File size: 8,605 Bytes
30e6218 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 | """Upload validation, text extraction, and upload storage.
Supported formats are plain text (.txt), Markdown (.md), reStructuredText
(.rst, treated as plain text: directives are never executed) and PDF (.pdf,
text layer only via pypdf; scanned PDFs without a text layer are rejected).
Extraction produces a *normalized* text (``\\r\\n`` -> ``\\n``, NUL bytes
removed) plus page spans so that chunk offsets can be mapped back to pages.
"""
from __future__ import annotations
import hashlib
import io
import logging
import os
import re
import unicodedata
from dataclasses import dataclass, field
from pathlib import Path
from typing import Dict, List, Optional
from ..core.types import IngestionError
logger = logging.getLogger(__name__)
SUPPORTED_EXTENSIONS = {".txt", ".md", ".rst", ".pdf"}
_TEXT_EXTENSIONS = {".txt", ".md", ".rst"}
_PDF_MAGIC = b"%PDF-"
@dataclass(frozen=True)
class PageSpan:
page_number: int
char_start: int
char_end: int
@dataclass
class ExtractedDocument:
text: str
extension: str
pages: List[PageSpan] = field(default_factory=list)
page_count: Optional[int] = None
warnings: List[str] = field(default_factory=list)
def content_hash(content: bytes) -> str:
return hashlib.sha256(content).hexdigest()
def normalize_display_filename(filename: Optional[str], max_length: int) -> str:
"""Return a safe display name (never used as a storage path)."""
name = (filename or "").strip()
name = name.replace("\\", "/").split("/")[-1]
name = unicodedata.normalize("NFC", name)
name = "".join(ch for ch in name if ch.isprintable() and ch not in "\x00")
if not name or name in {".", ".."}:
raise IngestionError("A filename is required", code="missing_filename")
if len(name) > max_length:
raise IngestionError(
f"Filename longer than {max_length} characters", code="filename_too_long"
)
return name
def detect_extension(display_filename: str) -> str:
ext = Path(display_filename).suffix.lower()
if ext not in SUPPORTED_EXTENSIONS:
raise IngestionError(
f"Unsupported file type '{ext or '(none)'}'. Supported: "
+ ", ".join(sorted(SUPPORTED_EXTENSIONS)),
code="unsupported_type",
)
return ext
def _normalize_text(text: str) -> str:
text = text.replace("\r\n", "\n").replace("\r", "\n").replace("\x00", "")
return text
def _decode_text(content: bytes) -> str:
for encoding in ("utf-8-sig", "utf-16"):
try:
text = content.decode(encoding)
except UnicodeDecodeError:
continue
# utf-16 will happily decode ASCII garbage; require a BOM for it.
if encoding == "utf-16" and not content.startswith((b"\xff\xfe", b"\xfe\xff")):
continue
return text
raise IngestionError(
"Text files must be UTF-8 (or UTF-16 with a byte-order mark)",
code="invalid_encoding",
)
def _extract_pdf(content: bytes, max_pages: int) -> ExtractedDocument:
try:
from pypdf import PdfReader
from pypdf.errors import PdfReadError
except ImportError as exc: # pragma: no cover - dependency is in base reqs
raise IngestionError("PDF support is not installed", status=500) from exc
if not content.startswith(_PDF_MAGIC):
raise IngestionError("File does not look like a PDF", code="invalid_pdf")
try:
reader = PdfReader(io.BytesIO(content))
if reader.is_encrypted:
# pypdf can open some encrypted PDFs with an empty password.
try:
if reader.decrypt("") == 0:
raise IngestionError("Encrypted PDFs are not supported", code="encrypted_pdf")
except IngestionError:
raise
except Exception as exc:
raise IngestionError(
"Encrypted PDFs are not supported", code="encrypted_pdf"
) from exc
page_count = len(reader.pages)
except IngestionError:
raise
except (PdfReadError, ValueError, TypeError, KeyError, IndexError) as exc:
raise IngestionError(f"Malformed PDF: {exc}", code="invalid_pdf") from exc
except Exception as exc: # pypdf raises a wide variety of exceptions
raise IngestionError(f"Malformed PDF: {exc}", code="invalid_pdf") from exc
if page_count > max_pages:
raise IngestionError(
f"PDF has {page_count} pages; the limit is {max_pages}",
code="too_many_pages",
)
parts: List[str] = []
spans: List[PageSpan] = []
warnings: List[str] = []
cursor = 0
for index, page in enumerate(reader.pages):
try:
page_text = page.extract_text() or ""
except Exception as exc: # pragma: no cover - depends on PDF internals
warnings.append(f"page {index + 1}: extraction failed ({exc})")
page_text = ""
page_text = _normalize_text(page_text).strip()
if not page_text:
warnings.append(f"page {index + 1}: no text layer")
continue
if parts:
cursor += 2 # separator "\n\n"
start = cursor
parts.append(page_text)
cursor += len(page_text)
spans.append(PageSpan(page_number=index + 1, char_start=start, char_end=cursor))
text = "\n\n".join(parts)
return ExtractedDocument(
text=text, extension=".pdf", pages=spans, page_count=page_count, warnings=warnings
)
def extract_document(
display_filename: str,
content: bytes,
*,
max_extracted_chars: int,
max_pdf_pages: int,
) -> ExtractedDocument:
"""Validate ``content`` and extract normalized text.
Raises ``IngestionError`` for unsupported, malformed, encrypted, empty, or
oversized inputs. Never executes embedded scripts or fetches resources.
"""
extension = detect_extension(display_filename)
if not content:
raise IngestionError("Uploaded file is empty", code="empty_file")
if extension == ".pdf":
extracted = _extract_pdf(content, max_pages=max_pdf_pages)
else:
if content.startswith(_PDF_MAGIC):
raise IngestionError(
"File content looks like a PDF but the extension is not .pdf",
code="extension_mismatch",
)
text = _normalize_text(_decode_text(content))
extracted = ExtractedDocument(text=text, extension=extension)
if len(extracted.text) > max_extracted_chars:
raise IngestionError(
f"Extracted text exceeds {max_extracted_chars} characters",
code="too_much_text",
)
if not extracted.text.strip():
raise IngestionError(
"No extractable text found (scanned or empty document)",
code="no_text",
)
return extracted
_HEADING_RE = re.compile(r"^(#{1,6})\s+(.+?)\s*#*\s*$", re.MULTILINE)
def markdown_headings(text: str) -> List[Dict[str, object]]:
"""Return ``[{"start": offset, "title": str}]`` for Markdown headings."""
return [
{"start": m.start(), "title": m.group(2).strip()[:200]} for m in _HEADING_RE.finditer(text)
]
class UploadStorage:
"""Stores uploaded bytes under server-generated names inside ``root``."""
def __init__(self, root: Path):
self.root = Path(root).resolve()
def ensure(self) -> None:
self.root.mkdir(parents=True, exist_ok=True)
def _path_for(self, storage_name: str) -> Path:
path = (self.root / storage_name).resolve()
if path.parent != self.root:
raise IngestionError("Invalid storage name", status=500)
return path
def save(self, doc_id: str, version: int, extension: str, content: bytes) -> str:
self.ensure()
storage_name = f"{doc_id}.v{version}{extension}"
path = self._path_for(storage_name)
fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o600)
try:
with os.fdopen(fd, "wb") as handle:
handle.write(content)
except Exception:
path.unlink(missing_ok=True)
raise
return storage_name
def delete(self, storage_name: Optional[str]) -> bool:
if not storage_name:
return False
path = self._path_for(storage_name)
if path.is_file():
path.unlink()
return True
return False
def exists(self, storage_name: Optional[str]) -> bool:
if not storage_name:
return False
return self._path_for(storage_name).is_file()
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