[issue17428] replace readdir to readdir_r in function posix_listdir
New submission from Rock Li: When I'm how glob module is implemented. I found in file posixmodule.c, the function posix_listdir is using readdir to get all the entries under one directory and the context is setted to allow multi threads. But the function readdir is not thread-safe, so I changed this call to use readdir_r instead. I'm using the lastest codes in the repo. -- components: Extension Modules files: mywork.patch keywords: patch messages: 184224 nosy: Rock priority: normal severity: normal status: open title: replace readdir to readdir_r in function posix_listdir type: enhancement versions: Python 3.4 Added file: http://bugs.python.org/file29413/mywork.patch ___ Python tracker <http://bugs.python.org/issue17428> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue17428] replace readdir to readdir_r in function posix_listdir
Rock Li added the comment: Hi Ross, What about if one implementation of posix use the global variable to store something. From `man readdir`, I didn't see the sentence "This data is not overwritten by another call to readdir() on a different directory stream.". And from the link you gived, "" Background The POSIX readdir_r function is a thread-safe version of the readdir function used to read directory entries. Whereas readdir returns a pointer to a system-allocated buffer and may use global state without mutual exclusion, readdir_r uses a user-supplied buffer and is guaranteed to be reentrant. Its use is therefore preferable or even essential in portable multithreaded programs. "" Actually readdir_r is guaranteed to be reentrant. By using readdir, I think just like to use errno in a multi thread programs, we can't always think it will work as the right way. But readdir_r, we can. And another question, you say "struct dirent should not be allocated on the stack since the last field may be an unspecified size." What does this mean? Can you explain detail to me? Thx. -- ___ Python tracker <http://bugs.python.org/issue17428> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue17428] replace readdir to readdir_r in function posix_listdir
Rock Li added the comment: You are right. I checked the GLibc implementation of readdir and readdir_r, there's no global variale used in the function readdir. Just as the POSIX standards says, "This data is not overwritten by another call to readdir() on a different directory stream". To the second question, now I understood. POSIX does not specify the size of the d_name field. This will cause our codes a bit inconvenient. Next time, I will check the POSIX specifications and related several implementations first, not just the documents. Thx All. -- status: open -> closed ___ Python tracker <http://bugs.python.org/issue17428> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
