1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 * 6 * @(#)subr_log.c 7.8 (Berkeley) 06/24/90 7 */ 8 9 /* 10 * Error log buffer for kernel printf's. 11 */ 12 13 #include "param.h" 14 #include "user.h" 15 #include "proc.h" 16 #include "vnode.h" 17 #include "ioctl.h" 18 #include "msgbuf.h" 19 #include "file.h" 20 #include "errno.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 proc *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 logopen(dev) 37 dev_t dev; 38 { 39 40 if (log_open) 41 return (EBUSY); 42 log_open = 1; 43 logsoftc.sc_pgid = u.u_procp->p_pid; /* signal process only */ 44 /* 45 * Potential race here with putchar() but since putchar should be 46 * called by autoconf, msg_magic should be initialized by the time 47 * we get here. 48 */ 49 if (msgbuf.msg_magic != MSG_MAGIC) { 50 register int i; 51 52 msgbuf.msg_magic = MSG_MAGIC; 53 msgbuf.msg_bufx = msgbuf.msg_bufr = 0; 54 for (i=0; i < MSG_BSIZE; i++) 55 msgbuf.msg_bufc[i] = 0; 56 } 57 return (0); 58 } 59 60 /*ARGSUSED*/ 61 logclose(dev, flag) 62 dev_t dev; 63 { 64 log_open = 0; 65 logsoftc.sc_state = 0; 66 logsoftc.sc_selp = 0; 67 } 68 69 /*ARGSUSED*/ 70 logread(dev, uio, flag) 71 dev_t dev; 72 struct uio *uio; 73 int flag; 74 { 75 register long l; 76 register int s; 77 int error = 0; 78 79 s = splhigh(); 80 while (msgbuf.msg_bufr == msgbuf.msg_bufx) { 81 if (flag & IO_NDELAY) { 82 splx(s); 83 return (EWOULDBLOCK); 84 } 85 logsoftc.sc_state |= LOG_RDWAIT; 86 if (error = tsleep((caddr_t)&msgbuf, LOG_RDPRI | PCATCH, 87 "klog", 0)) { 88 splx(s); 89 return (error); 90 } 91 } 92 splx(s); 93 logsoftc.sc_state &= ~LOG_RDWAIT; 94 95 while (uio->uio_resid > 0) { 96 l = msgbuf.msg_bufx - msgbuf.msg_bufr; 97 if (l < 0) 98 l = MSG_BSIZE - msgbuf.msg_bufr; 99 l = MIN(l, uio->uio_resid); 100 if (l == 0) 101 break; 102 error = uiomove((caddr_t)&msgbuf.msg_bufc[msgbuf.msg_bufr], 103 (int)l, uio); 104 if (error) 105 break; 106 msgbuf.msg_bufr += l; 107 if (msgbuf.msg_bufr < 0 || msgbuf.msg_bufr >= MSG_BSIZE) 108 msgbuf.msg_bufr = 0; 109 } 110 return (error); 111 } 112 113 /*ARGSUSED*/ 114 logselect(dev, rw) 115 dev_t dev; 116 int rw; 117 { 118 int s = splhigh(); 119 120 switch (rw) { 121 122 case FREAD: 123 if (msgbuf.msg_bufr != msgbuf.msg_bufx) { 124 splx(s); 125 return (1); 126 } 127 logsoftc.sc_selp = u.u_procp; 128 break; 129 } 130 splx(s); 131 return (0); 132 } 133 134 logwakeup() 135 { 136 struct proc *p; 137 138 if (!log_open) 139 return; 140 if (logsoftc.sc_selp) { 141 selwakeup(logsoftc.sc_selp, 0); 142 logsoftc.sc_selp = 0; 143 } 144 if (logsoftc.sc_state & LOG_ASYNC) { 145 if (logsoftc.sc_pgid < 0) 146 gsignal(logsoftc.sc_pgid, SIGIO); 147 else if (p = pfind(logsoftc.sc_pgid)) 148 psignal(p, SIGIO); 149 } 150 if (logsoftc.sc_state & LOG_RDWAIT) { 151 wakeup((caddr_t)&msgbuf); 152 logsoftc.sc_state &= ~LOG_RDWAIT; 153 } 154 } 155 156 /*ARGSUSED*/ 157 logioctl(dev, com, data, flag) 158 caddr_t data; 159 { 160 long l; 161 int s; 162 163 switch (com) { 164 165 /* return number of characters immediately available */ 166 case FIONREAD: 167 s = splhigh(); 168 l = msgbuf.msg_bufx - msgbuf.msg_bufr; 169 splx(s); 170 if (l < 0) 171 l += MSG_BSIZE; 172 *(off_t *)data = l; 173 break; 174 175 case FIONBIO: 176 break; 177 178 case FIOASYNC: 179 if (*(int *)data) 180 logsoftc.sc_state |= LOG_ASYNC; 181 else 182 logsoftc.sc_state &= ~LOG_ASYNC; 183 break; 184 185 case TIOCSPGRP: 186 logsoftc.sc_pgid = *(int *)data; 187 break; 188 189 case TIOCGPGRP: 190 *(int *)data = logsoftc.sc_pgid; 191 break; 192 193 default: 194 return (-1); 195 } 196 return (0); 197 } 198