FA-76546 / Email MIME structure / Open access
Build a bounded MIME tree summary from parser events: unclosed report · case 01
A message whose outermost multipart is never closed is accepted as complete.
ROOT CAUSE
The unclosed report decision evaluates `if len(stack) > 1: errors.append` where the contract requires `if stack: errors.append`.
VERIFIED REPAIR
Use `if stack: errors.append` for the unclosed report decision and keep every other rule of the model unchanged.
Unsuccessful approach: Reporting only skipped or doubly nested containers still accepts an unclosed root. The attempted `if skip or len(stack) > 1: errors.append` still disagrees with a fixture.
Case contract
events are ["open", type] (multipart start), ["leaf", type, size] and ["close"]. The root multipart has depth 1. An open that would exceed max_depth records "too-deep" and its whole subtree (including nested opens) is skipped, but it still counts as a child of its parent. A multipart closing with no children records "empty-multipart", a close with nothing open records "stray-close", and containers left open record "unclosed". Result {leaves, depth (maximum reached), errors}.
Why this case matters
Bounding MIME nesting protects mail parsers from resource exhaustion while keeping the reachable structure intact.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events, max_depth):
stack = []
skip = 0
leaves = 0
depth = 0
errors = []
for ev in events:
kind = ev[0]
if skip:
if kind == 'open':
skip += 1
elif kind == 'close':
skip -= 1
continue
if kind == 'open':
if stack:
stack[-1] += 1
if len(stack) + 1 > max_depth:
errors.append('too-deep')
skip = 1
continue
stack.append(0)
depth = max(depth, len(stack))
elif kind == 'leaf':
leaves += 1
if stack:
stack[-1] += 1
elif not stack:
errors.append('stray-close')
elif stack.pop() == 0:
errors.append('empty-multipart')
if len(stack) > 1:
errors.append('unclosed')
return {'leaves': leaves, 'depth': depth, 'errors': errors}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 1}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 4], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 1}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 1], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 1], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 2: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 2}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 5], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 2], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 2}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 2], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 2], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 3: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 3}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 6], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 3], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 3}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 3], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 3], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 4: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 4}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 7], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 4], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 4}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 4], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 4], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 5: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['leaf', 'image/png', 4], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 5}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 8], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 5], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3], ['leaf', 'text/plain', 4]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 5}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 5], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})]}
for _label, _args, _expected in _CASES[N]:
check(_label, 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 |
|---|---|---|---|
| three levels with limit two | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| deep skipped subtree | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| skipped child keeps parent non-empty | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | Passed |
| unterminated root | {'depth': 1, 'errors': [], 'leaves': 1} | {'depth': 1, 'errors': ['unclosed'], 'leaves': 1} | Failed |
| deepest branch first | {'depth': 3, 'errors': [], 'leaves': 2} | {'depth': 3, 'errors': [], 'leaves': 2} | Passed |
| stray close | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | Passed |
| empty multipart | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | Passed |
SHA-256 / dca19e6055e402d09d04c0ca07dfba453524949331867c3ced2e9fafd7716762
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events, max_depth):
stack = []
skip = 0
leaves = 0
depth = 0
errors = []
for ev in events:
kind = ev[0]
if skip:
if kind == 'open':
skip += 1
elif kind == 'close':
skip -= 1
continue
if kind == 'open':
if stack:
stack[-1] += 1
if len(stack) + 1 > max_depth:
errors.append('too-deep')
skip = 1
continue
stack.append(0)
depth = max(depth, len(stack))
elif kind == 'leaf':
leaves += 1
if stack:
stack[-1] += 1
elif not stack:
errors.append('stray-close')
elif stack.pop() == 0:
errors.append('empty-multipart')
if skip or len(stack) > 1:
errors.append('unclosed')
return {'leaves': leaves, 'depth': depth, 'errors': errors}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 1}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 4], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 1}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 1], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 1], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 2: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 2}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 5], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 2], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 2}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 2], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 2], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 3: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 3}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 6], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 3], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 3}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 3], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 3], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 4: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 4}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 7], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 4], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 4}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 4], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 4], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 5: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['leaf', 'image/png', 4], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 5}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 8], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 5], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3], ['leaf', 'text/plain', 4]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 5}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 5], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})]}
for _label, _args, _expected in _CASES[N]:
check(_label, 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 |
|---|---|---|---|
| three levels with limit two | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| deep skipped subtree | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| skipped child keeps parent non-empty | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | Passed |
| unterminated root | {'depth': 1, 'errors': [], 'leaves': 1} | {'depth': 1, 'errors': ['unclosed'], 'leaves': 1} | Failed |
| deepest branch first | {'depth': 3, 'errors': [], 'leaves': 2} | {'depth': 3, 'errors': [], 'leaves': 2} | Passed |
| stray close | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | Passed |
| empty multipart | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | Passed |
SHA-256 / 575a02d90527223459414a7cffa10a39c848993ec20cca9cd7745538accc6db3
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events, max_depth):
stack = []
skip = 0
leaves = 0
depth = 0
errors = []
for ev in events:
kind = ev[0]
if skip:
if kind == 'open':
skip += 1
elif kind == 'close':
skip -= 1
continue
if kind == 'open':
if stack:
stack[-1] += 1
if len(stack) + 1 > max_depth:
errors.append('too-deep')
skip = 1
continue
stack.append(0)
depth = max(depth, len(stack))
elif kind == 'leaf':
leaves += 1
if stack:
stack[-1] += 1
elif not stack:
errors.append('stray-close')
elif stack.pop() == 0:
errors.append('empty-multipart')
if stack:
errors.append('unclosed')
return {'leaves': leaves, 'depth': depth, 'errors': errors}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 1}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 4], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 1}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 1], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 1], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 2: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 2}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 5], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 2], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 2}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 2], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 2], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 3: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 3}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 6], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 3], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 3}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 3], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 3], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 4: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 4}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 7], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 4], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 4}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 4], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 4], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})], 5: [('three levels with limit two', ([['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close'], ['leaf', 'image/png', 0], ['leaf', 'image/png', 1], ['leaf', 'image/png', 2], ['leaf', 'image/png', 3], ['leaf', 'image/png', 4], ['close']], 2), {'depth': 2, 'errors': ['too-deep'], 'leaves': 5}), ('deep skipped subtree', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['leaf', 'text/plain', 2], ['close'], ['leaf', 'text/plain', 8], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 1}), ('skipped child keeps parent non-empty', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['leaf', 'text/plain', 5], ['close'], ['close']], 1), {'depth': 1, 'errors': ['too-deep'], 'leaves': 0}), ('unterminated root', ([['open', 'multipart/mixed'], ['leaf', 'text/plain', 0], ['leaf', 'text/plain', 1], ['leaf', 'text/plain', 2], ['leaf', 'text/plain', 3], ['leaf', 'text/plain', 4]], 3), {'depth': 1, 'errors': ['unclosed'], 'leaves': 5}), ('deepest branch first', ([['open', 'multipart/mixed'], ['open', 'multipart/mixed'], ['open', 'multipart/alternative'], ['leaf', 'text/plain', 1], ['close'], ['close'], ['open', 'multipart/related'], ['leaf', 'text/html', 5], ['close'], ['close']], 5), {'depth': 3, 'errors': [], 'leaves': 2}), ('stray close', ([['leaf', 'text/plain', 5], ['close']], 2), {'depth': 0, 'errors': ['stray-close'], 'leaves': 1}), ('empty multipart', ([['open', 'multipart/mixed'], ['close']], 2), {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0})]}
for _label, _args, _expected in _CASES[N]:
check(_label, 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 |
|---|---|---|---|
| three levels with limit two | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 2, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| deep skipped subtree | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 1} | Passed |
| skipped child keeps parent non-empty | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | {'depth': 1, 'errors': ['too-deep'], 'leaves': 0} | Passed |
| unterminated root | {'depth': 1, 'errors': ['unclosed'], 'leaves': 1} | {'depth': 1, 'errors': ['unclosed'], 'leaves': 1} | Passed |
| deepest branch first | {'depth': 3, 'errors': [], 'leaves': 2} | {'depth': 3, 'errors': [], 'leaves': 2} | Passed |
| stray close | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | {'depth': 0, 'errors': ['stray-close'], 'leaves': 1} | Passed |
| empty multipart | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | {'depth': 1, 'errors': ['empty-multipart'], 'leaves': 0} | Passed |
SHA-256 / 3cfd44a122e85ff0428bcbb58adeea26488f54ea442855b83a0b4583647abd4a
Verification & scope
Stipulated offline model over pre-parsed MIME dictionaries; not a conforming MIME parser, generator or mail client. 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 2026-09-29T14:49:17.268396+00:00.
Case digest / 5af8f139713ea20699caa45a1dbf8b39d39fe80ce0cc7a6194c3668bb2836cfc