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 7.13 (Berkeley) 02/15/92 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 selinfo 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, mode, p) 64 dev_t dev; 65 int flag, mode; 66 struct proc *p; 67 { 68 69 log_open = 0; 70 logsoftc.sc_state = 0; 71 } 72 73 /*ARGSUSED*/ 74 logread(dev, uio, flag) 75 dev_t dev; 76 struct uio *uio; 77 int flag; 78 { 79 register struct msgbuf *mbp = msgbufp; 80 register long l; 81 register int s; 82 int error = 0; 83 84 s = splhigh(); 85 while (mbp->msg_bufr == mbp->msg_bufx) { 86 if (flag & IO_NDELAY) { 87 splx(s); 88 return (EWOULDBLOCK); 89 } 90 logsoftc.sc_state |= LOG_RDWAIT; 91 if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH, 92 "klog", 0)) { 93 splx(s); 94 return (error); 95 } 96 } 97 splx(s); 98 logsoftc.sc_state &= ~LOG_RDWAIT; 99 100 while (uio->uio_resid > 0) { 101 l = mbp->msg_bufx - mbp->msg_bufr; 102 if (l < 0) 103 l = MSG_BSIZE - mbp->msg_bufr; 104 l = MIN(l, uio->uio_resid); 105 if (l == 0) 106 break; 107 error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr], 108 (int)l, uio); 109 if (error) 110 break; 111 mbp->msg_bufr += l; 112 if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE) 113 mbp->msg_bufr = 0; 114 } 115 return (error); 116 } 117 118 /*ARGSUSED*/ 119 logselect(dev, rw, p) 120 dev_t dev; 121 int rw; 122 struct proc *p; 123 { 124 int s = splhigh(); 125 126 switch (rw) { 127 128 case FREAD: 129 if (msgbufp->msg_bufr != msgbufp->msg_bufx) { 130 splx(s); 131 return (1); 132 } 133 selrecord(p, &logsoftc.sc_selp); 134 break; 135 } 136 splx(s); 137 return (0); 138 } 139 140 logwakeup() 141 { 142 struct proc *p; 143 144 if (!log_open) 145 return; 146 selwakeup(&logsoftc.sc_selp); 147 if (logsoftc.sc_state & LOG_ASYNC) { 148 if (logsoftc.sc_pgid < 0) 149 gsignal(-logsoftc.sc_pgid, SIGIO); 150 else if (p = pfind(logsoftc.sc_pgid)) 151 psignal(p, SIGIO); 152 } 153 if (logsoftc.sc_state & LOG_RDWAIT) { 154 wakeup((caddr_t)msgbufp); 155 logsoftc.sc_state &= ~LOG_RDWAIT; 156 } 157 } 158 159 /*ARGSUSED*/ 160 logioctl(dev, com, data, flag, p) 161 dev_t dev; 162 int com; 163 caddr_t data; 164 int flag; 165 struct proc *p; 166 { 167 long l; 168 int s; 169 170 switch (com) { 171 172 /* return number of characters immediately available */ 173 case FIONREAD: 174 s = splhigh(); 175 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 176 splx(s); 177 if (l < 0) 178 l += MSG_BSIZE; 179 *(off_t *)data = l; 180 break; 181 182 case FIONBIO: 183 break; 184 185 case FIOASYNC: 186 if (*(int *)data) 187 logsoftc.sc_state |= LOG_ASYNC; 188 else 189 logsoftc.sc_state &= ~LOG_ASYNC; 190 break; 191 192 case TIOCSPGRP: 193 logsoftc.sc_pgid = *(int *)data; 194 break; 195 196 case TIOCGPGRP: 197 *(int *)data = logsoftc.sc_pgid; 198 break; 199 200 default: 201 return (-1); 202 } 203 return (0); 204 } 205