blob: 70d1db6319348db7006d26812e19296fb5a1cc16 [file] [log] [blame]
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +00001/* vi: set sw=4 ts=4: */
2/*
3 * circular buffer syslog implementation for busybox
4 *
Glenn L McGrath6ed77592002-12-12 10:54:48 +00005 * Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com>
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +00006 *
Glenn L McGrath6ed77592002-12-12 10:54:48 +00007 * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +00008 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 * 02111-1307 USA
23 *
24 */
25
26
27#include <stdio.h>
28#include <stdlib.h>
29#include <string.h>
30#include <sys/ipc.h>
31#include <sys/types.h>
32#include <sys/sem.h>
33#include <sys/shm.h>
34#include <signal.h>
35#include <setjmp.h>
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +000036#include <unistd.h>
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000037#include "busybox.h"
38
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000039static const long KEY_ID = 0x414e4547; /*"GENA"*/
40
41static struct shbuf_ds {
42 int size; // size of data written
43 int head; // start of message list
44 int tail; // end of message list
45 char data[1]; // data/messages
46} *buf = NULL; // shared memory pointer
47
48
49// Semaphore operation structures
50static struct sembuf SMrup[1] = {{0, -1, IPC_NOWAIT | SEM_UNDO}}; // set SMrup
51static struct sembuf SMrdn[2] = {{1, 0}, {0, +1, SEM_UNDO}}; // set SMrdn
52
Eric Andersen8ffaf8d2001-03-23 17:04:47 +000053static int log_shmid = -1; // ipc shared memory id
54static int log_semid = -1; // ipc semaphore id
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000055static jmp_buf jmp_env;
56
57static void error_exit(const char *str);
58static void interrupted(int sig);
59
60/*
61 * sem_up - up()'s a semaphore.
62 */
63static inline void sem_up(int semid)
64{
Eric Andersenc7bda1c2004-03-15 08:29:22 +000065 if ( semop(semid, SMrup, 1) == -1 )
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000066 error_exit("semop[SMrup]");
67}
68
69/*
70 * sem_down - down()'s a semaphore
Eric Andersenc7bda1c2004-03-15 08:29:22 +000071 */
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000072static inline void sem_down(int semid)
73{
74 if ( semop(semid, SMrdn, 2) == -1 )
75 error_exit("semop[SMrdn]");
76}
77
78extern int logread_main(int argc, char **argv)
79{
80 int i;
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +000081 int follow=0;
Eric Andersenc7bda1c2004-03-15 08:29:22 +000082
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +000083 if (argc == 2 && strcmp(argv[1],"-f")==0) {
84 follow = 1;
85 } else {
86 /* no options, no getopt */
87 if (argc > 1)
88 bb_show_usage();
89 }
Eric Andersenc7bda1c2004-03-15 08:29:22 +000090
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000091 // handle intrrupt signal
92 if (setjmp(jmp_env)) goto output_end;
Eric Andersenc7bda1c2004-03-15 08:29:22 +000093
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000094 // attempt to redefine ^C signal
95 signal(SIGINT, interrupted);
Eric Andersenc7bda1c2004-03-15 08:29:22 +000096
Eric Andersen8ffaf8d2001-03-23 17:04:47 +000097 if ( (log_shmid = shmget(KEY_ID, 0, 0)) == -1)
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +000098 error_exit("Can't find circular buffer");
Eric Andersenc7bda1c2004-03-15 08:29:22 +000099
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000100 // Attach shared memory to our char*
Eric Andersen8ffaf8d2001-03-23 17:04:47 +0000101 if ( (buf = shmat(log_shmid, NULL, SHM_RDONLY)) == NULL)
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000102 error_exit("Can't get access to circular buffer from syslogd");
103
Eric Andersen8ffaf8d2001-03-23 17:04:47 +0000104 if ( (log_semid = semget(KEY_ID, 0, 0)) == -1)
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000105 error_exit("Can't get access to semaphone(s) for circular buffer from syslogd");
106
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000107 // Suppose atomic memory move
108 i = follow ? buf->tail : buf->head;
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000109
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000110 do {
Eric Andersend4a5e252003-12-19 11:32:14 +0000111#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000112 char *buf_data;
113 int log_len,j;
114#endif
115
Eric Andersenc7bda1c2004-03-15 08:29:22 +0000116 sem_down(log_semid);
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000117
118 //printf("head: %i tail: %i size: %i\n",buf->head,buf->tail,buf->size);
119 if (buf->head == buf->tail || i==buf->tail) {
120 if (follow) {
121 sem_up(log_semid);
122 sleep(1); /* TODO: replace me with a sleep_on */
123 continue;
124 } else {
125 printf("<empty syslog>\n");
126 }
127 }
Eric Andersenc7bda1c2004-03-15 08:29:22 +0000128
129 // Read Memory
Eric Andersend4a5e252003-12-19 11:32:14 +0000130#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000131 log_len = buf->tail - i;
132 if (log_len < 0)
133 log_len += buf->size;
134 buf_data = (char *)malloc(log_len);
135 if (!buf_data)
136 error_exit("malloc failed");
137
138 if (buf->tail < i) {
139 memcpy(buf_data, buf->data+i, buf->size-i);
140 memcpy(buf_data+buf->size-i, buf->data, buf->tail);
141 } else {
142 memcpy(buf_data, buf->data+i, buf->tail-i);
143 }
144 i = buf->tail;
145
146#else
147 while ( i != buf->tail) {
148 printf("%s", buf->data+i);
149 i+= strlen(buf->data+i) + 1;
150 if (i >= buf->size )
151 i=0;
152 }
153#endif
154 // release the lock on the log chain
155 sem_up(log_semid);
156
Eric Andersend4a5e252003-12-19 11:32:14 +0000157#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
Glenn L McGrathf7dd10f2003-09-26 01:03:16 +0000158 for (j=0; j < log_len; j+=strlen(buf_data+j)+1) {
159 printf("%s", buf_data+j);
160 if (follow)
161 fflush(stdout);
162 }
163 free(buf_data);
164#endif
165 } while (follow);
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000166
167output_end:
Eric Andersenc7bda1c2004-03-15 08:29:22 +0000168 if (log_shmid != -1)
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000169 shmdt(buf);
Eric Andersenc7bda1c2004-03-15 08:29:22 +0000170
171 return EXIT_SUCCESS;
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000172}
173
174static void interrupted(int sig){
175 signal(SIGINT, SIG_IGN);
176 longjmp(jmp_env, 1);
177}
178
179static void error_exit(const char *str){
180 perror(str);
181 //release all acquired resources
Eric Andersenc7bda1c2004-03-15 08:29:22 +0000182 if (log_shmid != -1)
Mark Whitleyb0c2b7d2001-03-15 19:05:59 +0000183 shmdt(buf);
184
185 exit(1);
186}