xv6/pipe.c

121 lines
2.3 KiB
C
Raw Normal View History

2006-06-27 14:35:53 +00:00
#include "types.h"
2007-08-27 23:26:33 +00:00
#include "defs.h"
2006-06-27 14:35:53 +00:00
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "fs.h"
2006-09-06 18:40:28 +00:00
#include "file.h"
#include "spinlock.h"
2006-06-27 14:35:53 +00:00
#define PIPESIZE 512
struct pipe {
struct spinlock lock;
2006-06-27 14:35:53 +00:00
char data[PIPESIZE];
2009-07-13 01:33:37 +00:00
uint nread; // number of bytes read
uint nwrite; // number of bytes written
int readopen; // read fd is still open
int writeopen; // write fd is still open
2006-06-27 14:35:53 +00:00
};
int
2007-08-28 04:22:35 +00:00
pipealloc(struct file **f0, struct file **f1)
2006-06-27 14:35:53 +00:00
{
2007-08-10 16:35:01 +00:00
struct pipe *p;
2006-06-27 14:35:53 +00:00
2007-08-10 16:35:01 +00:00
p = 0;
*f0 = *f1 = 0;
2007-08-27 16:06:19 +00:00
if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0)
goto bad;
if((p = (struct pipe*)kalloc()) == 0)
2007-08-27 16:06:19 +00:00
goto bad;
p->readopen = 1;
p->writeopen = 1;
2009-07-13 01:33:37 +00:00
p->nwrite = 0;
p->nread = 0;
initlock(&p->lock, "pipe");
2006-09-08 13:44:42 +00:00
(*f0)->type = FD_PIPE;
(*f0)->readable = 1;
(*f0)->writable = 0;
(*f0)->pipe = p;
(*f1)->type = FD_PIPE;
(*f1)->readable = 0;
(*f1)->writable = 1;
(*f1)->pipe = p;
2006-06-27 14:35:53 +00:00
return 0;
2007-08-14 18:42:34 +00:00
2007-08-28 05:00:53 +00:00
//PAGEBREAK: 20
2007-08-27 16:06:19 +00:00
bad:
2006-06-27 14:35:53 +00:00
if(p)
kfree((char*)p);
2009-05-31 02:07:51 +00:00
if(*f0)
2006-09-08 13:44:42 +00:00
fileclose(*f0);
2009-05-31 02:07:51 +00:00
if(*f1)
2006-09-08 13:44:42 +00:00
fileclose(*f1);
2006-06-27 14:35:53 +00:00
return -1;
}
void
2007-08-28 04:22:35 +00:00
pipeclose(struct pipe *p, int writable)
2006-06-27 14:35:53 +00:00
{
acquire(&p->lock);
2006-09-06 18:06:04 +00:00
if(writable){
2006-06-27 14:35:53 +00:00
p->writeopen = 0;
2009-07-13 01:33:37 +00:00
wakeup(&p->nread);
2007-08-28 18:37:41 +00:00
} else {
2006-06-27 14:35:53 +00:00
p->readopen = 0;
2009-07-13 01:33:37 +00:00
wakeup(&p->nwrite);
}
if(p->readopen == 0 && p->writeopen == 0) {
release(&p->lock);
kfree((char*)p);
} else
release(&p->lock);
2006-06-27 14:35:53 +00:00
}
//PAGEBREAK: 40
2006-06-27 14:35:53 +00:00
int
2007-08-28 04:22:35 +00:00
pipewrite(struct pipe *p, char *addr, int n)
2006-06-27 14:35:53 +00:00
{
int i;
acquire(&p->lock);
2006-06-27 14:35:53 +00:00
for(i = 0; i < n; i++){
2009-07-13 01:33:37 +00:00
while(p->nwrite == p->nread + PIPESIZE) { //DOC: pipewrite-full
if(p->readopen == 0 || proc->killed){
release(&p->lock);
2006-06-27 14:35:53 +00:00
return -1;
}
2009-07-13 01:33:37 +00:00
wakeup(&p->nread);
sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep
2006-06-27 14:35:53 +00:00
}
2009-07-13 01:33:37 +00:00
p->data[p->nwrite++ % PIPESIZE] = addr[i];
2006-06-27 14:35:53 +00:00
}
2009-07-13 01:33:37 +00:00
wakeup(&p->nread); //DOC: pipewrite-wakeup1
release(&p->lock);
2009-07-13 01:33:37 +00:00
return n;
2006-06-27 14:35:53 +00:00
}
int
2007-08-28 04:22:35 +00:00
piperead(struct pipe *p, char *addr, int n)
2006-06-27 14:35:53 +00:00
{
int i;
acquire(&p->lock);
2009-07-13 01:33:37 +00:00
while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty
if(proc->killed){
release(&p->lock);
2007-08-27 16:06:19 +00:00
return -1;
}
2009-07-13 01:33:37 +00:00
sleep(&p->nread, &p->lock); //DOC: piperead-sleep
2006-06-27 14:35:53 +00:00
}
2009-07-13 01:33:37 +00:00
for(i = 0; i < n; i++){ //DOC: piperead-copy
if(p->nread == p->nwrite)
2006-06-27 14:35:53 +00:00
break;
2009-07-13 01:33:37 +00:00
addr[i] = p->data[p->nread++ % PIPESIZE];
2006-06-27 14:35:53 +00:00
}
2009-07-13 01:33:37 +00:00
wakeup(&p->nwrite); //DOC: piperead-wakeup
release(&p->lock);
2006-06-27 14:35:53 +00:00
return i;
}