spa: add locale independent spa_dtoa

And use this in spa_json_format_float() where we also avoid invalid
json floats.
Use json float format in some places where we serialize json floats.
Add a unit test.

See #2223

spa/include/spa/utils/json.h

@@ -258,14 +258,17 @@ static inline int spa_json_get_float(struct spa_json *iter, float *res)
 	return spa_json_parse_float(value, len, res);
 }
 
-static inline char *spa_json_format_double(char *str, int size, const double val)
+static inline char *spa_json_format_float(char *str, int size, float val)
 {
-	int i, l;
-	l = snprintf(str, size, "%f", val);
-	for (i = 0; i < l; i++)
-		if (str[i] == ',')
-			str[i] = '.';
-	return str;
+	if (SPA_UNLIKELY(!isnormal(val))) {
+		if (val == INFINITY)
+			val = FLT_MAX;
+		else if (val == -INFINITY)
+			val = FLT_MIN;
+		else
+			val = 0.0f;
+	}
+	return spa_dtoa(str, size, val);
 }
 
 /* int */

spa/include/spa/utils/string.h

@@ -354,6 +354,16 @@ static inline bool spa_atod(const char *str, double *val)
 	return true;
 }
 
+static inline char *spa_dtoa(char *str, size_t size, double val)
+{
+	int i, l;
+	l = spa_scnprintf(str, size, "%f", val);
+	for (i = 0; i < l; i++)
+		if (str[i] == ',')
+			str[i] = '.';
+	return str;
+}
+
 /**
  * \}
  */

spa/plugins/audioconvert/channelmix.c

@@ -695,7 +695,7 @@ static int parse_prop_params(struct impl *this, struct spa_pod *params)
 	while (true) {
 		const char *name;
 		struct spa_pod *pod;
-		char value[512];
+		char value[512], buf[128];
 
 		if (spa_pod_parser_get_string(&prs, &name) < 0)
 			break;
@@ -706,8 +706,9 @@ static int parse_prop_params(struct impl *this, struct spa_pod *params)
 		if (spa_pod_is_string(pod)) {
 			spa_pod_copy_string(pod, sizeof(value), value);
 		} else if (spa_pod_is_float(pod)) {
-			snprintf(value, sizeof(value), "%f",
-					SPA_POD_VALUE(struct spa_pod_float, pod));
+			snprintf(value, sizeof(value), "%s",
+					spa_json_format_float(buf, sizeof(buf),
+						SPA_POD_VALUE(struct spa_pod_float, pod)));
 		} else if (spa_pod_is_int(pod)) {
 			snprintf(value, sizeof(value), "%d",
 					SPA_POD_VALUE(struct spa_pod_int, pod));

src/modules/module-protocol-pulse/extensions/ext-stream-restore.c

@@ -235,7 +235,7 @@ static int do_extension_stream_restore_write(struct client *client, uint32_t com
 		FILE *f;
 		char *ptr;
 		size_t size;
-		char key[1024];
+		char key[1024], buf[128];
 
 		spa_zero(map);
 		spa_zero(vol);
@@ -260,7 +260,8 @@ static int do_extension_stream_restore_write(struct client *client, uint32_t com
 		if (vol.channels > 0) {
 			fprintf(f, ", \"volumes\": [");
 			for (i = 0; i < vol.channels; i++)
-				fprintf(f, "%s%f", (i == 0 ? " ":", "), vol.values[i]);
+				fprintf(f, "%s%s", (i == 0 ? " ":", "),
+						spa_json_format_float(buf, sizeof(buf), vol.values[i]));
 			fprintf(f, " ]");
 		}
 		if (map.channels > 0) {

src/tools/pw-dump.c

@@ -280,7 +280,7 @@ static void put_double(struct data *d, const char *key, double val)
 {
 	char buf[128];
 	put_fmt(d, key, "%s%s%s", NUMBER,
-			spa_json_format_double(buf, sizeof(buf), val), NORMAL);
+			spa_json_format_float(buf, sizeof(buf), val), NORMAL);
 }
 
 static void put_value(struct data *d, const char *key, const char *val)

test/test-spa-json.c

@@ -247,6 +247,7 @@ PWTEST(json_float)
 	};
 	float v;
 	unsigned i;
+	char buf1[128], buf2[128], *b1 = buf1, *b2 = buf2;
 
 	pwtest_int_eq(spa_json_parse_float("", 0, &v), 0);
 
@@ -260,6 +261,17 @@ PWTEST(json_float)
 		pwtest_int_gt(spa_json_parse_float(val[i].str, strlen(val[i].str), &v), 0);
 		pwtest_double_eq(v, val[i].val);
 	}
+	pwtest_ptr_eq(spa_json_format_float(buf1, sizeof(buf1), 0.0f), b1);
+	pwtest_str_eq(buf1, "0.000000");
+	pwtest_ptr_eq(spa_json_format_float(buf1, sizeof(buf1), NAN), b1);
+	pwtest_str_eq(buf1, "0.000000");
+	pwtest_ptr_eq(spa_json_format_float(buf1, sizeof(buf1), INFINITY), b1);
+	pwtest_ptr_eq(spa_json_format_float(buf2, sizeof(buf2), FLT_MAX), b2);
+	pwtest_str_eq(buf1, buf2);
+	pwtest_ptr_eq(spa_json_format_float(buf1, sizeof(buf1), -INFINITY), b1);
+	pwtest_ptr_eq(spa_json_format_float(buf2, sizeof(buf2), FLT_MIN), b2);
+	pwtest_str_eq(buf1, buf2);
+
 	return PWTEST_PASS;
 }