1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/* 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
*
*/
#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"
#if __GNU_LIBRARY__ < 5
#error Sorry. Looks like you are using libc5.
#error libc5 shm support isnt good enough.
#error Please disable CONFIG_FEATURE_IPC_SYSLOG
#endif
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 log_shmid = -1; // ipc shared memory id
static int log_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 ( (log_shmid = shmget(KEY_ID, 0, 0)) == -1)
error_exit("Can't find circular buffer");
// Attach shared memory to our char*
if ( (buf = shmat(log_shmid, NULL, SHM_RDONLY)) == NULL)
error_exit("Can't get access to circular buffer from syslogd");
if ( (log_semid = semget(KEY_ID, 0, 0)) == -1)
error_exit("Can't get access to semaphone(s) for circular buffer from syslogd");
sem_down(log_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(log_semid);
output_end:
if (log_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 (log_shmid != -1)
shmdt(buf);
exit(1);
}
|
