22.1.1 File Operations

locking(fd, mode, nbytes): Lock part of a file based on file descriptor fd from the C runtime. Raises IOError on failure. The locked region of the file extends from the current file position for nbytes bytes, and may continue beyond the end of the file. mode must be one of the LK_* constants listed below. Multiple regions in a file may be locked at the same time, but may not overlap. Adjacent regions are not merged; they must be unlocked individually.

LK_LOCK
LK_RLCK: Locks the specified bytes. If the bytes cannot be locked, the program immediately tries again after 1 second. If, after 10 attempts, the bytes cannot be locked, IOError is raised.

LK_NBLCK
LK_NBRLCK: Locks the specified bytes. If the bytes cannot be locked, IOError is raised.

LK_UNLCK: Unlocks the specified bytes, which must have been previously locked.

setmode(fd, flags): Set the line-end translation mode for the file descriptor fd. To set it to text mode, flags should be os.O_TEXT; for binary, it should be os.O_BINARY.

open_osfhandle(handle, flags): Create a C runtime file descriptor from the file handle handle. The flags parameter should be a bit-wise OR of os.O_APPEND, os.O_RDONLY, and os.O_TEXT. The returned file descriptor may be used as a parameter to os.fdopen() to create a file object.

get_osfhandle(fd): Return the file handle for the file descriptor fd. Raises IOError if fd is not recognized.

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