138 lines
2.5 KiB
C
138 lines
2.5 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 "file.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 file_table_lock;
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struct devsw devsw[NDEV];
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struct file file[NFILE];
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void
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fileinit(void)
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{
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initlock(&file_table_lock, "file_table");
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}
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// Allocate a file structure
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struct file*
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filealloc(void)
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{
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int i;
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acquire(&file_table_lock);
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for(i = 0; i < NFILE; i++){
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if(file[i].type == FD_CLOSED){
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file[i].type = FD_NONE;
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file[i].ref = 1;
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release(&file_table_lock);
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return file + i;
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}
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}
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release(&file_table_lock);
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return 0;
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}
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// Write to file f. Addr is kernel address.
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int
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filewrite(struct file *f, char *addr, int n)
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{
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if(f->writable == 0)
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return -1;
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if(f->type == FD_PIPE){
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return pipe_write(f->pipe, addr, n);
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} else if(f->type == FD_FILE) {
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ilock(f->ip);
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int r = writei(f->ip, addr, f->off, n);
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if(r > 0) {
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f->off += r;
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}
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iunlock(f->ip);
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return r;
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} else {
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panic("filewrite");
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return -1;
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}
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}
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// Read from file f. Addr is kernel address.
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int
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fileread(struct file *f, char *addr, int n)
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{
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if(f->readable == 0)
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return -1;
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if(f->type == FD_PIPE){
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return pipe_read(f->pipe, addr, n);
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} else if(f->type == FD_FILE){
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ilock(f->ip);
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int cc = readi(f->ip, addr, f->off, n);
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if(cc > 0)
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f->off += cc;
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iunlock(f->ip);
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return cc;
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} else {
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panic("fileread");
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return -1;
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}
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}
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// Close file f. (Decrement ref count, close when reaches 0.)
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void
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fileclose(struct file *f)
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{
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acquire(&file_table_lock);
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if(f->ref < 1 || f->type == FD_CLOSED)
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panic("fileclose");
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if(--f->ref == 0){
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struct file dummy = *f;
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f->ref = 0;
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f->type = FD_CLOSED;
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release(&file_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("fileclose");
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}
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} else {
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release(&file_table_lock);
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}
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}
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// Get metadata about file f.
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int
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filestat(struct file *f, struct stat *st)
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{
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if(f->type == FD_FILE){
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ilock(f->ip);
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stati(f->ip, st);
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iunlock(f->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 ref count for file f.
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void
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fileincref(struct file *f)
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{
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acquire(&file_table_lock);
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if(f->ref < 1 || f->type == FD_CLOSED)
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panic("fileincref");
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f->ref++;
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release(&file_table_lock);
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}
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