1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)subr_log.c 7.11 (Berkeley) 03/17/91 8 */ 9 10 /* 11 * Error log buffer for kernel printf's. 12 */ 13 14 #include "param.h" 15 #include "proc.h" 16 #include "vnode.h" 17 #include "ioctl.h" 18 #include "msgbuf.h" 19 #include "file.h" 20 21 #define LOG_RDPRI (PZERO + 1) 22 23 #define LOG_ASYNC 0x04 24 #define LOG_RDWAIT 0x08 25 26 struct logsoftc { 27 int sc_state; /* see above for possibilities */ 28 struct proc *sc_selp; /* process waiting on select call */ 29 int sc_pgid; /* process/group for async I/O */ 30 } logsoftc; 31 32 int log_open; /* also used in log() */ 33 34 /*ARGSUSED*/ 35 logopen(dev, flags, mode, p) 36 dev_t dev; 37 int flags, mode; 38 struct proc *p; 39 { 40 register struct msgbuf *mbp = msgbufp; 41 42 if (log_open) 43 return (EBUSY); 44 log_open = 1; 45 logsoftc.sc_pgid = p->p_pid; /* signal process only */ 46 /* 47 * Potential race here with putchar() but since putchar should be 48 * called by autoconf, msg_magic should be initialized by the time 49 * we get here. 50 */ 51 if (mbp->msg_magic != MSG_MAGIC) { 52 register int i; 53 54 mbp->msg_magic = MSG_MAGIC; 55 mbp->msg_bufx = mbp->msg_bufr = 0; 56 for (i=0; i < MSG_BSIZE; i++) 57 mbp->msg_bufc[i] = 0; 58 } 59 return (0); 60 } 61 62 /*ARGSUSED*/ 63 logclose(dev, flag) 64 dev_t dev; 65 { 66 log_open = 0; 67 logsoftc.sc_state = 0; 68 logsoftc.sc_selp = 0; 69 } 70 71 /*ARGSUSED*/ 72 logread(dev, uio, flag) 73 dev_t dev; 74 struct uio *uio; 75 int flag; 76 { 77 register struct msgbuf *mbp = msgbufp; 78 register long l; 79 register int s; 80 int error = 0; 81 82 s = splhigh(); 83 while (mbp->msg_bufr == mbp->msg_bufx) { 84 if (flag & IO_NDELAY) { 85 splx(s); 86 return (EWOULDBLOCK); 87 } 88 logsoftc.sc_state |= LOG_RDWAIT; 89 if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH, 90 "klog", 0)) { 91 splx(s); 92 return (error); 93 } 94 } 95 splx(s); 96 logsoftc.sc_state &= ~LOG_RDWAIT; 97 98 while (uio->uio_resid > 0) { 99 l = mbp->msg_bufx - mbp->msg_bufr; 100 if (l < 0) 101 l = MSG_BSIZE - mbp->msg_bufr; 102 l = MIN(l, uio->uio_resid); 103 if (l == 0) 104 break; 105 error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr], 106 (int)l, uio); 107 if (error) 108 break; 109 mbp->msg_bufr += l; 110 if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE) 111 mbp->msg_bufr = 0; 112 } 113 return (error); 114 } 115 116 /*ARGSUSED*/ 117 logselect(dev, rw, p) 118 dev_t dev; 119 int rw; 120 struct proc *p; 121 { 122 int s = splhigh(); 123 124 switch (rw) { 125 126 case FREAD: 127 if (msgbufp->msg_bufr != msgbufp->msg_bufx) { 128 splx(s); 129 return (1); 130 } 131 logsoftc.sc_selp = p; 132 break; 133 } 134 splx(s); 135 return (0); 136 } 137 138 logwakeup() 139 { 140 struct proc *p; 141 142 if (!log_open) 143 return; 144 if (logsoftc.sc_selp) { 145 selwakeup(logsoftc.sc_selp, 0); 146 logsoftc.sc_selp = 0; 147 } 148 if (logsoftc.sc_state & LOG_ASYNC) { 149 if (logsoftc.sc_pgid < 0) 150 gsignal(-logsoftc.sc_pgid, SIGIO); 151 else if (p = pfind(logsoftc.sc_pgid)) 152 psignal(p, SIGIO); 153 } 154 if (logsoftc.sc_state & LOG_RDWAIT) { 155 wakeup((caddr_t)msgbufp); 156 logsoftc.sc_state &= ~LOG_RDWAIT; 157 } 158 } 159 160 /*ARGSUSED*/ 161 logioctl(dev, com, data, flag) 162 caddr_t data; 163 { 164 long l; 165 int s; 166 167 switch (com) { 168 169 /* return number of characters immediately available */ 170 case FIONREAD: 171 s = splhigh(); 172 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 173 splx(s); 174 if (l < 0) 175 l += MSG_BSIZE; 176 *(off_t *)data = l; 177 break; 178 179 case FIONBIO: 180 break; 181 182 case FIOASYNC: 183 if (*(int *)data) 184 logsoftc.sc_state |= LOG_ASYNC; 185 else 186 logsoftc.sc_state &= ~LOG_ASYNC; 187 break; 188 189 case TIOCSPGRP: 190 logsoftc.sc_pgid = *(int *)data; 191 break; 192 193 case TIOCGPGRP: 194 *(int *)data = logsoftc.sc_pgid; 195 break; 196 197 default: 198 return (-1); 199 } 200 return (0); 201 } 202