minix/kernel/utility.c

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/* This file contains a collection of miscellaneous procedures:
* panic: abort MINIX due to a fatal error
* kprintf: diagnostic output for the kernel
*
* Changes:
* Dec 10, 2004 kernel printing to circular buffer (Jorrit N. Herder)
*
* This file contains the routines that take care of kernel messages, i.e.,
* diagnostic output within the kernel. Kernel messages are not directly
* displayed on the console, because this must be done by the output driver.
* Instead, the kernel accumulates characters in a buffer and notifies the
* output driver when a new message is ready.
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*/
#include <minix/com.h>
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#include "kernel.h"
#include <stdarg.h>
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#include <unistd.h>
#include <stddef.h>
#include <stdlib.h>
#include <signal.h>
#include "proc.h"
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#define END_OF_KMESS -1
FORWARD _PROTOTYPE(void kputc, (int c));
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/*===========================================================================*
* panic *
*===========================================================================*/
PUBLIC void panic(mess,nr)
_CONST char *mess;
int nr;
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{
/* The system has run aground of a fatal kernel error. Terminate execution. */
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static int panicking = 0;
if (panicking ++) return; /* prevent recursive panics */
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if (mess != NULL) {
kprintf("\nKernel panic: %s", mess);
if (nr != NO_NUM) kprintf(" %d", nr);
kprintf("\n",NO_NUM);
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}
/* Abort MINIX. */
prepare_shutdown(RBT_PANIC);
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}
/*===========================================================================*
* kprintf *
*===========================================================================*/
PUBLIC void kprintf(const char *fmt, ...) /* format to be printed */
{
int c; /* next character in fmt */
int d;
unsigned long u; /* hold number argument */
int base; /* base of number arg */
int negative = 0; /* print minus sign */
static char x2c[] = "0123456789ABCDEF"; /* nr conversion table */
char ascii[8 * sizeof(long) / 3 + 2]; /* string for ascii number */
char *s = NULL; /* string to be printed */
va_list argp; /* optional arguments */
va_start(argp, fmt); /* init variable arguments */
while((c=*fmt++) != 0) {
if (c == '%') { /* expect format '%key' */
switch(c = *fmt++) { /* determine what to do */
/* Known keys are %d, %u, %x, %s, and %%. This is easily extended
* with number types like %b and %o by providing a different base.
* Number type keys don't set a string to 's', but use the general
* conversion after the switch statement.
*/
case 'd': /* output decimal */
d = va_arg(argp, signed int);
if (d < 0) { negative = 1; u = -d; } else { u = d; }
base = 10;
break;
case 'u': /* output unsigned long */
u = va_arg(argp, unsigned long);
base = 10;
break;
case 'x': /* output hexadecimal */
u = va_arg(argp, unsigned long);
base = 0x10;
break;
case 's': /* output string */
s = va_arg(argp, char *);
if (s == NULL) s = "(null)";
break;
case '%': /* output percent */
s = "%";
break;
/* Unrecognized key. */
default: /* echo back %key */
s = "%?";
s[1] = c; /* set unknown key */
}
/* Assume a number if no string is set. Convert to ascii. */
if (s == NULL) {
s = ascii + sizeof(ascii)-1;
*s = 0;
do { *--s = x2c[(u % base)]; } /* work backwards */
while ((u /= base) > 0);
}
/* This is where the actual output for format "%key" is done. */
if (negative) kputc('-'); /* print sign if negative */
while(*s != 0) { kputc(*s++); } /* print string/ number */
s = NULL; /* reset for next round */
}
else {
kputc(c); /* print and continue */
}
}
kputc(END_OF_KMESS); /* terminate output */
va_end(argp); /* end variable arguments */
}
/*===========================================================================*
* kputc *
*===========================================================================*/
PRIVATE void kputc(c)
int c; /* character to append */
{
/* Accumulate a single character for a kernel message. Send a notification
* the to output driver if an END_OF_KMESS is encountered.
*/
if (c != END_OF_KMESS) {
kmess.km_buf[kmess.km_next] = c; /* put normal char in buffer */
if (kmess.km_size < KMESS_BUF_SIZE)
kmess.km_size += 1;
kmess.km_next = (kmess.km_next + 1) % KMESS_BUF_SIZE;
} else {
send_sig(OUTPUT_PROC_NR, SIGKMESS);
}
}