Secret printing in libraries and shell and silencing randcall.

userland/lib/libc/stdio/printf.c

@@ -31,6 +31,8 @@
 #include <stdarg.h>
 #include <unistd.h>
 #include <errno.h>
+#include <string.h>
+#include <kern/secret.h>
 
 /*
  * printf - C standard I/O function.
@@ -76,3 +78,36 @@ vprintf(const char *fmt, va_list ap)
 	}
 	return chars;
 }
+
+/* printf variant that is quiet during automated testing */
+int
+tprintf(const char *fmt, ...)
+{
+	int chars;
+	va_list ap;
+	
+	if (strcmp(KERNEL_SECRET, "") != 0) {
+		return 0;
+	}
+	
+	va_start(ap, fmt);
+	chars = vprintf(fmt, ap);
+	va_end(ap);
+
+	return chars;
+}
+
+/* printf variant that prepends the kernel secret */
+int
+printsf(const char *fmt, ...)
+{
+	int chars;
+	va_list ap;
+	
+	printf("%s: ", KERNEL_SECRET);	
+	va_start(ap, fmt);
+	chars = vprintf(fmt, ap);
+	va_end(ap);
+
+	return chars;
+}