/*
* circular buffer syslog implementation for busybox
*
- * Copyright (C) 2000 by Gennady Feldman <gfeldman@cachier.com>
+ * Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.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
+ * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
*
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include "busybox.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
+#define DEBUG 0
-
-static const long KEY_ID = 0x414e4547; /*"GENA"*/
+enum { 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
-
+ int32_t size; // size of data written
+ int32_t head; // start of message list
+ int32_t tail; // end of message list
+ char data[1]; // data/messages
+} *buf; // 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);
+static void error_exit(const char *str) ATTRIBUTE_NORETURN;
+static void error_exit(const char *str)
+{
+ //release all acquired resources
+ shmdt(buf);
+ bb_perror_msg_and_die(str);
+}
/*
* sem_up - up()'s a semaphore.
*/
-static inline void sem_up(int semid)
+static void sem_up(int semid)
{
- if ( semop(semid, SMrup, 1) == -1 )
+ if (semop(semid, SMrup, 1) == -1)
error_exit("semop[SMrup]");
}
-/*
- * sem_down - down()'s a semaphore
- */
-static inline void sem_down(int semid)
+static void interrupted(int sig ATTRIBUTE_UNUSED)
{
- if ( semop(semid, SMrdn, 2) == -1 )
- error_exit("semop[SMrdn]");
+ signal(SIGINT, SIG_IGN);
+ shmdt(buf);
+ exit(0);
}
-extern int logread_main(int argc, char **argv)
+int logread_main(int argc, char **argv);
+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");
-
+ int cur;
+ int log_semid; /* ipc semaphore id */
+ int log_shmid; /* ipc shared memory id */
+ smallint follow = getopt32(argc, argv, "f");
+
+ log_shmid = shmget(KEY_ID, 0, 0);
+ if (log_shmid == -1)
+ bb_perror_msg_and_die("can't find syslogd 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;
-}
+ buf = shmat(log_shmid, NULL, SHM_RDONLY);
+ if (buf == NULL)
+ bb_perror_msg_and_die("can't access syslogd buffer");
-static void interrupted(int sig){
- signal(SIGINT, SIG_IGN);
- longjmp(jmp_env, 1);
-}
+ log_semid = semget(KEY_ID, 0, 0);
+ if (log_semid == -1)
+ error_exit("can't get access to semaphores for syslogd buffer");
-static void error_exit(const char *str){
- perror(str);
- //release all acquired resources
- if (log_shmid != -1)
- shmdt(buf);
+ // attempt to redefine ^C signal
+ signal(SIGINT, interrupted);
- exit(1);
+ // Suppose atomic memory move
+ cur = follow ? buf->tail : buf->head;
+
+ do {
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ char *buf_data;
+ int log_len, j;
+#endif
+ if (semop(log_semid, SMrdn, 2) == -1)
+ error_exit("semop[SMrdn]");
+
+ if (DEBUG)
+ printf("head:%i cur:%d tail:%i size:%i\n",
+ buf->head, cur, buf->tail, buf->size);
+
+ if (buf->head == buf->tail || cur == buf->tail) {
+ if (follow) {
+ sem_up(log_semid);
+ fflush(stdout);
+ sleep(1); /* TODO: replace me with a sleep_on */
+ continue;
+ }
+ puts("<empty syslog>");
+ }
+
+ // Read Memory
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ log_len = buf->tail - cur;
+ if (log_len < 0)
+ log_len += buf->size;
+ buf_data = xmalloc(log_len);
+
+ if (buf->tail >= cur)
+ j = log_len;
+ else
+ j = buf->size - cur;
+ memcpy(buf_data, buf->data + cur, j);
+
+ if (buf->tail < cur)
+ memcpy(buf_data + buf->size - cur, buf->data, buf->tail);
+ cur = buf->tail;
+#else
+ while (cur != buf->tail) {
+ fputs(buf->data + cur, stdout);
+ cur += strlen(buf->data + cur) + 1;
+ if (cur >= buf->size)
+ cur = 0;
+ }
+#endif
+ // release the lock on the log chain
+ sem_up(log_semid);
+
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) {
+ fputs(buf_data + j, stdout);
+ }
+ free(buf_data);
+#endif
+ } while (follow);
+
+ shmdt(buf);
+
+ fflush_stdout_and_exit(EXIT_SUCCESS);
}
projects / oweals / busybox.git / blobdiff