1 #include "types.h" 2 #include "param.h" 3 #include "x86.h" 4 #include "mmu.h" 5 #include "proc.h" 6 #include "defs.h" 7 #include "file.h" 8 #include "spinlock.h" 9 10 #define PIPESIZE 512 11 12 struct pipe { 13 int readopen; // read fd is still open 14 int writeopen; // write fd is still open 15 int writep; // next index to write 16 int readp; // next index to read 17 struct spinlock lock; 18 char data[PIPESIZE]; 19 }; 20 21 int 22 pipe_alloc(struct file **f0, struct file **f1) 23 { 24 struct pipe *p; 25 26 p = 0; 27 *f0 = *f1 = 0; 28 if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0) 29 goto bad; 30 if((p = (struct pipe*)kalloc(PAGE)) == 0) 31 goto bad; 32 p->readopen = 1; 33 p->writeopen = 1; 34 p->writep = 0; 35 p->readp = 0; 36 initlock(&p->lock, "pipe"); 37 (*f0)->type = FD_PIPE; 38 (*f0)->readable = 1; 39 (*f0)->writable = 0; 40 (*f0)->pipe = p; 41 (*f1)->type = FD_PIPE; 42 (*f1)->readable = 0; 43 (*f1)->writable = 1; 44 (*f1)->pipe = p; 45 return 0; 46 47 bad: 48 if(p) 49 kfree((char*)p, PAGE); 50 if(*f0){ 51 (*f0)->type = FD_NONE; 52 fileclose(*f0); 53 } 54 if(*f1){ 55 (*f1)->type = FD_NONE; 56 fileclose(*f1); 57 } 58 return -1; 59 } 60 61 void 62 pipe_close(struct pipe *p, int writable) 63 { 64 acquire(&p->lock); 65 if(writable){ 66 p->writeopen = 0; 67 wakeup(&p->readp); 68 } else { 69 p->readopen = 0; 70 wakeup(&p->writep); 71 } 72 release(&p->lock); 73 74 if(p->readopen == 0 && p->writeopen == 0) 75 kfree((char*)p, PAGE); 76 } 77 78 //PAGEBREAK: 20 79 int 80 pipe_write(struct pipe *p, char *addr, int n) 81 { 82 int i; 83 84 acquire(&p->lock); 85 for(i = 0; i < n; i++){ 86 while(((p->writep + 1) % PIPESIZE) == p->readp){ 87 if(p->readopen == 0 || cp->killed){ 88 release(&p->lock); 89 return -1; 90 } 91 wakeup(&p->readp); 92 sleep(&p->writep, &p->lock); 93 } 94 p->data[p->writep] = addr[i]; 95 p->writep = (p->writep + 1) % PIPESIZE; 96 } 97 wakeup(&p->readp); 98 release(&p->lock); 99 return i; 100 } 101 102 int 103 pipe_read(struct pipe *p, char *addr, int n) 104 { 105 int i; 106 107 acquire(&p->lock); 108 while(p->readp == p->writep && p->writeopen){ 109 if(cp->killed){ 110 release(&p->lock); 111 return -1; 112 } 113 sleep(&p->readp, &p->lock); 114 } 115 for(i = 0; i < n; i++){ 116 if(p->readp == p->writep) 117 break; 118 addr[i] = p->data[p->readp]; 119 p->readp = (p->readp + 1) % PIPESIZE; 120 } 121 wakeup(&p->writep); 122 release(&p->lock); 123 return i; 124 } 125