128 lines
2.2 KiB
C
128 lines
2.2 KiB
C
#include "types.h"
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#include "defs.h"
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#include "param.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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struct devsw devsw[NDEV];
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struct spinlock file_table_lock;
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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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// Increment ref count for file f.
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struct file*
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filedup(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("filedup");
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f->ref++;
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release(&file_table_lock);
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return f;
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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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struct file ff;
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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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release(&file_table_lock);
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return;
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}
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ff = *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(ff.type == FD_PIPE)
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pipeclose(ff.pipe, ff.writable);
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else if(ff.type == FD_INODE)
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iput(ff.ip);
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else
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panic("fileclose");
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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_INODE){
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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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}
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return -1;
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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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int r;
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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 piperead(f->pipe, addr, n);
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if(f->type == FD_INODE){
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ilock(f->ip);
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if((r = readi(f->ip, addr, f->off, n)) > 0)
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f->off += r;
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iunlock(f->ip);
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return r;
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}
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panic("fileread");
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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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int r;
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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 pipewrite(f->pipe, addr, n);
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if(f->type == FD_INODE){
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ilock(f->ip);
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if((r = writei(f->ip, addr, f->off, n)) > 0)
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f->off += r;
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iunlock(f->ip);
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return r;
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}
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panic("filewrite");
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}
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