156 lines
3.2 KiB
C
156 lines
3.2 KiB
C
//
|
|
// File descriptors
|
|
//
|
|
|
|
#include "types.h"
|
|
#include "defs.h"
|
|
#include "param.h"
|
|
#include "fs.h"
|
|
#include "spinlock.h"
|
|
#include "sleeplock.h"
|
|
#include "file.h"
|
|
|
|
struct devsw devsw[NDEV];
|
|
struct {
|
|
struct spinlock lock;
|
|
struct file file[NFILE];
|
|
} ftable;
|
|
|
|
void fileinit(void) {
|
|
initlock(&ftable.lock, "ftable");
|
|
}
|
|
|
|
// Allocate a file structure.
|
|
struct file* filealloc(void) {
|
|
struct file *f;
|
|
|
|
acquire(&ftable.lock);
|
|
for (f = ftable.file; f < ftable.file + NFILE; f++) {
|
|
if (f->ref == 0) {
|
|
f->ref = 1;
|
|
release(&ftable.lock);
|
|
return f;
|
|
}
|
|
}
|
|
release(&ftable.lock);
|
|
return 0;
|
|
}
|
|
|
|
// Increment ref count for file f.
|
|
struct file* filedup(struct file *f) {
|
|
acquire(&ftable.lock);
|
|
if (f->ref < 1) {
|
|
panic("filedup");
|
|
}
|
|
f->ref++;
|
|
release(&ftable.lock);
|
|
return f;
|
|
}
|
|
|
|
// Close file f. (Decrement ref count, close when reaches 0.)
|
|
void fileclose(struct file *f) {
|
|
struct file ff;
|
|
|
|
acquire(&ftable.lock);
|
|
if (f->ref < 1) {
|
|
panic("fileclose");
|
|
}
|
|
if (--f->ref > 0) {
|
|
release(&ftable.lock);
|
|
return;
|
|
}
|
|
ff = *f;
|
|
f->ref = 0;
|
|
f->type = FD_NONE;
|
|
release(&ftable.lock);
|
|
|
|
if (ff.type == FD_PIPE) {
|
|
pipeclose(ff.pipe, ff.writable);
|
|
}
|
|
else if (ff.type == FD_INODE) {
|
|
begin_op();
|
|
iput(ff.ip);
|
|
end_op();
|
|
}
|
|
}
|
|
|
|
// Get metadata about file f.
|
|
int filestat(struct file *f, struct stat *st) {
|
|
if (f->type == FD_INODE) {
|
|
ilock(f->ip);
|
|
stati(f->ip, st);
|
|
iunlock(f->ip);
|
|
return 0;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
// Read from file f.
|
|
int fileread(struct file *f, char *addr, int n) {
|
|
int r;
|
|
|
|
if (f->readable == 0) {
|
|
return -1;
|
|
}
|
|
if (f->type == FD_PIPE) {
|
|
return piperead(f->pipe, addr, n);
|
|
}
|
|
if (f->type == FD_INODE) {
|
|
ilock(f->ip);
|
|
if ((r = readi(f->ip, addr, f->off, n)) > 0) {
|
|
f->off += r;
|
|
}
|
|
iunlock(f->ip);
|
|
return r;
|
|
}
|
|
panic("fileread");
|
|
}
|
|
|
|
|
|
// Write to file f.
|
|
int filewrite(struct file *f, char *addr, int n) {
|
|
int r;
|
|
|
|
if (f->writable == 0) {
|
|
return -1;
|
|
}
|
|
if (f->type == FD_PIPE) {
|
|
return pipewrite(f->pipe, addr, n);
|
|
}
|
|
if (f->type == FD_INODE) {
|
|
// write a few blocks at a time to avoid exceeding
|
|
// the maximum log transaction size, including
|
|
// i-node, indirect block, allocation blocks,
|
|
// and 2 blocks of slop for non-aligned writes.
|
|
// this really belongs lower down, since writei()
|
|
// might be writing a device like the console.
|
|
int max = ((MAXOPBLOCKS - 1 - 1 - 2) / 2) * 512;
|
|
int i = 0;
|
|
while (i < n) {
|
|
int n1 = n - i;
|
|
if (n1 > max) {
|
|
n1 = max;
|
|
}
|
|
|
|
begin_op();
|
|
ilock(f->ip);
|
|
if ((r = writei(f->ip, addr + i, f->off, n1)) > 0) {
|
|
f->off += r;
|
|
}
|
|
iunlock(f->ip);
|
|
end_op();
|
|
|
|
if (r < 0) {
|
|
break;
|
|
}
|
|
if (r != n1) {
|
|
panic("short filewrite");
|
|
}
|
|
i += r;
|
|
}
|
|
return i == n ? n : -1;
|
|
}
|
|
panic("filewrite");
|
|
}
|
|
|