json: do something remotely reasonable when we see NaN/infinity

JSON doesn't have NaN/infinity/-infinity concepts in the spec.
Implementations vary what they do with it. JSON5 + Python simply
generate special words "NAN" and "Inifinity" from it. Others generate
"null" for it.

At this point we never actually want to output this, so let's be
conservative and generate RFC compliant JSON, i.e. convert to null.

One day should JSON5 actually become a thing we can revisit this, but in
that case we should implement things via a flag, and only optinally
process nan/infinity/-infinity.

This patch is extremely simple: whenever accepting a
nan/infinity/-infinity from outside it converts it to NULL. I.e. we
convert on input, not output.

diff --git a/src/shared/json.c b/src/shared/json.c
index 02829929602c6c23ef6844ab6bf654615c52f8e4..1bb95078cbe17a6b494e86fb2f84eff86b126eed 100644 (file)
--- a/src/shared/json.c
+++ b/src/shared/json.c
@@ -359,6 +359,12 @@ int json_variant_new_real(JsonVariant **ret, long double d) {
         }
         REENABLE_WARNING;
 
+        /* JSON doesn't know NaN, +Infinity or -Infinity. Let's silently convert to 'null'. */
+        if (isnan(d) || isinf(d)) {
+                *ret = JSON_VARIANT_MAGIC_NULL;
+                return 0;
+        }
+
         r = json_variant_new(&v, JSON_VARIANT_REAL, sizeof(d));
         if (r < 0)
                 return r;