Patch from Fillod Stephane:
You will find in the attached file "syslog.patch" a patch which adds
config options to set at compile time the size of the circular buffer,
and some documentation update.
diff --git a/docs/busybox.sgml b/docs/busybox.sgml
index 1d2e926..ac400c7 100644
--- a/docs/busybox.sgml
+++ b/docs/busybox.sgml
@@ -1976,6 +1976,38 @@
</para>
</sect1>
+ <sect1 id="logread">
+ <title>logread</title>
+
+ <para>
+ Usage: logread [OPTION]...
+ </para>
+
+ <para>
+ Shows the messages from syslogd (using circular buffer).
+ </para>
+
+ <para>
+ Options:
+ </para>
+
+ <para>
+ <screen>
+ -f Output data as the log grows.
+ </screen>
+ </para>
+
+ <para>
+ Example:
+ </para>
+
+ <para>
+ <screen>
+ $ logread
+ </screen>
+ </para>
+ </sect1>
+
<sect1 id="ls">
<title>ls</title>
@@ -3110,7 +3142,7 @@
-O FILE Use an alternate log file (default=/var/log/messages)
-R HOST[:PORT] Log remotely to IP or hostname on PORT (default PORT=514/UDP)
-L Log locally as well as network logging (default is network only)
- -C Log to a circular buffer. Read this buffer using 'logread'
+ -C [size(KiB)] Log to a circular buffer. Read this buffer using 'logread'
</screen>
</para>
diff --git a/include/usage.h b/include/usage.h
index 6db0385..ea1b5d5 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1458,10 +1458,12 @@
"root\n"
#define logread_trivial_usage \
- ""
+ "[OPTION]..."
#define logread_full_usage \
- "Shows the messages from syslogd (using circular buffer)."
+ "Shows the messages from syslogd (using circular buffer).\n\n"
+ "Options:\n" \
+ "\t-f\t\toutput data as the log grows"
#define losetup_trivial_usage \
"[OPTION]... LOOPDEVICE FILE\n" \
@@ -2280,7 +2282,7 @@
"\n\t-R HOST[:PORT]\tLog to IP or hostname on PORT (default PORT=514/UDP)\n" \
"\t-L\t\tLog locally and via network logging (default is network only)") \
USAGE_IPC_LOG( \
- "\n\t-C\t\tLog to a circular buffer (read the buffer using logread)")
+ "\n\t-C [size(KiB)]\tLog to a circular buffer (read the buffer using logread)")
#define syslogd_example_usage \
"$ syslogd -R masterlog:514\n" \
"$ syslogd -R 192.168.1.1:601\n"
diff --git a/sysklogd/Config.in b/sysklogd/Config.in
index cb2ee08..a671f59 100644
--- a/sysklogd/Config.in
+++ b/sysklogd/Config.in
@@ -56,6 +56,14 @@
entire filesystem, which may cause your system to
break badly.
+config CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
+ int " Circular buffer size in Kbytes (minimum 4KB)"
+ default 16
+ depends on CONFIG_FEATURE_IPC_SYSLOG
+ help
+ This option sets the size of the circular buffer
+ used to record system log messages.
+
config CONFIG_LOGREAD
bool " logread"
default y
@@ -66,6 +74,17 @@
utility will allow you to read the messages that are
stored in the syslogd circular buffer.
+config CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
+ bool " logread double buffering"
+ default n
+ depends on CONFIG_LOGREAD
+ help
+ 'logread' ouput to slow serial terminals can have
+ side effects on syslog because of the semaphore.
+ This option make logread to double buffer copy
+ from circular buffer, minimizing semaphore
+ contention at some minor memory expense.
+
config CONFIG_KLOGD
bool "klogd"
default n
diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index 524178f..207e78b 100644
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -108,8 +108,7 @@
i = follow ? buf->tail : buf->head;
do {
-#undef RC_LOGREAD
-#ifdef RC_LOGREAD
+#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
char *buf_data;
int log_len,j;
#endif
@@ -128,7 +127,7 @@
}
// Read Memory
-#ifdef RC_LOGREAD
+#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
log_len = buf->tail - i;
if (log_len < 0)
log_len += buf->size;
@@ -155,7 +154,7 @@
// release the lock on the log chain
sem_up(log_semid);
-#ifdef RC_LOGREAD
+#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)
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 622500e..42426ed 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -94,6 +94,12 @@
/* circular buffer variables/structures */
#ifdef CONFIG_FEATURE_IPC_SYSLOG
+
+#if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
+#error Sorry, you must set the syslogd buffer size to at least 4KB.
+#error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
+#endif
+
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
@@ -114,7 +120,7 @@
static int shmid = -1; // ipc shared memory id
static int s_semid = -1; // ipc semaphore id
-static int data_size = 16000; // default data size
+static int shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024); // default shm size
static int circular_logging = FALSE;
/*
@@ -156,7 +162,7 @@
void ipcsyslog_init(void)
{
if (buf == NULL) {
- if ((shmid = shmget(KEY_ID, data_size, IPC_CREAT | 1023)) == -1) {
+ if ((shmid = shmget(KEY_ID, shm_size, IPC_CREAT | 1023)) == -1) {
bb_perror_msg_and_die("shmget");
}
@@ -164,7 +170,7 @@
bb_perror_msg_and_die("shmat");
}
- buf->size = data_size - sizeof(*buf);
+ buf->size = shm_size - sizeof(*buf);
buf->head = buf->tail = 0;
// we'll trust the OS to set initial semval to 0 (let's hope)
@@ -654,7 +660,7 @@
if (optarg) {
int buf_size = atoi(optarg);
if (buf_size >= 4) {
- data_size = buf_size;
+ shm_size = buf_size;
}
}
circular_logging = TRUE;