diff options
Diffstat (limited to 'sysklogd/logread.c')
| -rw-r--r-- | sysklogd/logread.c | 140 |
1 files changed, 65 insertions, 75 deletions
diff --git a/sysklogd/logread.c b/sysklogd/logread.c index 745f976..4427cf3 100644 --- a/sysklogd/logread.c +++ b/sysklogd/logread.c @@ -9,46 +9,48 @@ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ - #include "busybox.h" -#include <stdio.h> -#include <stdlib.h> -#include <string.h> #include <sys/ipc.h> -#include <sys/types.h> +//#include <sys/types.h> #include <sys/sem.h> #include <sys/shm.h> -#include <signal.h> -#include <setjmp.h> -#include <unistd.h> +//#include <signal.h> +//#include <setjmp.h> + +#define DEBUG 0 -static const long KEY_ID = 0x414e4547; /*"GENA"*/ +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 + 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 = NULL; // shared memory pointer +} *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 int log_shmid = -1; // ipc shared memory id +static int log_semid = -1; // ipc semaphore id -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 + if (log_shmid != -1) + shmdt(buf); + bb_perror_msg_and_die(str); +} /* * sem_up - up()'s a semaphore. */ static void sem_up(int semid) { - if ( semop(semid, SMrup, 1) == -1 ) + if (semop(semid, SMrup, 1) == -1) error_exit("semop[SMrup]"); } @@ -57,52 +59,59 @@ static void sem_up(int semid) */ static void sem_down(int semid) { - if ( semop(semid, SMrdn, 2) == -1 ) + if (semop(semid, SMrdn, 2) == -1) error_exit("semop[SMrdn]"); } +static void interrupted(int sig) +{ + signal(SIGINT, SIG_IGN); + shmdt(buf); + exit(0); +} + int logread_main(int argc, char **argv) { - int i; - int follow=0; + int cur; + int follow = 1; - if (argc == 2 && argv[1][0]=='-' && argv[1][1]=='f') { - follow = 1; - } else { + if (argc != 2 || argv[1][0]!='-' || argv[1][1]!='f' ) { + follow = 0; /* no options, no getopt */ if (argc > 1) bb_show_usage(); } - // handle interrupt 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"); + log_shmid = shmget(KEY_ID, 0, 0); + if (log_shmid == -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"); + buf = shmat(log_shmid, NULL, SHM_RDONLY); + if (buf == NULL) + error_exit("can't get access to syslogd buffer"); + + log_semid = semget(KEY_ID, 0, 0); + if (log_semid == -1) + error_exit("can't get access to semaphores for syslogd buffer"); - if ( (log_semid = semget(KEY_ID, 0, 0)) == -1) - error_exit("Can't get access to semaphore(s) for circular buffer from syslogd"); + // attempt to redefine ^C signal + signal(SIGINT, interrupted); // Suppose atomic memory move - i = follow ? buf->tail : buf->head; + cur = follow ? buf->tail : buf->head; do { #ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING char *buf_data; - int log_len,j; + int log_len, j; #endif - sem_down(log_semid); - //printf("head: %i tail: %i size: %i\n",buf->head,buf->tail,buf->size); - if (buf->head == buf->tail || i==buf->tail) { + 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); sleep(1); /* TODO: replace me with a sleep_on */ @@ -114,58 +123,39 @@ int logread_main(int argc, char **argv) // Read Memory #ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING - log_len = buf->tail - i; + log_len = buf->tail - cur; if (log_len < 0) log_len += buf->size; buf_data = xmalloc(log_len); - if (buf->tail < i) { - memcpy(buf_data, buf->data+i, buf->size-i); - memcpy(buf_data+buf->size-i, buf->data, buf->tail); + if (buf->tail >= cur) { + memcpy(buf_data, buf->data + cur, log_len); } else { - memcpy(buf_data, buf->data+i, buf->tail-i); + memcpy(buf_data, buf->data + cur, buf->size - cur); + memcpy(buf_data + buf->size - cur, buf->data, buf->tail); } - i = buf->tail; - + cur = buf->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 != 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); #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); + for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) { + fputs(buf_data + j, stdout); } free(buf_data); #endif fflush(stdout); } while (follow); -output_end: - if (log_shmid != -1) - shmdt(buf); + 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){ - bb_perror_msg(str); - //release all acquired resources - if (log_shmid != -1) - shmdt(buf); - - exit(1); -} |