json: add spdk_json_write_named_double

Signed-off-by: Thanos Makatos <thanos.makatos@nutanix.com>
Suggested-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I2439cd739240fb2d95c5cdaccc557ba9a8f6501b
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/15490
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: John Levon <levon@movementarian.org>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

CHANGELOG.md

@@ -60,6 +60,11 @@ It can now be found inside `examples/bdev/bdevperf`.
 New API `spdk_fd_group_get_epoll_event` that returns the epoll(7) event that
 caused a function callback in file descriptor group to execute.
 
+### json
+
+Added API `spdk_json_write_double` and `spdk_json_write_named_double` to allow
+for writing and decoding of the the double data type.
+
 ## v22.09
 
 ### accel

include/spdk/json.h

@@ -188,6 +188,7 @@ int spdk_json_write_uint32(struct spdk_json_write_ctx *w, uint32_t val);
 int spdk_json_write_int64(struct spdk_json_write_ctx *w, int64_t val);
 int spdk_json_write_uint64(struct spdk_json_write_ctx *w, uint64_t val);
 int spdk_json_write_uint128(struct spdk_json_write_ctx *w, uint64_t low_val, uint64_t high_val);
+int spdk_json_write_double(struct spdk_json_write_ctx *w, double val);
 int spdk_json_write_string(struct spdk_json_write_ctx *w, const char *val);
 int spdk_json_write_string_raw(struct spdk_json_write_ctx *w, const char *val, size_t len);
 int spdk_json_write_bytearray(struct spdk_json_write_ctx *w, const void *val, size_t len);
@@ -243,6 +244,8 @@ int spdk_json_write_named_int64(struct spdk_json_write_ctx *w, const char *name,
 int spdk_json_write_named_uint64(struct spdk_json_write_ctx *w, const char *name, uint64_t val);
 int spdk_json_write_named_uint128(struct spdk_json_write_ctx *w, const char *name,
 				  uint64_t low_val, uint64_t high_val);
+int spdk_json_write_named_double(struct spdk_json_write_ctx *w, const char *name, double val);
+
 int spdk_json_write_named_string(struct spdk_json_write_ctx *w, const char *name, const char *val);
 int spdk_json_write_named_string_fmt(struct spdk_json_write_ctx *w, const char *name,
 				     const char *fmt, ...) __attribute__((__format__(__printf__, 3, 4)));

lib/json/Makefile

@@ -7,7 +7,7 @@ SPDK_ROOT_DIR := $(abspath $(CURDIR)/../..)
 include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 
 SO_VER := 4
-SO_MINOR := 0
+SO_MINOR := 1
 
 C_SRCS = json_parse.c json_util.c json_write.c
 LIBNAME = json

lib/json/json_write.c

@@ -309,6 +309,18 @@ spdk_json_write_named_uint128(struct spdk_json_write_ctx *w, const char *name,
 	return rc ? rc : spdk_json_write_uint128(w, low_val, high_val);
 }
 
+int
+spdk_json_write_double(struct spdk_json_write_ctx *w, double val)
+{
+	char buf[32];
+	int count;
+
+	if (begin_value(w)) { return fail(w); }
+	count = snprintf(buf, sizeof(buf), "%.20e", val);
+	if (count <= 0 || (size_t)count >= sizeof(buf)) { return fail(w); }
+	return emit(w, buf, count);
+}
+
 static void
 write_hex_2(void *dest, uint8_t val)
 {
@@ -724,6 +736,14 @@ spdk_json_write_named_uint64(struct spdk_json_write_ctx *w, const char *name, ui
 	return rc ? rc : spdk_json_write_uint64(w, val);
 }
 
+int
+spdk_json_write_named_double(struct spdk_json_write_ctx *w, const char *name, double val)
+{
+	int rc = spdk_json_write_name(w, name);
+
+	return rc ? rc : spdk_json_write_double(w, val);
+}
+
 int
 spdk_json_write_named_string(struct spdk_json_write_ctx *w, const char *name, const char *val)
 {

lib/json/spdk_json.map

@@ -37,6 +37,7 @@
 	spdk_json_write_int64;
 	spdk_json_write_uint64;
 	spdk_json_write_uint128;
+	spdk_json_write_double;
 	spdk_json_write_string;
 	spdk_json_write_string_raw;
 	spdk_json_write_string_utf16le;
@@ -62,6 +63,7 @@
 	spdk_json_write_named_int64;
 	spdk_json_write_named_uint64;
 	spdk_json_write_named_uint128;
+	spdk_json_write_named_double;
 	spdk_json_write_named_string;
 	spdk_json_write_named_string_fmt;
 	spdk_json_write_named_string_fmt_v;

test/unit/lib/json/json_write.c/json_write_ut.c

@@ -49,6 +49,10 @@ write_cb(void *cb_ctx, const void *data, size_t size)
 #define END_NOCMP() \
 	CU_ASSERT(spdk_json_write_end(w) == 0)
 
+#define END_SIZE_NOCMP(size) \
+	CU_ASSERT(spdk_json_write_end(w) == 0); \
+	CU_ASSERT(g_write_pos - g_buf == size)
+
 #define END_FAIL() \
 	CU_ASSERT(spdk_json_write_end(w) < 0)
 
@@ -94,6 +98,8 @@ write_cb(void *cb_ctx, const void *data, size_t size)
 #define VAL_NAME_UINT128(name, low, high) \
 	CU_ASSERT(spdk_json_write_named_uint128(w, name, low, high) == 0);
 
+#define VAL_DOUBLE(d) CU_ASSERT(spdk_json_write_double(w, d) == 0);
+
 #define VAL_ARRAY_BEGIN() CU_ASSERT(spdk_json_write_array_begin(w) == 0)
 #define VAL_ARRAY_END() CU_ASSERT(spdk_json_write_array_end(w) == 0)
 
@@ -521,6 +527,29 @@ test_write_number_uint64(void)
 	END("18446744073709551615");
 }
 
+static void
+test_write_number_double(void)
+{
+	struct spdk_json_write_ctx *w;
+
+	BEGIN();
+	VAL_DOUBLE(0);
+	END_SIZE("0.00000000000000000000e+00", 26);
+
+	BEGIN();
+	VAL_DOUBLE(1.2);
+	END_SIZE("1.19999999999999995559e+00", 26);
+
+
+	BEGIN();
+	VAL_DOUBLE(1234.5678);
+	END_SIZE("1.23456780000000003383e+03", 26);
+
+	BEGIN();
+	VAL_DOUBLE(-1234.5678);
+	END_SIZE("-1.23456780000000003383e+03", 27);
+}
+
 static void
 test_write_array(void)
 {
@@ -837,6 +866,7 @@ main(int argc, char **argv)
 	CU_ADD_TEST(suite, test_write_string_number_uint128);
 	CU_ADD_TEST(suite, test_write_number_int64);
 	CU_ADD_TEST(suite, test_write_number_uint64);
+	CU_ADD_TEST(suite, test_write_number_double);
 	CU_ADD_TEST(suite, test_write_array);
 	CU_ADD_TEST(suite, test_write_object);
 	CU_ADD_TEST(suite, test_write_nesting);