Open files (struct file, in fs/vfs.h): what open(), pipe(), socket() and accept() make, and what descriptors refer to. More...

#include <core/system.h>
#include <core/panic.h>
#include <fs/vfs.h>
#include <sys/proc.h>
#include <sys/thread.h>
#include <sys/sched.h>

Functions
struct file *	file_new (void)
	Makes a new open file, with one reference.
struct file *	file_ref (struct file *file)
	Adds a reference to an open file.
int	file_put (struct file *file)
	Drops a reference to an open file.
struct file *	file_hold (struct file *file)
	Holds an open file for the current system call, until it returns.
void	thread_files_release (struct thread *thread)
	Lets go of the open files a thread's system call held, when the call returns or the thread is killed.

Detailed Description

Open files (struct file, in fs/vfs.h): what open(), pipe(), socket() and accept() make, and what descriptors refer to.

An open file is shared by everything that refers to it: descriptors that dup() and fork() copied share it, with its offset and status flags (what POSIX calls an open file description). It counts its references, from descriptors and from system calls using it. When the last one goes, the file is closed (the filesystem's or the device's close runs once) and freed.

A system call holds the files it uses (file_hold()) until it returns, so that a close() by another thread meanwhile can't free a file under it. The thread keeps the list, so a thread killed in the middle of a call lets go of them too.

Definition in file file.c.