[console] Add "log message" console usage and an internal syslog() call

Provide an internal syslog() function (unrelated to the syslog
console) which can be used to create log messages with specified
priorities.

The build-time constant LOG_LEVEL can be used to select the minimum
required priority for log messages.  Any messages that do not have a
sufficient priority will be ignored (and will be optimised away at
compile-time).

The default LOG_LEVEL is LOG_NONE.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/console.h

@@ -23,6 +23,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 #define	KEYBOARD_MAP	us
 
+#define	LOG_LEVEL	LOG_NONE
+
 #include <config/local/console.h>
 
 #endif /* CONFIG_CONSOLE_H */

src/core/log.c

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * System logger
+ *
+ */
+
+#include <stdarg.h>
+#include <syslog.h>
+#include <ipxe/console.h>
+
+/**
+ * Write message to system log
+ *
+ * @v fmt		Format string
+ * @v args		Arguments
+ */
+void log_vprintf ( const char *fmt, va_list args ) {
+	int saved_usage;
+
+	/* Mark console as in use for log messages */
+	saved_usage = console_set_usage ( CONSOLE_USAGE_LOG );
+
+	/* Print message */
+	vprintf ( fmt, args );
+
+	/* Restore console usage */
+	console_set_usage ( saved_usage );
+}
+
+/**
+ * Write message to system log
+ *
+ * @v fmt		Format string
+ * @v ...		Arguments
+ */
+void log_printf ( const char *fmt, ... ) {
+	va_list args;
+
+	va_start ( args, fmt );
+	log_vprintf ( fmt, args );
+	va_end ( args );
+}

src/include/ipxe/console.h

@@ -120,9 +120,12 @@ struct console_driver {
 /** Text-based user interface */
 #define CONSOLE_USAGE_TUI 0x0004
 
+/** Log messages */
+#define CONSOLE_USAGE_LOG 0x0008
+
 /** All console usages */
-#define CONSOLE_USAGE_ALL \
-	( CONSOLE_USAGE_STDOUT | CONSOLE_USAGE_DEBUG | CONSOLE_USAGE_TUI )
+#define CONSOLE_USAGE_ALL ( CONSOLE_USAGE_STDOUT | CONSOLE_USAGE_DEBUG | \
+			    CONSOLE_USAGE_TUI | CONSOLE_USAGE_LOG )
 
 /** @} */
 

src/include/ipxe/syslog.h

@@ -9,6 +9,8 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
+#include <syslog.h>
+
 /** Syslog server port */
 #define SYSLOG_PORT 514
 
@@ -28,7 +30,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  * This is a policy decision
  */
-#define SYSLOG_SEVERITY 6 /* informational */
+#define SYSLOG_SEVERITY LOG_INFO
 
 /** Syslog priority */
 #define SYSLOG_PRIORITY( facility, severity ) ( 8 * (facility) + (severity) )

src/include/syslog.h

@@ -0,0 +1,84 @@
+#ifndef _SYSLOG_H
+#define _SYSLOG_H
+
+/** @file
+ *
+ * System logger
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdarg.h>
+#include <config/console.h>
+
+/**
+ * @defgroup syslogpri Syslog priorities
+ *
+ * These values are chosen to match those used in the syslog network
+ * protocol (RFC 5424).
+ *
+ * @{
+ */
+
+/** Emergency: system is unusable */
+#define LOG_EMERG 0
+
+/** Alert: action must be taken immediately */
+#define LOG_ALERT 1
+
+/** Critical: critical conditions */
+#define LOG_CRIT 2
+
+/** Error: error conditions */
+#define LOG_ERR 3
+
+/** Warning: warning conditions */
+#define LOG_WARNING 4
+
+/** Notice: normal but significant conditions */
+#define LOG_NOTICE 5
+
+/** Informational: informational messages */
+#define LOG_INFO 6
+
+/** Debug: debug-level messages */
+#define LOG_DEBUG 7
+
+/** @} */
+
+/** Do not log any messages */
+#define LOG_NONE -1
+
+extern void log_vprintf ( const char *fmt, va_list args );
+
+extern void __attribute__ (( format ( printf, 1, 2 ) ))
+log_printf ( const char *fmt, ... );
+
+/**
+ * Write message to system log
+ *
+ * @v priority		Message priority
+ * @v fmt		Format string
+ * @v ...		Arguments
+ */
+#define vsyslog( priority, fmt, args ) do {		\
+	if ( (priority) <= LOG_LEVEL ) {		\
+		log_vprintf ( fmt, (args) );		\
+	}						\
+	} while ( 0 )
+
+/**
+ * Write message to system log
+ *
+ * @v priority		Message priority
+ * @v fmt		Format string
+ * @v ...		Arguments
+ */
+#define syslog( priority, fmt, ... ) do {		\
+	if ( (priority) <= LOG_LEVEL ) {		\
+		log_printf ( fmt, ##__VA_ARGS__ );	\
+	}						\
+	} while ( 0 )
+
+#endif /* _SYSLOG_H */