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code shrinkage by Bernhard Fischer <rep.nop@aon.at>

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This commit is contained in:
Denis Vlasenko 2007-01-10 22:35:54 +00:00
parent 1a8bf7f5d3
commit 085231fbba
1 changed files with 31 additions and 49 deletions
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80
sysklogd/logread.c
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@ -11,37 +11,30 @@
#include "busybox.h" #include "busybox.h"
#include <sys/ipc.h> #include <sys/ipc.h>
//#include <sys/types.h>
#include <sys/sem.h> #include <sys/sem.h>
#include <sys/shm.h> #include <sys/shm.h>
//#include <signal.h>
//#include <setjmp.h>
#define DEBUG 0 #define DEBUG 0
static const long KEY_ID = 0x414e4547; /* "GENA" */ enum { KEY_ID = 0x414e4547 }; /* "GENA" */
static struct shbuf_ds { static struct shbuf_ds {
int32_t size; // size of data written int32_t size; // size of data written
int32_t head; // start of message list int32_t head; // start of message list
int32_t tail; // end of message list int32_t tail; // end of message list
char data[1]; // data/messages char data[1]; // data/messages
} *buf; // shared memory pointer } *buf; // shared memory pointer
// Semaphore operation structures // Semaphore operation structures
static struct sembuf SMrup[1] = {{0, -1, IPC_NOWAIT | SEM_UNDO}}; // set SMrup 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 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 void error_exit(const char *str) ATTRIBUTE_NORETURN; static void error_exit(const char *str) ATTRIBUTE_NORETURN;
static void error_exit(const char *str) static void error_exit(const char *str)
{ {
//release all acquired resources //release all acquired resources
if (log_shmid != -1) shmdt(buf);
shmdt(buf);
bb_perror_msg_and_die(str); bb_perror_msg_and_die(str);
} }
@ -54,16 +47,7 @@ static void sem_up(int semid)
error_exit("semop[SMrup]"); error_exit("semop[SMrup]");
} }
/* static void interrupted(int sig ATTRIBUTE_UNUSED)
* sem_down - down()'s a semaphore
*/
static void sem_down(int semid)
{
if (semop(semid, SMrdn, 2) == -1)
error_exit("semop[SMrdn]");
}
static void interrupted(int sig)
{ {
signal(SIGINT, SIG_IGN); signal(SIGINT, SIG_IGN);
shmdt(buf); shmdt(buf);
@ -73,23 +57,18 @@ static void interrupted(int sig)
int logread_main(int argc, char **argv) int logread_main(int argc, char **argv)
{ {
int cur; int cur;
int follow = 1; int log_semid; /* ipc semaphore id */
int log_shmid; /* ipc shared memory id */
if (argc != 2 || argv[1][0]!='-' || argv[1][1]!='f' ) { smallint follow = getopt32(argc, argv, "f");
follow = 0;
/* no options, no getopt */
if (argc > 1)
bb_show_usage();
}
log_shmid = shmget(KEY_ID, 0, 0); log_shmid = shmget(KEY_ID, 0, 0);
if (log_shmid == -1) if (log_shmid == -1)
error_exit("can't find circular buffer"); bb_perror_msg_and_die("can't find syslogd buffer");
// Attach shared memory to our char* // Attach shared memory to our char*
buf = shmat(log_shmid, NULL, SHM_RDONLY); buf = shmat(log_shmid, NULL, SHM_RDONLY);
if (buf == NULL) if (buf == NULL)
error_exit("can't get access to syslogd buffer"); bb_perror_msg_and_die("can't access syslogd buffer");
log_semid = semget(KEY_ID, 0, 0); log_semid = semget(KEY_ID, 0, 0);
if (log_semid == -1) if (log_semid == -1)
@ -102,38 +81,42 @@ int logread_main(int argc, char **argv)
cur = follow ? buf->tail : buf->head; cur = follow ? buf->tail : buf->head;
do { do {
#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING #if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
char *buf_data; char *buf_data;
int log_len, j; int log_len, j;
#endif #endif
sem_down(log_semid); if (semop(log_semid, SMrdn, 2) == -1)
error_exit("semop[SMrdn]");
if (DEBUG) if (DEBUG)
printf("head:%i cur:%d tail:%i size:%i\n", buf->head, cur, buf->tail, buf->size); 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 (buf->head == buf->tail || cur == buf->tail) {
if (follow) { if (follow) {
sem_up(log_semid); 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; continue;
} else {
printf("<empty syslog>\n");
} }
puts("<empty syslog>");
} }
// Read Memory // Read Memory
#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING #if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
log_len = buf->tail - cur; log_len = buf->tail - cur;
if (log_len < 0) if (log_len < 0)
log_len += buf->size; log_len += buf->size;
buf_data = xmalloc(log_len); buf_data = xmalloc(log_len);
if (buf->tail >= cur) { if (buf->tail >= cur)
memcpy(buf_data, buf->data + cur, log_len); j = log_len;
} else { else
memcpy(buf_data, buf->data + cur, buf->size - cur); 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); memcpy(buf_data + buf->size - cur, buf->data, buf->tail);
}
cur = buf->tail; cur = buf->tail;
#else #else
while (cur != buf->tail) { while (cur != buf->tail) {
@ -146,16 +129,15 @@ int logread_main(int argc, char **argv)
// release the lock on the log chain // release the lock on the log chain
sem_up(log_semid); sem_up(log_semid);
#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING #if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) { for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) {
fputs(buf_data + j, stdout); fputs(buf_data + j, stdout);
} }
free(buf_data); free(buf_data);
#endif #endif
fflush(stdout);
} while (follow); } while (follow);
shmdt(buf); shmdt(buf);
return EXIT_SUCCESS; fflush_stdout_and_exit(EXIT_SUCCESS);
} }