151 lines
2.7 KiB
C
151 lines
2.7 KiB
C
#include "types.h"
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#include "stat.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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#include "dev.h"
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#include "fs.h"
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#include "fsvar.h"
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struct spinlock fd_table_lock;
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struct devsw devsw[NDEV];
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struct fd fds[NFD];
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void
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fd_init(void)
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{
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initlock(&fd_table_lock, "fd_table");
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}
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// Allocate a file descriptor number for curproc.
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int
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fd_ualloc(void)
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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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// Allocate a file descriptor structure
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struct fd*
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fd_alloc(void)
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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].ref = 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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// Write to file descriptor;
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// addr is a kernel address, pointing into some process's p->mem.
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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->writable == 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 if(fd->type == FD_FILE) {
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ilock(fd->ip);
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int r = writei(fd->ip, addr, fd->off, n);
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if(r > 0) {
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fd->off += r;
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}
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iunlock(fd->ip);
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return r;
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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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// Read from file descriptor.
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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 if(fd->type == FD_FILE){
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ilock(fd->ip);
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int cc = readi(fd->ip, addr, fd->off, n);
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if(cc > 0)
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fd->off += cc;
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iunlock(fd->ip);
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return cc;
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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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// Close file descriptor.
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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->ref < 1 || fd->type == FD_CLOSED)
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panic("fd_close");
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if(--fd->ref == 0){
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struct fd dummy = *fd;
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fd->ref = 0;
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fd->type = FD_CLOSED;
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release(&fd_table_lock);
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if(dummy.type == FD_PIPE){
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pipe_close(dummy.pipe, dummy.writable);
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} else if(dummy.type == FD_FILE){
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idecref(dummy.ip);
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} else {
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panic("fd_close");
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}
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} else {
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release(&fd_table_lock);
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}
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}
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// Get metadata about file descriptor.
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int
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fd_stat(struct fd *fd, struct stat *st)
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{
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if(fd->type == FD_FILE){
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ilock(fd->ip);
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stati(fd->ip, st);
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iunlock(fd->ip);
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return 0;
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} else
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return -1;
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}
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// Increment file descriptor reference count.
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void
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fd_incref(struct fd *fd)
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{
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acquire(&fd_table_lock);
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if(fd->ref < 1 || fd->type == FD_CLOSED)
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panic("fd_incref");
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fd->ref++;
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release(&fd_table_lock);
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}
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