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bpo-37129: Add os.RWF_APPEND flag for os.pwritev #13735

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bpo-37129: Add os.RWF_APPEND flag for os.pwritev #13735

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98608b9
add RWF_APPEND flag
bezoka Jun 1, 2019
f4ab619
📜🤖 Added by blurb_it.
blurb-it[bot] Jun 1, 2019
10c34b4
fix typo
bezoka Jun 1, 2019
d0cedc4
Merge branch 'master' of https://github.com/bezoka/cpython
bezoka Jun 1, 2019
2504743
Extend documentation
bezoka Jun 1, 2019
8ba3028
Add test to RWF_NOWAIT flag
bezoka Jun 1, 2019
884466e
remove not needed test
bezoka Jun 2, 2019
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11 changes: 11 additions & 0 deletions Doc/library/os.rst
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Expand Up @@ -1196,6 +1196,7 @@ or `the MSDN <https://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>`_ on Windo

- :data:`RWF_DSYNC`
- :data:`RWF_SYNC`
- :data:`RWF_APPEND`

Return the total number of bytes actually written.

Expand Down Expand Up @@ -1230,6 +1231,16 @@ or `the MSDN <https://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>`_ on Windo
.. versionadded:: 3.7


.. data:: RWF_APPEND

Append data to the end of the file. See the description of the flag 'O_APPEND' in ''os.open()''.
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sorry "Provide a per-write equivalent of the O_APPEND in os.open(). This flag effect applies only to the data range written by the system call. The offset argument does not affect the write operation; the data is always appended to the end of the file. However, if the offset argument is -1, the current file offset is updated." I am sure vstinner will want to change this description again :)

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'O_APPEND' should be written :data:O_APPEND.

''os.open()'' should be written :func:os.open to add a link.

But os.open() doesn't document O_APPEND, just "The above constants are available on Unix and Windows"...

I would prefer to copy preadv Linux manual page:

       RWF_APPEND (since Linux 4.16)
              Provide a per-write equivalent of  the  O_APPEND  open(2)  flag.
              This  flag  is  meaningful  only  for pwritev2(), and its effect
              applies only to the data range written by the system call.   The
              offset argument does not affect the write operation; the data is
              always appended to the end of the file.  However, if the  offset
              argument is -1, the current file offset is updated.

(Adapt it to Python names.)

The *offset* field is ignored. The file *offset* is not changed.

.. availability:: Linux 4.16 and newer.

.. versionadded:: 3.8
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Suggested change
.. versionadded:: 3.8
.. versionadded:: 3.9



.. function:: read(fd, n)

Read at most *n* bytes from file descriptor *fd*.
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2019-06-01-21-58-50.bpo-37129.Uzw_V-.rst
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@@ -0,0 +1 @@
add RWF_APPEND flag
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I suggest:

Add a new :data:`os.RWF_APPEND` flag for :func:`os.pwritev`.

1 change: 1 addition & 0 deletions Modules/clinic/posixmodule.c.h
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3 changes: 3 additions & 0 deletions Modules/posixmodule.c
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Expand Up @@ -14023,6 +14023,9 @@ all_ins(PyObject *m)
#ifdef RWF_NOWAIT
if (PyModule_AddIntConstant(m, "RWF_NOWAIT", RWF_NOWAIT)) return -1;
#endif
#ifdef RWF_APPEND
if (PyModule_AddIntConstant(m, "RWF_APPEND", RWF_APPEND)) return -1;
#endif

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Need to add - RWF_APPEND on line: 9396

/* constants for posix_spawn */
#ifdef HAVE_POSIX_SPAWN
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