dde_linux: fully enable printk format specifiers

The new Lx_kit::Console::print_string() method skips leading
log-level markers in strings if detected.

Issue #4542

repos/dde_linux/src/include/lx_emul/log.h

@@ -1,6 +1,7 @@
 /*
  * \brief  Lx_emul support to log messages from the kernel code
  * \author Stefan Kalkowski
+ * \author Christian Helmuth
  * \date   2021-03-24
  */
 
@@ -19,6 +20,7 @@ extern "C" {
 #endif
 
 void lx_emul_vprintf(char const *, va_list);
+void lx_emul_print_string(char const *);
 
 #ifdef __cplusplus
 }

repos/dde_linux/src/include/lx_kit/console.h

@@ -2,6 +2,7 @@
  * \brief  Lx_kit format string backend
  * \author Stefan Kalkowski
  * \author Sebastian Sumpf
+ * \author Christian Helmuth
  * \date   2021-03-17
  *
  * Greatly inspired by the former DDE Linux Lx_kit implementation.
@@ -127,6 +128,7 @@ class Lx_kit::Console
 	public:
 
 		void vprintf(const char *format, va_list list);
+		void print_string(const char *str);
 };
 
 #endif /* _LX_KIT__CONSOLE_H_ */

repos/dde_linux/src/lib/lx_emul/log.cc

@@ -1,6 +1,7 @@
 /*
  * \brief  Linux Kernel log messages
  * \author Stefan Kalkowski
+ * \author Christian Helmuth
  * \date   2021-03-22
  */
 
@@ -16,3 +17,6 @@
 
 extern "C" void lx_emul_vprintf(char const *fmt, va_list va) {
 	 Lx_kit::env().console.vprintf(fmt, va); }
+
+extern "C" void lx_emul_print_string(char const *str) {
+	 Lx_kit::env().console.print_string(str); }

repos/dde_linux/src/lib/lx_emul/shadow/kernel/printk/printk.c

@@ -1,6 +1,7 @@
 /*
  * \brief  Replaces kernel/printk/printk.c
  * \author Stefan Kalkowski
+ * \author Christian Helmuth
  * \date   2021-03-16
  */
 
@@ -12,22 +13,29 @@
  */
 
 #include <linux/printk.h>
+#include <linux/kernel.h>
 #include <lx_emul/log.h>
 #include <lx_emul/debug.h>
 
+
+static char print_string[2048];
+
 asmlinkage __visible int printk(const char * fmt,...)
 {
 	va_list args;
 	va_start(args, fmt);
-	lx_emul_vprintf(fmt, args);
+	vsnprintf(print_string, sizeof(print_string), fmt, args);
 	va_end(args);
+
+	lx_emul_print_string(print_string);
 	return 0;
 }
 
 
 asmlinkage int vprintk(const char * fmt, va_list args)
 {
-	lx_emul_vprintf(fmt, args);
+	vsnprintf(print_string, sizeof(print_string), fmt, args);
+	lx_emul_print_string(print_string);
 	return 0;
 }
 
@@ -36,7 +44,8 @@ asmlinkage int vprintk_emit(int facility, int level,
                             const struct dev_printk_info *dev_info,
                             const char * fmt, va_list args)
 {
-	lx_emul_vprintf(fmt, args);
+	vsnprintf(print_string, sizeof(print_string), fmt, args);
+	lx_emul_print_string(print_string);
 	return 0;
 }
 

repos/dde_linux/src/lib/lx_kit/console.cc

@@ -2,6 +2,7 @@
  * \brief  Lx_kit format string backend
  * \author Stefan Kalkowski
  * \author Sebastian Sumpf
+ * \author Christian Helmuth
  * \date   2021-03-17
  *
  * Greatly inspired by the former DDE Linux Lx_kit implementation.
@@ -208,6 +209,21 @@ void Lx_kit::Console::_out_string(const char *str)
 }
 
 
+void Lx_kit::Console::print_string(const char *str)
+{
+	if (!str) {
+		_out_string("<null string>");
+		return;
+	}
+
+	/* strip potential control characters for log level */
+	if (*str == 1)
+		str += 2;
+
+	_out_string(str);
+}
+
+
 void Lx_kit::Console::vprintf(const char *format, va_list list)
 {
 	while (*format) {