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<div>You are a helpful software engineer assistant.<span class="token yellow"><｜User｜></span><uploaded_files> |
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/testbed |
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</uploaded_files> |
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I've uploaded a code repository in the directory /testbed (not in /tmp/inputs). Consider the following PR description: |
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<pr_description> |
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Bug in posix implementation of django/core/files/locks.py |
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Description |
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The posix version of locks (the version which supports import fcntl) has a bug. The code attempts to return True to indicate success or failure acquiring a lock, but instead it always returns False. The reason is that cpython fcntl module returns None if successful, and raises an OSError to indicate failure (see https://docs.python.org/3/library/fcntl.html#fcntl.flock). |
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Anyone interested in using the non-blocking (i.e. locks.LOCKS_NB) requires a valid return value to know if they have successfully acquired the lock. |
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I believe the correct implementation should be the following: |
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diff --git a/django/core/files/locks.py b/django/core/files/locks.py |
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index c46b00b905..4938347ea7 100644 |
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--- a/django/core/files/locks.py |
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+++ b/django/core/files/locks.py |
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@@ -107,9 +107,15 @@ else: |
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return True |
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else: |
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def lock(f, flags): |
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- ret = fcntl.flock(_fd(f), flags) |
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- return ret == 0 |
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+ try: |
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+ fcntl.flock(_fd(f), flags) |
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+ return True |
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+ except OSError: |
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+ return False |
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def unlock(f): |
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- ret = fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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- return ret == 0 |
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+ try: |
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+ fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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+ return True |
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+ except OSError: |
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+ return False |
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</pr_description> |
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Can you help me implement the necessary changes to the repository so that the requirements specified in the <pr_description> are met? |
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I've already taken care of all changes to any of the test files described in the <pr_description>. This means you DON'T have to modify the testing logic or any of the tests in any way! |
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Your task is to make the minimal changes to non-tests files in the /testbed directory to ensure the <pr_description> is satisfied. |
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You are only allowed to call **ONE** function each time!<span class="token yellow"><｜Assistant｜></span><span class="token red"></think></span>I'll help you implement the necessary changes to fix the bug in the posix implementation of `django/core/files/locks.py`. Let me start by examining the current state of the file.<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "view", "path": "/testbed/django/core/files/locks.py"}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>Here's the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 116 lines): |
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1 """ |
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2 Portable file locking utilities. |
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3 |
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4 Based partially on an example by Jonathan Feignberg in the Python |
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5 Cookbook [1] (licensed under the Python Software License) and a ctypes port by |
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6 Anatoly Techtonik for Roundup [2] (license [3]). |
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7 |
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8 [1] http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203 |
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9 [2] https://sourceforge.net/p/roundup/code/ci/default/tree/roundup/backends/portalocker.py |
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10 [3] https://sourceforge.net/p/roundup/code/ci/default/tree/COPYING.txt |
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11 |
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12 Example Usage:: |
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13 |
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14 >>> from django.core.files import locks |
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15 >>> with open('./file', 'wb') as f: |
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16 ... locks.lock(f, locks.LOCK_EX) |
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17 ... f.write('Django') |
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18 """ |
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19 import os |
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20 |
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21 __all__ = ('LOCK_EX', 'LOCK_SH', 'LOCK_NB', 'lock', 'unlock') |
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22 |
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23 |
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24 def _fd(f): |
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25 """Get a filedescriptor from something which could be a file or an fd.""" |
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26 return f.fileno() if hasattr(f, 'fileno') else f |
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27 |
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28 |
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29 if os.name == 'nt': |
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30 import msvcrt |
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31 from ctypes import ( |
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32 POINTER, Structure, Union, byref, c_int64, c_ulong, c_void_p, sizeof, |
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33 windll, |
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34 ) |
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35 from ctypes.wintypes import BOOL, DWORD, HANDLE |
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36 |
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37 LOCK_SH = 0 # the default |
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38 LOCK_NB = 0x1 # LOCKFILE_FAIL_IMMEDIATELY |
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39 LOCK_EX = 0x2 # LOCKFILE_EXCLUSIVE_LOCK |
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40 |
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41 # --- Adapted from the pyserial project --- |
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42 # detect size of ULONG_PTR |
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43 if sizeof(c_ulong) != sizeof(c_void_p): |
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44 ULONG_PTR = c_int64 |
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45 else: |
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46 ULONG_PTR = c_ulong |
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47 PVOID = c_void_p |
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48 |
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49 # --- Union inside Structure by stackoverflow:3480240 --- |
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50 class _OFFSET(Structure): |
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51 _fields_ = [ |
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52 ('Offset', DWORD), |
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53 ('OffsetHigh', DWORD)] |
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54 |
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55 class _OFFSET_UNION(Union): |
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56 _anonymous_ = ['_offset'] |
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57 _fields_ = [ |
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58 ('_offset', _OFFSET), |
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59 ('Pointer', PVOID)] |
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60 |
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61 class OVERLAPPED(Structure): |
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62 _anonymous_ = ['_offset_union'] |
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63 _fields_ = [ |
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64 ('Internal', ULONG_PTR), |
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65 ('InternalHigh', ULONG_PTR), |
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66 ('_offset_union', _OFFSET_UNION), |
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67 ('hEvent', HANDLE)] |
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68 |
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69 LPOVERLAPPED = POINTER(OVERLAPPED) |
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70 |
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71 # --- Define function prototypes for extra safety --- |
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72 LockFileEx = windll.kernel32.LockFileEx |
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73 LockFileEx.restype = BOOL |
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74 LockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, DWORD, LPOVERLAPPED] |
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75 UnlockFileEx = windll.kernel32.UnlockFileEx |
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76 UnlockFileEx.restype = BOOL |
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77 UnlockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, LPOVERLAPPED] |
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78 |
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79 def lock(f, flags): |
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80 hfile = msvcrt.get_osfhandle(_fd(f)) |
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81 overlapped = OVERLAPPED() |
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82 ret = LockFileEx(hfile, flags, 0, 0, 0xFFFF0000, byref(overlapped)) |
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83 return bool(ret) |
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84 |
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85 def unlock(f): |
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86 hfile = msvcrt.get_osfhandle(_fd(f)) |
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87 overlapped = OVERLAPPED() |
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88 ret = UnlockFileEx(hfile, 0, 0, 0xFFFF0000, byref(overlapped)) |
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89 return bool(ret) |
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90 else: |
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91 try: |
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92 import fcntl |
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93 LOCK_SH = fcntl.LOCK_SH # shared lock |
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94 LOCK_NB = fcntl.LOCK_NB # non-blocking |
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95 LOCK_EX = fcntl.LOCK_EX |
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96 except (ImportError, AttributeError): |
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97 # File locking is not supported. |
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98 LOCK_EX = LOCK_SH = LOCK_NB = 0 |
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99 |
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100 # Dummy functions that don't do anything. |
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101 def lock(f, flags): |
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102 # File is not locked |
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103 return False |
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104 |
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105 def unlock(f): |
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106 # File is unlocked |
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107 return True |
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108 else: |
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109 def lock(f, flags): |
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110 ret = fcntl.flock(_fd(f), flags) |
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111 return ret == 0 |
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112 |
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113 def unlock(f): |
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114 ret = fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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115 return ret == 0 |
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116 |
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<span class="token green"><｜tool▁output▁end｜></span>Now I can see the issue. Looking at the current implementation in lines 109-115, the code is trying to compare the return value of `fcntl.flock()` with 0, but according to the PR description, `fcntl.flock()` returns `None` on success and raises an `OSError` on failure. This means the current implementation will always return `False` because `None == 0` is `False`. |
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Let me examine the specific lines that need to be changed:<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "view", "path": "/testbed/django/core/files/locks.py", "view_range": [109,116]}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>Here's the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 116 lines) with view_range=[109, 116]: |
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109 def lock(f, flags): |
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110 ret = fcntl.flock(_fd(f), flags) |
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111 return ret == 0 |
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112 |
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113 def unlock(f): |
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114 ret = fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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115 return ret == 0 |
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116 |
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<span class="token green"><｜tool▁output▁end｜></span>Now I'll implement the fix as described in the PR description. The fix should wrap the `fcntl.flock()` calls in try-except blocks, returning `True` on success and `False` on `OSError`:<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "str_replace", "path": "/testbed/django/core/files/locks.py", "old_str": " def lock(f, flags):\n ret = fcntl.flock(_fd(f), flags)\n return ret == 0\n\n def unlock(f):\n ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)\n return ret == 0", "new_str": " def lock(f, flags):\n try:\n fcntl.flock(_fd(f), flags)\n return True\n except OSError:\n return False\n\n def unlock(f):\n try:\n fcntl.flock(_fd(f), fcntl.LOCK_UN)\n return True\n except OSError:\n return False"}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>The file /testbed/django/core/files/locks.py has been edited successfully.<span class="token green"><｜tool▁output▁end｜></span>Let me verify the changes by viewing the modified section:<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "view", "path": "/testbed/django/core/files/locks.py", "view_range": [109,116]}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>Here's the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[109, 116]: |
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109 def lock(f, flags): |
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110 try: |
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111 fcntl.flock(_fd(f), flags) |
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112 return True |
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113 except OSError: |
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114 return False |
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115 |
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116 def unlock(f): |
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<span class="token green"><｜tool▁output▁end｜></span><span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "view", "path": "/testbed/django/core/files/locks.py", "view_range": [116,122]}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>Here's the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[116, 122]: |
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116 def unlock(f): |
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117 try: |
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118 fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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119 return True |
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120 except OSError: |
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121 return False |
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122 |
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<span class="token green"><｜tool▁output▁end｜></span>Perfect! The changes have been successfully implemented. Let me verify the complete file structure to ensure everything looks correct:<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>str_replace_editor<span class="token green"><｜tool▁sep｜></span>{"command": "view", "path": "/testbed/django/core/files/locks.py", "view_range": [90,122]}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span>Here's the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[90, 122]: |
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90 else: |
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91 try: |
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92 import fcntl |
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93 LOCK_SH = fcntl.LOCK_SH # shared lock |
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94 LOCK_NB = fcntl.LOCK_NB # non-blocking |
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95 LOCK_EX = fcntl.LOCK_EX |
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96 except (ImportError, AttributeError): |
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97 # File locking is not supported. |
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98 LOCK_EX = LOCK_SH = LOCK_NB = 0 |
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99 |
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100 # Dummy functions that don't do anything. |
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101 def lock(f, flags): |
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102 # File is not locked |
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103 return False |
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104 |
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105 def unlock(f): |
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106 # File is unlocked |
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107 return True |
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108 else: |
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109 def lock(f, flags): |
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110 try: |
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111 fcntl.flock(_fd(f), flags) |
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112 return True |
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113 except OSError: |
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114 return False |
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115 |
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116 def unlock(f): |
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117 try: |
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118 fcntl.flock(_fd(f), fcntl.LOCK_UN) |
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119 return True |
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120 except OSError: |
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121 return False |
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122 |
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<span class="token green"><｜tool▁output▁end｜></span>Excellent! The changes have been successfully implemented. Let me run a quick test to make sure the file is syntactically correct:<span class="token green"><｜tool▁calls▁begin｜></span><span class="token green"><｜tool▁call▁begin｜></span>bash<span class="token green"><｜tool▁sep｜></span>{"command": "cd /testbed && python -m py_compile django/core/files/locks.py"}<span class="token green"><｜tool▁call▁end｜></span><span class="token green"><｜tool▁calls▁end｜></span><span class="token yellow"><｜end▁of▁sentence｜></span><span class="token green"><｜tool▁output▁begin｜></span><span class="token green"><｜tool▁output▁end｜></span>Great! The file compiles without any syntax errors. |
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## Summary |
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I have successfully implemented the fix for the bug in the posix implementation of `django/core/files/locks.py`. The changes made are: |
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1. **Modified the `lock()` function** (lines 109-114): Wrapped the `fcntl.flock()` call in a try-except block that returns `True` on success and `False` when an `OSError` is raised. |
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2. **Modified the `unlock()` function** (lines 116-121): Similarly wrapped the `fcntl.flock()` call in a try-except block that returns `True` on success and `False` when an `OSError` is raised. |
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The fix addresses the core issue described in the PR: |
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- The original code incorrectly compared the return value of `fcntl.flock()` with 0, but `fcntl.flock()` returns `None` on success and raises an `OSError` on failure |
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- This meant the functions always returned `False` (`None == 0` is `False`) |
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- The new implementation properly handles the success/failure cases by using try-except blocks |
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- This is particularly important for non-blocking locks (`LOCK_NB`) where callers need to know if the lock was successfully acquired |
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The changes are minimal and focused, exactly matching the suggested fix in the PR description.<span class="token yellow"><｜end▁of▁sentence｜></span></div> |
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