def lock_and_write_buffer(obj, fname, offset, size):
"""Write the contents of a buffer to disk at a given offset, and explicitly
lock the region of the file whilst doing so.
Parameters
----------
obj : buffer
Data to write to disk.
fname : string
Filename to write.
offset : integer
Offset into the file to start writing at.
size : integer
Size of the region to write to (and lock).
"""
import os
import os.fcntl as fcntl
buf = buffer(obj)
if len(buf) > size:
raise Exception("Size doesn't match array length.")
fd = os.open(fname, os.O_RDRW | os.O_CREAT)
fcntl.lockf(fd, fcntl.LOCK_EX, size, offset, os.SEEK_SET)
nb = os.write(fd, buf)
if nb != len(buf):
raise Exception("Something funny happened with the reading.")
fcntl.lockf(fd, fcntl.LOCK_UN)
os.close(fd)
def lock_and_write_buffer(obj, fname, offset, size):
"""Write the contents of a buffer to disk at a given offset, and explicitly
lock the region of the file whilst doing so.
Parameters
----------
obj : buffer
Data to write to disk.
fname : string
Filename to write.
offset : integer
Offset into the file to start writing at.
size : integer
Size of the region to write to (and lock).
"""
import os
import os.fcntl as fcntl
buf = buffer(obj)
if len(buf) > size:
raise Exception("Size doesn't match array length.")
fd = os.open(fname, os.O_RDRW | os.O_CREAT)
fcntl.lockf(fd, fcntl.LOCK_EX, size, offset, os.SEEK_SET)
nb = os.write(fd, buf)
if nb != len(buf):
raise Exception("Something funny happened with the reading.")
fcntl.lockf(fd, fcntl.LOCK_UN)
os.close(fd)