| 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) %G% |
| 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 | } |