file.c

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#include <core/system.h>
#include <core/panic.h>
#include <fs/vfs.h>
#include <sys/proc.h>
#include <sys/thread.h>
#include <sys/sched.h>
 
MALLOC_DEFINE(M_FILE, "file", "open file");

struct file *file_new(void)
{
    struct file *file = kmalloc(sizeof(struct file), &M_FILE, M_ZERO);
 
    if (file)
        file->ref = 1;
 
    return file;
}

struct file *file_ref(struct file *file)
{
    file->ref++;
    return file;
}

int file_put(struct file *file)
{
    if (!file->ref)
        panic("file_put: a file no one refers to");
 
    if (--file->ref)
        return 0;
 
    /* a file that was set up only halfway (its open failed) has
     * nothing to close */
    int err = file->vnode ? vfs_file_close(file) : 0;
 
    kfree(file);
    return err;
}

struct file *file_hold(struct file *file)
{
    struct thread *thread = curthread;
 
    if (thread->files_held == THREAD_FILES_HELD)
        panic("file_hold: a system call holds too many files");
 
    thread->files[thread->files_held++] = file_ref(file);
    return file;
}

void thread_files_release(struct thread *thread)
{
    while (thread->files_held)
        file_put(thread->files[--thread->files_held]);
}