Python C 扩展导致 stat ENOENT
Python C extension causes stat ENOENT
我正在尝试在 Python 中实现 C 扩展。扩展有效，但一旦导入模块，errno 就会设置为 ENOENT (2)。
simple.c
#include <Python.h>
#include <errno.h>
static PyMethodDef KeypadMethods[] = {
{NULL, NULL, 0, NULL} /* Sentinel */
};
PyMODINIT_FUNC initkeypadinterface(void)
{
PyObject* m;
int stat;
stat = errno;
if (stat)
{
printf("There was an error: %d\n", stat);
}
m = Py_InitModule3("keypadinterface", KeypadMethods, "Interface to the keypad driver");
if (m == NULL)
{
return;
}
}
setup.py
from distutils.core import setup, Extension
module1 = Extension('keypadinterface',
sources = ['simple.c'])
setup (name = 'KeypadInterface',
version = '0.1',
description = 'Provides a python interface to the keypad driver',
ext_modules = [module1])
python setup.py build 输出：
running build
running build_ext
building 'keypadinterface' extension
creating build
creating build/temp.linux-x86_64-2.7
x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c simple.c -o build/temp.linux-x86_64-2.7/simple.o
creating build/lib.linux-x86_64-2.7
x86_64-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/simple.o -o build/lib.linux-x86_64-2.7/keypadinterface.so
在 errno 上使用带有监视的 gdb 会导致此回溯：
(gdb) c
Continuing.
Hardware watchpoint 1: errno
Old value = 0
New value = 2
0x00007f9974e271d0 in __xstat64 () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0 0x00007f9974e271d0 in __xstat64 () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00000000004d4ea6 in stat (__path=<optimized out>, __statbuf=<optimized out>)
at /usr/include/x86_64-linux-gnu/sys/stat.h:455
#2 isdir (path=0x14bf430 "keypadinterface") at ../Python/import.c:133
#3 find_module.38998 (fullname=fullname@entry=0x14be420 "keypadinterface", subname=<optimized out>,
subname@entry=0x14be420 "keypadinterface",
path=['', '/usr/local/lib/python2.7/dist-packages/esptool-0.1.0-py2.7.egg', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'], path@entry=0x0, buf=<optimized out>, buf@entry=0x14bf430 "keypadinterface",
buflen=buflen@entry=4097, p_fp=p_fp@entry=0x7fff1d45bb80, p_loader=p_loader@entry=0x7fff1d45bb70)
at ../Python/import.c:1497
#4 0x0000000000540922 in import_submodule.39248 (mod=mod@entry=None,
subname=subname@entry=0x14be420 "keypadinterface", fullname=0x14be420 "keypadinterface")
at ../Python/import.c:2689
#5 0x0000000000540d08 in load_next (mod=None, altmod=None, p_name=p_name@entry=0x7fff1d45bc78,
buf=buf@entry=0x14be420 "keypadinterface", p_buflen=p_buflen@entry=0x7fff1d45bc80)
at ../Python/import.c:2515
#6 0x000000000054111b in import_module_level.isra.3.39267 (name=0x0,
name@entry=0x7f99753d4d74 "keypadinterface",
globals=globals@entry={'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, fromlist=fromlist@entry=None, level=level@entry=-1) at ../Python/import.c:2224
#7 0x000000000051dc50 in PyImport_ImportModuleLevel (level=-1, fromlist=None, locals=<optimized out>,
globals={'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, name=0x7f99753d4d74 "keypadinterface") at ../Python/import.c:2288
#8 builtin___import__ (self=<optimized out>, args=<optimized out>, kwds=<optimized out>)
at ../Python/bltinmodule.c:49
#9 0x00000000004dc9cb in PyObject_Call (kw=0x0,
arg=('keypadinterface', {'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, {...}, None), func=<built-in function __import__>)
at ../Objects/abstract.c:2529
#10 PyEval_CallObjectWithKeywords (func=func@entry=<built-in function __import__>,
arg=arg@entry=('keypadinterface', {'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, {...}, None), kw=kw@entry=0x0) at ../Python/ceval.c:3889
#11 0x000000000049b87e in PyEval_EvalFrameEx (
f=f@entry=Frame 0x7f9975504c20, for file <stdin>, line 1, in <module> (), throwflag=throwflag@entry=0)
at ../Python/ceval.c:2333
#12 0x00000000004a1634 in PyEval_EvalCodeEx (closure=0x0, defcount=0, defs=0x0, kwcount=0, kws=0x0,
argcount=0, args=0x0, locals=<optimized out>, globals=<optimized out>, co=0x7f9975415b30)
at ../Python/ceval.c:3252
#13 PyEval_EvalCode (locals=<optimized out>, globals=<optimized out>, co=0x7f9975415b30)
at ../Python/ceval.c:667
#14 run_mod.42576 (mod=mod@entry=0x14bc470, filename=filename@entry=0x60e5bd "<stdin>",
globals=<optimized out>, locals=<optimized out>, flags=flags@entry=0x7fff1d45c0b0,
arena=arena@entry=0x1444780) at ../Python/pythonrun.c:1370
#15 0x000000000044e87c in PyRun_InteractiveOneFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", flags=flags@entry=0x7fff1d45c0b0) at ../Python/pythonrun.c:857
#16 0x000000000044e998 in PyRun_InteractiveLoopFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", flags=flags@entry=0x7fff1d45c0b0) at ../Python/pythonrun.c:777
#17 0x000000000044ed70 in PyRun_AnyFileExFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", closeit=closeit@entry=0, flags=flags@entry=0x7fff1d45c0b0)
at ../Python/pythonrun.c:746
---Type <return> to continue, or q <return> to quit---
#18 0x000000000044f904 in Py_Main (argc=<optimized out>, argv=0x7fff1d45c268) at ../Modules/main.c:640
#19 0x00007f9974d5dec5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#20 0x0000000000578c4e in _start ()
(gdb)
我读到统计函数可以将 errno 设置为 ENOENT 当被 stat 编辑的路径组件不存在时。但是模块还能用所以路径一定是正确的吧？
一定是我做了什么蠢到家的事，但我还没找到。
以防万一：Python 2.7.6 on Linux Mint 17.1 with GCC 4.8.4
lot 的代码集 errno 在执行操作之前先发制人，因为多个代码路径可能会导致返回相同的错误。因此，errno 中的值应 忽略 除非代码 显式 returns 错误结果。
我正在尝试在 Python 中实现 C 扩展。扩展有效，但一旦导入模块，errno 就会设置为 ENOENT (2)。
simple.c
#include <Python.h>
#include <errno.h>
static PyMethodDef KeypadMethods[] = {
{NULL, NULL, 0, NULL} /* Sentinel */
};
PyMODINIT_FUNC initkeypadinterface(void)
{
PyObject* m;
int stat;
stat = errno;
if (stat)
{
printf("There was an error: %d\n", stat);
}
m = Py_InitModule3("keypadinterface", KeypadMethods, "Interface to the keypad driver");
if (m == NULL)
{
return;
}
}
setup.py
from distutils.core import setup, Extension
module1 = Extension('keypadinterface',
sources = ['simple.c'])
setup (name = 'KeypadInterface',
version = '0.1',
description = 'Provides a python interface to the keypad driver',
ext_modules = [module1])
python setup.py build 输出：
running build
running build_ext
building 'keypadinterface' extension
creating build
creating build/temp.linux-x86_64-2.7
x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c simple.c -o build/temp.linux-x86_64-2.7/simple.o
creating build/lib.linux-x86_64-2.7
x86_64-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/simple.o -o build/lib.linux-x86_64-2.7/keypadinterface.so
在 errno 上使用带有监视的 gdb 会导致此回溯：
(gdb) c
Continuing.
Hardware watchpoint 1: errno
Old value = 0
New value = 2
0x00007f9974e271d0 in __xstat64 () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0 0x00007f9974e271d0 in __xstat64 () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00000000004d4ea6 in stat (__path=<optimized out>, __statbuf=<optimized out>)
at /usr/include/x86_64-linux-gnu/sys/stat.h:455
#2 isdir (path=0x14bf430 "keypadinterface") at ../Python/import.c:133
#3 find_module.38998 (fullname=fullname@entry=0x14be420 "keypadinterface", subname=<optimized out>,
subname@entry=0x14be420 "keypadinterface",
path=['', '/usr/local/lib/python2.7/dist-packages/esptool-0.1.0-py2.7.egg', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'], path@entry=0x0, buf=<optimized out>, buf@entry=0x14bf430 "keypadinterface",
buflen=buflen@entry=4097, p_fp=p_fp@entry=0x7fff1d45bb80, p_loader=p_loader@entry=0x7fff1d45bb70)
at ../Python/import.c:1497
#4 0x0000000000540922 in import_submodule.39248 (mod=mod@entry=None,
subname=subname@entry=0x14be420 "keypadinterface", fullname=0x14be420 "keypadinterface")
at ../Python/import.c:2689
#5 0x0000000000540d08 in load_next (mod=None, altmod=None, p_name=p_name@entry=0x7fff1d45bc78,
buf=buf@entry=0x14be420 "keypadinterface", p_buflen=p_buflen@entry=0x7fff1d45bc80)
at ../Python/import.c:2515
#6 0x000000000054111b in import_module_level.isra.3.39267 (name=0x0,
name@entry=0x7f99753d4d74 "keypadinterface",
globals=globals@entry={'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, fromlist=fromlist@entry=None, level=level@entry=-1) at ../Python/import.c:2224
#7 0x000000000051dc50 in PyImport_ImportModuleLevel (level=-1, fromlist=None, locals=<optimized out>,
globals={'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, name=0x7f99753d4d74 "keypadinterface") at ../Python/import.c:2288
#8 builtin___import__ (self=<optimized out>, args=<optimized out>, kwds=<optimized out>)
at ../Python/bltinmodule.c:49
#9 0x00000000004dc9cb in PyObject_Call (kw=0x0,
arg=('keypadinterface', {'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, {...}, None), func=<built-in function __import__>)
at ../Objects/abstract.c:2529
#10 PyEval_CallObjectWithKeywords (func=func@entry=<built-in function __import__>,
arg=arg@entry=('keypadinterface', {'__builtins__': <module at remote 0x7f99754dbb08>, '__name__': '__main__', '__doc__': None, '__package__': None}, {...}, None), kw=kw@entry=0x0) at ../Python/ceval.c:3889
#11 0x000000000049b87e in PyEval_EvalFrameEx (
f=f@entry=Frame 0x7f9975504c20, for file <stdin>, line 1, in <module> (), throwflag=throwflag@entry=0)
at ../Python/ceval.c:2333
#12 0x00000000004a1634 in PyEval_EvalCodeEx (closure=0x0, defcount=0, defs=0x0, kwcount=0, kws=0x0,
argcount=0, args=0x0, locals=<optimized out>, globals=<optimized out>, co=0x7f9975415b30)
at ../Python/ceval.c:3252
#13 PyEval_EvalCode (locals=<optimized out>, globals=<optimized out>, co=0x7f9975415b30)
at ../Python/ceval.c:667
#14 run_mod.42576 (mod=mod@entry=0x14bc470, filename=filename@entry=0x60e5bd "<stdin>",
globals=<optimized out>, locals=<optimized out>, flags=flags@entry=0x7fff1d45c0b0,
arena=arena@entry=0x1444780) at ../Python/pythonrun.c:1370
#15 0x000000000044e87c in PyRun_InteractiveOneFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", flags=flags@entry=0x7fff1d45c0b0) at ../Python/pythonrun.c:857
#16 0x000000000044e998 in PyRun_InteractiveLoopFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", flags=flags@entry=0x7fff1d45c0b0) at ../Python/pythonrun.c:777
#17 0x000000000044ed70 in PyRun_AnyFileExFlags (fp=fp@entry=0x7f99750fb640 <_IO_2_1_stdin_>,
filename=filename@entry=0x60e5bd "<stdin>", closeit=closeit@entry=0, flags=flags@entry=0x7fff1d45c0b0)
at ../Python/pythonrun.c:746
---Type <return> to continue, or q <return> to quit---
#18 0x000000000044f904 in Py_Main (argc=<optimized out>, argv=0x7fff1d45c268) at ../Modules/main.c:640
#19 0x00007f9974d5dec5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#20 0x0000000000578c4e in _start ()
(gdb)
我读到统计函数可以将 errno 设置为 ENOENT 当被 stat 编辑的路径组件不存在时。但是模块还能用所以路径一定是正确的吧？
一定是我做了什么蠢到家的事，但我还没找到。
以防万一：Python 2.7.6 on Linux Mint 17.1 with GCC 4.8.4
lot 的代码集 errno 在执行操作之前先发制人，因为多个代码路径可能会导致返回相同的错误。因此，errno 中的值应 忽略 除非代码 显式 returns 错误结果。