1a81e38b17
Variable declarations at top of function,
separate from initialization.
Use == 0 instead of ! for checking pointers.
Consistent spacing around {, *, casts.
Declare 0-parameter functions as (void) not ().
Integer valued functions return -1 on failure, 0 on success.
120 lines
2.3 KiB
C
120 lines
2.3 KiB
C
#include "types.h"
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#include "defs.h"
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#include "param.h"
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#include "mmu.h"
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#include "proc.h"
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#include "fs.h"
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#include "file.h"
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#include "spinlock.h"
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#define PIPESIZE 512
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struct pipe {
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struct spinlock lock;
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char data[PIPESIZE];
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uint nread; // number of bytes read
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uint nwrite; // number of bytes written
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int readopen; // read fd is still open
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int writeopen; // write fd is still open
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};
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int
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pipealloc(struct file **f0, struct file **f1)
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{
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struct pipe *p;
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p = 0;
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*f0 = *f1 = 0;
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if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0)
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goto bad;
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if((p = (struct pipe*)kalloc()) == 0)
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goto bad;
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p->readopen = 1;
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p->writeopen = 1;
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p->nwrite = 0;
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p->nread = 0;
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initlock(&p->lock, "pipe");
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(*f0)->type = FD_PIPE;
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(*f0)->readable = 1;
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(*f0)->writable = 0;
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(*f0)->pipe = p;
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(*f1)->type = FD_PIPE;
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(*f1)->readable = 0;
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(*f1)->writable = 1;
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(*f1)->pipe = p;
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return 0;
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//PAGEBREAK: 20
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bad:
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if(p)
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kfree((char*)p);
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if(*f0)
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fileclose(*f0);
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if(*f1)
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fileclose(*f1);
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return -1;
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}
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void
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pipeclose(struct pipe *p, int writable)
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{
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acquire(&p->lock);
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if(writable){
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p->writeopen = 0;
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wakeup(&p->nread);
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} else {
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p->readopen = 0;
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wakeup(&p->nwrite);
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}
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if(p->readopen == 0 && p->writeopen == 0){
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release(&p->lock);
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kfree((char*)p);
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} else
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release(&p->lock);
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}
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//PAGEBREAK: 40
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int
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pipewrite(struct pipe *p, char *addr, int n)
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{
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int i;
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acquire(&p->lock);
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for(i = 0; i < n; i++){
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while(p->nwrite == p->nread + PIPESIZE){ //DOC: pipewrite-full
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if(p->readopen == 0 || proc->killed){
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release(&p->lock);
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return -1;
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}
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wakeup(&p->nread);
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sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep
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}
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p->data[p->nwrite++ % PIPESIZE] = addr[i];
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}
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wakeup(&p->nread); //DOC: pipewrite-wakeup1
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release(&p->lock);
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return n;
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}
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int
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piperead(struct pipe *p, char *addr, int n)
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{
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int i;
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acquire(&p->lock);
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while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty
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if(proc->killed){
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release(&p->lock);
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return -1;
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}
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sleep(&p->nread, &p->lock); //DOC: piperead-sleep
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}
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for(i = 0; i < n; i++){ //DOC: piperead-copy
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if(p->nread == p->nwrite)
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break;
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addr[i] = p->data[p->nread++ % PIPESIZE];
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}
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wakeup(&p->nwrite); //DOC: piperead-wakeup
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release(&p->lock);
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return i;
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}
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