#include "types.h" #include "defs.h" #include "param.h" #include "mmu.h" #include "proc.h" #include "fs.h" #include "file.h" #include "spinlock.h" #define PIPESIZE 512 struct pipe { struct spinlock lock; char data[PIPESIZE]; 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 }; int pipealloc(struct file **f0, struct file **f1) { struct pipe *p; p = 0; *f0 = *f1 = 0; if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0) goto bad; if((p = (struct pipe*)kalloc(PAGE)) == 0) goto bad; p->readopen = 1; p->writeopen = 1; p->nwrite = 0; p->nread = 0; initlock(&p->lock, "pipe"); (*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; return 0; //PAGEBREAK: 20 bad: if(p) kfree((char*)p, PAGE); if(*f0) fileclose(*f0); if(*f1) fileclose(*f1); return -1; } void pipeclose(struct pipe *p, int writable) { acquire(&p->lock); if(writable){ p->writeopen = 0; wakeup(&p->nread); } else { p->readopen = 0; wakeup(&p->nwrite); } if(p->readopen == 0 && p->writeopen == 0) { release(&p->lock); kfree((char*)p, PAGE); } else release(&p->lock); } //PAGEBREAK: 40 int pipewrite(struct pipe *p, char *addr, int n) { int i; acquire(&p->lock); for(i = 0; i < n; i++){ while(p->nwrite == p->nread + PIPESIZE) { //DOC: pipewrite-full if(p->readopen == 0 || cp->killed){ release(&p->lock); return -1; } wakeup(&p->nread); sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep } p->data[p->nwrite++ % PIPESIZE] = addr[i]; } wakeup(&p->nread); //DOC: pipewrite-wakeup1 release(&p->lock); return n; } int piperead(struct pipe *p, char *addr, int n) { int i; acquire(&p->lock); while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty if(cp->killed){ release(&p->lock); return -1; } sleep(&p->nread, &p->lock); //DOC: piperead-sleep } for(i = 0; i < n; i++){ //DOC: piperead-copy if(p->nread == p->nwrite) break; addr[i] = p->data[p->nread++ % PIPESIZE]; } wakeup(&p->nwrite); //DOC: piperead-wakeup release(&p->lock); return i; }