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) 29 goto oops; 30 if((*f1 = filealloc()) == 0) 31 goto oops; 32 if((p = (struct pipe*) kalloc(PAGE)) == 0) 33 goto oops; 34 p->readopen = 1; 35 p->writeopen = 1; 36 p->writep = 0; 37 p->readp = 0; 38 initlock(&p->lock, "pipe"); 39 (*f0)->type = FD_PIPE; 40 (*f0)->readable = 1; 41 (*f0)->writable = 0; 42 (*f0)->pipe = p; 43 (*f1)->type = FD_PIPE; 44 (*f1)->readable = 0; 45 (*f1)->writable = 1; 46 (*f1)->pipe = p; 47 return 0; 48 oops: 49 if(p) 50 kfree((char*) p, PAGE); 51 if(*f0){ 52 (*f0)->type = FD_NONE; 53 fileclose(*f0); 54 } 55 if(*f1){ 56 (*f1)->type = FD_NONE; 57 fileclose(*f1); 58 } 59 return -1; 60 } 61 62 void 63 pipe_close(struct pipe *p, int writable) 64 { 65 acquire(&p->lock); 66 67 if(writable){ 68 p->writeopen = 0; 69 wakeup(&p->readp); 70 } else { 71 p->readopen = 0; 72 wakeup(&p->writep); 73 } 74 75 release(&p->lock); 76 77 if(p->readopen == 0 && p->writeopen == 0) 78 kfree((char*) p, PAGE); 79 } 80 81 int 82 pipe_write(struct pipe *p, char *addr, int n) 83 { 84 int i; 85 86 acquire(&p->lock); 87 88 for(i = 0; i < n; i++){ 89 while(((p->writep + 1) % PIPESIZE) == p->readp){ 90 if(p->readopen == 0 || curproc[cpu()]->killed){ 91 release(&p->lock); 92 return -1; 93 } 94 wakeup(&p->readp); 95 sleep(&p->writep, &p->lock); 96 } 97 p->data[p->writep] = addr[i]; 98 p->writep = (p->writep + 1) % PIPESIZE; 99 } 100 101 release(&p->lock); 102 wakeup(&p->readp); 103 return i; 104 } 105 106 int 107 pipe_read(struct pipe *p, char *addr, int n) 108 { 109 int i; 110 111 acquire(&p->lock); 112 113 while(p->readp == p->writep){ 114 if(p->writeopen == 0 || curproc[cpu()]->killed){ 115 release(&p->lock); 116 return 0; 117 } 118 sleep(&p->readp, &p->lock); 119 } 120 121 for(i = 0; i < n; i++){ 122 if(p->readp == p->writep) 123 break; 124 addr[i] = p->data[p->readp]; 125 p->readp = (p->readp + 1) % PIPESIZE; 126 } 127 128 release(&p->lock); 129 wakeup(&p->writep); 130 return i; 131 } 132