*
* Maintainer: Gennady Feldman <gfeldman@gena01.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
- *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include "libbb.h"
#include <sys/ipc.h>
-#include <sys/types.h>
#include <sys/sem.h>
#include <sys/shm.h>
-#include <signal.h>
-#include <setjmp.h>
-#include <unistd.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 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);
+#define DEBUG 0
+
+enum { KEY_ID = 0x414e4547 }; /* "GENA" */
+
+struct shbuf_ds {
+ int32_t size; // size of data - 1
+ int32_t tail; // end of message list
+ char data[1]; // messages
+};
+
+static const struct sembuf init_sem[3] = {
+ {0, -1, IPC_NOWAIT | SEM_UNDO},
+ {1, 0}, {0, +1, SEM_UNDO}
+};
+
+struct globals {
+ struct sembuf SMrup[1]; // {0, -1, IPC_NOWAIT | SEM_UNDO},
+ struct sembuf SMrdn[2]; // {1, 0}, {0, +1, SEM_UNDO}
+ struct shbuf_ds *shbuf;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define SMrup (G.SMrup)
+#define SMrdn (G.SMrdn)
+#define shbuf (G.shbuf)
+#define INIT_G() \
+ do { \
+ memcpy(SMrup, init_sem, sizeof(init_sem)); \
+ } while (0)
+
+static void error_exit(const char *str) ATTRIBUTE_NORETURN;
+static void error_exit(const char *str)
+{
+ //release all acquired resources
+ shmdt(shbuf);
+ 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(shbuf);
+ exit(0);
}
-extern int logread_main(int argc, char **argv)
+int logread_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int logread_main(int argc, char **argv)
{
- int i;
- int follow=0;
-
- if (argc == 2 && strcmp(argv[1],"-f")==0) {
- follow = 1;
- } else {
- /* no options, no getopt */
- if (argc > 1)
- bb_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");
+ int cur;
+ int log_semid; /* ipc semaphore id */
+ int log_shmid; /* ipc shared memory id */
+ smallint follow = getopt32(argv, "f");
- if ( (log_semid = semget(KEY_ID, 0, 0)) == -1)
- error_exit("Can't get access to semaphone(s) for circular buffer from syslogd");
+ INIT_G();
- // Suppose atomic memory move
- i = follow ? buf->tail : buf->head;
+ log_shmid = shmget(KEY_ID, 0, 0);
+ if (log_shmid == -1)
+ bb_perror_msg_and_die("can't find syslogd buffer");
- do {
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
- char *buf_data;
- int log_len,j;
-#endif
+ /* Attach shared memory to our char* */
+ shbuf = shmat(log_shmid, NULL, SHM_RDONLY);
+ if (shbuf == NULL)
+ bb_perror_msg_and_die("can't access syslogd buffer");
- sem_down(log_semid);
+ log_semid = semget(KEY_ID, 0, 0);
+ if (log_semid == -1)
+ error_exit("can't get access to semaphores for syslogd buffer");
- //printf("head: %i tail: %i size: %i\n",buf->head,buf->tail,buf->size);
- if (buf->head == buf->tail || i==buf->tail) {
- if (follow) {
+ signal(SIGINT, interrupted);
+
+ /* Suppose atomic memory read */
+ /* Max possible value for tail is shbuf->size - 1 */
+ cur = shbuf->tail;
+
+ /* Loop for logread -f, one pass if there was no -f */
+ do {
+ unsigned shbuf_size;
+ unsigned shbuf_tail;
+ const char *shbuf_data;
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ int i;
+ int len_first_part;
+ int len_total = len_total; /* for gcc */
+ char *copy = copy; /* for gcc */
+#endif
+ if (semop(log_semid, SMrdn, 2) == -1)
+ error_exit("semop[SMrdn]");
+
+ /* Copy the info, helps gcc to realize that it doesn't change */
+ shbuf_size = shbuf->size;
+ shbuf_tail = shbuf->tail;
+ shbuf_data = shbuf->data; /* pointer! */
+
+ if (DEBUG)
+ printf("cur:%d tail:%i size:%i\n",
+ cur, shbuf_tail, shbuf_size);
+
+ if (!follow) {
+ /* advance to oldest complete message */
+ /* find NUL */
+ cur += strlen(shbuf_data + cur);
+ if (cur >= shbuf_size) { /* last byte in buffer? */
+ cur = strnlen(shbuf_data, shbuf_tail);
+ if (cur == shbuf_tail)
+ goto unlock; /* no complete messages */
+ }
+ /* advance to first byte of the message */
+ cur++;
+ if (cur >= shbuf_size) /* last byte in buffer? */
+ cur = 0;
+ } else { /* logread -f */
+ if (cur == shbuf_tail) {
sem_up(log_semid);
- sleep(1); /* TODO: replace me with a sleep_on */
+ fflush(stdout);
+ sleep(1); /* TODO: replace me with a sleep_on */
continue;
- } else {
- printf("<empty syslog>\n");
}
}
-
- // Read Memory
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
- log_len = buf->tail - i;
- if (log_len < 0)
- log_len += buf->size;
- buf_data = (char *)malloc(log_len);
- if (!buf_data)
- error_exit("malloc failed");
-
- if (buf->tail < i) {
- memcpy(buf_data, buf->data+i, buf->size-i);
- memcpy(buf_data+buf->size-i, buf->data, buf->tail);
- } else {
- memcpy(buf_data, buf->data+i, buf->tail-i);
- }
- i = buf->tail;
+ /* Read from cur to tail */
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ len_first_part = len_total = shbuf_tail - cur;
+ if (len_total < 0) {
+ /* message wraps: */
+ /* [SECOND PART.........FIRST PART] */
+ /* ^data ^tail ^cur ^size */
+ len_total += shbuf_size;
+ }
+ copy = xmalloc(len_total + 1);
+ if (len_first_part < 0) {
+ /* message wraps (see above) */
+ len_first_part = shbuf_size - cur;
+ memcpy(copy + len_first_part, shbuf_data, shbuf_tail);
+ }
+ memcpy(copy, shbuf_data + cur, len_first_part);
+ copy[len_total] = '\0';
+ cur = shbuf_tail;
#else
- while ( i != buf->tail) {
- printf("%s", buf->data+i);
- i+= strlen(buf->data+i) + 1;
- if (i >= buf->size )
- i=0;
+ while (cur != shbuf_tail) {
+ fputs(shbuf_data + cur, stdout);
+ cur += strlen(shbuf_data + cur) + 1;
+ if (cur >= shbuf_size)
+ cur = 0;
}
#endif
- // release the lock on the log chain
+ unlock:
+ /* release the lock on the log chain */
sem_up(log_semid);
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
- for (j=0; j < log_len; j+=strlen(buf_data+j)+1) {
- printf("%s", buf_data+j);
- if (follow)
- fflush(stdout);
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ for (i = 0; i < len_total; i += strlen(copy + i) + 1) {
+ fputs(copy + i, stdout);
}
- free(buf_data);
+ free(copy);
#endif
} while (follow);
-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);
+ shmdt(shbuf);
- exit(1);
+ fflush_stdout_and_exit(EXIT_SUCCESS);
}
projects / oweals / busybox.git / blobdiff