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#include "types.h"
#include "param.h"
#include "x86.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "fd.h"
#include "spinlock.h"
struct spinlock fd_table_lock;
struct fd fds[NFD];
/*
* allocate a file descriptor number for curproc.
*/
int
fd_ualloc()
{
int fd;
struct proc *p = curproc[cpu()];
for(fd = 0; fd < NOFILE; fd++)
if(p->fds[fd] == 0)
return fd;
return -1;
}
/*
* allocate a file descriptor structure
*/
struct fd *
fd_alloc()
{
int i;
acquire(&fd_table_lock);
for(i = 0; i < NFD; i++){
if(fds[i].type == FD_CLOSED){
fds[i].type = FD_NONE;
fds[i].count = 1;
release(&fd_table_lock);
return fds + i;
}
}
release(&fd_table_lock);
return 0;
}
/*
* addr is a kernel address, pointing into some process's p->mem.
*/
int
fd_write(struct fd *fd, char *addr, int n)
{
if(fd->writeable == 0)
return -1;
if(fd->type == FD_PIPE){
return pipe_write(fd->pipe, addr, n);
} else {
panic("fd_write");
return -1;
}
}
int
fd_read(struct fd *fd, char *addr, int n)
{
if(fd->readable == 0)
return -1;
if(fd->type == FD_PIPE){
return pipe_read(fd->pipe, addr, n);
} else {
panic("fd_read");
return -1;
}
}
void
fd_close(struct fd *fd)
{
acquire(&fd_table_lock);
if(fd->count < 1 || fd->type == FD_CLOSED)
panic("fd_close");
fd->count -= 1;
if(fd->count == 0){
if(fd->type == FD_PIPE){
pipe_close(fd->pipe, fd->writeable);
} else {
panic("fd_close");
}
fd->count = 0;
fd->type = FD_CLOSED;
}
release(&fd_table_lock);
}
void
fd_reference(struct fd *fd)
{
acquire(&fd_table_lock);
if(fd->count < 1 || fd->type == FD_CLOSED)
panic("fd_reference");
fd->count += 1;
release(&fd_table_lock);
}
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