From 4a2310a3a09a4e9bde51b003c2a562a4a49cfabf Mon Sep 17 00:00:00 2001
From: Philipp Otterbein <potterbein@blockstream.com>
Date: Tue, 31 Dec 2024 17:52:06 +0100
Subject: [PATCH] toJSON: re-throw serialization exception

---
 src/libexpr/value-to-json.cc                             | 6 +++++-
 src/libexpr/value-to-json.hh                             | 3 +++
 tests/functional/lang/eval-fail-toJSON-non-utf-8.err.exp | 8 ++++++++
 tests/functional/lang/eval-fail-toJSON-non-utf-8.nix     | 1 +
 4 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 tests/functional/lang/eval-fail-toJSON-non-utf-8.err.exp
 create mode 100644 tests/functional/lang/eval-fail-toJSON-non-utf-8.nix

diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 8044fe347..5aa4fe4fd 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -108,7 +108,11 @@ json printValueAsJSON(EvalState & state, bool strict,
 void printValueAsJSON(EvalState & state, bool strict,
     Value & v, const PosIdx pos, std::ostream & str, NixStringContext & context, bool copyToStore)
 {
-    str << printValueAsJSON(state, strict, v, pos, context, copyToStore);
+    try {
+        str << printValueAsJSON(state, strict, v, pos, context, copyToStore);
+    } catch (nlohmann::json::exception & e) {
+        throw JSONSerializationError("JSON serialization error: %s", e.what());
+    }
 }
 
 json ExternalValueBase::printValueAsJSON(EvalState & state, bool strict,
diff --git a/src/libexpr/value-to-json.hh b/src/libexpr/value-to-json.hh
index 47ac90313..867c4e3a8 100644
--- a/src/libexpr/value-to-json.hh
+++ b/src/libexpr/value-to-json.hh
@@ -16,4 +16,7 @@ nlohmann::json printValueAsJSON(EvalState & state, bool strict,
 void printValueAsJSON(EvalState & state, bool strict,
     Value & v, const PosIdx pos, std::ostream & str, NixStringContext & context, bool copyToStore = true);
 
+
+MakeError(JSONSerializationError, Error);
+
 }
diff --git a/tests/functional/lang/eval-fail-toJSON-non-utf-8.err.exp b/tests/functional/lang/eval-fail-toJSON-non-utf-8.err.exp
new file mode 100644
index 000000000..129d58bcb
--- /dev/null
+++ b/tests/functional/lang/eval-fail-toJSON-non-utf-8.err.exp
@@ -0,0 +1,8 @@
+error:
+       … while calling the 'toJSON' builtin
+         at /pwd/lang/eval-fail-toJSON-non-utf-8.nix:1:1:
+            1| builtins.toJSON "_invalid UTF-8: ÿ_"
+             | ^
+            2|
+
+       error: JSON serialization error: [json.exception.type_error.316] invalid UTF-8 byte at index 16: 0xFF
diff --git a/tests/functional/lang/eval-fail-toJSON-non-utf-8.nix b/tests/functional/lang/eval-fail-toJSON-non-utf-8.nix
new file mode 100644
index 000000000..bd1f74de7
--- /dev/null
+++ b/tests/functional/lang/eval-fail-toJSON-non-utf-8.nix
@@ -0,0 +1 @@
+builtins.toJSON "_invalid UTF-8: ÿ_"