xref: /csrg-svn/sys/kern/subr_log.c (revision 17093)
1 /*	subr_log.c	6.3	84/08/29	*/
2 
3 /*
4  * Error log buffer for kernel printf's.
5  */
6 
7 #include "param.h"
8 #include "dir.h"
9 #include "user.h"
10 #include "proc.h"
11 #include "ioctl.h"
12 #include "msgbuf.h"
13 #include "file.h"
14 #include "errno.h"
15 
16 #define LOG_RDPRI	(PZERO + 1)
17 
18 #define LOG_OPEN	0x01
19 #define LOG_NBIO	0x02
20 #define LOG_ASYNC	0x04
21 #define LOG_RDWAIT	0x08
22 
23 struct logsoftc {
24 	int	sc_state;		/* see above for possibilities */
25 	struct	proc *sc_selp;		/* process waiting on select call */
26 	int	sc_pgrp;		/* process group for async I/O */
27 } logsoftc;
28 
29 #ifdef LOGDEBUG
30 /*VARARGS1*/
31 xprintf(fmt, x1)
32 	char *fmt;
33 	unsigned x1;
34 {
35 
36 	prf(fmt, &x1, 1, (struct tty *)0);
37 }
38 #endif
39 
40 logopen(dev)
41 	dev_t dev;
42 {
43 
44 #ifdef LOGDEBUG
45 	xprintf("logopen: dev=0x%x\n", dev);
46 #endif
47 	if (logsoftc.sc_state & LOG_OPEN)
48 		return (EBUSY);
49 	logsoftc.sc_state |= LOG_OPEN;
50 	logsoftc.sc_selp = 0;
51 	logsoftc.sc_pgrp = u.u_procp->p_pgrp;
52 	/*
53 	 * Potential race here with putchar() but since putchar should be
54 	 * called by autoconf, msg_magic should be initialized by the time
55 	 * we get here.
56 	 */
57 	if (msgbuf.msg_magic != MSG_MAGIC) {
58 		register int i;
59 
60 		msgbuf.msg_magic = MSG_MAGIC;
61 		msgbuf.msg_bufx = msgbuf.msg_bufr = 0;
62 		for (i=0; i < MSG_BSIZE; i++)
63 			msgbuf.msg_bufc[i] = 0;
64 	}
65 #ifdef LOGDEBUG
66 	xprintf("logopen: bufx=%d, bufr=%d\n", msgbuf.msg_bufx, msgbuf.msg_bufr);
67 #endif
68 	return (0);
69 }
70 
71 logclose(dev, flag)
72 	dev_t dev;
73 {
74 	logsoftc.sc_state = 0;
75 	logsoftc.sc_selp = 0;
76 	logsoftc.sc_pgrp = 0;
77 #ifdef LOGDEBUG
78 	xprintf("logclose: dev=0x%x\n", dev);
79 #endif
80 }
81 
82 logread(dev, uio)
83 	dev_t dev;
84 	struct uio *uio;
85 {
86 	register long l;
87 	register u_int c;
88 	register struct iovec *iov;
89 	register int s;
90 	int error = 0;
91 
92 #ifdef LOGDEBUG
93 	xprintf("logread: dev=0x%x\n", dev);
94 #endif
95 
96 	s = splhigh();
97 	while (msgbuf.msg_bufr == msgbuf.msg_bufx) {
98 		if (logsoftc.sc_state & LOG_NBIO) {
99 			splx(s);
100 			return (EWOULDBLOCK);
101 		}
102 		logsoftc.sc_state |= LOG_RDWAIT;
103 		sleep((caddr_t)&msgbuf, LOG_RDPRI);
104 	}
105 	splx(s);
106 	logsoftc.sc_state &= ~LOG_RDWAIT;
107 
108 	while (uio->uio_resid > 0) {
109 		l = msgbuf.msg_bufx - msgbuf.msg_bufr;
110 		if (l < 0)
111 			l = MSG_BSIZE - msgbuf.msg_bufr;
112 		c = min((u_int) l, (u_int)uio->uio_resid);
113 #ifdef LOGDEBUG
114 		xprintf("logread: bufx=%d, bufr=%d, l=%d, c=%d\n",
115 			msgbuf.msg_bufx, msgbuf.msg_bufr, l, c);
116 #endif
117 		if (c <= 0)
118 			break;
119 		error = uiomove((caddr_t)&msgbuf.msg_bufc[msgbuf.msg_bufr],
120 			(int)c, UIO_READ, uio);
121 		if (error)
122 			break;
123 		msgbuf.msg_bufr += c;
124 		if (msgbuf.msg_bufr < 0 || msgbuf.msg_bufr >= MSG_BSIZE)
125 			msgbuf.msg_bufr = 0;
126 	}
127 	return (error);
128 }
129 
130 logselect(dev, rw)
131 	dev_t dev;
132 	int rw;
133 {
134 	int s = splhigh();
135 
136 	switch (rw) {
137 
138 	case FREAD:
139 		if (msgbuf.msg_bufr != msgbuf.msg_bufx)
140 			goto win;
141 #ifdef LOGDEBUG
142 		if (logsoftc.sc_selp)
143 			xprintf("logselect: collision\n");
144 #endif
145 		logsoftc.sc_selp = u.u_procp;
146 		break;
147 
148 	case FWRITE:
149 #ifdef LOGDEBUG
150 		xprintf("logselect: FWRITE\n");
151 #endif
152 		break;
153 	}
154 	splx(s);
155 	return (0);
156 win:
157 	splx(s);
158 	return (1);
159 }
160 
161 logwakeup()
162 {
163 
164 	if (logsoftc.sc_selp) {
165 		selwakeup(logsoftc.sc_selp, 0);
166 		logsoftc.sc_selp = 0;
167 	}
168 	if (logsoftc.sc_state & LOG_ASYNC)
169 		gsignal(logsoftc.sc_pgrp, SIGIO);
170 	if (logsoftc.sc_state & LOG_RDWAIT) {
171 		wakeup((caddr_t)&msgbuf);
172 		logsoftc.sc_state &= ~LOG_RDWAIT;
173 	}
174 }
175 
176 /*ARGSUSED*/
177 logioctl(com, data, flag)
178 	caddr_t data;
179 {
180 	long l;
181 	int s;
182 
183 	switch (com) {
184 
185 	/* return number of characters immediately available */
186 	case FIONREAD:
187 		s = splhigh();
188 		l = msgbuf.msg_bufx - msgbuf.msg_bufr;
189 		splx(s);
190 		if (l < 0)
191 			l += MSG_BSIZE;
192 		*(off_t *)data = l;
193 		break;
194 
195 	case FIONBIO:
196 		if (*(int *)data)
197 			logsoftc.sc_state |= LOG_NBIO;
198 		else
199 			logsoftc.sc_state &= ~LOG_NBIO;
200 		break;
201 
202 	case FIOASYNC:
203 		if (*(int *)data)
204 			logsoftc.sc_state |= LOG_ASYNC;
205 		else
206 			logsoftc.sc_state &= ~LOG_ASYNC;
207 		break;
208 
209 	case TIOCSPGRP:
210 		logsoftc.sc_pgrp = *(int *)data;
211 		break;
212 
213 	case TIOCGPGRP:
214 		*(int *)data = logsoftc.sc_pgrp;
215 		break;
216 
217 	default:
218 		return (-1);
219 	}
220 	return (0);
221 }
222