From 6eadb6e939ffa7882ff5437033c11a9464d3385c Mon Sep 17 00:00:00 2001
From: Jacek Sieka <jacek@status.im>
Date: Sat, 19 Oct 2024 11:28:17 +0200
Subject: [PATCH] check length before converting to range type (#102)

The index type of an array is a `range` meaning that converting an
out-of-bounds value to it will raise a `Defect`.

This PR fixes the defect but does nothing for arrays which are not
"full" - probably, this should become an error.

* bump version
---
 json_serialization.nimble          | 2 +-
 json_serialization/reader_impl.nim | 8 ++++----
 tests/test_reader.nim              | 9 +++++++++
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/json_serialization.nimble b/json_serialization.nimble
index ef00b6b..48459a1 100644
--- a/json_serialization.nimble
+++ b/json_serialization.nimble
@@ -10,7 +10,7 @@
 mode = ScriptMode.Verbose
 
 packageName   = "json_serialization"
-version       = "0.2.8"
+version       = "0.2.9"
 author        = "Status Research & Development GmbH"
 description   = "Flexible JSON serialization not relying on run-time type information"
 license       = "Apache License 2.0"
diff --git a/json_serialization/reader_impl.nim b/json_serialization/reader_impl.nim
index b4cd801..f4574b3 100644
--- a/json_serialization/reader_impl.nim
+++ b/json_serialization/reader_impl.nim
@@ -312,11 +312,11 @@ proc readValue*[T](r: var JsonReader, value: var T)
   elif value is array:
     type IDX = typeof low(value)
     r.parseArray(idx):
-      let i = IDX(idx + low(value).int)
-      if i <= high(value):
-        # TODO: dont's ask. this makes the code compile
-        if false: value[i] = value[i]
+      if idx < value.len:
+        let i = IDX(idx + low(value).int)
         readValue(r, value[i])
+      else:
+        r.raiseUnexpectedValue("Too many items for " & $(typeof(value)))
 
   elif value is (object or tuple):
     mixin flavorUsesAutomaticObjectSerialization
diff --git a/tests/test_reader.nim b/tests/test_reader.nim
index 52f79ce..9c84170 100644
--- a/tests/test_reader.nim
+++ b/tests/test_reader.nim
@@ -211,3 +211,12 @@ suite "JsonReader basic test":
 
     var z = toReaderNullFields("""{"something":null,"bool":999,"string":100}""")
     check execReadObject(z) == 2
+
+  test "readValue of array":
+    var r = toReader "[false, true, false]"
+    check r.readValue(array[3, bool]) == [false, true, false]
+
+  test "readValue of array error":
+    var r = toReader "[false, true, false]"
+    expect JsonReaderError:
+      discard r.readValue(array[2, bool])