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