1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
#include "types.h"
#include "riscv.h"
#include "defs.h"
#include "param.h"
#include "spinlock.h"
#include "proc.h"
#include "fs.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 *pi;
pi = 0;
*f0 = *f1 = 0;
if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0)
goto bad;
if((pi = (struct pipe*)kalloc()) == 0)
goto bad;
pi->readopen = 1;
pi->writeopen = 1;
pi->nwrite = 0;
pi->nread = 0;
initlock(&pi->lock, "pipe");
(*f0)->type = FD_PIPE;
(*f0)->readable = 1;
(*f0)->writable = 0;
(*f0)->pipe = pi;
(*f1)->type = FD_PIPE;
(*f1)->readable = 0;
(*f1)->writable = 1;
(*f1)->pipe = pi;
return 0;
bad:
if(pi)
kfree((char*)pi);
if(*f0)
fileclose(*f0);
if(*f1)
fileclose(*f1);
return -1;
}
void
pipeclose(struct pipe *pi, int writable)
{
acquire(&pi->lock);
if(writable){
pi->writeopen = 0;
wakeup(&pi->nread);
} else {
pi->readopen = 0;
wakeup(&pi->nwrite);
}
if(pi->readopen == 0 && pi->writeopen == 0){
release(&pi->lock);
kfree((char*)pi);
} else
release(&pi->lock);
}
int
pipewrite(struct pipe *pi, uint64 addr, int n)
{
int i = 0;
struct proc *pr = myproc();
acquire(&pi->lock);
while(i < n){
if(pi->readopen == 0 || killed(pr)){
release(&pi->lock);
return -1;
}
if(pi->nwrite == pi->nread + PIPESIZE){ //DOC: pipewrite-full
wakeup(&pi->nread);
sleep(&pi->nwrite, &pi->lock);
} else {
char ch;
if(copyin(pr->pagetable, &ch, addr + i, 1) == -1)
break;
pi->data[pi->nwrite++ % PIPESIZE] = ch;
i++;
}
}
wakeup(&pi->nread);
release(&pi->lock);
return i;
}
int
piperead(struct pipe *pi, uint64 addr, int n)
{
int i;
struct proc *pr = myproc();
char ch;
acquire(&pi->lock);
while(pi->nread == pi->nwrite && pi->writeopen){ //DOC: pipe-empty
if(killed(pr)){
release(&pi->lock);
return -1;
}
sleep(&pi->nread, &pi->lock); //DOC: piperead-sleep
}
for(i = 0; i < n; i++){ //DOC: piperead-copy
if(pi->nread == pi->nwrite)
break;
ch = pi->data[pi->nread++ % PIPESIZE];
if(copyout(pr->pagetable, addr + i, &ch, 1) == -1)
break;
}
wakeup(&pi->nwrite); //DOC: piperead-wakeup
release(&pi->lock);
return i;
}
|
