1 #include <u.h>
2 #include <libc.h>
3 #include <thread.h>
4 #include "ioproc.h"
5 
6 enum
7 {
8 	STACK = 32768,
9 };
10 
11 void
12 iointerrupt(Ioproc *io)
13 {
14 	if(!io->inuse)
15 		return;
16 	fprint(2, "bug: cannot iointerrupt yet\n");
17 }
18 
19 static void
20 xioproc(void *a)
21 {
22 	Ioproc *io, *x;
23 	io = a;
24 	/*
25 	 * first recvp acquires the ioproc.
26 	 * second tells us that the data is ready.
27 	 */
28 	for(;;){
29 		while(recv(io->c, &x) == -1)
30 			;
31 		if(x == 0)	/* our cue to leave */
32 			break;
33 		assert(x == io);
34 
35 		/* caller is now committed -- even if interrupted he'll return */
36 		while(recv(io->creply, &x) == -1)
37 			;
38 		if(x == 0)	/* caller backed out */
39 			continue;
40 		assert(x == io);
41 
42 		io->ret = io->op(&io->arg);
43 		if(io->ret < 0)
44 			rerrstr(io->err, sizeof io->err);
45 		while(send(io->creply, &io) == -1)
46 			;
47 		while(recv(io->creply, &x) == -1)
48 			;
49 	}
50 }
51 
52 Ioproc*
53 ioproc(void)
54 {
55 	Ioproc *io;
56 
57 	io = mallocz(sizeof(*io), 1);
58 	if(io == nil)
59 		sysfatal("ioproc malloc: %r");
60 	io->c = chancreate(sizeof(void*), 0);
61 	chansetname(io->c, "ioc%p", io->c);
62 	io->creply = chancreate(sizeof(void*), 0);
63 	chansetname(io->creply, "ior%p", io->c);
64 	io->tid = proccreate(xioproc, io, STACK);
65 	return io;
66 }
67 
68 void
69 closeioproc(Ioproc *io)
70 {
71 	if(io == nil)
72 		return;
73 	iointerrupt(io);
74 	while(send(io->c, 0) == -1)
75 		;
76 	chanfree(io->c);
77 	chanfree(io->creply);
78 	free(io);
79 }
80 
81 long
82 iocall(Ioproc *io, long (*op)(va_list*), ...)
83 {
84 	char e[ERRMAX];
85 	int ret, inted;
86 	Ioproc *msg;
87 
88 	if(send(io->c, &io) == -1){
89 		werrstr("interrupted");
90 		return -1;
91 	}
92 	assert(!io->inuse);
93 	io->inuse = 1;
94 	io->op = op;
95 	va_start(io->arg, op);
96 	msg = io;
97 	inted = 0;
98 	while(send(io->creply, &msg) == -1){
99 		msg = nil;
100 		inted = 1;
101 	}
102 	if(inted){
103 		werrstr("interrupted");
104 		return -1;
105 	}
106 
107 	/*
108 	 * If we get interrupted, we have stick around so that
109 	 * the IO proc has someone to talk to.  Send it an interrupt
110 	 * and try again.
111 	 */
112 	inted = 0;
113 	while(recv(io->creply, nil) == -1){
114 		inted = 1;
115 		iointerrupt(io);
116 	}
117 	USED(inted);
118 	va_end(io->arg);
119 	ret = io->ret;
120 	if(ret < 0)
121 		strecpy(e, e+sizeof e, io->err);
122 	io->inuse = 0;
123 
124 	/* release resources */
125 	while(send(io->creply, &io) == -1)
126 		;
127 	if(ret < 0)
128 		errstr(e, sizeof e);
129 	return ret;
130 }