1 /*
2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 *
7 * @(#)subr_log.c 8.3 (Berkeley) 02/14/95
8 */
9
10 /*
11 * Error log buffer for kernel printf's.
12 */
13
14 #include <sys/param.h>
15 #include <sys/systm.h>
16 #include <sys/proc.h>
17 #include <sys/vnode.h>
18 #include <sys/ioctl.h>
19 #include <sys/msgbuf.h>
20 #include <sys/file.h>
21
22 #define LOG_RDPRI (PZERO + 1)
23
24 #define LOG_ASYNC 0x04
25 #define LOG_RDWAIT 0x08
26
27 struct logsoftc {
28 int sc_state; /* see above for possibilities */
29 struct selinfo sc_selp; /* process waiting on select call */
30 int sc_pgid; /* process/group for async I/O */
31 } logsoftc;
32
33 int log_open; /* also used in log() */
34
35 /*ARGSUSED*/
36 int
logopen(dev,flags,mode,p)37 logopen(dev, flags, mode, p)
38 dev_t dev;
39 int flags, mode;
40 struct proc *p;
41 {
42 register struct msgbuf *mbp = msgbufp;
43
44 if (log_open)
45 return (EBUSY);
46 log_open = 1;
47 logsoftc.sc_pgid = p->p_pid; /* signal process only */
48 /*
49 * Potential race here with putchar() but since putchar should be
50 * called by autoconf, msg_magic should be initialized by the time
51 * we get here.
52 */
53 if (mbp->msg_magic != MSG_MAGIC) {
54 register int i;
55
56 mbp->msg_magic = MSG_MAGIC;
57 mbp->msg_bufx = mbp->msg_bufr = 0;
58 for (i=0; i < MSG_BSIZE; i++)
59 mbp->msg_bufc[i] = 0;
60 }
61 return (0);
62 }
63
64 /*ARGSUSED*/
65 int
logclose(dev,flag,mode,p)66 logclose(dev, flag, mode, p)
67 dev_t dev;
68 int flag, mode;
69 struct proc *p;
70 {
71
72 log_open = 0;
73 logsoftc.sc_state = 0;
74 return (0);
75 }
76
77 /*ARGSUSED*/
78 int
logread(dev,uio,flag)79 logread(dev, uio, flag)
80 dev_t dev;
81 struct uio *uio;
82 int flag;
83 {
84 register struct msgbuf *mbp = msgbufp;
85 register long l;
86 register int s;
87 int error = 0;
88
89 s = splhigh();
90 while (mbp->msg_bufr == mbp->msg_bufx) {
91 if (flag & IO_NDELAY) {
92 splx(s);
93 return (EWOULDBLOCK);
94 }
95 logsoftc.sc_state |= LOG_RDWAIT;
96 if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
97 "klog", 0)) {
98 splx(s);
99 return (error);
100 }
101 }
102 splx(s);
103 logsoftc.sc_state &= ~LOG_RDWAIT;
104
105 while (uio->uio_resid > 0) {
106 l = mbp->msg_bufx - mbp->msg_bufr;
107 if (l < 0)
108 l = MSG_BSIZE - mbp->msg_bufr;
109 l = min(l, uio->uio_resid);
110 if (l == 0)
111 break;
112 error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
113 (int)l, uio);
114 if (error)
115 break;
116 mbp->msg_bufr += l;
117 if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
118 mbp->msg_bufr = 0;
119 }
120 return (error);
121 }
122
123 /*ARGSUSED*/
124 int
logselect(dev,rw,p)125 logselect(dev, rw, p)
126 dev_t dev;
127 int rw;
128 struct proc *p;
129 {
130 int s = splhigh();
131
132 switch (rw) {
133
134 case FREAD:
135 if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
136 splx(s);
137 return (1);
138 }
139 selrecord(p, &logsoftc.sc_selp);
140 break;
141 }
142 splx(s);
143 return (0);
144 }
145
146 void
logwakeup()147 logwakeup()
148 {
149 struct proc *p;
150
151 if (!log_open)
152 return;
153 selwakeup(&logsoftc.sc_selp);
154 if (logsoftc.sc_state & LOG_ASYNC) {
155 if (logsoftc.sc_pgid < 0)
156 gsignal(-logsoftc.sc_pgid, SIGIO);
157 else if (p = pfind(logsoftc.sc_pgid))
158 psignal(p, SIGIO);
159 }
160 if (logsoftc.sc_state & LOG_RDWAIT) {
161 wakeup((caddr_t)msgbufp);
162 logsoftc.sc_state &= ~LOG_RDWAIT;
163 }
164 }
165
166 /*ARGSUSED*/
167 int
logioctl(dev,com,data,flag,p)168 logioctl(dev, com, data, flag, p)
169 dev_t dev;
170 u_long com;
171 caddr_t data;
172 int flag;
173 struct proc *p;
174 {
175 long l;
176 int s;
177
178 switch (com) {
179
180 /* return number of characters immediately available */
181 case FIONREAD:
182 s = splhigh();
183 l = msgbufp->msg_bufx - msgbufp->msg_bufr;
184 splx(s);
185 if (l < 0)
186 l += MSG_BSIZE;
187 *(int *)data = l;
188 break;
189
190 case FIONBIO:
191 break;
192
193 case FIOASYNC:
194 if (*(int *)data)
195 logsoftc.sc_state |= LOG_ASYNC;
196 else
197 logsoftc.sc_state &= ~LOG_ASYNC;
198 break;
199
200 case TIOCSPGRP:
201 logsoftc.sc_pgid = *(int *)data;
202 break;
203
204 case TIOCGPGRP:
205 *(int *)data = logsoftc.sc_pgid;
206 break;
207
208 default:
209 return (-1);
210 }
211 return (0);
212 }
213