printf-hook-builtin: Print NaN/Infinity floating point values as such

src/libstrongswan/tests/test_printf.c

@@ -16,6 +16,7 @@
 #include "test_suite.h"
 
 #include <errno.h>
+#include <math.h>
 
 static void verify(char *expected, char *format, ...)
 {
@@ -133,6 +134,19 @@ START_TEST(test_printf_float)
 	verify("-1.12", "%.2f", -1.1249);
 	verify("-1.124", "%.3f", -1.12351);
 	verify("-1.123", "%.3f", -1.12349);
+
+#ifdef NAN
+	verify("nan", "%.3f", NAN);
+	verify("  nan", "%5.3f", NAN);
+	verify("NAN", "%.3F", NAN);
+	verify("NAN  ", "%-5.3F", NAN);
+#endif
+#ifdef INFINITY
+	verify("inf", "%.3f", INFINITY);
+	verify("-inf", "%.4f", -INFINITY);
+	verify("INF", "%.3F", INFINITY);
+	verify("-INF", "%.4F", -INFINITY);
+#endif
 }
 END_TEST
 

src/libstrongswan/utils/printf_hook/printf_hook_builtin.c

@@ -923,9 +923,29 @@ int builtin_vsnprintf(char *buffer, size_t n, const char *format, va_list ap)
 							}
 							is_double:
 							{
+								double dval;
+
+								dval = va_arg(ap, double);
+								if (isinf(dval) == 1)
+								{
+									sarg = flags & FL_UPPER ? "INF" : "inf";
+									slen = strlen(sarg);
+									goto is_string;
+								}
+								if (isinf(dval) == -1)
+								{
+									sarg = flags & FL_UPPER ? "-INF" : "-inf";
+									slen = strlen(sarg);
+									goto is_string;
+								}
+								if (isnan(dval))
+								{
+									sarg = flags & FL_UPPER ? "NAN" : "nan";
+									slen = strlen(sarg);
+									goto is_string;
+								}
 								sz = format_double(q, (o < n) ? n - o : 0,
-												   va_arg(ap, double),
+												dval, flags, base, width, prec);
-												   flags, base, width, prec);
 								q += sz;
 								o += sz;
 								break;