Rewrote printf and friends to better support standard C semantics.

src/include/vsprintf.h

@@ -44,8 +44,40 @@
  *
  */
 
-extern int sprintf ( char *buf, const char *fmt, ... );
-extern int snprintf ( char *buf, size_t size, const char *fmt, ... );
-extern int printf ( const char *fmt, ... );
+#include <stdarg.h>
+
+#define PRINTF_NO_LENGTH ( ( size_t ) -1 )
+
+extern int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args );
+extern int vprintf ( const char *fmt, va_list args );
+
+extern int __attribute__ (( format ( printf, 3, 4 ) ))
+snprintf ( char *buf, size_t size, const char *fmt, ... );
+
+extern int __attribute__ (( format ( printf, 1, 2 ) ))
+printf ( const char *fmt, ... );
+
+/**
+ * Write a formatted string to a buffer
+ *
+ * @v buf		Buffer into which to write the string
+ * @v fmt		Format string
+ * @v ...		Arguments corresponding to the format string
+ * @ret len		Length of formatted string
+ */
+#define sprintf( buf, fmt, ... ) \
+	snprintf ( (buf), PRINTF_NO_LENGTH, (fmt), ## __VA_ARGS__ )
+
+/**
+ * Write a formatted string to a buffer
+ *
+ * @v buf		Buffer into which to write the string
+ * @v fmt		Format string
+ * @v args		Arguments corresponding to the format string
+ * @ret len		Length of formatted string
+ */
+static inline int vsprintf ( char *buf, const char *fmt, va_list args ) {
+	return vsnprintf ( buf, PRINTF_NO_LENGTH, fmt, args );
+}
 
 #endif /* VSPRINTF_H */