fix(secret): skip non-seekable files during scanning

changelog.d/20251020_174722_salome.voltz_scrt_5971_ggshield_runs_into_oserror_errno_22_invalid_argument_when.md

@@ -0,0 +1,42 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Removed
+
+- A bullet item for the Removed category.
+
+-->
+<!--
+### Added
+
+- A bullet item for the Added category.
+
+-->
+<!--
+### Changed
+
+- A bullet item for the Changed category.
+
+-->
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category.
+
+-->
+
+### Fixed
+
+- Skip non-seekable files instead of crashing.
+
+<!--
+### Security
+
+- A bullet item for the Security category.
+
+-->

ggshield/core/scan/__init__.py

@@ -2,14 +2,15 @@
 from .file import File, create_files_from_paths
 from .scan_context import ScanContext
 from .scan_mode import ScanMode
-from .scannable import DecodeError, Scannable, StringScannable
+from .scannable import DecodeError, NonSeekableFileError, Scannable, StringScannable
 
 
 __all__ = [
     "create_files_from_paths",
     "Commit",
     "DecodeError",
     "File",
+    "NonSeekableFileError",
     "ScanContext",
     "ScanMode",
     "Scannable",

ggshield/core/scan/scannable.py

@@ -31,6 +31,12 @@ class DecodeError(Exception):
     pass
 
 
+class NonSeekableFileError(Exception):
+    """Raised when a file cannot be seeked"""
+
+    pass
+
+
 class Scannable(ABC):
     """Base class for content that can be scanned by GGShield"""
 
@@ -143,8 +149,12 @@ def _is_file_longer_than(
         Raises DecodeError if the file cannot be decoded.
         """
         # Get the byte size
-        assert fp.seekable()
-        byte_size = fp.seek(0, SEEK_END)
+        # Note: IOBase.seekable() returns True on some non-seekable files like /proc/self/mounts
+        try:
+            byte_size = fp.seek(0, SEEK_END)
+            fp.seek(0, SEEK_SET)
+        except OSError as exc:
+            raise NonSeekableFileError() from exc
 
         if byte_size > max_utf8_encoded_size * UTF8_TO_WORSE_OTHER_ENCODING_RATIO:
             # Even if the file used the worst encoding (UTF-32), encoding the content of
@@ -153,7 +163,6 @@ def _is_file_longer_than(
             return True, None, None
 
         # Determine the encoding
-        fp.seek(0, SEEK_SET)
         charset_matches = charset_normalizer.from_fp(fp)
         charset_match = charset_matches.best()
         if charset_match is None:

ggshield/verticals/secret/secret_scanner.py

@@ -16,6 +16,7 @@
 from ggshield.core.constants import MAX_WORKERS
 from ggshield.core.errors import handle_api_error
 from ggshield.core.scan import DecodeError, ScanContext, Scannable
+from ggshield.core.scan.scannable import NonSeekableFileError
 from ggshield.core.scanner_ui.scanner_ui import ScannerUI
 from ggshield.core.text_utils import pluralize
 
@@ -157,6 +158,9 @@ def _start_scans(
             except DecodeError:
                 scanner_ui.on_skipped(scannable, "can't detect encoding")
                 continue
+            except NonSeekableFileError:
+                scanner_ui.on_skipped(scannable, "file cannot be seeked")
+                continue
 
             if content:
                 if (

tests/unit/core/scan/test_scannable.py

@@ -1,8 +1,10 @@
 from pathlib import Path
+from unittest.mock import patch
 
 import pytest
 
-from ggshield.core.scan import StringScannable
+from ggshield.core.scan import File, StringScannable
+from ggshield.core.scan.scannable import NonSeekableFileError
 
 
 def test_string_scannable_path():
@@ -32,3 +34,23 @@ def test_string_scannable_is_longer_than(content, is_longer):
     """
     scannable = StringScannable(content=content, url="u")
     assert scannable.is_longer_than(50) == is_longer
+
+
+@patch("pathlib.Path.open")
+def test_file_non_seekable(mock_open, tmp_path):
+    """
+    GIVEN a File instance
+    AND the file reports as seekable but seeking operations fail
+    WHEN is_longer_than() is called on it
+    THEN it raises NonSeekableFileError
+    """
+    mock_file = mock_open.return_value.__enter__.return_value
+    mock_file.seekable.return_value = True
+    mock_file.seek.side_effect = OSError(22, "Invalid argument")
+
+    test_file = tmp_path / "test.txt"
+    test_file.write_text("test content")
+    file_obj = File(test_file)
+
+    with pytest.raises(NonSeekableFileError):
+        file_obj.is_longer_than(1000)