From: James Jones <jejones3141@gmail.com>
Date: Mon, 18 Jan 2021 01:09:33 +0000 (-0600)
Subject: Turn floating point comparison into memcmp() to silence compiler (#3849)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0da1ecc80d9047c5ca226561fe4168f281cb0105;p=thirdparty%2Ffreeradius-server.git

Turn floating point comparison into memcmp() to silence compiler (#3849)

In numerical methods, it is indeed a bad idea to compare
floating point numbers for equality, but this just tests
that fr_dbuff_in() and fr_dbuff_out(), barring lack of space
breaking fr_dbuff_in(), are inverses for float and double.
No floating point arithmetic involved, so it's reasonable to
compare the raw bits. We'll use memcmp() to (1) emphasize that
and (2) keep the compiler from warning about comparing floating
point values for equality.
---

diff --git a/src/lib/util/dbuff_tests.c b/src/lib/util/dbuff_tests.c
index 77510f47242..70fe95a5bc1 100644
--- a/src/lib/util/dbuff_tests.c
+++ b/src/lib/util/dbuff_tests.c
@@ -108,8 +108,10 @@ static void test_dbuff_net_encode(void)
 	int16_t		i16val = 0x1234;
 	int32_t		i32val = 0xd34d;
 	int64_t		i64val = 0x123456789abcdef0;
-	float		fval = 0;
-	double		dval = 0;
+	float		float_in = 1.0f + FLT_EPSILON;
+	float		float_out = 0;
+	double		double_in = 1.0 + DBL_EPSILON;
+	double		double_out = 0;
 
 	TEST_CASE("Generate wire format unsigned 16-bit value");
 	memset(buff, 0, sizeof(buff));
@@ -254,18 +256,18 @@ static void test_dbuff_net_encode(void)
 	TEST_CASE("Generate wire-format float");
 	memset(buff, 0, sizeof(buff));
 	fr_dbuff_init(&dbuff, buff, sizeof(buff));
-	TEST_CHECK(fr_dbuff_in(&dbuff, 1.0f + FLT_EPSILON) == 4);
+	TEST_CHECK(fr_dbuff_in(&dbuff, float_in) == 4);
 	fr_dbuff_set_to_start(&dbuff);
-	TEST_CHECK(fr_dbuff_out(&fval, &dbuff) == 4);
-	TEST_CHECK(fval == 1.0f + FLT_EPSILON);
+	TEST_CHECK(fr_dbuff_out(&float_out, &dbuff) == 4);
+	TEST_CHECK(memcmp(&float_out, &float_in, sizeof(float)) == 0);
 
 	TEST_CASE("Generate wire-format double");
 	memset(buff, 0, sizeof(buff));
 	fr_dbuff_init(&dbuff, buff, sizeof(buff));
-	TEST_CHECK(fr_dbuff_in(&dbuff, 1.0 + DBL_EPSILON) == 8);
+	TEST_CHECK(fr_dbuff_in(&dbuff, double_in) == 8);
 	fr_dbuff_set_to_start(&dbuff);
-	TEST_CHECK(fr_dbuff_out(&dval, &dbuff) == 8);
-	TEST_CHECK(dval == 1.0 + DBL_EPSILON);
+	TEST_CHECK(fr_dbuff_out(&double_out, &dbuff) == 8);
+	TEST_CHECK(memcmp(&double_out, &double_in, sizeof(double)) == 0);
 
 	TEST_CASE("Refuse to write to too-small space");
 	fr_dbuff_init(&dbuff, buff, sizeof(uint32_t));