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Subject[patch 1/4] Add <linux/klog.h>
This patch introduces <linux/klog.h> with symbolic constants for the
various sys_syslog() opcodes, and changes all in-kernel references to
those opcodes to use the constants. The header is added to the set of
user/kernel interface headers; there is no #ifdef __KERNEL__ block in
it yet, but there will be in subsequent patches, so I put it in as an
'unifdef' header.

zw

Index: linux-2.6/include/linux/Kbuild
===================================================================
--- linux-2.6.orig/include/linux/Kbuild 2006-11-10 13:36:58.000000000 -0800
+++ linux-2.6/include/linux/Kbuild 2006-11-10 13:37:13.000000000 -0800
@@ -253,6 +253,7 @@
unifdef-y += kernelcapi.h
unifdef-y += kernel.h
unifdef-y += keyboard.h
+unifdef-y += klog.h
unifdef-y += llc.h
unifdef-y += loop.h
unifdef-y += lp.h
Index: linux-2.6/include/linux/klog.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/include/linux/klog.h 2006-11-10 14:16:35.000000000 -0800
@@ -0,0 +1,26 @@
+#ifndef _LINUX_KLOG_H
+#define _LINUX_KLOG_H
+
+/*
+ * Constants for the first argument to the syslog() system call
+ * (aka klogctl()). These numbers are part of the user space ABI!
+ */
+enum {
+ KLOG_CLOSE = 0, /* close log */
+ KLOG_OPEN = 1, /* open log */
+ KLOG_READ = 2, /* read from log (klogd) */
+
+ KLOG_READ_HIST = 3, /* read history of log messages (dmesg) */
+ KLOG_READ_CLEAR_HIST = 4, /* read and clear history */
+ KLOG_CLEAR_HIST = 5, /* just clear history */
+
+ KLOG_DISABLE_CONSOLE = 6, /* disable printk to console */
+ KLOG_ENABLE_CONSOLE = 7, /* enable printk to console */
+ KLOG_SET_CONSOLE_LVL = 8, /* set minimum severity of messages to be
+ * printed to console */
+
+ KLOG_GET_UNREAD = 9, /* return number of unread characters */
+ KLOG_GET_SIZE = 10 /* return size of log buffer */
+};
+
+#endif /* klog.h */
Index: linux-2.6/kernel/printk.c
===================================================================
--- linux-2.6.orig/kernel/printk.c 2006-11-10 13:16:47.000000000 -0800
+++ linux-2.6/kernel/printk.c 2006-11-10 14:16:34.000000000 -0800
@@ -32,6 +32,7 @@
#include <linux/bootmem.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
+#include <linux/klog.h>

#include <asm/uaccess.h>

@@ -165,21 +166,7 @@

__setup("log_buf_len=", log_buf_len_setup);

-/*
- * Commands to do_syslog:
- *
- * 0 -- Close the log. Currently a NOP.
- * 1 -- Open the log. Currently a NOP.
- * 2 -- Read from the log.
- * 3 -- Read all messages remaining in the ring buffer.
- * 4 -- Read and clear all messages remaining in the ring buffer
- * 5 -- Clear ring buffer.
- * 6 -- Disable printk's to console
- * 7 -- Enable printk's to console
- * 8 -- Set level of messages printed to console
- * 9 -- Return number of unread characters in the log buffer
- * 10 -- Return size of the log buffer
- */
+/* See linux/klog.h for the command numbers passed as the first argument. */
int do_syslog(int type, char __user *buf, int len)
{
unsigned long i, j, limit, count;
@@ -192,11 +179,11 @@
return error;

switch (type) {
- case 0: /* Close log */
+ case KLOG_CLOSE:
break;
- case 1: /* Open log */
+ case KLOG_OPEN:
break;
- case 2: /* Read from log */
+ case KLOG_READ:
error = -EINVAL;
if (!buf || len < 0)
goto out;
@@ -227,10 +214,10 @@
if (!error)
error = i;
break;
- case 4: /* Read/clear last kernel messages */
+ case KLOG_READ_CLEAR_HIST:
do_clear = 1;
/* FALL THRU */
- case 3: /* Read last kernel messages */
+ case KLOG_READ_HIST:
error = -EINVAL;
if (!buf || len < 0)
goto out;
@@ -283,16 +270,16 @@
}
}
break;
- case 5: /* Clear ring buffer */
+ case KLOG_CLEAR_HIST:
logged_chars = 0;
break;
- case 6: /* Disable logging to console */
+ case KLOG_DISABLE_CONSOLE:
console_loglevel = minimum_console_loglevel;
break;
- case 7: /* Enable logging to console */
+ case KLOG_ENABLE_CONSOLE:
console_loglevel = default_console_loglevel;
break;
- case 8: /* Set level of messages printed to console */
+ case KLOG_SET_CONSOLE_LVL:
error = -EINVAL;
if (len < 1 || len > 8)
goto out;
@@ -301,10 +288,10 @@
console_loglevel = len;
error = 0;
break;
- case 9: /* Number of chars in the log buffer */
+ case KLOG_GET_UNREAD:
error = log_end - log_start;
break;
- case 10: /* Size of the log buffer */
+ case KLOG_GET_SIZE:
error = log_buf_len;
break;
default:
Index: linux-2.6/fs/proc/kmsg.c
===================================================================
--- linux-2.6.orig/fs/proc/kmsg.c 2006-11-10 14:16:41.000000000 -0800
+++ linux-2.6/fs/proc/kmsg.c 2006-11-10 14:22:56.000000000 -0800
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/poll.h>
#include <linux/fs.h>
+#include <linux/klog.h>

#include <asm/uaccess.h>
#include <asm/io.h>
@@ -21,27 +22,28 @@

static int kmsg_open(struct inode * inode, struct file * file)
{
- return do_syslog(1,NULL,0);
+ return do_syslog(KLOG_OPEN,NULL,0);
}

static int kmsg_release(struct inode * inode, struct file * file)
{
- (void) do_syslog(0,NULL,0);
+ (void) do_syslog(KLOG_CLOSE,NULL,0);
return 0;
}

static ssize_t kmsg_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
- if ((file->f_flags & O_NONBLOCK) && !do_syslog(9, NULL, 0))
+ if ((file->f_flags & O_NONBLOCK)
+ && !do_syslog(KLOG_GET_UNREAD, NULL, 0))
return -EAGAIN;
- return do_syslog(2, buf, count);
+ return do_syslog(KLOG_READ, buf, count);
}

static unsigned int kmsg_poll(struct file *file, poll_table *wait)
{
poll_wait(file, &log_wait, wait);
- if (do_syslog(9, NULL, 0))
+ if (do_syslog(KLOG_GET_UNREAD, NULL, 0))
return POLLIN | POLLRDNORM;
return 0;
}
--

-
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