prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Improve exception handling in FileSystemTimelineJob
  Under certain conditions, dfvfs may throw exceptions that are not currently being handked:
  
  ```
  dfvfs.lib.errors.BackEndError: Unable to open file system with error: pyfsext_volume_open_file_object: unable to open volume. libfsext_superblock_read_data: unsupported read-only compatible features flags: 0xff000003. libfsext_superblock_read_file_io_handle: unable to read superblock at offset: 1024 (0x00000400). libfsext_internal_volume_read_block_groups: unable to read superblock: 0 at offset: 1024 (0x00000400). libfsext_internal_volume_open_read: unable to read block groups. libfsext_volume_open_file_io_handle: unable to read from file IO handle.
  ```
  
  
  </issue>
  <code>
  [start of turbinia/workers/file_system_timeline.py]
  1 # -*- coding: utf-8 -*-
  2 # Copyright 2022 Google Inc.
  3 #
  4 # Licensed under the Apache License, Version 2.0 (the "License");
  5 # you may not use this file except in compliance with the License.
  6 # You may obtain a copy of the License at
  7 #
  8 #      http://www.apache.org/licenses/LICENSE-2.0
  9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15 """Task to run dfimagetools FileEntryLister on disk partitions."""
  16 
  17 from __future__ import unicode_literals
  18 
  19 import os
  20 
  21 from turbinia import TurbiniaException
  22 from turbinia.workers import TurbiniaTask
  23 from turbinia.evidence import EvidenceState as state
  24 from turbinia.evidence import BodyFile
  25 
  26 if TurbiniaTask.check_worker_role():
  27   try:
  28     from dfvfs.helpers import volume_scanner
  29     from dfvfs.lib import errors as dfvfs_errors
  30     from dfimagetools import file_entry_lister
  31   except ImportError as exception:
  32     message = 'Could not import libraries: {0!s}'.format(exception)
  33     raise TurbiniaException(message)
  34 
  35 
  36 class FileSystemTimelineTask(TurbiniaTask):
  37 
  38   REQUIRED_STATES = [state.ATTACHED]
  39 
  40   TASK_CONFIG = {'partitions': ['all']}
  41 
  42   def run(self, evidence, result):
  43     """Task to execute (dfimagetools) FileEntryLister.
  44 
  45     Args:
  46         evidence (Evidence object):  The evidence we will process.
  47         result (TurbiniaTaskResult): The object to place task results into.
  48 
  49     Returns:
  50         TurbiniaTaskResult object.
  51     """
  52     bodyfile_output = os.path.join(self.output_dir, 'file_system.bodyfile')
  53     output_evidence = BodyFile(source_path=bodyfile_output)
  54     number_of_entries = 0
  55 
  56     # Set things up for the FileEntryLister client. We will scan all
  57     # partitions in the volume.
  58     volume_scanner_options = volume_scanner.VolumeScannerOptions()
  59     volume_scanner_options.partitions = self.task_config.get('partitions')
  60 
  61     # Create the FileEntryLister client and generate the path specs
  62     # for all available partitions.
  63     entry_lister = file_entry_lister.FileEntryLister()
  64     base_path_specs = entry_lister.GetBasePathSpecs(
  65         evidence.device_path, options=volume_scanner_options)
  66 
  67     # Iterate over all file entries and generate the output in bodyfile
  68     # format.
  69     try:
  70       with open(bodyfile_output, 'w') as file_object:
  71         for file_entry, path_segments in entry_lister.ListFileEntries(
  72             base_path_specs):
  73           bodyfile_entries = entry_lister.GetBodyfileEntries(
  74               file_entry, path_segments)
  75           for bodyfile_entry in bodyfile_entries:
  76             file_object.write(bodyfile_entry)
  77             file_object.write('\n')
  78             number_of_entries += 1
  79       output_evidence.number_of_entries = number_of_entries
  80       result.add_evidence(output_evidence, evidence.config)
  81       status = 'Generated file system timeline containing [{0:d}] entries'.format(
  82           number_of_entries)
  83       result.close(self, success=True, status=status)
  84     except dfvfs_errors.ScannerError as exception:
  85       result.log('Error generating bodyfile {0!s}'.format(exception))
  86       status = 'Unable to generate bodyfile using provided evidence data.'
  87       result.close(self, success=False, status=status)
  88       raise TurbiniaException(
  89           'Could not process volume: {0!s}'.format(exception))
  90 
  91     return result
  92
  [end of turbinia/workers/file_system_timeline.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/turbinia/workers/file_system_timeline.py b/turbinia/workers/file_system_timeline.py
  --- a/turbinia/workers/file_system_timeline.py
  +++ b/turbinia/workers/file_system_timeline.py
  @@ -34,6 +34,7 @@
   
   
   class FileSystemTimelineTask(TurbiniaTask):
  +  """Task to generate file system timelines. """
   
     REQUIRED_STATES = [state.ATTACHED]
   
  @@ -61,31 +62,49 @@
       # Create the FileEntryLister client and generate the path specs
       # for all available partitions.
       entry_lister = file_entry_lister.FileEntryLister()
  -    base_path_specs = entry_lister.GetBasePathSpecs(
  -        evidence.device_path, options=volume_scanner_options)
  +    try:
  +      base_path_specs = entry_lister.GetBasePathSpecs(
  +          evidence.device_path, options=volume_scanner_options)
  +    except dfvfs_errors.ScannerError as exception:
  +      status = 'Unable to open evidence: {0!s}'.format(exception)
  +      result.close(self, success=False, status=status)
   
       # Iterate over all file entries and generate the output in bodyfile
       # format.
       try:
  -      with open(bodyfile_output, 'w') as file_object:
  -        for file_entry, path_segments in entry_lister.ListFileEntries(
  -            base_path_specs):
  -          bodyfile_entries = entry_lister.GetBodyfileEntries(
  -              file_entry, path_segments)
  -          for bodyfile_entry in bodyfile_entries:
  -            file_object.write(bodyfile_entry)
  -            file_object.write('\n')
  -            number_of_entries += 1
  -      output_evidence.number_of_entries = number_of_entries
  -      result.add_evidence(output_evidence, evidence.config)
  -      status = 'Generated file system timeline containing [{0:d}] entries'.format(
  -          number_of_entries)
  -      result.close(self, success=True, status=status)
  -    except dfvfs_errors.ScannerError as exception:
  -      result.log('Error generating bodyfile {0!s}'.format(exception))
  -      status = 'Unable to generate bodyfile using provided evidence data.'
  +      file_entries = None
  +      with open(bodyfile_output, 'w', encoding='utf-8') as file_object:
  +        file_entries = enumerate(entry_lister.ListFileEntries(base_path_specs))
  +        while file_entries:
  +          try:
  +            _, (file_entry, path_segments) = next(file_entries)
  +            bodyfile_entries = entry_lister.GetBodyfileEntries(
  +                file_entry, path_segments)
  +            for bodyfile_entry in bodyfile_entries:
  +              file_object.write(bodyfile_entry)
  +              file_object.write('\n')
  +              number_of_entries += 1
  +          except StopIteration:
  +            break
  +          except (dfvfs_errors.AccessError, dfvfs_errors.BackEndError,
  +                  dfvfs_errors.MountPointError,
  +                  dfvfs_errors.PathSpecError) as exception:
  +            status = 'Unable to process file entry: {0!s}'.format(exception)
  +            result.log(status)
  +
  +      if number_of_entries > 0:
  +        output_evidence.number_of_entries = number_of_entries
  +        result.add_evidence(output_evidence, evidence.config)
  +        status = 'Generated file system timeline containing [{0:d}] entries'.format(
  +            number_of_entries)
  +        result.close(self, success=True, status=status)
  +      else:
  +        status = 'Unable to process any file entries.'
  +        result.close(self, success=False, status=status)
  +
  +    except IOError as exception:
  +      status = 'Unable to create bodyfile local output file: {0!s}'.format(
  +          exception)
         result.close(self, success=False, status=status)
  -      raise TurbiniaException(
  -          'Could not process volume: {0!s}'.format(exception))
   
       return result
  
verification_info: {"golden_diff": "diff --git a/turbinia/workers/file_system_timeline.py b/turbinia/workers/file_system_timeline.py\n--- a/turbinia/workers/file_system_timeline.py\n+++ b/turbinia/workers/file_system_timeline.py\n@@ -34,6 +34,7 @@\n \n \n class FileSystemTimelineTask(TurbiniaTask):\n+  \"\"\"Task to generate file system timelines. \"\"\"\n \n   REQUIRED_STATES = [state.ATTACHED]\n \n@@ -61,31 +62,49 @@\n     # Create the FileEntryLister client and generate the path specs\n     # for all available partitions.\n     entry_lister = file_entry_lister.FileEntryLister()\n-    base_path_specs = entry_lister.GetBasePathSpecs(\n-        evidence.device_path, options=volume_scanner_options)\n+    try:\n+      base_path_specs = entry_lister.GetBasePathSpecs(\n+          evidence.device_path, options=volume_scanner_options)\n+    except dfvfs_errors.ScannerError as exception:\n+      status = 'Unable to open evidence: {0!s}'.format(exception)\n+      result.close(self, success=False, status=status)\n \n     # Iterate over all file entries and generate the output in bodyfile\n     # format.\n     try:\n-      with open(bodyfile_output, 'w') as file_object:\n-        for file_entry, path_segments in entry_lister.ListFileEntries(\n-            base_path_specs):\n-          bodyfile_entries = entry_lister.GetBodyfileEntries(\n-              file_entry, path_segments)\n-          for bodyfile_entry in bodyfile_entries:\n-            file_object.write(bodyfile_entry)\n-            file_object.write('\\n')\n-            number_of_entries += 1\n-      output_evidence.number_of_entries = number_of_entries\n-      result.add_evidence(output_evidence, evidence.config)\n-      status = 'Generated file system timeline containing [{0:d}] entries'.format(\n-          number_of_entries)\n-      result.close(self, success=True, status=status)\n-    except dfvfs_errors.ScannerError as exception:\n-      result.log('Error generating bodyfile {0!s}'.format(exception))\n-      status = 'Unable to generate bodyfile using provided evidence data.'\n+      file_entries = None\n+      with open(bodyfile_output, 'w', encoding='utf-8') as file_object:\n+        file_entries = enumerate(entry_lister.ListFileEntries(base_path_specs))\n+        while file_entries:\n+          try:\n+            _, (file_entry, path_segments) = next(file_entries)\n+            bodyfile_entries = entry_lister.GetBodyfileEntries(\n+                file_entry, path_segments)\n+            for bodyfile_entry in bodyfile_entries:\n+              file_object.write(bodyfile_entry)\n+              file_object.write('\\n')\n+              number_of_entries += 1\n+          except StopIteration:\n+            break\n+          except (dfvfs_errors.AccessError, dfvfs_errors.BackEndError,\n+                  dfvfs_errors.MountPointError,\n+                  dfvfs_errors.PathSpecError) as exception:\n+            status = 'Unable to process file entry: {0!s}'.format(exception)\n+            result.log(status)\n+\n+      if number_of_entries > 0:\n+        output_evidence.number_of_entries = number_of_entries\n+        result.add_evidence(output_evidence, evidence.config)\n+        status = 'Generated file system timeline containing [{0:d}] entries'.format(\n+            number_of_entries)\n+        result.close(self, success=True, status=status)\n+      else:\n+        status = 'Unable to process any file entries.'\n+        result.close(self, success=False, status=status)\n+\n+    except IOError as exception:\n+      status = 'Unable to create bodyfile local output file: {0!s}'.format(\n+          exception)\n       result.close(self, success=False, status=status)\n-      raise TurbiniaException(\n-          'Could not process volume: {0!s}'.format(exception))\n \n     return result\n", "issue": "Improve exception handling in FileSystemTimelineJob\nUnder certain conditions, dfvfs may throw exceptions that are not currently being handked:\r\n\r\n```\r\ndfvfs.lib.errors.BackEndError: Unable to open file system with error: pyfsext_volume_open_file_object: unable to open volume. libfsext_superblock_read_data: unsupported read-only compatible features flags: 0xff000003. libfsext_superblock_read_file_io_handle: unable to read superblock at offset: 1024 (0x00000400). libfsext_internal_volume_read_block_groups: unable to read superblock: 0 at offset: 1024 (0x00000400). libfsext_internal_volume_open_read: unable to read block groups. libfsext_volume_open_file_io_handle: unable to read from file IO handle.\r\n```\r\n\n", "before_files": [{"content": "# -*- coding: utf-8 -*-\n# Copyright 2022 Google Inc.\n#\n# Licensed under the Apache License, Version 2.0 (the \"License\");\n# you may not use this file except in compliance with the License.\n# You may obtain a copy of the License at\n#\n#      http://www.apache.org/licenses/LICENSE-2.0\n#\n# Unless required by applicable law or agreed to in writing, software\n# distributed under the License is distributed on an \"AS IS\" BASIS,\n# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n# See the License for the specific language governing permissions and\n# limitations under the License.\n\"\"\"Task to run dfimagetools FileEntryLister on disk partitions.\"\"\"\n\nfrom __future__ import unicode_literals\n\nimport os\n\nfrom turbinia import TurbiniaException\nfrom turbinia.workers import TurbiniaTask\nfrom turbinia.evidence import EvidenceState as state\nfrom turbinia.evidence import BodyFile\n\nif TurbiniaTask.check_worker_role():\n  try:\n    from dfvfs.helpers import volume_scanner\n    from dfvfs.lib import errors as dfvfs_errors\n    from dfimagetools import file_entry_lister\n  except ImportError as exception:\n    message = 'Could not import libraries: {0!s}'.format(exception)\n    raise TurbiniaException(message)\n\n\nclass FileSystemTimelineTask(TurbiniaTask):\n\n  REQUIRED_STATES = [state.ATTACHED]\n\n  TASK_CONFIG = {'partitions': ['all']}\n\n  def run(self, evidence, result):\n    \"\"\"Task to execute (dfimagetools) FileEntryLister.\n\n    Args:\n        evidence (Evidence object):  The evidence we will process.\n        result (TurbiniaTaskResult): The object to place task results into.\n\n    Returns:\n        TurbiniaTaskResult object.\n    \"\"\"\n    bodyfile_output = os.path.join(self.output_dir, 'file_system.bodyfile')\n    output_evidence = BodyFile(source_path=bodyfile_output)\n    number_of_entries = 0\n\n    # Set things up for the FileEntryLister client. We will scan all\n    # partitions in the volume.\n    volume_scanner_options = volume_scanner.VolumeScannerOptions()\n    volume_scanner_options.partitions = self.task_config.get('partitions')\n\n    # Create the FileEntryLister client and generate the path specs\n    # for all available partitions.\n    entry_lister = file_entry_lister.FileEntryLister()\n    base_path_specs = entry_lister.GetBasePathSpecs(\n        evidence.device_path, options=volume_scanner_options)\n\n    # Iterate over all file entries and generate the output in bodyfile\n    # format.\n    try:\n      with open(bodyfile_output, 'w') as file_object:\n        for file_entry, path_segments in entry_lister.ListFileEntries(\n            base_path_specs):\n          bodyfile_entries = entry_lister.GetBodyfileEntries(\n              file_entry, path_segments)\n          for bodyfile_entry in bodyfile_entries:\n            file_object.write(bodyfile_entry)\n            file_object.write('\\n')\n            number_of_entries += 1\n      output_evidence.number_of_entries = number_of_entries\n      result.add_evidence(output_evidence, evidence.config)\n      status = 'Generated file system timeline containing [{0:d}] entries'.format(\n          number_of_entries)\n      result.close(self, success=True, status=status)\n    except dfvfs_errors.ScannerError as exception:\n      result.log('Error generating bodyfile {0!s}'.format(exception))\n      status = 'Unable to generate bodyfile using provided evidence data.'\n      result.close(self, success=False, status=status)\n      raise TurbiniaException(\n          'Could not process volume: {0!s}'.format(exception))\n\n    return result\n", "path": "turbinia/workers/file_system_timeline.py"}]}