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<div>You are a helpful software engineer assistant.<span class="token yellow"><｜User｜></span><uploaded_files>
/testbed
</uploaded_files>
I've uploaded a code repository in the directory /testbed (not in /tmp/inputs). Consider the following PR description:
<pr_description>
Bug in posix implementation of django/core/files/locks.py
Description
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).
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.
I believe the correct implementation should be the following:
diff --git a/django/core/files/locks.py b/django/core/files/locks.py
index c46b00b905..4938347ea7 100644
--- a/django/core/files/locks.py
+++ b/django/core/files/locks.py
@@ -107,9 +107,15 @@ else:
return True
else:
def lock(f, flags):
- ret = fcntl.flock(_fd(f), flags)
- return ret == 0
+ try:
+ fcntl.flock(_fd(f), flags)
+ return True
+ except OSError:
+ return False
def unlock(f):
- ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
- return ret == 0
+ try:
+ fcntl.flock(_fd(f), fcntl.LOCK_UN)
+ return True
+ except OSError:
+ return False
</pr_description>
Can you help me implement the necessary changes to the repository so that the requirements specified in the <pr_description> are met?
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!
Your task is to make the minimal changes to non-tests files in the /testbed directory to ensure the <pr_description> is satisfied.
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):
1 """
2 Portable file locking utilities.
3
4 Based partially on an example by Jonathan Feignberg in the Python
5 Cookbook [1] (licensed under the Python Software License) and a ctypes port by
6 Anatoly Techtonik for Roundup [2] (license [3]).
7
8 [1] http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203
9 [2] https://sourceforge.net/p/roundup/code/ci/default/tree/roundup/backends/portalocker.py
10 [3] https://sourceforge.net/p/roundup/code/ci/default/tree/COPYING.txt
11
12 Example Usage::
13
14 >>> from django.core.files import locks
15 >>> with open('./file', 'wb') as f:
16 ... locks.lock(f, locks.LOCK_EX)
17 ... f.write('Django')
18 """
19 import os
20
21 __all__ = ('LOCK_EX', 'LOCK_SH', 'LOCK_NB', 'lock', 'unlock')
22
23
24 def _fd(f):
25 """Get a filedescriptor from something which could be a file or an fd."""
26 return f.fileno() if hasattr(f, 'fileno') else f
27
28
29 if os.name == 'nt':
30 import msvcrt
31 from ctypes import (
32 POINTER, Structure, Union, byref, c_int64, c_ulong, c_void_p, sizeof,
33 windll,
34 )
35 from ctypes.wintypes import BOOL, DWORD, HANDLE
36
37 LOCK_SH = 0 # the default
38 LOCK_NB = 0x1 # LOCKFILE_FAIL_IMMEDIATELY
39 LOCK_EX = 0x2 # LOCKFILE_EXCLUSIVE_LOCK
40
41 # --- Adapted from the pyserial project ---
42 # detect size of ULONG_PTR
43 if sizeof(c_ulong) != sizeof(c_void_p):
44 ULONG_PTR = c_int64
45 else:
46 ULONG_PTR = c_ulong
47 PVOID = c_void_p
48
49 # --- Union inside Structure by stackoverflow:3480240 ---
50 class _OFFSET(Structure):
51 _fields_ = [
52 ('Offset', DWORD),
53 ('OffsetHigh', DWORD)]
54
55 class _OFFSET_UNION(Union):
56 _anonymous_ = ['_offset']
57 _fields_ = [
58 ('_offset', _OFFSET),
59 ('Pointer', PVOID)]
60
61 class OVERLAPPED(Structure):
62 _anonymous_ = ['_offset_union']
63 _fields_ = [
64 ('Internal', ULONG_PTR),
65 ('InternalHigh', ULONG_PTR),
66 ('_offset_union', _OFFSET_UNION),
67 ('hEvent', HANDLE)]
68
69 LPOVERLAPPED = POINTER(OVERLAPPED)
70
71 # --- Define function prototypes for extra safety ---
72 LockFileEx = windll.kernel32.LockFileEx
73 LockFileEx.restype = BOOL
74 LockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, DWORD, LPOVERLAPPED]
75 UnlockFileEx = windll.kernel32.UnlockFileEx
76 UnlockFileEx.restype = BOOL
77 UnlockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, LPOVERLAPPED]
78
79 def lock(f, flags):
80 hfile = msvcrt.get_osfhandle(_fd(f))
81 overlapped = OVERLAPPED()
82 ret = LockFileEx(hfile, flags, 0, 0, 0xFFFF0000, byref(overlapped))
83 return bool(ret)
84
85 def unlock(f):
86 hfile = msvcrt.get_osfhandle(_fd(f))
87 overlapped = OVERLAPPED()
88 ret = UnlockFileEx(hfile, 0, 0, 0xFFFF0000, byref(overlapped))
89 return bool(ret)
90 else:
91 try:
92 import fcntl
93 LOCK_SH = fcntl.LOCK_SH # shared lock
94 LOCK_NB = fcntl.LOCK_NB # non-blocking
95 LOCK_EX = fcntl.LOCK_EX
96 except (ImportError, AttributeError):
97 # File locking is not supported.
98 LOCK_EX = LOCK_SH = LOCK_NB = 0
99
100 # Dummy functions that don't do anything.
101 def lock(f, flags):
102 # File is not locked
103 return False
104
105 def unlock(f):
106 # File is unlocked
107 return True
108 else:
109 def lock(f, flags):
110 ret = fcntl.flock(_fd(f), flags)
111 return ret == 0
112
113 def unlock(f):
114 ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
115 return ret == 0
116
<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`.
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]:
109 def lock(f, flags):
110 ret = fcntl.flock(_fd(f), flags)
111 return ret == 0
112
113 def unlock(f):
114 ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
115 return ret == 0
116
<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]:
109 def lock(f, flags):
110 try:
111 fcntl.flock(_fd(f), flags)
112 return True
113 except OSError:
114 return False
115
116 def unlock(f):
<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]:
116 def unlock(f):
117 try:
118 fcntl.flock(_fd(f), fcntl.LOCK_UN)
119 return True
120 except OSError:
121 return False
122
<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]:
90 else:
91 try:
92 import fcntl
93 LOCK_SH = fcntl.LOCK_SH # shared lock
94 LOCK_NB = fcntl.LOCK_NB # non-blocking
95 LOCK_EX = fcntl.LOCK_EX
96 except (ImportError, AttributeError):
97 # File locking is not supported.
98 LOCK_EX = LOCK_SH = LOCK_NB = 0
99
100 # Dummy functions that don't do anything.
101 def lock(f, flags):
102 # File is not locked
103 return False
104
105 def unlock(f):
106 # File is unlocked
107 return True
108 else:
109 def lock(f, flags):
110 try:
111 fcntl.flock(_fd(f), flags)
112 return True
113 except OSError:
114 return False
115
116 def unlock(f):
117 try:
118 fcntl.flock(_fd(f), fcntl.LOCK_UN)
119 return True
120 except OSError:
121 return False
122
<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.
## Summary
I have successfully implemented the fix for the bug in the posix implementation of `django/core/files/locks.py`. The changes made are:
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.
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.
The fix addresses the core issue described in the PR:
- 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
- This meant the functions always returned `False` (`None == 0` is `False`)
- The new implementation properly handles the success/failure cases by using try-except blocks
- This is particularly important for non-blocking locks (`LOCK_NB`) where callers need to know if the lock was successfully acquired
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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