By experiment, we can know that all the fields of struct file are copied to the child. Here is what it happens. When fork() is executed, * A new array of struct file is created for the child. * All the entries of the fd array of the parent is copied into the new array of the child. * Now both the parent and the child point to the same struct file pointer for every opened file that has been opened before fork. * f_count (file object's usage count) is incremented by 1, indicating that there is one more task that is using this particular file object. This comes handy when a task invokes close(), i.e. when close() function is invoked by any task, the kernel just decrements this reference count. When the reference count is 0, VFS, invokes the release() function of the driver associated with this file and frees the respective file object. Hope this helps... Regards, Prabhu On Wed, Jan 26, 2011 at 4:29 PM, Daniel Baluta <daniel.baluta@gmail.com>wrote:
Hi all,
We know that each file descriptor fd, has an associated 'struct file'. How is the 'struct file' copied/cloned at fork?
Are all fields of 'struct file' inherited by child? I want to know if there is a function which takes a struct file* and creates a consistent copy/clone of it.
thanks, Daniel.
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