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| author | Robert Morris <rtm@csail.mit.edu> | 2019-06-11 09:57:14 -0400 |
|---|---|---|
| committer | Robert Morris <rtm@csail.mit.edu> | 2019-06-11 09:57:14 -0400 |
| commit | 5753553213df8f9de851adb68377db43faecb91f (patch) | |
| tree | 3b629ff54897fca414146677532cb459a2ed11ba /kernel/pipe.c | |
| parent | 91ba81110acd3163f7de3580b677eece0c57f5e7 (diff) | |
| download | xv6-labs-5753553213df8f9de851adb68377db43faecb91f.tar.gz xv6-labs-5753553213df8f9de851adb68377db43faecb91f.tar.bz2 xv6-labs-5753553213df8f9de851adb68377db43faecb91f.zip | |
separate source into kernel/ user/ mkfs/
Diffstat (limited to 'kernel/pipe.c')
| -rw-r--r-- | kernel/pipe.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/kernel/pipe.c b/kernel/pipe.c new file mode 100644 index 0000000..31bf0cc --- /dev/null +++ b/kernel/pipe.c @@ -0,0 +1,129 @@ +#include "types.h" +#include "riscv.h" +#include "defs.h" +#include "param.h" +#include "proc.h" +#include "fs.h" +#include "spinlock.h" +#include "sleeplock.h" +#include "file.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()) == 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); + 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); + } else + release(&p->lock); +} + +//PAGEBREAK: 40 +int +pipewrite(struct pipe *p, uint64 addr, int n) +{ + int i; + char ch; + struct proc *pr = myproc(); + + acquire(&p->lock); + for(i = 0; i < n; i++){ + while(p->nwrite == p->nread + PIPESIZE){ //DOC: pipewrite-full + if(p->readopen == 0 || myproc()->killed){ + release(&p->lock); + return -1; + } + wakeup(&p->nread); + sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep + } + if(copyin(pr->pagetable, &ch, addr + i, 1) == -1) + break; + p->data[p->nwrite++ % PIPESIZE] = ch; + } + wakeup(&p->nread); //DOC: pipewrite-wakeup1 + release(&p->lock); + return n; +} + +int +piperead(struct pipe *p, uint64 addr, int n) +{ + int i; + struct proc *pr = myproc(); + char ch; + + acquire(&p->lock); + while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty + if(myproc()->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; + ch = p->data[p->nread++ % PIPESIZE]; + if(copyout(pr->pagetable, addr + i, &ch, 1) == -1) + break; + } + wakeup(&p->nwrite); //DOC: piperead-wakeup + release(&p->lock); + return i; +} |