From: Sebastian Harl <sh@tokkee.org>
Date: Tue, 23 Dec 2014 17:16:13 +0000 (+0100)
Subject: proto: Added support for marshaling double-precision values.
X-Git-Tag: sysdb-0.7.0~100
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=7624ec9003444dbd76f03dfeda38167f3831fc48;p=sysdb.git

proto: Added support for marshaling double-precision values.

For this, determine the memory layout of doubles in 'configure' and then use
IEEE-754 big-endian encoding on the wire. For now, only little- and big-endian
IEEE-754 doubles are supported but that'll cover the vast majority of all
systems.
---

diff --git a/configure.ac b/configure.ac
index baf1137..59f4ee7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -341,6 +341,66 @@ fi
 AC_SUBST([PROFILING_CFLAGS])
 AC_SUBST([PROFILING_LDFLAGS])
 
+ieee754_layout="unknown"
+AC_MSG_CHECKING([the memory layout of double precision values])
+AC_COMPILE_IFELSE(
+		[AC_LANG_PROGRAM(
+			[[
+#include <string.h>
+#include <inttypes.h>
+			]],
+			[[
+double d = 3.141592653e130;
+char c[8];
+if (sizeof(d) != 8)
+	return 2;
+memcpy(&c, &d, 8);
+if (c[0] == '\x04' && c[1] == '\x10' && c[2] == '\x1E' && c[3] == '\x66' &&
+	c[4] == '\x40' && c[5] == '\xA9' && c[6] == '\x06' && c[7] == '\x5B')
+	return 0;
+else
+	return 1;
+			]]
+		)],
+		[ieee754_layout="little-endian"], [ieee754_layout="unknown"])
+if test "x$ieee754_layout" = "xunknown"; then
+	AC_COMPILE_IFELSE(
+			[AC_LANG_PROGRAM(
+				[[
+#include <string.h>
+#include <inttypes.h>
+				]],
+				[[
+double d = 3.141592653e130;
+char c[8];
+if (sizeof(d) != 8)
+	return 2;
+memcpy(&c, &d, 8);
+if (c[7] == '\x04' && c[6] == '\x10' && c[5] == '\x1E' && c[4] == '\x66' &&
+	c[3] == '\x40' && c[2] == '\xA9' && c[1] == '\x06' && c[0] == '\x5B')
+	return 0;
+else
+	return 1;
+				]]
+			)],
+			[ieee754_layout="big-endian"], [ieee754_layout="unknown"])
+fi
+AC_MSG_RESULT([IEEE-754 $ieee754_layout])
+
+AC_DEFINE([IEEE754_DOUBLE_LITTLE_ENDIAN], 1234,
+		[Identifier for IEEE-754 little-endian encoding of double precision values])
+AC_DEFINE([IEEE754_DOUBLE_BIG_ENDIAN], 4321,
+		[Identifier for IEEE-754 big-endian encoding of double precision values])
+if test "x$ieee754_layout" = "xlittle-endian"; then
+	AC_DEFINE([IEEE754_DOUBLE_BYTE_ORDER], 1234,
+			[Define to 1 if double precision values use IEEE-754 little-endian encoding])
+else if test "x$ieee754_layout" = "xbig-endian"; then
+	AC_DEFINE([IEEE754_DOUBLE_BYTE_ORDER], 4321,
+			[Define to 1 if double precision values use IEEE-754 little-endian encoding])
+else
+	AC_MSG_ERROR([Unknown memory layout of double precision values])
+fi; fi
+
 m4_divert_once([HELP_ENABLE], [
 Build dependencies:])
 
diff --git a/src/utils/proto.c b/src/utils/proto.c
index cb88887..af4215b 100644
--- a/src/utils/proto.c
+++ b/src/utils/proto.c
@@ -25,14 +25,19 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#if HAVE_CONFIG_H
+#	include "config.h"
+#endif
+
 #include "core/data.h"
 #include "core/time.h"
 #include "utils/error.h"
 #include "utils/proto.h"
 
-#include <arpa/inet.h>
+#include <assert.h>
 #include <errno.h>
 
+#include <arpa/inet.h>
 #include <limits.h>
 
 #include <string.h>
@@ -62,13 +67,18 @@ marshal_int(char *buf, size_t buf_len, int64_t v)
 } /* marshal_int */
 
 static ssize_t
-marshal_double(char __attribute__((unused)) *buf,
-		size_t __attribute__((unused)) buf_len,
-		double __attribute__((unused)) v)
+marshal_double(char *buf, size_t buf_len, double v)
 {
-	/* XXX: find a good network representation */
-	errno = ENOTSUP;
-	return -1;
+	uint64_t t = 0;
+	assert(sizeof(v) == sizeof(t));
+	memcpy(&t, &v, sizeof(v));
+#if IEEE754_DOUBLE_BYTE_ORDER != IEEE754_DOUBLE_BIG_ENDIAN
+	t = (((int64_t)ntohl((int32_t)t)) << 32)
+		+ ((int64_t)ntohl((int32_t)(t >> 32)));
+#endif
+	if (buf_len >= sizeof(t))
+		memcpy(buf, &t, sizeof(t));
+	return sizeof(t);
 } /* marshal_double */
 
 static ssize_t
diff --git a/t/unit/utils/proto_test.c b/t/unit/utils/proto_test.c
index d0516b3..1ec0615 100644
--- a/t/unit/utils/proto_test.c
+++ b/t/unit/utils/proto_test.c
@@ -49,6 +49,7 @@ START_TEST(test_marshal_data)
 
 	regex_t dummy_re;
 	int64_t int_values[] = { 47, 11, 23 };
+	double dec_values[] = { 47.11, .5 };
 	char *string_values[] = { "foo", "abcd" };
 
 	struct {
@@ -65,8 +66,8 @@ START_TEST(test_marshal_data)
 			12, INT_TYPE "\0\0\0\0\0\0\x12\x67",
 		},
 		{
-			{ SDB_TYPE_DECIMAL, { .integer = 4711 } },
-			-1, NULL, /* not supported yet */
+			{ SDB_TYPE_DECIMAL, { .decimal = 3.141592653e130 } },
+			12, DECIMAL_TYPE "\x5b\x6\xa9\x40\x66\x1e\x10\x4",
 		},
 		{
 			{ SDB_TYPE_STRING, { .string = "some string" } },
@@ -92,6 +93,12 @@ START_TEST(test_marshal_data)
 			32, INT_ARRAY "\0\0\0\x3" "\0\0\0\0\0\0\0\x2f"
 				"\0\0\0\0\0\0\0\xb" "\0\0\0\0\0\0\0\x17"
 		},
+		{
+			{ SDB_TYPE_DECIMAL | SDB_TYPE_ARRAY, { .array = {
+				2, dec_values } } },
+			24, DECIMAL_ARRAY "\0\0\0\x2" "\x40\x47\x8e\x14\x7a\xe1\x47\xae"
+				"\x3f\xe0\0\0\0\0\0\0"
+		},
 		{
 			{ SDB_TYPE_STRING | SDB_TYPE_ARRAY, { .array = {
 				2, string_values } } },