[issue12103] Documentation of open() does not claim 'e' support in mode string
New submission from Марк Коренберг <socketpair@gmail.com>: open() and friends (like temporaryfile) does not document 'e' letter in second arguement. At least on Linux, it opens file with O_CLOEXEC. Not sure under Windows. Also, there are other interesting letters (man -a fopen), like: c (since glibc 2.3.3) Do not make the open operation, or subsequent read and write operations, thread cancellation points. e (since glibc 2.7) Open the file with the O_CLOEXEC flag. See open(2) for more information. m (since glibc 2.3) Attempt to access the file using mmap(2), rather than I/O system calls (read(2), write(2)). Currently, use of mmap(2) is only attempted for a file opened for reading. x Open the file exclusively (like the O_EXCL flag of open(2)). If the file already exists, fopen() fails, and sets errno to EEXIST. This flag is ignored for fdopen(). ---------- assignee: docs@python components: Documentation messages: 136223 nosy: docs@python, mmarkk priority: normal severity: normal status: open title: Documentation of open() does not claim 'e' support in mode string _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
Changes by Марк Коренберг <socketpair@gmail.com>: ---------- type: -> behavior _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
STINNER Victor <victor.stinner@haypocalc.com> added the comment: c, e, m and x flags are specific to the GNU libc. Python 2 does basically pass the mode to fopen() unmodified (there is one exception, the U flag). fopen() of Visual C++ 2005 has other flags: c Enable the commit flag for the associated filename so that the contents of the file buffer are written directly to disk if either fflush or _flushall is called. n Reset the commit flag for the associated filename to "no-commit." This is the default. It also overrides the global commit flag if you link your program with COMMODE.OBJ. The global commit flag default is "no-commit" unless you explicitly link your program with COMMODE.OBJ (see Link Options). N Specifies that the file is not inherited by child processes. S Specifies that caching is optimized for, but not restricted to, sequential access from disk. R Specifies that caching is optimized for, but not restricted to, random access from disk. T Specifies a file as temporary. If possible, it is not flushed to disk. D Specifies a file as temporary. It is deleted when the last file pointer is closed. ccs=ENCODING Specifies the coded character set to use (UTF-8, UTF-16LE, or UNICODE) for this file. Leave unspecified if you want ANSI encoding. This option is available in Visual C++ 2005 and later. http://msdn.microsoft.com/en-us/library/yeby3zcb(v=vs.80).aspx I don't think that non standard modes should be documented in Python doc, but we may add links to specific documentations like the GNU libc and Microsoft fopen(). -- This issue is specific to Python 2, Python 3 doesn't use fopen() anymore. ---------- nosy: +haypo versions: +Python 2.7 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
STINNER Victor <victor.stinner@haypocalc.com> added the comment: Issue #12105 adds os.O_CLOEXEC flag, so we will be able to write open(os.open(filename, os.O_RDONLY|os.O_CLOEXEC)). Do you want to work on a doc patch? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
Changes by Éric Araujo <merwok@netwok.org>: ---------- keywords: +easy nosy: +eric.araujo title: Documentation of open() does not claim 'e' support in mode string -> Document how to use open with os.O_CLOEXEC versions: +Python 3.3 -Python 2.7 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
STINNER Victor added the comment:
x Open the file exclusively (like the O_EXCL flag of open(2)). If the file already exists, fopen() fails, and sets errno to EEXIST. This flag is ignored for fdopen().
Python 3.3 adds support for this mode: see issue #12760.
e (since glibc 2.7) Open the file with the O_CLOEXEC flag. See open(2) for more information.
I created the issue #16850 for this mode. -- Other modes seem to be very specific to some platforms. I don't think that it would be possible to expose them in a portable way using the open() function directly. Can we close this issue? I prefer to work on #16850 for the close-on-exec mode. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
Christian Heimes added the comment: Sounds good to me. ---------- nosy: +christian.heimes resolution: -> out of date status: open -> closed _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12103> _______________________________________
participants (4)
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Christian Heimes -
STINNER Victor
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Éric Araujo
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Марк Коренберг