prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Import-check may return error saying "director does not exist" when it actually just lack permissions
  Endpoint /pulp/api/v3/importers/core/pulp/import-check/ returns error saying "Directory does not exist" when pulp user lack permissions to read said directory.
  
  **To Reproduce**
  
  Try importing content from a directory where pulp user doesn't have read access.
  
  **Expected behavior**
  Error returned should indicate the permission error.
  
  **Additional context**
  
  Pulp is using os.path.exists() method to verify if the directory exists: https://github.com/pulp/pulpcore/blob/main/pulpcore/app/views/importer.py#L44-L45
  
  However, the method can return false if permission is not granted to access the directory even if the directory exists
  
  ~~~
  os.path.exists(path)
  Return True if path refers to an existing path or an open file descriptor. Returns False for broken symbolic links. On some platforms, this function may return False if permission is not granted to execute os.stat() on the requested file, even if the path physically exists.
  ~~~
  
  os.path method documentation -> https://docs.python.org/3/library/os.path.html
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `pulpcore/app/views/importer.py`
  Content:
  ```
  1 from gettext import gettext as _
  2 import json
  3 import os
  4 from drf_spectacular.utils import extend_schema
  5 from rest_framework.views import APIView
  6 from rest_framework.response import Response
  7 
  8 from pulpcore.app import settings
  9 from pulpcore.app.serializers import PulpImportCheckResponseSerializer, PulpImportCheckSerializer
  10 
  11 
  12 def _check_allowed_import_path(a_path):
  13     user_provided_realpath = os.path.realpath(a_path)
  14     for allowed_path in settings.ALLOWED_IMPORT_PATHS:
  15         if user_provided_realpath.startswith(allowed_path):
  16             return True, None
  17     return False, _(
  18         "{} is not an allowed import path".format(os.path.dirname(os.path.realpath(a_path)))
  19     )
  20 
  21 
  22 def _validate_file(in_param, data):
  23     """
  24     Returns a (is-valid, msgs[]) tuple describing all problems found with data[in_param]
  25 
  26     We check for a number of things, attempting to return all the errors we can find. We don't want
  27     to give out information for files in arbitrary locations on the filesystem; if the check
  28     for ALLOWED_IMPORT_PATHS fails, we report that and ignore any other problems.
  29 
  30     If the directory containing the base-file doesn't exist, or isn't readable, or the specified
  31     file doesn't exist, report and return.
  32 
  33     Error-messages for all other checks are additive.
  34     """
  35     # check allowed, leave if failed
  36     file = data[in_param]
  37     real_file = os.path.realpath(file)
  38     rc, msg = _check_allowed_import_path(real_file)
  39     if not rc:
  40         return rc, [msg]
  41 
  42     # check directory-sanity, leave if failed
  43     owning_dir = os.path.dirname(real_file)
  44     if not os.path.exists(owning_dir):
  45         return False, [_("directory {} does not exist").format(owning_dir)]
  46     if not os.access(owning_dir, os.R_OK):
  47         return False, [_("directory {} does not allow read-access").format(owning_dir)]
  48 
  49     # check file-exists, leave if failed
  50     if not os.path.exists(real_file):
  51         return False, [_("file {} does not exist").format(real_file)]
  52 
  53     # check file-sanity
  54     msgs = []
  55     isfile = os.path.isfile(real_file)
  56     readable = os.access(real_file, os.R_OK)
  57 
  58     rc = isfile and readable
  59     if not isfile:
  60         msgs.append(_("{} is not a file".format(real_file)))
  61     if not readable:
  62         msgs.append(_("{} exists but cannot be read".format(real_file)))
  63 
  64     # extra check for toc-dir-write
  65     if in_param == "toc":
  66         if not os.access(owning_dir, os.W_OK):
  67             rc = False
  68             msgs.append(_("directory {} must allow pulp write-access".format(owning_dir)))
  69 
  70     return rc, msgs
  71 
  72 
  73 class PulpImporterImportCheckView(APIView):
  74     """
  75     Returns validity of proposed parameters for a PulpImport call.
  76     """
  77 
  78     @extend_schema(
  79         summary="Validate the parameters to be used for a PulpImport call",
  80         operation_id="pulp_import_check_post",
  81         request=PulpImportCheckSerializer,
  82         responses={200: PulpImportCheckResponseSerializer},
  83     )
  84     def post(self, request, format=None):
  85         """
  86         Evaluates validity of proposed PulpImport parameters 'toc', 'path', and 'repo_mapping'.
  87 
  88         * Checks that toc, path are in ALLOWED_IMPORT_PATHS
  89         * if ALLOWED:
  90           * Checks that toc, path exist and are readable
  91           * If toc specified, checks that containing dir is writeable
  92         * Checks that repo_mapping is valid JSON
  93         """
  94         serializer = PulpImportCheckSerializer(data=request.data)
  95         if serializer.is_valid():
  96             data = {}
  97             if "toc" in serializer.data:
  98                 data["toc"] = {}
  99                 data["toc"]["context"] = serializer.data["toc"]
  100                 data["toc"]["is_valid"], data["toc"]["messages"] = _validate_file(
  101                     "toc", serializer.data
  102                 )
  103 
  104             if "path" in serializer.data:
  105                 data["path"] = {}
  106                 data["path"]["context"] = serializer.data["path"]
  107                 data["path"]["is_valid"], data["path"]["messages"] = _validate_file(
  108                     "path", serializer.data
  109                 )
  110 
  111             if "repo_mapping" in serializer.data:
  112                 data["repo_mapping"] = {}
  113                 data["repo_mapping"]["context"] = serializer.data["repo_mapping"]
  114                 try:
  115                     json.loads(serializer.data["repo_mapping"])
  116                     data["repo_mapping"]["is_valid"] = True
  117                     data["repo_mapping"]["messages"] = []
  118                 except json.JSONDecodeError:
  119                     data["repo_mapping"]["is_valid"] = False
  120                     data["repo_mapping"]["messages"] = [_("invalid JSON")]
  121 
  122             crs = PulpImportCheckResponseSerializer(data, context={"request": request})
  123             return Response(crs.data)
  124         return Response(serializer.errors, status=400)
  125
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/pulpcore/app/views/importer.py b/pulpcore/app/views/importer.py
  --- a/pulpcore/app/views/importer.py
  +++ b/pulpcore/app/views/importer.py
  @@ -40,11 +40,14 @@
           return rc, [msg]
   
       # check directory-sanity, leave if failed
  +    # use os.stat to ensure directory exists and pulp has read-access
  +    # return any errors received from os.stat to the user
  +
       owning_dir = os.path.dirname(real_file)
  -    if not os.path.exists(owning_dir):
  -        return False, [_("directory {} does not exist").format(owning_dir)]
  -    if not os.access(owning_dir, os.R_OK):
  -        return False, [_("directory {} does not allow read-access").format(owning_dir)]
  +    try:
  +        os.stat(owning_dir)
  +    except OSError as e:
  +        return False, [_("{}").format(e)]
   
       # check file-exists, leave if failed
       if not os.path.exists(real_file):
  
verification_info: {"golden_diff": "diff --git a/pulpcore/app/views/importer.py b/pulpcore/app/views/importer.py\n--- a/pulpcore/app/views/importer.py\n+++ b/pulpcore/app/views/importer.py\n@@ -40,11 +40,14 @@\n         return rc, [msg]\n \n     # check directory-sanity, leave if failed\n+    # use os.stat to ensure directory exists and pulp has read-access\n+    # return any errors received from os.stat to the user\n+\n     owning_dir = os.path.dirname(real_file)\n-    if not os.path.exists(owning_dir):\n-        return False, [_(\"directory {} does not exist\").format(owning_dir)]\n-    if not os.access(owning_dir, os.R_OK):\n-        return False, [_(\"directory {} does not allow read-access\").format(owning_dir)]\n+    try:\n+        os.stat(owning_dir)\n+    except OSError as e:\n+        return False, [_(\"{}\").format(e)]\n \n     # check file-exists, leave if failed\n     if not os.path.exists(real_file):\n", "issue": "Import-check may return error saying \"director does not exist\" when it actually just lack permissions\nEndpoint /pulp/api/v3/importers/core/pulp/import-check/ returns error saying \"Directory does not exist\" when pulp user lack permissions to read said directory.\r\n\r\n**To Reproduce**\r\n\r\nTry importing content from a directory where pulp user doesn't have read access.\r\n\r\n**Expected behavior**\r\nError returned should indicate the permission error.\r\n\r\n**Additional context**\r\n\r\nPulp is using os.path.exists() method to verify if the directory exists: https://github.com/pulp/pulpcore/blob/main/pulpcore/app/views/importer.py#L44-L45\r\n\r\nHowever, the method can return false if permission is not granted to access the directory even if the directory exists\r\n\r\n~~~\r\nos.path.exists(path)\r\nReturn True if path refers to an existing path or an open file descriptor. Returns False for broken symbolic links. On some platforms, this function may return False if permission is not granted to execute os.stat() on the requested file, even if the path physically exists.\r\n~~~\r\n\r\nos.path method documentation -> https://docs.python.org/3/library/os.path.html\r\n\n", "before_files": [{"content": "from gettext import gettext as _\nimport json\nimport os\nfrom drf_spectacular.utils import extend_schema\nfrom rest_framework.views import APIView\nfrom rest_framework.response import Response\n\nfrom pulpcore.app import settings\nfrom pulpcore.app.serializers import PulpImportCheckResponseSerializer, PulpImportCheckSerializer\n\n\ndef _check_allowed_import_path(a_path):\n    user_provided_realpath = os.path.realpath(a_path)\n    for allowed_path in settings.ALLOWED_IMPORT_PATHS:\n        if user_provided_realpath.startswith(allowed_path):\n            return True, None\n    return False, _(\n        \"{} is not an allowed import path\".format(os.path.dirname(os.path.realpath(a_path)))\n    )\n\n\ndef _validate_file(in_param, data):\n    \"\"\"\n    Returns a (is-valid, msgs[]) tuple describing all problems found with data[in_param]\n\n    We check for a number of things, attempting to return all the errors we can find. We don't want\n    to give out information for files in arbitrary locations on the filesystem; if the check\n    for ALLOWED_IMPORT_PATHS fails, we report that and ignore any other problems.\n\n    If the directory containing the base-file doesn't exist, or isn't readable, or the specified\n    file doesn't exist, report and return.\n\n    Error-messages for all other checks are additive.\n    \"\"\"\n    # check allowed, leave if failed\n    file = data[in_param]\n    real_file = os.path.realpath(file)\n    rc, msg = _check_allowed_import_path(real_file)\n    if not rc:\n        return rc, [msg]\n\n    # check directory-sanity, leave if failed\n    owning_dir = os.path.dirname(real_file)\n    if not os.path.exists(owning_dir):\n        return False, [_(\"directory {} does not exist\").format(owning_dir)]\n    if not os.access(owning_dir, os.R_OK):\n        return False, [_(\"directory {} does not allow read-access\").format(owning_dir)]\n\n    # check file-exists, leave if failed\n    if not os.path.exists(real_file):\n        return False, [_(\"file {} does not exist\").format(real_file)]\n\n    # check file-sanity\n    msgs = []\n    isfile = os.path.isfile(real_file)\n    readable = os.access(real_file, os.R_OK)\n\n    rc = isfile and readable\n    if not isfile:\n        msgs.append(_(\"{} is not a file\".format(real_file)))\n    if not readable:\n        msgs.append(_(\"{} exists but cannot be read\".format(real_file)))\n\n    # extra check for toc-dir-write\n    if in_param == \"toc\":\n        if not os.access(owning_dir, os.W_OK):\n            rc = False\n            msgs.append(_(\"directory {} must allow pulp write-access\".format(owning_dir)))\n\n    return rc, msgs\n\n\nclass PulpImporterImportCheckView(APIView):\n    \"\"\"\n    Returns validity of proposed parameters for a PulpImport call.\n    \"\"\"\n\n    @extend_schema(\n        summary=\"Validate the parameters to be used for a PulpImport call\",\n        operation_id=\"pulp_import_check_post\",\n        request=PulpImportCheckSerializer,\n        responses={200: PulpImportCheckResponseSerializer},\n    )\n    def post(self, request, format=None):\n        \"\"\"\n        Evaluates validity of proposed PulpImport parameters 'toc', 'path', and 'repo_mapping'.\n\n        * Checks that toc, path are in ALLOWED_IMPORT_PATHS\n        * if ALLOWED:\n          * Checks that toc, path exist and are readable\n          * If toc specified, checks that containing dir is writeable\n        * Checks that repo_mapping is valid JSON\n        \"\"\"\n        serializer = PulpImportCheckSerializer(data=request.data)\n        if serializer.is_valid():\n            data = {}\n            if \"toc\" in serializer.data:\n                data[\"toc\"] = {}\n                data[\"toc\"][\"context\"] = serializer.data[\"toc\"]\n                data[\"toc\"][\"is_valid\"], data[\"toc\"][\"messages\"] = _validate_file(\n                    \"toc\", serializer.data\n                )\n\n            if \"path\" in serializer.data:\n                data[\"path\"] = {}\n                data[\"path\"][\"context\"] = serializer.data[\"path\"]\n                data[\"path\"][\"is_valid\"], data[\"path\"][\"messages\"] = _validate_file(\n                    \"path\", serializer.data\n                )\n\n            if \"repo_mapping\" in serializer.data:\n                data[\"repo_mapping\"] = {}\n                data[\"repo_mapping\"][\"context\"] = serializer.data[\"repo_mapping\"]\n                try:\n                    json.loads(serializer.data[\"repo_mapping\"])\n                    data[\"repo_mapping\"][\"is_valid\"] = True\n                    data[\"repo_mapping\"][\"messages\"] = []\n                except json.JSONDecodeError:\n                    data[\"repo_mapping\"][\"is_valid\"] = False\n                    data[\"repo_mapping\"][\"messages\"] = [_(\"invalid JSON\")]\n\n            crs = PulpImportCheckResponseSerializer(data, context={\"request\": request})\n            return Response(crs.data)\n        return Response(serializer.errors, status=400)\n", "path": "pulpcore/app/views/importer.py"}], "after_files": [{"content": "from gettext import gettext as _\nimport json\nimport os\nfrom drf_spectacular.utils import extend_schema\nfrom rest_framework.views import APIView\nfrom rest_framework.response import Response\n\nfrom pulpcore.app import settings\nfrom pulpcore.app.serializers import PulpImportCheckResponseSerializer, PulpImportCheckSerializer\n\n\ndef _check_allowed_import_path(a_path):\n    user_provided_realpath = os.path.realpath(a_path)\n    for allowed_path in settings.ALLOWED_IMPORT_PATHS:\n        if user_provided_realpath.startswith(allowed_path):\n            return True, None\n    return False, _(\n        \"{} is not an allowed import path\".format(os.path.dirname(os.path.realpath(a_path)))\n    )\n\n\ndef _validate_file(in_param, data):\n    \"\"\"\n    Returns a (is-valid, msgs[]) tuple describing all problems found with data[in_param]\n\n    We check for a number of things, attempting to return all the errors we can find. We don't want\n    to give out information for files in arbitrary locations on the filesystem; if the check\n    for ALLOWED_IMPORT_PATHS fails, we report that and ignore any other problems.\n\n    If the directory containing the base-file doesn't exist, or isn't readable, or the specified\n    file doesn't exist, report and return.\n\n    Error-messages for all other checks are additive.\n    \"\"\"\n    # check allowed, leave if failed\n    file = data[in_param]\n    real_file = os.path.realpath(file)\n    rc, msg = _check_allowed_import_path(real_file)\n    if not rc:\n        return rc, [msg]\n\n    # check directory-sanity, leave if failed\n    # use os.stat to ensure directory exists and pulp has read-access\n    # return any errors received from os.stat to the user\n\n    owning_dir = os.path.dirname(real_file)\n    try:\n        os.stat(owning_dir)\n    except OSError as e:\n        return False, [_(\"{}\").format(e)]\n\n    # check file-exists, leave if failed\n    if not os.path.exists(real_file):\n        return False, [_(\"file {} does not exist\").format(real_file)]\n\n    # check file-sanity\n    msgs = []\n    isfile = os.path.isfile(real_file)\n    readable = os.access(real_file, os.R_OK)\n\n    rc = isfile and readable\n    if not isfile:\n        msgs.append(_(\"{} is not a file\".format(real_file)))\n    if not readable:\n        msgs.append(_(\"{} exists but cannot be read\".format(real_file)))\n\n    # extra check for toc-dir-write\n    if in_param == \"toc\":\n        if not os.access(owning_dir, os.W_OK):\n            rc = False\n            msgs.append(_(\"directory {} must allow pulp write-access\".format(owning_dir)))\n\n    return rc, msgs\n\n\nclass PulpImporterImportCheckView(APIView):\n    \"\"\"\n    Returns validity of proposed parameters for a PulpImport call.\n    \"\"\"\n\n    @extend_schema(\n        summary=\"Validate the parameters to be used for a PulpImport call\",\n        operation_id=\"pulp_import_check_post\",\n        request=PulpImportCheckSerializer,\n        responses={200: PulpImportCheckResponseSerializer},\n    )\n    def post(self, request, format=None):\n        \"\"\"\n        Evaluates validity of proposed PulpImport parameters 'toc', 'path', and 'repo_mapping'.\n\n        * Checks that toc, path are in ALLOWED_IMPORT_PATHS\n        * if ALLOWED:\n          * Checks that toc, path exist and are readable\n          * If toc specified, checks that containing dir is writeable\n        * Checks that repo_mapping is valid JSON\n        \"\"\"\n        serializer = PulpImportCheckSerializer(data=request.data)\n        if serializer.is_valid():\n            data = {}\n            if \"toc\" in serializer.data:\n                data[\"toc\"] = {}\n                data[\"toc\"][\"context\"] = serializer.data[\"toc\"]\n                data[\"toc\"][\"is_valid\"], data[\"toc\"][\"messages\"] = _validate_file(\n                    \"toc\", serializer.data\n                )\n\n            if \"path\" in serializer.data:\n                data[\"path\"] = {}\n                data[\"path\"][\"context\"] = serializer.data[\"path\"]\n                data[\"path\"][\"is_valid\"], data[\"path\"][\"messages\"] = _validate_file(\n                    \"path\", serializer.data\n                )\n\n            if \"repo_mapping\" in serializer.data:\n                data[\"repo_mapping\"] = {}\n                data[\"repo_mapping\"][\"context\"] = serializer.data[\"repo_mapping\"]\n                try:\n                    json.loads(serializer.data[\"repo_mapping\"])\n                    data[\"repo_mapping\"][\"is_valid\"] = True\n                    data[\"repo_mapping\"][\"messages\"] = []\n                except json.JSONDecodeError:\n                    data[\"repo_mapping\"][\"is_valid\"] = False\n                    data[\"repo_mapping\"][\"messages\"] = [_(\"invalid JSON\")]\n\n            crs = PulpImportCheckResponseSerializer(data, context={\"request\": request})\n            return Response(crs.data)\n        return Response(serializer.errors, status=400)\n", "path": "pulpcore/app/views/importer.py"}]}