146 lines
3.7 KiB
C
146 lines
3.7 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/*
|
|
* circular buffer syslog implementation for busybox
|
|
*
|
|
* Copyright (C) 2000 by Gennady Feldman <gfeldman@cachier.com>
|
|
*
|
|
* Maintainer: Gennady Feldman <gena01@cachier.com> as of Mar 12, 2001
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
* 02111-1307 USA
|
|
*
|
|
*/
|
|
|
|
|
|
/* Stupid libc doesn't have a reliable way for use to know
|
|
* that libc5 is being used. Assume this is good enough */
|
|
#if defined __GLIBC__ || defined __UCLIBC__
|
|
#error Sorry. Looks like you are using libc5.
|
|
#error libc5 shm support isn't good enough.
|
|
#error Please disable BB_FEATURE_IPC_SYSLOG
|
|
#endif
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/ipc.h>
|
|
#include <sys/types.h>
|
|
#include <sys/sem.h>
|
|
#include <sys/shm.h>
|
|
#include <signal.h>
|
|
#include <setjmp.h>
|
|
#include "busybox.h"
|
|
|
|
static const long KEY_ID = 0x414e4547; /*"GENA"*/
|
|
|
|
static struct shbuf_ds {
|
|
int size; // size of data written
|
|
int head; // start of message list
|
|
int tail; // end of message list
|
|
char data[1]; // data/messages
|
|
} *buf = NULL; // shared memory pointer
|
|
|
|
|
|
// Semaphore operation structures
|
|
static struct sembuf SMrup[1] = {{0, -1, IPC_NOWAIT | SEM_UNDO}}; // set SMrup
|
|
static struct sembuf SMrdn[2] = {{1, 0}, {0, +1, SEM_UNDO}}; // set SMrdn
|
|
|
|
static int shmid = -1; // ipc shared memory id
|
|
static int semid = -1; // ipc semaphore id
|
|
static jmp_buf jmp_env;
|
|
|
|
static void error_exit(const char *str);
|
|
static void interrupted(int sig);
|
|
|
|
/*
|
|
* sem_up - up()'s a semaphore.
|
|
*/
|
|
static inline void sem_up(int semid)
|
|
{
|
|
if ( semop(semid, SMrup, 1) == -1 )
|
|
error_exit("semop[SMrup]");
|
|
}
|
|
|
|
/*
|
|
* sem_down - down()'s a semaphore
|
|
*/
|
|
static inline void sem_down(int semid)
|
|
{
|
|
if ( semop(semid, SMrdn, 2) == -1 )
|
|
error_exit("semop[SMrdn]");
|
|
}
|
|
|
|
extern int logread_main(int argc, char **argv)
|
|
{
|
|
int i;
|
|
|
|
/* no options, no getopt */
|
|
if (argc > 1)
|
|
show_usage();
|
|
|
|
// handle intrrupt signal
|
|
if (setjmp(jmp_env)) goto output_end;
|
|
|
|
// attempt to redefine ^C signal
|
|
signal(SIGINT, interrupted);
|
|
|
|
if ( (shmid = shmget(KEY_ID, 0, 0)) == -1)
|
|
error_exit("Can't find circular buffer");
|
|
|
|
// Attach shared memory to our char*
|
|
if ( (buf = shmat(shmid, NULL, SHM_RDONLY)) == NULL)
|
|
error_exit("Can't get access to circular buffer from syslogd");
|
|
|
|
if ( (semid = semget(KEY_ID, 0, 0)) == -1)
|
|
error_exit("Can't get access to semaphone(s) for circular buffer from syslogd");
|
|
|
|
sem_down(semid);
|
|
// Read Memory
|
|
i=buf->head;
|
|
|
|
//printf("head: %i tail: %i size: %i\n",buf->head,buf->tail,buf->size);
|
|
if (buf->head == buf->tail) {
|
|
printf("<empty syslog>\n");
|
|
}
|
|
|
|
while ( i != buf->tail) {
|
|
printf("%s", buf->data+i);
|
|
i+= strlen(buf->data+i) + 1;
|
|
if (i >= buf->size )
|
|
i=0;
|
|
}
|
|
sem_up(semid);
|
|
|
|
output_end:
|
|
if (shmid != -1)
|
|
shmdt(buf);
|
|
|
|
return EXIT_SUCCESS;
|
|
}
|
|
|
|
static void interrupted(int sig){
|
|
signal(SIGINT, SIG_IGN);
|
|
longjmp(jmp_env, 1);
|
|
}
|
|
|
|
static void error_exit(const char *str){
|
|
perror(str);
|
|
//release all acquired resources
|
|
if (shmid != -1)
|
|
shmdt(buf);
|
|
|
|
exit(1);
|
|
}
|