minix3/drivers/system/log/diag.c

58 lines
2.0 KiB
C

/* This file handle diagnostic output that is sent to the LOG driver. Output
* can be either from the kernel, or from other system processes. Output from
* system processes is also routed through the kernel. The kernel notifies
* this driver with a SIGKMESS signal if any messages are available.
*
* Changes:
* 21 July 2005: Created (Jorrit N. Herder)
*/
#include "log.h"
#include <assert.h>
extern struct minix_kerninfo *_minix_kerninfo;
/*==========================================================================*
* do_new_kmess *
*==========================================================================*/
void do_new_kmess(void)
{
/* Notification for a new kernel message. */
static struct kmessages *kmess; /* entire kmess structure */
static char print_buf[_KMESS_BUF_SIZE]; /* copy new message here */
int i, r, next, bytes;
static int prev_next = 0;
assert(_minix_kerninfo);
kmess = _minix_kerninfo->kmessages;
/* Print only the new part. Determine how many new bytes there are with
* help of the current and previous 'next' index. Note that the kernel
* buffer is circular. This works fine if less than KMESS_BUF_SIZE bytes
* are new data; else we miss % KMESS_BUF_SIZE here. Obtain 'next' only
* once, since we are operating on shared memory here.
* Check for size being positive, the buffer might as well be emptied!
*/
next = kmess->km_next;
bytes = ((next + _KMESS_BUF_SIZE) - prev_next) % _KMESS_BUF_SIZE;
if (bytes > 0) {
r= prev_next; /* start at previous old */
i=0;
while (bytes > 0) {
print_buf[i] = kmess->km_buf[(r%_KMESS_BUF_SIZE)];
bytes --;
r ++;
i ++;
}
/* Now terminate the new message and save it in the log. */
print_buf[i] = 0;
log_append(print_buf, i);
}
/* Almost done, store 'next' so that we can determine what part of the
* kernel messages buffer to print next time a notification arrives.
*/
prev_next = next;
}