1 /* This file handle diagnostic output that is sent to the LOG driver. Output 2 * can be either from the kernel, or from other system processes. Output from 3 * system processes is also routed through the kernel. The kernel notifies 4 * this driver with a SIGKMESS signal if any messages are available. 5 * 6 * Changes: 7 * 21 July 2005: Created (Jorrit N. Herder) 8 */ 9 10 #include "log.h" 11 12 #include <assert.h> 13 14 extern struct minix_kerninfo *_minix_kerninfo; 15 16 /*==========================================================================* 17 * do_new_kmess * 18 *==========================================================================*/ 19 void do_new_kmess(void) 20 { 21 /* Notification for a new kernel message. */ 22 static struct kmessages *kmess; /* entire kmess structure */ 23 static char print_buf[_KMESS_BUF_SIZE]; /* copy new message here */ 24 int i, r, next, bytes; 25 static int prev_next = 0; 26 27 assert(_minix_kerninfo); 28 kmess = _minix_kerninfo->kmessages; 29 30 /* Print only the new part. Determine how many new bytes there are with 31 * help of the current and previous 'next' index. Note that the kernel 32 * buffer is circular. This works fine if less than KMESS_BUF_SIZE bytes 33 * are new data; else we miss % KMESS_BUF_SIZE here. Obtain 'next' only 34 * once, since we are operating on shared memory here. 35 * Check for size being positive, the buffer might as well be emptied! 36 */ 37 next = kmess->km_next; 38 bytes = ((next + _KMESS_BUF_SIZE) - prev_next) % _KMESS_BUF_SIZE; 39 if (bytes > 0) { 40 r= prev_next; /* start at previous old */ 41 i=0; 42 while (bytes > 0) { 43 print_buf[i] = kmess->km_buf[(r%_KMESS_BUF_SIZE)]; 44 bytes --; 45 r ++; 46 i ++; 47 } 48 /* Now terminate the new message and save it in the log. */ 49 print_buf[i] = 0; 50 log_append(print_buf, i); 51 } 52 53 /* Almost done, store 'next' so that we can determine what part of the 54 * kernel messages buffer to print next time a notification arrives. 55 */ 56 prev_next = next; 57 } 58