os.writev() behaviour unpredictable when hitting file system full (28)

Bug report

os.writev() has an unpredictable behaviour when writing on a file system that becomes full:

For example:

try:
    fd=os.open(file,  os.O_WRONLY|os.O_CREAT|os.O_APPEND)
    result = os.writev(fd,iovtable[0:MAXIOV])
except OSError as e:
    ...
    # at this point result might return some bytes written (not necessarly corresponding to iov lengths, or even not be defined at all.

Your environment

centos 7.
Python 3.9 (but probably the same on 3.11)

This can easily be worked around by specifying in the documentation that os.writev() returns the actual number of bytes written in case of success, but the contents of the return value are unpredicatbale in case of errors.

從 os.writev() 的文件開始，檢視其中目前如何描述回傳值和 OSError 行為。將這些措辭與回報的檔案系統已滿情況進行比較；完成的標準是文件明確說明呼叫端在成功後和發生錯誤後可以依賴什麼。