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authorGravatar Glenn L McGrath <bug1@ihug.co.nz>2003-09-26 01:03:16 +0000
committerGravatar Glenn L McGrath <bug1@ihug.co.nz>2003-09-26 01:03:16 +0000
commitf7dd10f67ce892530b2a2093b149722cf4903e76 (patch)
treec8376bd83d6a883e3a8d445087a358463a3f91a3 /sysklogd
parenta79220db6e71b7fa509ffa88a02ff1ea785bf811 (diff)
downloadbusybox-f7dd10f67ce892530b2a2093b149722cf4903e76.tar.gz
busybox-f7dd10f67ce892530b2a2093b149722cf4903e76.tar.bz2
Patch from Fillod Stephane
Add follow mode to logread, ala "tail -f /var/log/messages" Note: output to a slow serial terminal can have side effects on syslog because of the semaphore. In such case, define RC_LOGREAD.
Diffstat (limited to 'sysklogd')
-rw-r--r--sysklogd/logread.c86
1 files changed, 68 insertions, 18 deletions
diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index 2692efbee..524178fe8 100644
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -33,6 +33,7 @@
#include <sys/shm.h>
#include <signal.h>
#include <setjmp.h>
+#include <unistd.h>
#include "busybox.h"
static const long KEY_ID = 0x414e4547; /*"GENA"*/
@@ -77,10 +78,15 @@ static inline void sem_down(int semid)
extern int logread_main(int argc, char **argv)
{
int i;
+ int follow=0;
- /* no options, no getopt */
- if (argc > 1)
- bb_show_usage();
+ 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;
@@ -98,22 +104,66 @@ extern int logread_main(int argc, char **argv)
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");
- }
+ // Suppose atomic memory move
+ i = follow ? buf->tail : buf->head;
+
+ do {
+#undef RC_LOGREAD
+#ifdef RC_LOGREAD
+ char *buf_data;
+ 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 (follow) {
+ sem_up(log_semid);
+ sleep(1); /* TODO: replace me with a sleep_on */
+ continue;
+ } else {
+ 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);
+ // Read Memory
+#ifdef RC_LOGREAD
+ 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;
+
+#else
+ while ( i != buf->tail) {
+ printf("%s", buf->data+i);
+ i+= strlen(buf->data+i) + 1;
+ if (i >= buf->size )
+ i=0;
+ }
+#endif
+ // release the lock on the log chain
+ sem_up(log_semid);
+
+#ifdef RC_LOGREAD
+ for (j=0; j < log_len; j+=strlen(buf_data+j)+1) {
+ printf("%s", buf_data+j);
+ if (follow)
+ fflush(stdout);
+ }
+ free(buf_data);
+#endif
+ } while (follow);
output_end:
if (log_shmid != -1)