FA-3666 / Binary formats / Open access

A terminated field consumes padding after the first zero · case 01

A terminated field consumes padding after the first zero.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Return bytes before the first zero; reject input without a zero.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Return bytes before the first zero; reject input without a zero.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Return bytes before the first zero; reject input without a zero.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return x
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve([65, 0, 66]), [65])
check('boundary 2', solve([0, 65]), [])
check('boundary 3', solve([65]), None)
check('boundary 4', solve([65, 66, 0]), [65, 66])
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
boundary 1	`[65, 0, 66]`	`[65]`	Failed
boundary 2	`[0, 65]`	`[]`	Failed
boundary 3	`[65]`	`None`	Failed
boundary 4	`[65, 66, 0]`	`[65, 66]`	Failed

SHA-256 / 63f1210c7a66e3141d1dfd72e3dc7e0809562a73c8c2b0ccb680256b62927cdc

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return [v for v in x if v]
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve([65, 0, 66]), [65])
check('boundary 2', solve([0, 65]), [])
check('boundary 3', solve([65]), None)
check('boundary 4', solve([65, 66, 0]), [65, 66])
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
boundary 1	`[65, 66]`	`[65]`	Failed
boundary 2	`[65]`	`[]`	Failed
boundary 3	`[65]`	`None`	Failed
boundary 4	`[65, 66]`	`[65, 66]`	Passed

SHA-256 / d58902202a8e3d9292d76e028a206b4c032d928b40c792b235ff592cefb75b47

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return x[:x.index(0)] if 0 in x else None
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve([65, 0, 66]), [65])
check('boundary 2', solve([0, 65]), [])
check('boundary 3', solve([65]), None)
check('boundary 4', solve([65, 66, 0]), [65, 66])
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
boundary 1	`[65]`	`[65]`	Passed
boundary 2	`[]`	`[]`	Passed
boundary 3	`None`	`None`	Passed
boundary 4	`[65, 66]`	`[65, 66]`	Passed

SHA-256 / 0741b3ca3bcdccc15baccfbe110d98594ab1fc9fc91561f8c777f83241e0a897

Verification & scope

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 2026-09-29T14:37:29.173934+00:00.

Case digest / 044fa9e8333dc8da126b8a81d74db072e126dfd59c8122ccc9ed3781ac10cadb