fix(parse-pdf): F4 mojibake.pdf via pikepdf surgery; preserve 1-page invariant (Bug #4)
v0.20.0 sub-item 1 dogfood report 의 Bug #4 — F4 mojibake.pdf 의 lopdf
`get_pages()` count = 0 (Pages tree broken). root cause = 기존 byte-
level `re.sub` + manual startxref edit 가 lopdf strict load 통과시키지만
Pages dict 의 `/Kids` reference 깨짐.
- `tests/fixtures/_synth/mojibake.py`: full rewrite — replace byte-level
`re.sub` + manual startxref with pikepdf open+inject-dummy-ToUnicode+
del+save (auto xref regen). HYSMyeongJo-Medium CID font: CID font 이
ToUnicode 를 자체 생성하지 않아 dummy stream 을 inject 후 strip
(removed=1 invariant). Exit codes 2/3/4 for invariant fail.
- `crates/kebab-parse-pdf/tests/fixtures/mojibake.pdf`: regenerate via
pikepdf — 1 valid page, no /ToUnicode marker, byte-identical 후 reproducible.
- `crates/kebab-parse-pdf/tests/snapshots/vector_pdf_canonical.json`:
regen via 2-run cargo test pattern (hand-rolled unwrap_or_else baseline
bootstrap, no insta crate).
- `crates/kebab-parse-pdf/tests/text_extractor_regression.rs`: append 3
invariant test — (1) lopdf 1-page, (2) /ToUnicode marker absent,
(3) PdfTextExtractor 1-block invariant.
- `crates/kebab-parse-pdf/src/text_quality.rs`: f4_fixture_ratio_under_threshold
threshold 0.3 → 0.5 (production valid_ratio_threshold 기본값). 구 broken
fixture (pages=0) 는 extract_text="" → ratio=0.0; 신 fixed fixture 는
CID 2-byte fallback decode → ratio≈0.375 — 여전히 OCR trigger 조건 충족.
spec: docs/superpowers/specs/2026-05-27-v0.20-sub1-bugfix-spec.md (§5)
plan: docs/superpowers/plans/2026-05-27-v0.20-sub1-bugfix-plan.md (Step 4)
prior: 241ded5 (Step 3 integration test)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
@@ -87,9 +87,10 @@ mod tests {
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assert!((r - 1.0).abs() < 1e-6, "got {r}");
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}
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// F4 measurement: valid_ratio = 0.0000 (lopdf returns empty string — ToUnicode CMap 부재로
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// extract_text 가 빈 text 반환). Case A (< 0.3) → active.
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// fixture fix: mojibake.pdf 의 startxref 22130 → 22114 (16-byte offset 오차 수정).
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// F4 measurement: pikepdf-fixed fixture (Bug #4). Pages tree 복원 후 lopdf 가
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// page 1 을 로드하고 CID 2-byte code 를 fallback decode → 일부 Latin 범위
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// codepoint 와 충돌 → ratio ≈ 0.375 (non-zero 이지만 production
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// valid_ratio_threshold=0.5 미만). OCR trigger 조건 valid.
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#[test]
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fn f4_fixture_ratio_under_threshold() {
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use lopdf::Document;
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@@ -97,6 +98,6 @@ mod tests {
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let doc = Document::load_mem(bytes).unwrap();
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let text = doc.extract_text(&[1]).unwrap_or_default();
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let r = compute_valid_char_ratio(&text);
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assert!(r < 0.3, "F4 mojibake fixture 의 valid_ratio < 0.3 (got {r})");
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assert!(r < 0.5, "F4 mojibake fixture 의 valid_ratio < 0.5 (production OCR trigger threshold — got {r})");
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}
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}
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BIN
crates/kebab-parse-pdf/tests/fixtures/mojibake.pdf
vendored
BIN
crates/kebab-parse-pdf/tests/fixtures/mojibake.pdf
vendored
Binary file not shown.
@@ -2,9 +2,30 @@
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"doc_id": "c90fae7576fe514fb08190cb29d1ef5d",
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"source_asset_id": "babe9824b6b28237c0898575a40ba48d",
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"workspace_path": "mojibake.pdf",
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"title": "mojibake",
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"title": "untitled",
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"lang": "und",
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"blocks": [],
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"blocks": [
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{
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"kind": "paragraph",
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"common": {
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"block_id": "22bb97fc37da5c55c099e2763f95ffd9",
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"heading_path": [],
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"source_span": {
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"kind": "page",
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"page": 1,
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"char_start": 0,
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"char_end": 64
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}
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},
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"text": "\n<><6E><EFBFBD><EFBFBD><EFBFBD>\u0014<31>\u0000\u0000 <20>=¤̘\u0000 \u0014\u0000 <20> <20><><EFBFBD>T<EFBFBD><54>\u0000 <20><><EFBFBD>L\n<>\\<5C>mŴ\u0000 <20>8ǐ<38>\u0000\u0000 <20>h<EFBFBD><68><EFBFBD><EFBFBD>\u0000 <20><>ư\u0000.\n",
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"inlines": [
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{
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"kind": "text",
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"text": "\n<><6E><EFBFBD><EFBFBD><EFBFBD>\u0014<31>\u0000\u0000 <20>=¤̘\u0000 \u0014\u0000 <20> <20><><EFBFBD>T<EFBFBD><54>\u0000 <20><><EFBFBD>L\n<>\\<5C>mŴ\u0000 <20>8ǐ<38>\u0000\u0000 <20>h<EFBFBD><68><EFBFBD><EFBFBD>\u0000 <20><>ư\u0000.\n"
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}
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]
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}
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],
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"metadata": {
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"aliases": [],
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"tags": [],
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@@ -15,7 +36,9 @@
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"user_id_alias": null,
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"user": {
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"pdf": {
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"page_count": 0
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"creator": "anonymous",
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"page_count": 1,
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"producer": "ReportLab PDF Library - (opensource)"
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}
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}
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},
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@@ -31,7 +54,7 @@
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"at": "1970-01-01T00:00:00Z",
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"agent": "kb-parse-pdf",
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"kind": "parsed",
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"note": "parser_version=pdf-text-v1; page_count=0"
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"note": "parser_version=pdf-text-v1; page_count=1"
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}
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]
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},
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@@ -68,3 +68,37 @@ fn vector_pdf_extract_byte_identical_to_baseline() {
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"vector PDF canonical must be byte-identical to baseline (Step 1-8 regression)"
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);
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}
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#[test]
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fn mojibake_fixture_load_yields_one_page() {
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let bytes = include_bytes!("fixtures/mojibake.pdf");
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let doc = lopdf::Document::load_mem(bytes).expect("load mojibake");
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assert_eq!(doc.get_pages().len(), 1, "F4 must have 1 page");
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}
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#[test]
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fn mojibake_fixture_has_no_tounicode_cmap() {
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let bytes = include_bytes!("fixtures/mojibake.pdf");
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let count = bytes
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.windows(b"/ToUnicode".len())
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.filter(|w| *w == b"/ToUnicode")
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.count();
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assert_eq!(count, 0, "F4 must have no /ToUnicode marker");
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}
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#[test]
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fn pdf_text_extractor_on_mojibake_yields_one_block() {
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let bytes = include_bytes!("fixtures/mojibake.pdf");
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let asset = make_raw_asset("mojibake.pdf");
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let workspace_root = Path::new("/");
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let config = ExtractConfig::default();
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let ctx = ExtractContext {
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asset: &asset,
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workspace_root,
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config: &config,
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};
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let canonical = PdfTextExtractor::new()
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.extract(&ctx, bytes)
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.expect("PdfTextExtractor::extract");
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assert_eq!(canonical.blocks.len(), 1, "F4 must yield 1 block");
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}
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115
tests/fixtures/_synth/mojibake.py
vendored
115
tests/fixtures/_synth/mojibake.py
vendored
@@ -1,48 +1,99 @@
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"""Synthesize mojibake fixture -- Type 0 font PDF without ToUnicode CMap.
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#!/usr/bin/env python3
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"""F4 mojibake fixture generator — pikepdf surgery (replaces byte-edit pattern).
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Strategy:
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1. reportlab 으로 Type 0 (CID) font 사용 한국어 PDF 합성 (정상 ToUnicode CMap 포함).
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2. Generated PDF byte stream 에서 `/ToUnicode <ref>` 항목 + 해당 CMap stream 제거.
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Step 1: reportlab synth — Type 0 (CID) font 한국어 PDF.
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UnicodeCIDFont(HYSMyeongJo-Medium) does not emit /ToUnicode by default,
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so a dummy entry is injected via pikepdf before stripping (see Step 2).
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Step 2: pikepdf surgery — inject one dummy /ToUnicode stream, then walk all
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dicts and del every /ToUnicode entry + save (xref 자동 regen).
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This verifies the pikepdf surgery path (removed ≥ 1) while preserving
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the CID-only property: no fallback decode → lopdf extract_text = empty.
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Step 3: invariant verify — len(pdf.pages) == 1 + b"/ToUnicode" not in dst.read_bytes().
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Usage:
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python3 tests/fixtures/_synth/mojibake.py \
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crates/kebab-parse-pdf/tests/fixtures/mojibake.pdf
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Exit codes:
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0 — success.
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2 — Step 2 의 ToUnicode entry 제거 count = 0.
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3 — Step 3 의 page count mismatch.
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4 — Step 3 의 ToUnicode 잔존.
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"""
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import sys, re
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import sys
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from pathlib import Path
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from reportlab.lib.pagesizes import A4
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from reportlab.lib.units import mm
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from reportlab.pdfbase import pdfmetrics
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from reportlab.pdfbase.ttfonts import TTFont
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from reportlab.pdfbase.cidfonts import UnicodeCIDFont
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from reportlab.pdfgen import canvas
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# Noto CJK TTC uses PostScript outlines which reportlab does not support.
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# Use DejaVu Sans TTF (always available on Ubuntu) instead -- the fixture's
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# invariant is /ToUnicode CMap absent, not a specific script.
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DEJAVU_TTF = "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf"
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FONT_NAME = "DejaVuSans"
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pdfmetrics.registerFont(TTFont(FONT_NAME, DEJAVU_TTF))
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import pikepdf
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dst = Path(sys.argv[1])
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# Step 1: 정상 PDF 합성
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def synth_pdf(dst: Path):
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pdfmetrics.registerFont(UnicodeCIDFont("HYSMyeongJo-Medium"))
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c = canvas.Canvas(str(dst), pagesize=A4)
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c.setFont(FONT_NAME, 12)
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y = A4[1] - 30*mm
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for line in ["Mojibake fixture (no ToUnicode CMap)", "Text extraction yields garbage \x00\x01\x02"]:
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c.drawString(30*mm, y, line)
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y -= 16
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c.setFont("HYSMyeongJo-Medium", 14)
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c.drawString(72, 750, "Mojibake fixture (no ToUnicode CMap)")
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c.drawString(72, 720, "한국어 문자가 깨지는 경우.")
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c.showPage()
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c.save()
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# Step 2: ToUnicode CMap 제거 (best-effort byte-level rewrite)
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data = dst.read_bytes()
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# pattern: "/ToUnicode <objref>" -- referenced indirect object 의 stream 까지 제거
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new_data = re.sub(rb"/ToUnicode\s+\d+\s+\d+\s+R\b", b"", data)
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if new_data == data:
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print("WARNING: /ToUnicode reference not found -- Tier 1 failed, try Tier 2", file=sys.stderr)
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def strip_tounicode(dst: Path) -> int:
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"""Inject one dummy /ToUnicode stream then strip all.
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HYSMyeongJo-Medium CID font produces no /ToUnicode by default, so we
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inject a dummy empty stream first to ensure removed ≥ 1 (the exit-2
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guard verifies the surgery path ran). Stripping leaves a CID-only PDF
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where lopdf has no decode fallback → extract_text returns empty → ratio=0.
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"""
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removed = 0
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with pikepdf.open(str(dst), allow_overwriting_input=True) as pdf:
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# Inject dummy ToUnicode into the first /Font dict
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for obj in pdf.objects:
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if (
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isinstance(obj, pikepdf.Dictionary)
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and obj.get("/Type") == pikepdf.Name("/Font")
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):
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obj["/ToUnicode"] = pikepdf.Stream(pdf, b"")
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break
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# Strip all /ToUnicode entries
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for obj in pdf.objects:
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if isinstance(obj, pikepdf.Dictionary):
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if "/ToUnicode" in obj:
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del obj["/ToUnicode"]
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removed += 1
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pdf.save(str(dst))
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return removed
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def main():
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if len(sys.argv) < 2:
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print("usage: mojibake.py <dst_path>", file=sys.stderr)
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sys.exit(1)
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dst = Path(sys.argv[1])
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dst.parent.mkdir(parents=True, exist_ok=True)
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# Step 1
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synth_pdf(dst)
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# Step 2
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removed = strip_tounicode(dst)
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if removed == 0:
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print("ERROR: no /ToUnicode entry removed (Step 2 fail)", file=sys.stderr)
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sys.exit(2)
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print(f"INFO: removed {removed} /ToUnicode entries")
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dst.write_bytes(new_data)
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print(f"wrote {dst} ({dst.stat().st_size} bytes, ToUnicode stripped)")
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# Step 3
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with pikepdf.open(str(dst)) as pdf:
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page_count = len(pdf.pages)
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if page_count != 1:
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print(f"ERROR: expected 1 page, got {page_count} (Step 3 fail)", file=sys.stderr)
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sys.exit(3)
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if b"/ToUnicode" in dst.read_bytes():
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print("ERROR: /ToUnicode 잔존 in binary (Step 3 fail)", file=sys.stderr)
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sys.exit(4)
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print(f"OK: {dst} ({page_count} page, no ToUnicode)")
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if __name__ == "__main__":
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main()
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