 32-bit reader reverses bytes for big-endian data instead of little-endian data.

Unsuccessful approach: Swapping 16-bit halves is a PDP-endian order that matches neither TIFF byte order.

Case contract

Parse the orientation from an APP1 Exif payload given as a list of byte values: a 6-byte "Exif\0\0" header, then a TIFF header (II little-endian or MM big-endian, magic 42 as a 16-bit value, 32-bit IFD0 offset relative to the TIFF header). Scan IFD0 12-byte entries; the first entry with tag 0x0112, type SHORT (3) and count 1 supplies the value from the first two bytes of its value field. Values outside 1..8 and a missing entry yield 1; structural problems (short payload, bad header, byte order, magic, truncated entry) yield "malformed".

Why this case matters

Camera, phone and scanner images carry an orientation hint separately from the stored pixels; galleries, thumbnailers, editors and upload pipelines must interpret it consistently or photos appear sideways, mirrored or doubly rotated.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(data):
    b = data
    if len(b) < 14 or b[:6] != [69, 120, 105, 102, 0, 0]:
        return 'malformed'
    t = b[6:]
    if t[:2] == [73, 73]:
        le = True
    elif t[:2] == [77, 77]:
        le = False
    else:
        return 'malformed'
    def u16(o):
        if o + 2 > len(t):
            return None
        return t[o] | (t[o + 1] << 8) if le else (t[o] << 8) | t[o + 1]
    def u32(o):
        if o + 4 > len(t):
            return None
        v = t[o:o + 4]
        if not le:
            v = v[::-1]
        return (v[0] << 24) | (v[1] << 16) | (v[2] << 8) | v[3]
    if u16(2) != 42:
        return 'malformed'
    ifd = u32(4)
    count = u16(ifd)
    if count is None:
        return 'malformed'
    for i in range(count):
        e = ifd + 2 + 12 * i
        if e + 12 > len(t):
            return 'malformed'
        tag = u16(e)
        typ = u16(e + 2)
        cnt = u32(e + 4)
        if tag == 0x0112 and typ == 3 and cnt == 1:
            val = u16(e + 8)
            return val if 1 <= val <= 8 else 1
    return 1
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 0, 7, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 114, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 73, 0, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 37, 0, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 3, 0, 18, 1, 3, 0, 1, 0, 0, 0, 3, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 118, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 3], [[69, 120, 105, 102, 0, 0, 73, 73, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 26, 1, 3, 0, 1, 0, 0, 0, 126, 1, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 43, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 4, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 10, 0, 0, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 0, 12, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 143, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 177, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 16, 1, 3, 0, 1, 0, 0, 0, 247, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 124, 1, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 1, 96, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 150], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 1, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 4], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 4, 0, 15, 1, 3, 0, 1, 0, 0, 0, 203, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 161, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 193, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8], [[69, 120, 105, 102, 0, 0, 73, 73, 43, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 8, 0, 5, 1, 18, 0, 4, 0, 0, 0, 2, 0, 0, 0, 6, 1, 26, 0, 3, 0, 0, 0, 1, 1, 200, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 17, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 9, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 111, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 1, 0, 18, 1, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 42, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 6, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 3, 0, 26, 1, 3, 0, 1, 0, 0, 0, 115, 1, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 111, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 10, 0, 0, 0, 1, 1, 18, 0, 4, 0, 0, 0, 2, 0, 0, 0, 6], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 18, 1, 4, 0, 2, 0, 0, 0, 8, 0, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 133, 1, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 18, 1, 3, 0, 2, 0, 0, 0, 6, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 4], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 16, 0, 3, 0, 0, 0, 1, 1, 192, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 63, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 103, 0, 0, 1, 18, 0, 3, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 0, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 1, 0, 16, 1, 3, 0, 1, 0, 0, 0, 171, 1, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 54, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 18, 0, 3, 0, 0, 0, 1, 0, 9, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 1, 115, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 244, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 186, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 18, 1, 3, 0, 2, 0, 0, 0, 8, 0, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 6, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 125, 1, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 225, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0], 5], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 18, 1, 3, 0, 1, 0, 0, 0, 9, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 211, 1, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 188, 1, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 104, 1, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 1, 1, 15, 0, 3], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 42, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 43, 0, 0, 0, 8, 0, 2, 1, 26, 0, 3, 0, 0, 0, 1, 0, 60, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 7, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 0, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 5, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 3, 0, 26, 1, 3, 0, 1, 0, 0, 0, 17, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 37, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 233, 0, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 18, 0, 3, 0, 0, 0, 2, 0, 8, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 0, 173, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 83, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 181, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 26, 1, 3, 0, 1, 0, 0, 0, 175, 1, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 198, 1, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 144, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 26, 1, 3, 0, 1, 0, 0, 0, 159, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 43, 0, 10, 0, 0, 0, 0, 0, 5, 0, 18, 1, 3, 0, 1, 0, 0, 0, 3, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 22, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 229, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 16, 1, 3, 0, 1, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 1, 166, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 1, 241, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 0, 229, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 2, 1, 18, 0, 3, 0, 0, 0, 1, 0, 2, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 135, 0, 0, 0, 0, 0, 0], 2]]]
labels = ["regression: LONG byte order", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
regression: LONG byte order 0	`malformed`	`1`	Failed
repair trap 1	`malformed`	`1`	Failed
combined fault 2	`malformed`	`3`	Failed
control 3	`malformed`	`malformed`	Passed
control 4	`malformed`	`malformed`	Passed
boundary 5	`malformed`	`malformed`	Passed
boundary 6	`malformed`	`malformed`	Passed
control 7	`malformed`	`1`	Failed

SHA-256 / cf51af10f0743bda51a49b8f721967a3ba95cd8c783643711309ae301dc39aa5

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(data):
    b = data
    if len(b) < 14 or b[:6] != [69, 120, 105, 102, 0, 0]:
        return 'malformed'
    t = b[6:]
    if t[:2] == [73, 73]:
        le = True
    elif t[:2] == [77, 77]:
        le = False
    else:
        return 'malformed'
    def u16(o):
        if o + 2 > len(t):
            return None
        return t[o] | (t[o + 1] << 8) if le else (t[o] << 8) | t[o + 1]
    def u32(o):
        if o + 4 > len(t):
            return None
        v = t[o:o + 4]
        if le:
            v = v[2:] + v[:2]
        return (v[0] << 24) | (v[1] << 16) | (v[2] << 8) | v[3]
    if u16(2) != 42:
        return 'malformed'
    ifd = u32(4)
    count = u16(ifd)
    if count is None:
        return 'malformed'
    for i in range(count):
        e = ifd + 2 + 12 * i
        if e + 12 > len(t):
            return 'malformed'
        tag = u16(e)
        typ = u16(e + 2)
        cnt = u32(e + 4)
        if tag == 0x0112 and typ == 3 and cnt == 1:
            val = u16(e + 8)
            return val if 1 <= val <= 8 else 1
    return 1
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 0, 7, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 114, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 73, 0, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 37, 0, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 3, 0, 18, 1, 3, 0, 1, 0, 0, 0, 3, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 118, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 3], [[69, 120, 105, 102, 0, 0, 73, 73, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 26, 1, 3, 0, 1, 0, 0, 0, 126, 1, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 43, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 4, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 10, 0, 0, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 0, 12, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 143, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 177, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 16, 1, 3, 0, 1, 0, 0, 0, 247, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 124, 1, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 1, 96, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 150], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 1, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 4], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 4, 0, 15, 1, 3, 0, 1, 0, 0, 0, 203, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 161, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 193, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8], [[69, 120, 105, 102, 0, 0, 73, 73, 43, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 77, 77, 0, 42, 0, 0, 0, 8, 0, 5, 1, 18, 0, 4, 0, 0, 0, 2, 0, 0, 0, 6, 1, 26, 0, 3, 0, 0, 0, 1, 1, 200, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 17, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 9, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 111, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 1, 0, 18, 1, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 42, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 6, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 3, 0, 26, 1, 3, 0, 1, 0, 0, 0, 115, 1, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 111, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 10, 0, 0, 0, 1, 1, 18, 0, 4, 0, 0, 0, 2, 0, 0, 0, 6], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 18, 1, 4, 0, 2, 0, 0, 0, 8, 0, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 133, 1, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 18, 1, 3, 0, 2, 0, 0, 0, 6, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 4], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 16, 0, 3, 0, 0, 0, 1, 1, 192, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 63, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 0, 103, 0, 0, 1, 18, 0, 3, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 0, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 1, 0, 16, 1, 3, 0, 1, 0, 0, 0, 171, 1, 0], 'malformed'], [[69, 120, 105, 102, 0, 255, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 54, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 18, 0, 3, 0, 0, 0, 1, 0, 9, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 1, 115, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 244, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 186, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 18, 1, 3, 0, 2, 0, 0, 0, 8, 0, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 6, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 125, 1, 0, 0, 16, 1, 3, 0, 1, 0, 0, 0, 225, 1, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0], 5], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 18, 1, 3, 0, 1, 0, 0, 0, 9, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 211, 1, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 188, 1, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 104, 1, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 1, 1, 15, 0, 3], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 42, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 43, 0, 0, 0, 8, 0, 2, 1, 26, 0, 3, 0, 0, 0, 1, 0, 60, 0, 0, 1, 18, 0, 3, 0, 0, 0, 1, 0, 7, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 0, 0, 0, 0, 0, 8, 0, 1, 1, 18, 0, 3, 0, 0, 0, 1, 0, 5, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 8, 0, 0, 0, 3, 0, 26, 1, 3, 0, 1, 0, 0, 0, 17, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 37, 1, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 233, 0, 0, 0, 0, 0, 0, 0], 1]], [[[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 4, 1, 18, 0, 3, 0, 0, 0, 2, 0, 8, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 0, 173, 0, 0, 1, 16, 0, 3, 0, 0, 0, 1, 1, 83, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 181, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 26, 1, 3, 0, 1, 0, 0, 0, 175, 1, 0, 0, 26, 1, 3, 0, 1, 0, 0, 0, 198, 1, 0, 0, 0, 0, 0, 0], 1], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 15, 1, 3, 0, 1, 0, 0, 0, 144, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0], 8], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 10, 0, 0, 0, 0, 0, 2, 0, 26, 1, 3, 0, 1, 0, 0, 0, 159, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 43, 0, 10, 0, 0, 0, 0, 0, 5, 0, 18, 1, 3, 0, 1, 0, 0, 0, 3, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 22, 0, 0, 0, 15, 1, 3, 0, 1, 0, 0, 0, 229, 0, 0, 0, 18, 1, 3, 0, 1, 0, 0, 0, 8, 0, 0, 0, 16, 1, 3, 0, 1, 0], 'malformed'], [[69, 120, 105, 102, 255, 225, 77, 77, 0, 42, 0, 0, 0, 8, 0, 3, 1, 15, 0, 3, 0, 0, 0, 1, 1, 166, 0, 0, 1, 26, 0, 3, 0, 0, 0, 1, 1, 241, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 0, 229, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 73, 73, 42, 0, 14, 0, 0, 0, 0, 0, 0, 0], 'malformed'], [[69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 2, 1, 18, 0, 3, 0, 0, 0, 1, 0, 2, 0, 0, 1, 15, 0, 3, 0, 0, 0, 1, 1, 135, 0, 0, 0, 0, 0, 0], 2]]]
labels = ["regression: LONG byte order", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
regression: LONG byte order 0	`1`	`1`	Passed
repair trap 1	`malformed`	`1`	Failed
combined fault 2	`malformed`	`3`	Failed
control 3	`malformed`	`malformed`	Passed
control 4	`malformed`	`malformed`	Passed
boundary 5	`malformed`	`malformed`	Passed
boundary 6	`malformed`	`malformed`	Passed
control 7	`malformed`	`1`	Failed

SHA-256 / 021e663bee52884f5ebfca4cb86b8c197bff3f1a70eef2b4df627f7a06d7d675

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

A deterministic bounded teaching model with a stipulated contract; it makes no claim of conformance to any published specification. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:49:39.845314+00:00.

Case digest / eebeafa3f70ea52e7c09ce26150d30de365c9f9a9c5e5a2647c332b00aed9beb