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#include "types.h"
#include "defs.h"
#include "param.h"
#include "file.h"
#include "spinlock.h"
#include "dev.h"
struct devsw devsw[NDEV];
struct spinlock file_table_lock;
struct file file[NFILE];
void
fileinit(void)
{
initlock(&file_table_lock, "file_table");
}
// Allocate a file structure.
struct file*
filealloc(void)
{
int i;
acquire(&file_table_lock);
for(i = 0; i < NFILE; i++){
if(file[i].type == FD_CLOSED){
file[i].type = FD_NONE;
file[i].ref = 1;
release(&file_table_lock);
return file + i;
}
}
release(&file_table_lock);
return 0;
}
// Increment ref count for file f.
struct file*
filedup(struct file *f)
{
acquire(&file_table_lock);
if(f->ref < 1 || f->type == FD_CLOSED)
panic("filedup");
f->ref++;
release(&file_table_lock);
return f;
}
// Close file f. (Decrement ref count, close when reaches 0.)
void
fileclose(struct file *f)
{
struct file ff;
acquire(&file_table_lock);
if(f->ref < 1 || f->type == FD_CLOSED)
panic("fileclose");
if(--f->ref > 0){
release(&file_table_lock);
return;
}
ff = *f;
f->ref = 0;
f->type = FD_CLOSED;
release(&file_table_lock);
if(ff.type == FD_PIPE)
pipeclose(ff.pipe, ff.writable);
else if(ff.type == FD_INODE)
iput(ff.ip);
else
panic("fileclose");
}
// Get metadata about file f.
int
filestat(struct file *f, struct stat *st)
{
if(f->type == FD_INODE){
ilock(f->ip);
stati(f->ip, st);
iunlock(f->ip);
return 0;
}
return -1;
}
// Read from file f. Addr is kernel address.
int
fileread(struct file *f, char *addr, int n)
{
int r;
if(f->readable == 0)
return -1;
if(f->type == FD_PIPE)
return piperead(f->pipe, addr, n);
if(f->type == FD_INODE){
ilock(f->ip);
if((r = readi(f->ip, addr, f->off, n)) > 0)
f->off += r;
iunlock(f->ip);
return r;
}
panic("fileread");
}
// Write to file f. Addr is kernel address.
int
filewrite(struct file *f, char *addr, int n)
{
int r;
if(f->writable == 0)
return -1;
if(f->type == FD_PIPE)
return pipewrite(f->pipe, addr, n);
if(f->type == FD_INODE){
ilock(f->ip);
if((r = writei(f->ip, addr, f->off, n)) > 0)
f->off += r;
iunlock(f->ip);
return r;
}
panic("filewrite");
}