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1 #include "types.h"
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2 #include "defs.h"
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3 #include "param.h"
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4 #include "mmu.h"
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5 #include "proc.h"
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6 #include "fs.h"
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7 #include "file.h"
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8 #include "spinlock.h"
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9
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10 #define PIPESIZE 512
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11
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12 struct pipe {
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13 struct spinlock lock;
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14 char data[PIPESIZE];
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15 uint nread; // number of bytes read
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16 uint nwrite; // number of bytes written
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17 int readopen; // read fd is still open
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18 int writeopen; // write fd is still open
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19 };
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20
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21 int pipealloc(struct file **f0, struct file **f1)
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22 {
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23 struct pipe *p;
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24
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25 p = 0;
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26 *f0 = *f1 = 0;
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27
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28 if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0) {
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29 goto bad;
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30 }
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31
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32 if((p = kmalloc (get_order(sizeof(*p)))) == 0) {
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33 goto bad;
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34 }
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35
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36 p->readopen = 1;
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37 p->writeopen = 1;
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38 p->nwrite = 0;
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39 p->nread = 0;
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40
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41 initlock(&p->lock, "pipe");
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42
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43 (*f0)->type = FD_PIPE;
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44 (*f0)->readable = 1;
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45 (*f0)->writable = 0;
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46 (*f0)->pipe = p;
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47 (*f1)->type = FD_PIPE;
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48 (*f1)->readable = 0;
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49 (*f1)->writable = 1;
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50 (*f1)->pipe = p;
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51
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52 return 0;
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53
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54 //PAGEBREAK: 20
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55 bad:
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56 if(p) {
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57 kfree (p, get_order(sizeof*p));
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58 }
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59
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60 if(*f0) {
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61 fileclose(*f0);
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62 }
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63
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64 if(*f1) {
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65 fileclose(*f1);
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66 }
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67
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68 return -1;
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69 }
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70
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71 void pipeclose(struct pipe *p, int writable)
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72 {
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73 acquire(&p->lock);
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74
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75 if(writable){
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76 p->writeopen = 0;
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77 wakeup(&p->nread);
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78
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79 } else {
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80 p->readopen = 0;
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81 wakeup(&p->nwrite);
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82 }
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83
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84 if(p->readopen == 0 && p->writeopen == 0){
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85 release(&p->lock);
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86 kfree (p, get_order(sizeof(*p)));
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87
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88 } else {
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89 release(&p->lock);
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90 }
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91 }
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92
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93 //PAGEBREAK: 40
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94 int pipewrite(struct pipe *p, char *addr, int n)
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95 {
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96 int i;
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97
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98 acquire(&p->lock);
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99
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100 for(i = 0; i < n; i++){
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101 while(p->nwrite == p->nread + PIPESIZE){ //DOC: pipewrite-full
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102 if(p->readopen == 0 /*|| proc->killed*/){
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103 release(&p->lock);
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104 return -1;
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105 }
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106
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107 wakeup(&p->nread);
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108 sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep
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109 }
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110
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111 p->data[p->nwrite++ % PIPESIZE] = addr[i];
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112 }
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113
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114 wakeup(&p->nread); //DOC: pipewrite-wakeup1
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115 release(&p->lock);
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116 return n;
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117 }
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118
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119 int piperead(struct pipe *p, char *addr, int n)
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120 {
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121 int i;
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122
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123 acquire(&p->lock);
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124
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125 while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty
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126 if(proc->killed){
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127 release(&p->lock);
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128 return -1;
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129 }
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130
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131 sleep(&p->nread, &p->lock); //DOC: piperead-sleep*/
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132 }
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133
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134 for(i = 0; i < n; i++){ //DOC: piperead-copy
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135 if(p->nread == p->nwrite) {
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136 break;
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137 }
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138
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139 addr[i] = p->data[p->nread++ % PIPESIZE];
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140 }
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141
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142 wakeup(&p->nwrite); //DOC: piperead-wakeup
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143 release(&p->lock);
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144
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145 return i;
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146 }
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