[syslog] Pass internal syslog() priority through to syslog console

Use a private ANSI escape sequence to convey the priority of an
internal syslog() message through to the syslog server.

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

src/include/ipxe/ansiesc.h

 /** Select graphic rendition */
 #define ANSIESC_SGR 'm'
 
+/** Explicit log message priority
+ *
+ * This is an iPXE private sequence identifier.  (The range 'p' to '~'
+ * is reserved for private sequences.)
+ */
+#define ANSIESC_LOG_PRIORITY 'p'
+
 /** @} */
 
 extern int ansiesc_process ( struct ansiesc_context *ctx, int c );

src/include/ipxe/syslog.h

  */
 #define SYSLOG_BUFSIZE 128
 
-/** Syslog facility
+/** Syslog default facility
  *
  * This is a policy decision
  */
-#define SYSLOG_FACILITY 0 /* kernel */
+#define SYSLOG_DEFAULT_FACILITY 0 /* kernel */
 
-/** Syslog severity
+/** Syslog default severity
  *
  * This is a policy decision
  */
-#define SYSLOG_SEVERITY LOG_INFO
+#define SYSLOG_DEFAULT_SEVERITY LOG_INFO
 
 /** Syslog priority */
 #define SYSLOG_PRIORITY( facility, severity ) ( 8 * (facility) + (severity) )

src/include/syslog.h

 FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <stdarg.h>
+#include <ipxe/ansiesc.h>
 #include <config/console.h>
 
 /**
 extern void __attribute__ (( format ( printf, 1, 2 ) ))
 log_printf ( const char *fmt, ... );
 
+/** ANSI private escape sequence to set syslog priority
+ *
+ * @v priority		Priority
+ */
+#define SYSLOG_SET_PRIORITY( priority ) \
+	"\033[" #priority "p"
+
+/** ANSI private escape sequence to clear syslog priority */
+#define SYSLOG_CLEAR_PRIORITY "\033[p"
+
 /**
  * Write message to system log
  *
  * @v fmt		Format string
  * @v ...		Arguments
  */
-#define vsyslog( priority, fmt, args ) do {		\
+#define vsyslog( priority, fmt, args ) do {				\
-	if ( (priority) <= LOG_LEVEL ) {		\
+	if ( (priority) <= LOG_LEVEL ) {				\
-		log_vprintf ( fmt, (args) );		\
+		log_vprintf ( SYSLOG_SET_PRIORITY ( priority ) fmt	\
-	}						\
+			      SYSLOG_CLEAR_PRIORITY, (args) );		\
+	}								\
 	} while ( 0 )
 
 /**
  * @v fmt		Format string
  * @v ...		Arguments
  */
-#define syslog( priority, fmt, ... ) do {		\
+#define syslog( priority, fmt, ... ) do {				\
-	if ( (priority) <= LOG_LEVEL ) {		\
+	if ( (priority) <= LOG_LEVEL ) {				\
-		log_printf ( fmt, ##__VA_ARGS__ );	\
+		log_printf ( SYSLOG_SET_PRIORITY ( priority ) fmt	\
-	}						\
+			     SYSLOG_CLEAR_PRIORITY, ##__VA_ARGS__ );	\
+	}								\
 	} while ( 0 )
 
 #endif /* _SYSLOG_H */

src/net/udp/syslog.c

 /** Syslog line buffer */
 static char syslog_buffer[SYSLOG_BUFSIZE];
 
+/** Syslog severity */
+static unsigned int syslog_severity = SYSLOG_DEFAULT_SEVERITY;
+
+/**
+ * Handle ANSI set syslog priority (private sequence)
+ *
+ * @v count		Parameter count
+ * @v params		List of graphic rendition aspects
+ */
+static void syslog_handle_priority ( unsigned int count __unused,
+				     int params[] ) {
+	if ( params[0] >= 0 ) {
+		syslog_severity = params[0];
+	} else {
+		syslog_severity = SYSLOG_DEFAULT_SEVERITY;
+	}
+}
+
 /** Syslog ANSI escape sequence handlers */
 static struct ansiesc_handler syslog_handlers[] = {
+	{ ANSIESC_LOG_PRIORITY, syslog_handle_priority },
 	{ 0, NULL }
 };
 
 
 	/* Send log message */
 	if ( ( rc = xfer_printf ( &syslogger, "<%d>ipxe: %s",
-				  SYSLOG_PRIORITY ( SYSLOG_FACILITY,
+				  SYSLOG_PRIORITY ( SYSLOG_DEFAULT_FACILITY,
-						    SYSLOG_SEVERITY ),
+						    syslog_severity ),
 				  syslog_buffer ) ) != 0 ) {
 		DBG ( "SYSLOG could not send log message: %s\n",
 		      strerror ( rc ) );