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 1d2e9268a4d259ff6c712791ae4703a9c03111ef..ac400c7c88a8797d0f607aba46e211a4e903787b 100644 (file)
--- 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 6db0385fb77b16e17ae8af4744586382887820e0..ea1b5d5fe40e3509be9ea399e12f78928d8c25c9 100644 (file)
--- 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 cb2ee0865de9289913524ea0324651bcea806a35..a671f59f13cdba1cef75077853e82cb2fab6fbe3 100644 (file)
--- a/sysklogd/Config.in
+++ b/sysklogd/Config.in
@@ -56,6 +56,14 @@ config CONFIG_FEATURE_IPC_SYSLOG
          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 @@ config CONFIG_LOGREAD
          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 524178fe8243df513af6e0083fb3f2db1d5764dc..207e78b57184d3927c8c898a63b824d353af6209 100644 (file)
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -108,8 +108,7 @@ extern int logread_main(int argc, char **argv)
        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 @@ extern int logread_main(int argc, char **argv)
                }
        
                // 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 @@ extern int logread_main(int argc, char **argv)
                // 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 622500e48e407ae910d224503676c6eb8f3ae664..42426ed805ead6e3c7b4385c823014e60c2fd608 100644 (file)
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -94,6 +94,12 @@ static int local_logging = FALSE;
 
 /* 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 struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };        // set SMwdn
 
 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_cleanup(void)
 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 @@ void ipcsyslog_init(void)
                        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 @@ extern int syslogd_main(int argc, char **argv)
                        if (optarg) {
                                int buf_size = atoi(optarg);
                                if (buf_size >= 4) {
-                                       data_size = buf_size;
+                                       shm_size = buf_size;
                                }
                        }
                        circular_logging = TRUE;