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 7.10 (Berkeley) 12/05/90 8 */ 9 10 /* 11 * Error log buffer for kernel printf's. 12 */ 13 14 #include "param.h" 15 #include "user.h" 16 #include "proc.h" 17 #include "vnode.h" 18 #include "ioctl.h" 19 #include "msgbuf.h" 20 #include "file.h" 21 #include "errno.h" 22 23 #define LOG_RDPRI (PZERO + 1) 24 25 #define LOG_ASYNC 0x04 26 #define LOG_RDWAIT 0x08 27 28 struct logsoftc { 29 int sc_state; /* see above for possibilities */ 30 struct proc *sc_selp; /* process waiting on select call */ 31 int sc_pgid; /* process/group for async I/O */ 32 } logsoftc; 33 34 int log_open; /* also used in log() */ 35 36 /*ARGSUSED*/ 37 logopen(dev) 38 dev_t dev; 39 { 40 register struct msgbuf *mbp = msgbufp; 41 42 if (log_open) 43 return (EBUSY); 44 log_open = 1; 45 logsoftc.sc_pgid = u.u_procp->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) 118 dev_t dev; 119 int rw; 120 { 121 int s = splhigh(); 122 123 switch (rw) { 124 125 case FREAD: 126 if (msgbufp->msg_bufr != msgbufp->msg_bufx) { 127 splx(s); 128 return (1); 129 } 130 logsoftc.sc_selp = u.u_procp; 131 break; 132 } 133 splx(s); 134 return (0); 135 } 136 137 logwakeup() 138 { 139 struct proc *p; 140 141 if (!log_open) 142 return; 143 if (logsoftc.sc_selp) { 144 selwakeup(logsoftc.sc_selp, 0); 145 logsoftc.sc_selp = 0; 146 } 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) 161 caddr_t data; 162 { 163 long l; 164 int s; 165 166 switch (com) { 167 168 /* return number of characters immediately available */ 169 case FIONREAD: 170 s = splhigh(); 171 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 172 splx(s); 173 if (l < 0) 174 l += MSG_BSIZE; 175 *(off_t *)data = l; 176 break; 177 178 case FIONBIO: 179 break; 180 181 case FIOASYNC: 182 if (*(int *)data) 183 logsoftc.sc_state |= LOG_ASYNC; 184 else 185 logsoftc.sc_state &= ~LOG_ASYNC; 186 break; 187 188 case TIOCSPGRP: 189 logsoftc.sc_pgid = *(int *)data; 190 break; 191 192 case TIOCGPGRP: 193 *(int *)data = logsoftc.sc_pgid; 194 break; 195 196 default: 197 return (-1); 198 } 199 return (0); 200 } 201