Import of Linus's Linux 1.1.68

1 files changed, 229 insertions, 0 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
new file mode 100644
index 000000000..d92269b30
--- /dev/null
+++ b/kernel/printk.c
@@ -0,0 +1,229 @@
+/*
+ *  linux/kernel/printk.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ * Modified to make sys_syslog() more flexible: added commands to
+ * return the last 4k of kernel messages, regardless of whether
+ * they've been read or not.  Added option to suppress kernel printk's
+ * to the console.  Added hook for sending the console messages
+ * elsewhere, in preparation for a serial line console (someday).
+ * Ted Ts'o, 2/11/93.
+ */
+
+#include <stdarg.h>
+
+#include <asm/segment.h>
+#include <asm/system.h>
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+
+#define LOG_BUF_LEN	4096
+
+static char buf[1024];
+
+extern void console_print(const char *);
+
+#define DEFAULT_MESSAGE_LOGLEVEL 7 /* KERN_DEBUG */
+#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything more serious than KERN_DEBUG */
+
+unsigned long log_size = 0;
+struct wait_queue * log_wait = NULL;
+int console_loglevel = DEFAULT_CONSOLE_LOGLEVEL;
+
+static void (*console_print_proc)(const char *) = 0;
+static char log_buf[LOG_BUF_LEN];
+static unsigned long log_start = 0;
+static unsigned long logged_chars = 0;
+
+/*
+ * Commands to sys_syslog:
+ *
+ * 	0 -- Close the log.  Currently a NOP.
+ * 	1 -- Open the log. Currently a NOP.
+ * 	2 -- Read from the log.
+ * 	3 -- Read up to the last 4k of messages in the ring buffer.
+ * 	4 -- Read and clear last 4k of messages 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
+ */
+asmlinkage int sys_syslog(int type, char * buf, int len)
+{
+	unsigned long i, j, count;
+	int do_clear = 0;
+	char c;
+	int error;
+
+	if ((type != 3) && !suser())
+		return -EPERM;
+	switch (type) {
+		case 0:		/* Close log */
+			return 0;
+		case 1:		/* Open log */
+			return 0;
+		case 2:		/* Read from log */
+			if (!buf || len < 0)
+				return -EINVAL;
+			if (!len)
+				return 0;
+			error = verify_area(VERIFY_WRITE,buf,len);
+			if (error)
+				return error;
+			cli();
+			while (!log_size) {
+				if (current->signal & ~current->blocked) {
+					sti();
+					return -ERESTARTSYS;
+				}
+				interruptible_sleep_on(&log_wait);
+			}
+			i = 0;
+			while (log_size && i < len) {
+				c = *((char *) log_buf+log_start);
+				log_start++;
+				log_size--;
+				log_start &= LOG_BUF_LEN-1;
+				sti();
+				put_fs_byte(c,buf);
+				buf++;
+				i++;
+				cli();
+			}
+			sti();
+			return i;
+		case 4:		/* Read/clear last kernel messages */
+			do_clear = 1; 
+			/* FALL THRU */
+		case 3:		/* Read last kernel messages */
+			if (!buf || len < 0)
+				return -EINVAL;
+			if (!len)
+				return 0;
+			error = verify_area(VERIFY_WRITE,buf,len);
+			if (error)
+				return error;
+			count = len;
+			if (count > LOG_BUF_LEN)
+				count = LOG_BUF_LEN;
+			if (count > logged_chars)
+				count = logged_chars;
+			j = log_start + log_size - count;
+			for (i = 0; i < count; i++) {
+				c = *((char *) log_buf+(j++ & (LOG_BUF_LEN-1)));
+				put_fs_byte(c, buf++);
+			}
+			if (do_clear)
+				logged_chars = 0;
+			return i;
+		case 5:		/* Clear ring buffer */
+			logged_chars = 0;
+			return 0;
+		case 6:		/* Disable logging to console */
+			console_loglevel = 1; /* only panic messages shown */
+			return 0;
+		case 7:		/* Enable logging to console */
+			console_loglevel = DEFAULT_CONSOLE_LOGLEVEL;
+			return 0;
+		case 8:
+			if (len < 0 || len > 8)
+				return -EINVAL;
+			console_loglevel = len;
+			return 0;
+	}
+	return -EINVAL;
+}
+
+
+asmlinkage int printk(const char *fmt, ...)
+{
+	va_list args;
+	int i;
+	char *msg, *p, *buf_end;
+	static char msg_level = -1;
+	long flags;
+
+	save_flags(flags);
+	cli();
+	va_start(args, fmt);
+	i = vsprintf(buf + 3, fmt, args); /* hopefully i < sizeof(buf)-4 */
+	buf_end = buf + 3 + i;
+	va_end(args);
+	for (p = buf + 3; p < buf_end; p++) {
+		msg = p;
+		if (msg_level < 0) {
+			if (
+				p[0] != '<' ||
+				p[1] < '0' || 
+				p[1] > '7' ||
+				p[2] != '>'
+			) {
+				p -= 3;
+				p[0] = '<';
+				p[1] = DEFAULT_MESSAGE_LOGLEVEL - 1 + '0';
+				p[2] = '>';
+			} else
+				msg += 3;
+			msg_level = p[1] - '0';
+		}
+		for (; p < buf_end; p++) {
+			log_buf[(log_start+log_size) & (LOG_BUF_LEN-1)] = *p;
+			if (log_size < LOG_BUF_LEN)
+				log_size++;
+			else
+				log_start++;
+			logged_chars++;
+			if (*p == '\n')
+				break;
+		}
+		if (msg_level < console_loglevel && console_print_proc) {
+			char tmp = p[1];
+			p[1] = '\0';
+			(*console_print_proc)(msg);
+			p[1] = tmp;
+		}
+		if (*p == '\n')
+			msg_level = -1;
+	}
+	restore_flags(flags);
+	wake_up_interruptible(&log_wait);
+	return i;
+}
+
+/*
+ * The console driver calls this routine during kernel initialization
+ * to register the console printing procedure with printk() and to
+ * print any messages that were printed by the kernel before the
+ * console driver was initialized.
+ */
+void register_console(void (*proc)(const char *))
+{
+	int	i,j;
+	int	p = log_start;
+	char	buf[16];
+	char	msg_level = -1;
+	char	*q;
+
+	console_print_proc = proc;
+
+	for (i=0,j=0; i < log_size; i++) {
+		buf[j++] = log_buf[p];
+		p++; p &= LOG_BUF_LEN-1;
+		if (buf[j-1] != '\n' && i < log_size - 1 && j < sizeof(buf)-1)
+			continue;
+		buf[j] = 0;
+		q = buf;
+		if (msg_level < 0) {
+			msg_level = buf[1] - '0';
+			q = buf + 3;
+		}
+		if (msg_level < console_loglevel)
+			(*proc)(q);
+		if (buf[j-1] == '\n')
+			msg_level = -1;
+		j = 0;
+	}
+}