bpo-26836: Add os.memfd_create()

[ZackerySpytz]

https://bugs.python.org/issue26836

[tiran]

Good work! 👍

Please modify the patch to use the glibc wrapper instead of the syscall interface and to use MFD_CLOEXEC as default value for the new FD. Feel free to use bits and pieces from my pending PR master...tiran:bpo-26836-memfd-seal (Co-authored-by appreciated).

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[ZackerySpytz]

Thank you, @tiran, for the comments. I will address them soon.

[ZackerySpytz]

MFD_CLOEXEC is now the default flag.

There were some issues with configure. It seems that someone had modified configure.ac without regenerating configure in a recent commit.

I have made the requested changes; please review again.

[bedevere-bot]

Thanks for making the requested changes!

@tiran: please review the changes made to this pull request.

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[ZackerySpytz]

I have made the requested changes; please review again.

[bedevere-bot]

Thanks for making the requested changes!

@tiran: please review the changes made to this pull request.

[tiran]

👍

[bedevere-bot]

@tiran: Please replace # with GH- in the commit message next time. Thanks!

[tiran]

Argh, I wanted to edit the commit message, too.

Thanks for your hard work. Is there a PR for sealing, too?

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot x86 Gentoo Non-Debug with X 3.x has failed when building commit 43fdbd2.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/99/builds/2738) and take a look at the build logs.
4. Check if the failure is related to this commit (43fdbd2) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/99/builds/2738

Click to see traceback logs

From https://github.com/python/cpython
 * branch                  master     -> FETCH_HEAD
Reset branch 'master'

Objects/unicodeobject.c: In function ‘_PyUnicode_CheckConsistency’:
Objects/unicodeobject.c:459:15: warning: variable ‘data’ set but not used [-Wunused-but-set-variable]
         void *data;
               ^~~~
Python/pystrhex.c: In function ‘_Py_strhex_impl’:
Python/pystrhex.c:18:45: warning: passing argument 1 of ‘PyObject_Size’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
         Py_ssize_t seplen = PyObject_Length(sep);
                                             ^~~
In file included from ./Include/Python.h:147,
                 from Python/pystrhex.c:3:
./Include/abstract.h:271:48: note: expected ‘PyObject *’ {aka ‘struct _object *’} but argument is of type ‘const PyObject *’ {aka ‘const struct _object *’}
 PyAPI_FUNC(Py_ssize_t) PyObject_Size(PyObject *o);
                                      ~~~~~~~~~~^
Python/pystrhex.c:60:27: warning: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘Py_ssize_t’ {aka ‘const int’} [-Wsign-compare]
     if (abs_bytes_per_sep >= arglen) {
                           ^~
Python/pystrhex.c: In function ‘_Py_strhex_with_sep’:
Python/pystrhex.c:90:29: warning: ‘sep_char’ may be used uninitialized in this function [-Wmaybe-uninitialized]
                 retbuf[j++] = sep_char;
                 ~~~~~~~~~~~~^~~~~~~~~~
Python/pystrhex.c:14:13: note: ‘sep_char’ was declared here
     Py_UCS1 sep_char;
             ^~~~~~~~
Python/pystrhex.c: In function ‘_Py_strhex_bytes_with_sep’:
Python/pystrhex.c:90:29: warning: ‘sep_char’ may be used uninitialized in this function [-Wmaybe-uninitialized]
                 retbuf[j++] = sep_char;
                 ~~~~~~~~~~~~^~~~~~~~~~
Python/pystrhex.c:14:13: note: ‘sep_char’ was declared here
     Py_UCS1 sep_char;
             ^~~~~~~~
In file included from ./Include/Python.h:137,
                 from ./Modules/posixmodule.c:27:
./Modules/posixmodule.c: In function ‘all_ins’:
./Modules/posixmodule.c:14058:33: error: ‘MFD_HUGE_32MB’ undeclared (first use in this function); did you mean ‘MFD_HUGE_2MB’?
     if (PyModule_AddIntMacro(m, MFD_HUGE_32MB)) return -1;
                                 ^~~~~~~~~~~~~
./Include/modsupport.h:139:67: note: in definition of macro ‘PyModule_AddIntMacro’
 #define PyModule_AddIntMacro(m, c) PyModule_AddIntConstant(m, #c, c)
                                                                   ^
./Modules/posixmodule.c:14058:33: note: each undeclared identifier is reported only once for each function it appears in
     if (PyModule_AddIntMacro(m, MFD_HUGE_32MB)) return -1;
                                 ^~~~~~~~~~~~~
./Include/modsupport.h:139:67: note: in definition of macro ‘PyModule_AddIntMacro’
 #define PyModule_AddIntMacro(m, c) PyModule_AddIntConstant(m, #c, c)
                                                                   ^
./Modules/posixmodule.c:14060:33: error: ‘MFD_HUGE_512MB’ undeclared (first use in this function); did you mean ‘MFD_HUGE_512KB’?
     if (PyModule_AddIntMacro(m, MFD_HUGE_512MB)) return -1;
                                 ^~~~~~~~~~~~~~
./Include/modsupport.h:139:67: note: in definition of macro ‘PyModule_AddIntMacro’
 #define PyModule_AddIntMacro(m, c) PyModule_AddIntConstant(m, #c, c)
                                                                   ^
make: *** [Makefile:1865: Modules/posixmodule.o] Error 1

find: ‘build’: No such file or directory
find: ‘build’: No such file or directory
find: ‘build’: No such file or directory
find: ‘build’: No such file or directory
make: [Makefile:1763: clean] Error 1 (ignored)

[tiran]

@ZackerySpytz Please see buildbot logs. It looks like some HUGE TABLE constants are not defined on all platforms. You may have to ifdef them all :(

[ZackerySpytz]

@tiran Okay, I'll take a look.